Vascular Protective Effects of Fruit Polyphenols

C H A P T E R

68 Vascular Protective Effects of Fruit Polyphenols Ve´ronique Habauzit, Dragan Milenkovic and Christine Morand Human Nutrition Unit, UMR 1019, INRA Clermont-Ferrand/Theix, St-Gene`s Champanelle, France

1. INTRODUCTION Many epidemiological studies have reported a protective role of a diet rich in fruits and vegetables (FV) against the development and progression of cardiovascular disease (CVD), one of the leading causes of morbidity and mortality worldwide. It has been projected that by increasing FV consumption to 600 g/day, the worldwide burden of ischemic heart disease and ischemic stroke could be reduced by 31 and 19%, respectively.1 However, the biological mechanisms whereby FV may exert their protective effects are unclear and are likely to be multiple. Functional aspects of FV, such as their low dietary glycemic load and energy supply, may play a pivotal role. Furthermore, the high nutritional density of FV, due to their content in fibers and many micronutrients including potassium, folates, antioxidant vitamins (C and E) and carotenoids, could be independently or jointly responsible for the apparent reduction in CVD risk.2 Due to the disappointing results of a number of large intervention studies performed with these antioxidant micronutrients, showing no reduction in overall mortality and even an increased cardiovascular risk,3,4 scientists were led to consider other potentially beneficial compounds present in FV. Thus, during the last 10 years, special attention has been paid to polyphenols, a group of phytochemicals which exhibit a large range of structures and functions. These phenolic compounds found in large amounts in all plant foods and beverages are considered as the most abundant antioxidants in our diet.5 Fruits are recognized as major contributors to the dietary polyphenol intakes in humans.6 Thus, fruits and fruit-derived products are considered as excellent sources of phenolic compounds that may individually, or in combination, benefit cardiovascular health. In

Polyphenols in Human Health and Disease. DOI: http://dx.doi.org/10.1016/B978-0-12-398456-2.00068-2

2009, Dauchet and collaborators7 underlined the greater evidence for a relationship between the consumption of fruits and the occurrence of CVD events in comparison with vegetables. This association between the frequency of fruit (and vegetable) consumption and CVD risk was shown to vary according to lifestyle. In particular, the lowest relative risks were found for smokers, suggesting that the consumption of fruits and their related phytochemicals could possibly prevent the increased CVD mortality induced by smoking throughout life.8 Furthermore, some prospective studies reported positive associations between the consumption of specific polyphenol-rich fruits such as apples, pears, grapefruit or strawberries and lower incidences of CVD.9 Research on the health-protective effects of fruit polyphenols has considerably evolved over the last few years. A large number of experimental studies (animal models, in vitro) examining the biological effects of various phenolic compounds found in fruits have been published. However, results from these studies are particularly difficult to transpose in humans, because most of them have been obtained in studies conducted with irrelevant nutritional and physiological conditions (in terms of doses and nature of the compounds). A growing number of randomized controlled trials have been performed to investigate the role of phenolic compounds in the prevention of CVD by assessing specific clinical outcomes. To date, most of these studies have been performed with polyphenol-rich beverages including tea, cocoa-based beverages or red wine while studies focusing on fruit phenolics are scarcer. In this chapter, we will consider the recent available literature on the effects of the consumption of the main categories of fruits (berries, grapes, citrus, pomes and drupes, pomegranate) and their specific associated

875

© 2014 Elsevier Inc. All rights reserved.

876

68. VASCULAR PROTECTIVE EFFECTS OF FRUIT POLYPHENOLS

polyphenols on well-identified intermediate markers of cardiovascular diseases (namely blood lipids, biomarkers related to oxidative stress and inflammation, blood pressure (BP), endothelial function, platelet function and arterial stiffness). When available, some insights into the biological mechanisms emanating from well-designed clinical, pre-clinical or in vitro studies will also be presented here.

2. FRUIT PHENOLIC COMPOUNDS: GENERALITIES 2.1 Classification and Chemical Structure Polyphenols are usually classified according to the number of phenol rings they contain: phenolic acids, flavonoids, stilbenes, lignans and tannins. Flavonoids (C6
C3
C6) which are distributed into six subclasses (flavanols, anthocyanidins, flavanones, flavones, flavonols and isoflavones) constitute the main group of bioactive compounds in fruits (Table 68.1). The flavanol subclass includes simple monomers (catechins), the oligomeric and polymeric proanthocyanidins that are also known as condensed tannins. In some plant foods, proanthocyanidins can occur as polymers of up to 50 units. When proanthocyanidins are exclusively constituted by (epi)catechin units, they are also called procyanidins.10 These procyanidins are abundant in fruits, particularly in apples, grapes and berries. Regarding the other flavonoid subclasses present in fruits (namely anthocyanidins, flavanones and flavonols), they rarely occur as free aglycones but mainly as glycosides.11 Phenolic acids constitute another group of phenolics found in fruits.12 These compounds are divided into two subgroups: hydroxycinnamic acids (C6
C3) and hydroxybenzoic acids (C6
C1) (Table 68.1). Hydroxycinnamic acids are largely present as chlorogenic acids (5-caffeoylquinic acid) in numerous fruits, particularly pomes and berries.10 Hydroxybenzoic acids (gallic, vanillic, ellagic and syringic acids) are also abundant in various fruits where they mostly occur as complex sugar esters, called hydrolysable tannins, like gallotannins. The ellagic acid-based ellagitannins, such as sanguiin H-6 and punicalagin (Table 68.1), are found in high amounts in a variety of fruits, including raspberries, strawberries, blackberries, pomegranate, persimmon and nuts.13

2.2 Polyphenol Content in Fruits The quantification of polyphenols in foods is essential to determine their dietary intake in populations and study their effects on health. However, this

information is not easily collected due to the variety of their chemical structures and the variability of their content in a given food. There is increasing demand for highly sensitive and selective analytical methods for the determination of polyphenols. Despite a great number of investigations, the separation and quantification of different polyphenolics remain difficult, especially the simultaneous determination of polyphenols in different groups.14 Historically, the main methodologies used to quantify the bioactive compounds in fruits are the colorimetric method of Folin-Ciocalteu that estimates the total polyphenols, the aluminum chloride colorimetric assay that quantifies the total flavonoids, and the pH differential method for total anthocyanins.12 Among the different methods available, reverse phase HPLC, with different detection systems, such as diode array detector, mass or tandem mass spectrometry, has become a dominating analytical tool for the separation as well as the qualitative and quantitative determination of polyphenols in fruits. The advances in the methods of extraction, separation and analysis of phenolic compounds in plant-food materials have been interestingly reviewed by Ignat and collaborators.15 Recently, several databases containing a large number of food items and their content in flavonoid compounds have become available. The former most significant databases on polyphenol content in foods were the USDA databases on monomeric flavonoids, proanthocyanidins (oligomeric and polymeric) and isoflavonoids (available at http://www.ars.usda.gov/ nutrientdata). More recently, a new database on polyphenol content in foods has been developed, the Phenol-Eplorer database (available at http://www. phenol-explorer.eu).16 This database allows retrieval of information on the content of 502 polyphenols (including glycosides, esters and aglycones) in 452 foods (fruits, vegetables, beverages, cereals and spices). Data extracted from these databases showed that catechins, flavonols, and proanthocyanidins are abundant in a multitude of fruits. In contrast, flavanones and flavones are restricted to specific categories of fruits. Black grapes are one of the richest fruit sources of catechins (4.9 and 4.7 mg/100 g FW, catechin (C) and epicatechin (EC), respectively) followed by apples (0.8 and 6.3 mg/100 g FW, C and EC, respectively). Catechins are also relatively abundant in stone fruits, such as blue plums (4.3 and 3.6 mg/100 g FW, C and EC, respectively) and apricots (2.6 and 3.0 mg/100 g FW, C and EC, respectively). The gallic acid esters of catechin: epigallocatechin (EGC), epigallocatechin gallate (EGCG), epicatechin gallate (ECG), and gallocatechin (GC), are abundant in tea but relatively uncommon in fruits; except berries, currants, and grapes, which only contain small amounts.

7. POLYPHENOLS AND VASCULAR HEALTH

TABLE 68.1 Fruit Phenolics: Classification, Sources, Contents and Chemical Structures of Main Compounds Classes

Sub-classes

Main fruit sources

Content (mg/100 g FW or mg/ 100 ml)

Chemical structures

Main compounds

Monomers

Catechin ( 1 ) Epicatechin ( 2 ) R 5 H

Flavonoids

Flavanols

Grapes (black, green)

60
100a

Black currant Blueberry Strawberry Plum Apple

100a

Polymers

Procyanidins (or condensed tannins)

(Continued)

TABLE 68.1 (Continued) Classes

Sub-classes

Main fruit sources

Flavanones

Orange Grapefruit Lemon

Content (mg/100 g FW or mg/ 100 ml) . 80 a

Chemical structures

Main compounds

Hesperetin: R1 5 OH; R2 5 OCH3 Naringenin: R1 5 H; R2 5 OH Eriodictyol: R1 5 R2 5 OH

Flavonoids

Flavonols

American cranberry Blueberry Lingonberry Black chokeberry

20
40a 80
100a

Quercetin: R1 5 R2 5 OH; R3 5 H Kaempferol: R2 5 OH; R1 5 R3 5 H Myricetin: R1 5 R2 5 R3 5 OH

Anthocyanidins Black grape Red raspberry Strawberry

60
80a

Pelargonidin: R1 5 R2 5 H Cyanidin: R1 5 OH; R2 5 H

Black chokeberry Black elderberry Blackberry Black currant Blueberry Sweet cherry

. 100a

Delphinidin: R1 5 R2 5 OH Petunidin: R1 5 OCH3; R2 5 OH Malvidin: R1 5 R2 5 OCH3

Hydroxycinnamic acids

Plum Cherry American cranberry

80
100a

Coumaric acid: R1 5 OH Caffeic acid: R1 5 R2 5 OH Ferulic acid: R1 5 OCH3, R2 5 OH

Black chokeberry Blueberry Prune . 100a

Phenolic acids

Chlorogenic acid (5-caffeoyl quinic acid)

Hydroxybenzoic acids

American cranberry Blackberry Pomegranate juice

40
60a

Red raspberry

. 100a

Protocatechuic acid: R1 5 R2 5 OH, R3 5 H Gallic acid: R1 5 R2 5 R3 5 OH Vanillic acid: R1 5 OCH3, R2 5 OH, R3 5 H

Sanguiin H-6

(Continued)

TABLE 68.1 (Continued) Classes

Sub-classes

Main fruit sources

Content (mg/100 g FW or mg/ 100 ml)

Hydrolysable tannins

Ellagitannins

Raspberry Strawberry

. 70 mg b 200 mgc

Chemical structures

Main compounds

Pomegranate juice

Punicalagin

a

Perez-Jimenez J, Neveu V, Vos F, Scalbert A. Systematic analysis of the content of 502 polyphenols in 452 foods and beverages: an application of the phenol-explorer database. J Agric Food Chem 2010;58(8):4959
69. Koponen JM, Happonen AM, Mattila PH, Torronen AR. Contents of anthocyanins and ellagitannins in selected foods consumed in Finland. J Agric Food Chem 2007;55(4):1612
9. c Gil MI, Tomas-Barberan FA, Hess-Pierce B, Holcroft DM, Kader AA. Antioxidant activity of pomegranate juice and its relationship with phenolic composition and processing. J Agric Food Chem 2000;48(10):4581
9. b

3. VASCULAR ACTION OF FRUIT PHENOLIC COMPOUNDS

Strawberries contain the most complex mixture of catechins, comprising C (75% of total catechins), ECG (18% of total catechins), EGC (5% of total catechins), and GC (3% of total catechins). Quercetin is the most common flavonol in fruits, elderberries (17.0 mg/100 g FW), lingonberries (12.6 mg/100 g FW), and cranberries (13.0 mg/100 g FW) being particularly rich sources. Berries and currants are also interesting sources of kaempferol and myricetin. For example, these two flavonol compounds account for 29 and 18%, respectively, of the total flavonol content in bilberries. Often termed the “citrus flavonoids,” flavanones are only found in citrus fruits. The main aglycones are naringenin (5,7,40 -trihydroxy flavanone) in grapefruit, hesperetin (40 -methoxy-30 ,5,7-trihydroxy flavanone) in orange and tangerine, and eriodictyol (5,7,30 ,40 -tetrahydroxy flavanone) in lemon. In citrus fruits and citrus-derived products, flavanones are generally glycosylated by a disaccharide at position 7 to give flavanone glycosides (naringin in grapefruit and hesperidin in oranges). In citrus fruits, the flavanone content varies depending on the part of fruit. In the edible parts of oranges (pulp), the flavanones content (hesperidin plus narirutin) ranges from 35 to 147 mg/100 g FW.17,18 In grapefruit, naringenin glycosides (naringin and narirutin) ranges from 44 to 106 mg/100 g FW in the edible fraction.16,19 The mean flavanone content in orange juice (hesperidin plus narirutin) has been estimated to range from 14 to 77 mg/100 mL.20 In another study, the content of naringenin glycosides in various brands of grapefruit juices was estimated to vary between 17 and 76 mg/100 mL.21 Anthocyanidins provide the characteristic red/blue colors of most fruits. Thus, berries are the main dietary source of anthocyanidins (66.8
947.5 mg/100 g FW). The commonly consumed berries include blackberries, black raspberries, blueberries, cranberries, red raspberries, and strawberries. Less commonly consumed berries include acai, black currant, chokeberries, and mulberries. Other fruits, such as red grapes, cherries, and plums are also sources of anthocyanidins, with contents ranging between 2 and 150 mg/100 g FW. Anthocyanidins are poorly distributed (,10 mg/100 g FW) in other fruits, such as peaches, nectarines, and some kinds of pears and apples. Besides anthocyanidins, berries are significant sources of phenolic acids. The best sources in total phenolic acids among berries are rowanberries (103 mg/100 g FW), chokeberries (96 mg/100 g FW), blueberries (85 mg/100 g FW), sweet rowanberries (75 mg/100 g FW), and saskatoon berries (59 mg/100 g FW). The concentrations of hydroxybenzoic acids in plants are low except for some fruits like berries (raspberries, strawberries, blackberries), currants (black-

881

and redcurrants) pomegranate, persimmon and nuts.13 In these fruits these phenolic acids mainly occur as ellagic acid-based ellagitannins, such as sanguiin H-6 and punicalagin. In contrast, the hydroxycinnamic acids are ubiquitous in plants and consequently in the human diet. As previously mentioned, they are particularly found as esters formed with acids such as quinic acid or tartaric acid. Among the various esters, the 5-caffeoylquinic acid, commonly called chlorogenic acid, is particularly abundant in fruits such as apples (62
385 mg/kg FW), pears (60
280 mg/kg FW) or berries (for example: 70 mg/kg FW in blackberries up to 2 g/kg FW in American blueberries).22 Ferulic acid is present in some specific fruits such as citrus fruits or bananas.23

2.3 Estimated Dietary Intakes A typical diet rich in fruits, vegetables and plant beverages has been estimated to provide more than 1 g of total polyphenols/day, with significant variations depending on the extent of consumption of drinks rich in polyphenols (tea, wine, coffee, fruit juices).24 In recent years, The Phenol-Explorer database has notably been used to determine the mean daily intake of polyphenols in a French cohort (SUVIMAX2, 4950 men and women, 50
65 years old) by analyzing the food frequency questionnaires collected over an 8-year period.6 The estimated total daily intake of polyphenols was about 1.2 g/day (40% of flavonoids, 60% of phenolic acids). The main food contributors to the polyphenols intake were non-alcoholic beverages and fruits. Similar observations have been recently reported in a Spanish population where the mean total polyphenol intake was estimated at 820 6 323 mg/day with 54% of flavonoids and 46% of phenolic acids.25 In cohorts of US health professionals, intake of total flavonoids was assessed using the USDA databases and food frequency questionnaires.26 The mean total flavonoid intakes in the studied cohorts ranged from 358 to 414 mg/day. Tea was the main source of total flavonoids followed by several fruits including apples, orange juice, and strawberries.

3. VASCULAR ACTION OF FRUIT PHENOLIC COMPOUNDS 3.1 Bioactive Compounds in Berries and Currants and Vascular Health The consumption of berry fruits and their benefits for cardiovascular health have become a subject of considerable interest in recent years. Berries are fruits

7. POLYPHENOLS AND VASCULAR HEALTH

882

68. VASCULAR PROTECTIVE EFFECTS OF FRUIT POLYPHENOLS

particularly rich in anthocyanins, responsible for their red/blue color. Several epidemiological studies reported specific associations between berries or berry polyphenols (mainly anthocyanins) and cardiovascular health. Data from the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD) showed a significantly lower risk of CVD-related deaths among 1950 men in the highest quartile of berry intake ( . 408 g/day) versus men with the lowest intake (,133 g/day) during a mean follow-up of 12.8 years.27 Post-menopausal women (n 5 34,489) participating in the Iowa Women’s Health Study, showed a significant reduction in CVD mortality associated with strawberry intake during a 16-year follow-up period. The data also reported that a mean anthocyanin intake of 0.2 mg/day was associated with a significantly reduced risk of CVD mortality in these postmenopausal women.9 Similarly, during a followup period of approximately 11 years, a decreasing trend in CVD was observed for female US health professionals enrolled in the Women’s Health Study (n 5 38,176) and consuming higher amounts of strawberries ($2 servings/week; p 5 0.06).28 Very recently, Cassidy et al.29 prospectively studied 93,600 young women from the Nurses’ Health Study II for up to 18 years and examined the relationship between intakes of flavonoid subclasses and the risk of myocardial infarction (MI). From this study it appears that individuals with a higher intake of anthocyanins had a significantly lower risk of MI than women with a low intake. The observed 32% reduction in risk was independent of established dietary/lifestyle CVD risk factors, including smoking, body mass index, and fruit and vegetable intake. The combined intake of the main consumed sources of anthocyanins (namely strawberries and blueberries) was also associated with a reduction in MI risk. Despite these interesting epidemiological data, consistent clinical evidence is still lacking essentially due to the limited number of the intervention trials assessing the effect of anthocyanin-rich foods consumption on clinically relevant end points. Several intervention studies have investigated the cardiovascular protective effects of various berries (acai berries, bilberries, boysenberries, blueberries, chokeberries, cranberries, lingonberries, raspberries, strawberries and wolfberries) and currants (blackcurrants) in healthy human subjects or in subjects with CVD risk factors. These studies were reviewed in 2010 by several authors.30,31 The most significant outcomes of these clinical studies show an increase in plasma or urinary antioxidant capacity in both fasting or postprandial status, a decrease in LDL oxidation and lipid peroxidation in both fasting or post-prandial status, a decrease in plasma glucose and total cholesterol (TC),

and an increase in HDL-cholesterol following berry intervention. The results from these studies suggest a positive impact of berry consumption in ameliorating traditional cardiovascular risk factors and in counteracting postprandial metabolic and oxidative stresses known to be associated with the development of atherosclerosis.32 In addition, bilberry and blackcurrant extracts, chokeberry juice, cranberry extracts, and freeze-dried strawberries were shown to have positive effects in subjects presenting diabetes mellitus (type 1 or type 2), dyslipidemia or metabolic syndrome.33
36 To date, limited evidence is available concerning a potential impact of the consumption of fresh berries or processed products derived from berries and their associated polyphenols on blood pressure (BP) levels. One study was conducted in middle-aged unmedicated subjects (n 5 72) with cardiovascular risk factors to investigate the hypotensive effect of the 8-week consumption of 160 g/day of a combination of berries providing 837 mg/day of polyphenols of which 60% were anthocyanins.37 The authors observed a significant decrease in systolic BP, the decrease mostly occurring in subjects with high baseline BP (2 7.3 mmHg for SBP in the highest tertile). The other relevant study reporting a significant effect of berries on BP was a parallel trial investigating the effect of a chokeberry flavonoid extract (Aronia melanocarpa E; 255 mg/day; about 25% of anthocyanins, 50% of monomeric and polymeric procyanidins and 9% of phenolic acids) or a placebo, consumed for a period of 6 weeks, in CAD patients.38 This study revealed a significant reduction in both systolic (211 mmHg) and diastolic BP (DBP, 27.2 mmHg). Increasing evidence indicates that alterations in the functional properties of the vascular endothelium are highly involved in the initiation, progression and clinical complications of atherosclerosis.39 Several intervention studies have suggested that the consumption of flavonoid-rich foods such as cocoa, tea, red wine and soya can improve endothelial function in patients with manifest CVD as well as in volunteers with or without cardiovascular risk factors.40,41 Zhu et al.42 have reported beneficial acute and long-term (12 weeks) effects of anthocyanin extracts on endothelial function as measured by flow-mediated dilation (FMD). Regarding a potential effect of berries on platelet aggregation, the available evidence comes from the study of Erlund and collaborators37 for which the combination of various berries was also associated with a significant inhibitory effect on platelet aggregation. However, a recent critical review43 has underlined that the chronic intake of polyphenols from berries (whole fruits or juices) may only induce a low inhibition of platelet aggregation under shear stress conditions.

7. POLYPHENOLS AND VASCULAR HEALTH

3. VASCULAR ACTION OF FRUIT PHENOLIC COMPOUNDS

In addition to their identified beneficial impact on blood lipids, oxidative stress, blood pressure and platelet aggregation, berries and their associated anthocyanins might also favorably modulate arterial stiffness, another important clinical marker of cardiovascular health. A recent cross-sectional study44 of 1898 women aged 18
75 years from the Twins UK registry that included direct measures of arterial stiffness (notably the measure of pulse wave velocity, considered as a gold standard marker for arterial stiffness) suggests that a higher intake of anthocyanins was inversely associated with lower arterial stiffness. The intakes of anthocyanins associated with these findings could be easily achievable in the habitual diet by daily incorporating 1
2 portions of either strawberries, raspberries, or blueberries. Furthermore, in a randomized controlled cross-over study with coronary patients, chronic consumption (4 weeks) of cranberry juice (54% juice, 835 mg total polyphenols, and 94 mg anthocyanins) was able to reduce carotid-femoral pulse wave velocity, a measure of central aortic stiffness.45 These promising results warrant further randomized trials on the effects of anthocyanidins from berries on metabolic and cardiovascular health.

3.2 Cardiovascular Health-Promoting Effects of Grape Polyphenols From the clue of the “French paradox,” polyphenols from various grape products, such as fruit, raisins, juice and wine attracted the attention of scientists to define their properties for human health. Grape is a phenol-rich plant, and these polyphenols are mainly distributed in the skin, stem, leaf and seed of grape, rather than in their juicy middle sections. The compounds present in significant amounts are oligomeric proanthocyanidins, anthocyanins, flavonols, flavanols, phenolic acids and resveratrol.46,47 Resveratrol, belonging to the class of stilbenes, is the most famous polyphenolic compound occurring in grapes and wine, particularly in red wine. Proanthocyanidins are the major phenolic compounds in grape seeds and the skin of grapes are responsible for its astringency.48 Anthocyanins are pigments responsible for the color of grape fruits, but the flesh does not contain any anthocyanins. There has been considerable interest in resveratrol and other polyphenols found in red wine in relation to human health. The biological activities of wine polyphenols will not be dealt with in this section; they have been discussed in the review by Rodrigo and coauthors.49 The antioxidant properties of phenolic compounds from grapes have been widely studied.47 However,

883

before outlining the corresponding literature, it is important to keep in mind that there is no evidence that the beneficial cardiovascular health effects associated with the consumption of polyphenol-rich foods are directly caused by improvements in antioxidant function (oxidative damage or antioxidant capacity).16 In a study by Zern et al.,50 grape polyphenols (administered through a lyophilized grape powder (LGP) rich in flavanols, anthocyanins, flavonols and resveratrol, 36 g of LGP/day for 4 weeks) were shown to reduce oxidative stress and lower plasma lipids in pre- and postmenopausal women. The authors proposed that such effects on blood lipids might be due to polyphenols’ ability to disrupt VLDL assembly and secretion, thus altering overall lipoprotein metabolism. Red grape juice has emerged as a beverage of similar properties to red wine with the advantage of being deprived of alcohol. The most documented effects associated with regular grape juice consumption in humans are reported to be cellular and tissue protection against oxidative damage and the inhibition of platelet activity and aggregation. In healthy subjects, a 2-week intake of Concord grape juice at 10 mL/kg/day was able to produce a similar antioxidant effect (improvement in serum antioxidant capacity and protection from LDL against oxidation) to an extent similar to that obtained with 400 IU alpha-tocopherol/ day.51 Freedman et al.52 demonstrated that a supplementation for 14 days with purple grape juice in healthy volunteers was not only effective in decreasing superoxide production but also in reducing platelet aggregation and increasing platelet-derived NO release in healthy volunteers. In another randomized crossover trial, drinking purple grape juice for one week (5
7.5 mL/kg/day) has been reported to reduce the whole blood platelet aggregation response to 1 mg/L of collagen by 77%.53 Some human intervention studies also support a benefit of grape beverage consumption on endothelial function. Two non-controlled chronic studies observed that consumption of purple grape juice for 2 or 4 weeks at doses of 4
8 mL/kg twice daily improved endothelial function, assessed by brachial artery FMD, in patients with coronary artery disease.54,55 Nevertheless, the scope of the results is strongly limited by the lack of control in these studies. Furthermore, there is a growing body of research showing that grape seed extract (GSE) may also have beneficial effects on the cardiovascular system. GSE, rich in proanthocyanidins is prepared from the seed of grapes and is typically commercialized as capsules or tablets. Thus, the nutritional relevance of the studies with GSE remains questionable. Recently, a systematic review and meta-analysis of randomized controlled trials have analyzed the relationship between a

7. POLYPHENOLS AND VASCULAR HEALTH

884

68. VASCULAR PROTECTIVE EFFECTS OF FRUIT POLYPHENOLS

supplementation with GSE and changes in different cardiovascular markers, including blood pressure, heart rate, lipid levels, and C-reactive protein (CRP) levels.56 Based on the literature selected for this metaanalysis, GSE appeared to significantly lower systolic BP (with a significant reduction of 21.54 mmHg; 95% confidence interval: 22.85 to 20.22, p 5 0.02) with no effect on blood lipids or CRP levels. Furthermore, the effects of a flavanol-rich GSE supplement (FRGSE) on platelet reactivity in a group of male smokers was assessed by Polagruto and collaborators.57 These authors observed that the acute administration of FRGSE significantly decreased ADP-stimulated platelet reactivity at 1, 2, and 6 hours following intake compared to baseline levels. Finally, whereas the health benefits of grapes and wine have been extensively studied, the potential cardiovascular protective effects related to polyphenols from dried grapes (raisins) have received comparatively little attention. However, the health benefits of raisins have been recently reviewed by Williamson and Carughi.58

3.3 Role of Citrus Fruit Flavonoids in Cardiovascular Prevention As previously reported, citrus fruits are the exclusive dietary sources of flavanones (mainly hesperidin and naringin). Several prospective studies have reported an inverse relationship between citrus fruit consumption and the risk of coronary events or cerebrovascular disease.59
62 In a recent epidemiological study involving 10,623 Japanese participants, a strong inverse association between citrus fruit consumption and CVD incidence was observed (hazard ratios for almost daily versus infrequent citrus fruit intake: 0.57, 95% CI 5 0.33
1.01, in men and 0.51, 95% CI 5 0.29
0.88, in women).63 In another study, grapefruit consumption has been associated with a reduced risk of death from coronary heart disease.9 However, few epidemiological studies have investigated the direct association between flavanones consumption and cardiovascular events.9,64,65 Some evidence for the role of citrus fruit flavonoids in cardiovascular protection is provided by several clinical trials assessing primary and secondary cardiovascular endpoints in healthy subjects or patients after the consumption of isolated flavanones or flavanonerich foods. First, citrus flavonoids have been proposed in the literature as potential blood-cholesterol-lowering agents.66 In particular, numerous pre-clinical animal studies support the lipid-lowering effect of flavanones.67,68 In humans, the effects of flavanones on the

blood lipid profile lack consistency. Consequently, further clinical intervention studies are necessary to clarify their impact on these traditional cardiovascular risk factors. In healthy middle-aged moderately overweight men, our research group found that TC, LDL cholesterol, and HDL cholesterol were not significantly different in groups consuming orange juice (500 mL/d providing 292 mg of hesperidin) or a control drink supplemented with pure hesperidin (equivalent dose), compared with the placebo group.69 In another trial enrolling healthy moderately hypercholesterolemic men and women, a 4-week supplementation with citrus flavonoids also failed to significantly affect blood lipids, even with doses as high as 800 mg of hesperidin or 500 mg of naringin.70 In contrast, a dose of 400 mg of naringin administered to hypercholesterolemic subjects for 8 weeks lowered the plasma TC by 14% and low-density lipoprotein cholesterol concentrations by 17%, while the plasma triglyceride and high-density lipoprotein cholesterol concentrations remained unaffected.71 In individuals with a metabolic syndrome, a 3-week supplementation with 500 mg of hesperidin also significantly reduced TC and apolipoprotein B (apo B) concentrations.72 With regard to an impact of citrus flavonoids on parameters related to oxidant/antioxidant status and inflammation, a few clinical data deserve attention. Jung et al.,71 who investigated the impact of an 8-week supplementation with 400 mg of naringin in hypercholesterolemic subjects, reported a significant increase in erythrocyte catalase and superoxide dismutase (SOD) activities.71 This study suggests that flavanones may improve endogenous antioxidant defense systems in dyslipidemic subjects, which may positively affect cardiovascular function. However, in healthy men with cardiovascular risk factors, no changes were observed in the plasma antioxidant capacity following hesperidin supplementation (292 mg) for 4 weeks.69 Several preclinical studies support the hypothesis of anti-inflammatory effects for citrus flavanones.67 In humans, the current clinical data are still insufficient to confirm such effects. However, in subjects with a metabolic syndrome, a 500 mg hesperidin supplementation was shown to reduce the plasma levels of inflammatory biomarkers: C-reactive protein (CRP) and serum amyloid A (SAA).72 In healthy, middleaged, moderately overweight men, despite no effect on circulating inflammatory markers,69 hesperidin intake (292 mg/day for 4 weeks) induced changes in gene expression in white blood cells towards an antiinflammatory profile.73 Endothelial dysfunction has been associated with the occurrence of hypertension. In individuals with stage I hypertension, a double-blind crossover trial evaluated the effect on blood pressure of the

7. POLYPHENOLS AND VASCULAR HEALTH

3. VASCULAR ACTION OF FRUIT PHENOLIC COMPOUNDS

consumption of a high-flavonoid citrus juice compared to a low-flavonoid citrus juice.74 Only consumption of the high-flavonoid citrus juice for 5 weeks resulted in a significant reduction in DBP (23.7 mmHg). In agreement with this, another randomized crossover intervention study carried out in overweight subjects, demonstrated a lower DBP after a 4-week supplementation with hesperidin (292 mg; equivalent to the amount found in 500 mL of orange juice) compared to the placebo group.69 The magnitude of the decrease of DBP after hesperidin consumption (24 mmHg) was similar to that observed after the consumption of 500 mL of orange juice. In addition, hesperidin intake significantly improved the postprandial microvascular endothelial reactivity compared to the placebo, and these changes were positively correlated with plasma hesperetin concentrations. Importantly, this study showed that the flavanone hesperidin might be causally linked to the vascular protective effects observed with orange juice. Recently, another controlled crossover trial involving individuals with metabolic syndrome has shown an improvement in flow-mediated dilation after a 3
week supplementation with 500 mg of hesperidin but without any effect on blood pressure.72 In this study, hesperidin supplementation also reduced sE-selectin concentrations, a soluble biomarker of endothelial dysfunction. Some studies conducted with polyphenol-rich citrus juices also revealed modifications of some intermediate biomarkers of cardiovascular risk.67 This further suggests that flavanones are one of the main bioactive compounds responsible for CVD prevention by citrus consumption. The recent study of Dow and co-authors underlined that other phenolic compounds present in specific citrus varieties such as red (blood) or pink grapefruit, particularly anthocyanidins, may positively affect blood pressure.75 Indeed, in this randomized controlled trial performed in overweight adults, the daily consumption of 1.5 fresh Rio-Red grapefruit for 6 weeks was associated with a significant reduction in systolic blood pressure (23.21 mmHg, p 5 0.03) compared with baseline values. By contrast, Giordano et al.,76 found that a 4-week consumption of blood orange juice (1 L/day; corresponding to an intake of B217.5 mg/L of total flavonoids and B53 mg/L of anthocyanins) resulted in measurable anthocyanin urinary levels, but did not affect markers related to cardiovascular risk such as blood pressure and platelet function. Finally, the effects of citrus flavonoids on intermediate risk factors for CVD in humans appear to be both interesting and promising, but clinical data are still scarce. Their impact on key targets of interest for the prevention of CV risk such as platelet function should be further investigated in humans.

885

3.4 Evidence for Cardiovascular Protective Effects of Pomes and Drupes Pomes (apples, pears and quince) and drupes (apricots, cherries, peaches and nectarines, plums) contain chlorogenic acids, anthocyanins, flavonols, catechins and proanthocyanidins. To date, the evidence for cardiovascular health-protective effects of these categories of fruits are quite limited. Some clinical trials have been performed with apples, cherries and plums, but most of them have examined the effect of whole fruits without considering the specific role of their phenolic components. 3.4.1 Apples The strong nutritional density of apples (rich in fibers, minerals and phytomicronutrients) suggests that these foods could present a health benefit for people who consume large quantities. Whole apples and apple-derived products contain a wide range of polyphenols including hydroxycinnamic acids, flavan3-ols/procyanidins, flavonols, anthocyanins in varieties with red peel, and phloridzin, a specific class of flavonoids.77 Several epidemiological studies have observed an inverse association between apples and appleflavonoid intake and coronary mortality. A group of Finnish women consuming .71 g of apple per day experienced a 43% reduction in coronary mortality compared to women who did not eat apples. In men, the risk reduction was 19% in the group consuming .54 g compared to no apple intake.78 These findings were consistent with prior data showing reduced coronary mortality in elderly Dutch men (65
84 years) who consumed apples (average 69 g/day) compared to men who had little or no apple intake.79 Recent clinical studies have emphasized the hypothesis that a relatively modest intake of apples can reduce the risk of cardiovascular diseases by modulating some biomarkers of risk; in particular, blood pressure and endothelial function. However, most of these published trials were conducted in small samples of heterogeneous populations and with poor control. Moreover, due to differences in study designs (apple varieties and baseline characteristics of study participants), it is difficult to compare the existing data and to determine the individual contribution of apple components (fibers, phenolic compounds or others) to the observed health effects.77 Several intervention studies have examined the effect of apple consumption (fresh fruit, apple juice, dried apples) on oxidative markers in humans (overall antioxidant capacity of plasma, antioxidant enzymes, oxidative damage). Globally, these studies have

7. POLYPHENOLS AND VASCULAR HEALTH

886

68. VASCULAR PROTECTIVE EFFECTS OF FRUIT POLYPHENOLS

suggested that regular apple consumption might reduce oxidative stress.80
84 A recent intervention cross-over study compared the effects of whole apples (550 g/day), apple pomace (22 g/day), and clear and cloudy apple juices (500 mL/day) on lipoproteins and blood pressure in a group of 23 healthy volunteers.85 The authors observed a discrepancy in results according to the polyphenol and pectin contents in products. Indeed, trends towards lower serum concentrations of total and LDL cholesterol were observed after a whole apple (6.7%), pomace (7.9%) and cloudy juice (2.2%) intake. On the other hand, TC and LDL-cholesterol concentrations increased by 6.9% with clear juice compared to whole apples and pomace. Polyphenols and pectin were the two potentially bioactive constituents responsible for the observed effects. However, the observations made with clear apple juice without water-soluble pectin and solid cell-wall-related fibers led authors to conclude that the fiber component was necessary for the cholesterol-lowering effect of apples. In a double-blind, randomized crossover trial, the impact of a 4-week regular consumption of a polyphenol-rich apple (providing 1.43 g of total polyphenols per day) was studied on both plasma lipids and endothelial function in hypercholesterolemic patients.86 Blood lipid concentrations as well as FMD did not differ between the group consuming polyphenol-rich apples and the control group supplemented with polyphenol-poor apples (providing 0.21 g total polyphenols/day). By contrast, a recent randomized controlled crossover study revealed that the acute intake of a high-flavonoid apple active mix (prepared by blending 120 g of apple flesh with 80 g of apple skins and providing 184 mg of quercetin and 180 mg of epicatechin) resulted in higher FMD, lower systolic blood pressure and lower pulse pressure.87 The impact of isolated polyphenols found abundantly in apples on cardiovascular endpoints was reviewed in 2010 by Weichselbaum and colleagues.88 Notably, four studies have reported positive effects of some polyphenols found in apples (such as quercetin, catechin, epicatechin and procyanidins) on one or more blood lipid parameters.50,89
91 The review also identified three studies demonstrating a beneficial effect of polyphenols found in apples on blood pressure.89,91,92 A few studies have reported that some phenolic compounds present in apples might exert anti-thrombotic effects, but the existing evidence is so far very limited.93
95 Most intervention studies available have not been performed with isolated polyphenols but rather with complex apple products or extracts containing nutrients that may potentially influence cardiovascular risk factors (e.g., dietary fibers). For this reason, these studies failed to specifically relate the observed health

effects to the polyphenolic fraction and were often inconclusive. This is why future well-controlled clinical trials using well-characterized apple products are clearly warranted to provide convincing findings on the role of apple polyphenols to prevent cardiovascular risk factors. 3.4.2 Cherries Cherry is a fruit belonging to the genus Prunus in the Rosaceae family, which contains over several hundred species distributed across northern temperate regions. The two most common species are Prunus avium L., know as “sweet cherry,” and Prunus cerasus L., known as “sour cherry or tart cherry.” The cherry fruit is considered to be a nutrient-dense food with a relatively low caloric content and a significant amount of not only dietary fiber but also important healthpromoting bioactive compounds including notably hydroxycinnamic acids, anthocyanins, flavonols (quercetin, kaempferol) and flavan-3-ols (catechin, epicatechin).96 Sour cherries tend to contain higher levels of total phenolics than sweet cherries. Much of the research suggesting cardio-protective effects of cherry polyphenols (mainly anthocyanins) lies in cell culture studies and animal models. In particular, antioxidant, anti-inflammatory and lipidlowering properties have been investigated in these experimental models.96,97 Although limited in number, clinical studies using polyphenol-rich cherry products have also suggested effectiveness in increasing antioxidant status and reducing inflammation in humans. In a randomized controlled cross-over trial, Traustadottir et al.98 investigated the effect of tart cherry juice supplementation (8 ounces twice daily for 14 days) on oxidative stress in healthy aged volunteers. Tart cherry juice supplementation decreased oxidative damage in response to reactive hyperemia, as revealed by significantly reduced F2-isoprostane levels in blood compared to placebo. In addition, urinary markers of oxidatively damaged DNA (measured as 8-OHdG) and RNA (measured as 8-oxo-G) were also significantly reduced. However, markers of oxidized proteins and lipids were unaffected by the intervention. Kelley et al.99 conducted a study examining the effects of consuming Bing sweet cherries (280 g/day for 28 days) on some markers of inflammation in healthy humans. Although the majority of the inflammatory markers evaluated were not affected by the intervention, circulating concentrations of NO, CRP, and RANTES significantly decreased by 18, 25, and 21%, respectively, after cherries were consumed for 28 days. Research evaluating the effect of cherries on blood lipid levels in humans is quite limited and the characteristics of the studied population are highly variable

7. POLYPHENOLS AND VASCULAR HEALTH

4. POTENTIAL MECHANISMS INVOLVED IN THE VASCULAR HEALTH BENEFITS OF POLYPHENOLS

between studies, making it difficult to directly compare study outcomes. Ataie-Jafari et al.100 conducted a pilot study to determine the effect of tart cherry juice on the blood lipid profiles of 19 women diagnosed with type-2 diabetes. For a period of 6 weeks, subjects consumed 40 g (or 3 tbsp) of concentrated tart cherry juice daily. Although no significant changes were observed in HDL or triglyceride levels following tart cherry juice supplementation, a significant reduction in TC and LDL cholesterol was observed (decrease from 213.9 to 193.2 mg/dL and 118.4 to 103.6 mg/dL, respectively). The effect of 100% tart cherry juice on lipid concentrations in blood of overweight/obese subjects was also examined in a randomized, placebocontrolled crossover pilot study by Martin et al.101 In contrast to the results reported by Ataie-Jafari et al.,100 a 4-week consumption of tart cherry juice did not induce changes in TC, LDL and HDL cholesterol concentrations in participants but a significant reduction in triglyceride levels was noted, which declined 14% from 147 6 55 to 127 6 45 mg/dL. Finally, in the previously cited study by Kelley et al.,99 the consumption of 280 g of Bing sweet cherries daily over a period of 28 days did not affect the plasma concentrations of total-, HDL-, LDL-, and VLDL cholesterol, triglycerides and subfractions of HDL, LDL, VLDL. This preliminary evidence suggests that the role of cherries and cherry bioactive phenolic compounds in protection against cardiovascular disease should be further explored in large-sample-size well-designed and controlled intervention clinical studies. 3.4.3 Plums Fresh plums and dried plums (also called prunes) are rich sources of polyphenols which mainly consist of chlorogenic acid, neochlorogenic acid, caffeic acid, coumaric acid, rutin102 and proanthocyanidin.103 In recent years, the health-protective activities of phenolics from dried plums have gained in interest. Total phenolic content and total antioxidant capacity of prunes were found to be higher than in other dry fruits including dates, figs and raisins.104 The consumption of dried plums and their associated fibers but also phenolic compounds may exert positive effects on lipid metabolism. Daily consumption of prunes (100 g, that is to say an equivalent of 12 prunes) for 8 weeks was shown to decrease total and LDL cholesterol in mild hypercholesterolemic men.105 More recently, the effect of a 1-year consumption of dried plums in reducing cardiovascular disease risk factors was evaluated in postmenopausal women.84 After a 3-month period of intervention, serum levels of C-reactive protein were lowered, whereas no significant changes in lipid profile or atherogenic risk ratios were observed. To date, clinical data of high quality

887

are too insufficient to reach a conclusion on the possible beneficial effect of plum polyphenols on cardiovascular health.

3.5 Vascular Health Benefits of Pomegranate Fruits Pomegranate, a fruit native to the Middle East, has gained widespread popularity as a source of bioactive compounds, mainly ellagitanins, gallotannins, ellagic acid as well as flavonoids such as anthocyanins. The health effects of the whole fruit, as well as its juices and extracts, have been studied in relation to a variety of chronic diseases. Most research on the vascular effects of pomegranate has been carried out with pomegranate juice in several pre-clinical models.106,107 However, promising results on vascular benefits of pomegranate juice (B50 ml/day for periods ranging from 8 weeks to 3 years) also emanate from human clinical trials. These studies reported a reduction of systolic BP (5 and 21%) in hypertensive patients and patients with carotid artery stenosis,108,109 a lower common carotid artery intima-media thickness (IMT) in patients with carotid artery stenosis109 and an improved lipid profile in diabetic patients.110,111 All these clinical studies were conducted in patients from Middle Eastern countries. Only a few studies have enrolled Western populations of patients112 or healthy subjects.113 The only randomized, controlled crossover trial performed in healthy young men showed that the acute consumption of a drink containing ellagitannin-rich pomegranate extract did not decrease postprandial plasma triglyceride concentrations, but suppressed the postprandial increase in systolic BP following a high-fat meal. Globally the role of plant foods, specifically fruits rich in complex and simple phenolic compounds, in postprandial metabolic management is a question for which the discussion is emerging.114

4. POTENTIAL MECHANISMS INVOLVED IN THE VASCULAR HEALTH BENEFITS OF POLYPHENOLS Understanding of the mechanisms behind the health effects of polyphenols will allow nutritionists to identify the fruits (and vegetables) and the bioactive compounds responsible for those effects, and finally define the best health-promoting diets.115 To understand and investigate the possible mechanisms of action of polyphenols, first we have to consider their bioavailability,

7. POLYPHENOLS AND VASCULAR HEALTH

888

68. VASCULAR PROTECTIVE EFFECTS OF FRUIT POLYPHENOLS

which is one of the main determinants of their effectiveness in vivo. Whatever the food source, only a small proportion of the polyphenols ingested is absorbed, and the rate and extent of absorption varies greatly depending on the structure of the molecules.116 The peak of absorption of polyphenols is generally reached between 1 and 6 hours after consumption, with plasma concentrations ranging between 0.1 and 7 µM according to the compounds.116 In addition, their half-lives in human plasma vary depending on the molecules, but generally do not exceed more than a few hours. This implies that a repeated and regular consumption of plant foods is required to sustain plasma levels of polyphenols. Otherwise, given the low plasma levels of polyphenols, compared with those of other endogenous (GSH, uric acid) or exogenous (vitamin E, C) antioxidants, it is very unlikely that polyphenols may act as free radical scavengers in the body. That’s why recent research has shifted focus from antioxidant effects to other aspects of bioactivity of phenolic compounds such as effects on signal transduction and on different enzyme systems as mediators of their antioxidant and anti-inflammatory properties.117,118 Thus, polyphenols are perceived as agents that may stimulate the antioxidant defense systems in the body. First, some flavonoids have been shown to act as modulators of intracellular signaling pathways such as Nrf2, involved in the transcriptional control of antioxidant enzymes (NADPH quinone oxyreductase-1, heme oxygenase-1) in vascular cells.119 Second, numerous flavonoids (including several flavanols monomers, procyanidins, flavonols and some anthocyanidins) have been shown to inhibit expression of pro-oxidant (NADPH oxidase: NOX) and pro-inflammatory (cyclooxygenase and lipooxygenase) enzymes, which are responsible for the production of superoxide anion production, prostanoids and leukotrienes, respectively.120
123 There is also in vitro evidence that some flavanols increase the activity of eNOS, the enzyme responsible for the endothelial production of nitric oxide (NO), an important vasoactive compound.124,125 In addition, flavanols have been shown to inhibit arginase, leading to an increased availability of arginine, the substrate of eNOS and precursor of NO.122 The combination of the effects of flavonoids on different enzyme activities that control the bioavailability and the bioactivity of NO could play a crucial role in the vascular protective effects of dietary polyphenols regarding both endothelial function and blood pressure.126 Besides, this hypothesis is supported by several acute intervention studies conducted with flavanol-rich sources, which showed that the improvement of endothelial function was consistent with the kinetics of absorption of flavanols and also related to an increased bioavailability of NO.127,128

Several polyphenols have also been reported to reduce pro-inflammatory mediators like cytokines, chemokines or adhesion molecules.129,130 Modulation of the cascade of molecular events leading to the overexpression of those mediators include inhibition of transcription factors such as nuclear factor kappa B, activator protein 1, signal transducers and activators of transcription, CCAAT/enhancer binding protein and others. Anti-inflammatory effects mediated through regulation of such signal cascades in various cellular targets (macrophages, lymphocytes, epithelial cells, endothelium) may contribute to preventive effects against endothelial dysfunction and atherosclerosis development.131 In addition, several catechins may also activate the enzyme AMP-activated protein kinase (AMPK), which plays a central role in the regulation of glucose and lipid metabolism. When activated, AMPK increases cellular energy availability by inhibiting anabolic pathways (e.g., synthesis of glucose and lipids) and stimulating catabolic pathways (e.g., glucose and fat oxidation).132 Actually, some hypotheses are emerging to propose polyphenols as relevant candidates to play a role in health prevention through postprandial metabolic management.114 By interacting with the gut metabolism, some dietary polyphenols could be able to attenuate excessive post-prandial glucose or blood lipids and lipoproteins variations that are recognized as major risk factors for developing metabolic syndrome and related pathologies such as diabetes and CVD.133
135 Looking at the role of dietary polyphenols in transcriptional gene regulation is particularly relevant to identify new molecular targets and related cell function that could underlie the observed cardiovascular health effect in humans. Many in vitro studies have demonstrated the ability of polyphenols to modulate the expression of genes related to cardiovascular diseases.136,137 However, the impact of these studies is limited because only a few target genes have been examined and, especially, because these experimental studies have not considered the bioavailability and metabolism of polyphenols and have used high concentrations and/or native forms not present in the body.138 Recently, using a transcriptomic approach, our group provided new insights into the mechanisms underlying the effects of dietary polyphenols in vascular protection. In animal models of atherosclerosis, the atheroprotective effects induced by nutritional supplementations with several fruit phenolics (catechin, anthocyanins or naringin) were associated with changes in the expression of genes related to inflammation and atherogenesis. Interestingly, most of these identified regulated genes in aorta were involved in processes that control the initial steps of atherosclerosis development.139
141

7. POLYPHENOLS AND VASCULAR HEALTH

REFERENCES

5. CONCLUSIONS The scientific community has become increasingly interested in the potential health effects of fruit polyphenols over the last 10 years. Among fruits, berries, grapes, citrus, apples and pomegranate are those that have received the highest attention in research. The lack of precise data on the composition in polyphenols in tropical fruits (such as mango, banana, pineapple, papaya, and kiwi) represents a major limitation in the promotion of studies investigating the healthpreventive role of polyphenols from these sources. Generally, the extraction, isolation, identification and quantification of polyphenols in fruits still present a challenge. Therefore, the development of new methodologies is essential for a better understanding of this class of phytochemicals. In addition, the establishment and consolidation of databases on polyphenol contents in food sources are of great importance to more accurately assess the levels of intake of specific compounds. Similarly, the recent development of Food Metabolome should enable significant advances in the methods of assessing exposure to plant phytochemicals and their metabolites.142 Together these new tools will likely refine the association between polyphenol intake and risk of disease in population studies. The absorption mechanism of phenolic compounds all along the digestive tract is still not completely wellestablished. Further investigations are necessary to better understand the bioaccessibility/bioavailability of polyphenols, focusing on the action of colonic microbiota on the metabolism and bioavailability of several polyphenols (particularly polymeric forms), and the effect of dietary fiber on polyphenol absorption. Furthermore, it is important to investigate the biological properties of conjugated polyphenols and active metabolites in experimental conditions as close as possible to the physiology. Although limited, current evidence from epidemiological studies and randomized controlled trials (RCTs) together with experimental data on vascular bioactivity suggests that fruits rich in anthocyanins, flavonols and procyanindins (such as berries, grapes and pomegranate) are effective in reducing CVD risk, particularly with respect to anti-hypertensive effects, increasing endothelial-dependent vasodilation and inhibition of platelet aggregation. Citrus fruits (rich in flavanones) and apples (rich in hydroxycinnamic acids and flavan-3-ols/procyanidins) were reported to have a moderate impact on blood pressure, endothelial and platelet functions and to exhibit hypolipidemic effects, especially in subjects presenting hyperlipidemia or other CVD risk factors. Overall, it appears that there are great inconsistencies in the findings from clinical studies examining the

889

impact of polyphenol-rich fruits on cardiovascular endpoints. To date, the interpretation of intervention studies on plant-derived food products is particularly complex due to a weakness in their design. Most often the composition in polyphenols of food products used in dietary interventions is not adequately assessed or reported and controls are lacking. In the future, the use of well-characterized and standardized foods/test materials (with regard to polyphenol content and profile), as well as appropriate controls (elaborated on the basis of the complete characterization in macro- and micronutrients of the fruit of interest), would enable significant advancement. Another key issue in this context is the lack of harmonization in the choice of standard evaluation criteria that does not allow comparisons between studies. Efforts should be made in the future to focus studies on markers recognized as “gold standards” to assess cardiovascular and metabolic endpoints. In addition, interventions should explore the dose
response effects of polyphenols of vascular endpoints143 and the potential synergistic actions of polyphenols with other plant-food nutrients should be investigated. We can reasonably assume that information emanating from such future studies would allow high-quality data comparisons and meta-analyses, and that they could represent significant support for the establishment of a rigorous causality chain. Thus, the potential impact of fruit phenolics on public health could be more comprehensively evaluated. To conclude, a number of epidemiological and clinical data indicate that some fruits rich in polyphenols may be beneficial to maintain cardiovascular health. However, the direct contribution of polyphenols in the observed effects is more or less convincing because very few clinical studies have been designed to establish the proper role of polyphenols in the effects associated with the consumption of these fruits. In the future, long-term well-controlled intervention studies with purified molecules are required to determine to what extent there is a causal link between a specific polyphenol compound from fruits and a lower risk of cardiovascular disease.

References 1. Lock K, Pomerleau J, Causer L, Altmann DR, McKee M. The global burden of disease attributable to low consumption of fruit and vegetables: implications for the global strategy on diet. Bull World Health Organ 2005;83(2):100
8. 2. Bazzano LA, Serdula MK, Liu S. Dietary intake of fruits and vegetables and risk of cardiovascular disease. Curr Atheroscler Rep 2003;5(6):492
9. 3. Vivekananthan DP, Penn MS, Sapp SK, Hsu A, Topol EJ. Use of antioxidant vitamins for the prevention of cardiovascular disease: meta-analysis of randomised trials. Lancet 2003;361(9374): 2017
23.

7. POLYPHENOLS AND VASCULAR HEALTH

890

68. VASCULAR PROTECTIVE EFFECTS OF FRUIT POLYPHENOLS

4. Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and metaanalysis. JAMA 2007;297(8):842
57. 5. Scalbert A, Johnson IT, Saltmarsh M. Polyphenols: antioxidants and beyond. Am J Clin Nutr 2005;81(1 Suppl):215S
7S. 6. Perez-Jimenez J, Fezeu L, Touvier M, Arnault N, Manach C, Hercberg S, et al. Dietary intake of 337 polyphenols in French adults. Am J Clin Nutr 2011;93(6):1220
8. 7. Dauchet L, Amouyel P, Dallongeville J. Fruits, vegetables and coronary heart disease. Nat Rev Cardiol 2009;6(9):599
608. 8. Dauchet L, Montaye M, Ruidavets JB, Arveiler D, Kee F, Bingham A, et al. Association between the frequency of fruit and vegetable consumption and cardiovascular disease in male smokers and non-smokers. Eur J Clin Nutr 2010;64(6):578
86. 9. Mink PJ, Scrafford CG, Barraj LM, Harnack L, Hong CP, Nettleton JA, et al. Flavonoid intake and cardiovascular disease mortality: a prospective study in postmenopausal women. Am J Clin Nutr 2007;85(3):895
909. 10. Manach C, Scalbert A, Morand C, Remesy C, Jimenez L. Polyphenols: food sources and bioavailability. Am J Clin Nutr 2004;79(5):727
47. 11. Clifford MN, Brown JE. Dietary flavonoids and health
broadening the perspective. In: Andersen OM, Markham KR, editors. Flavonoids: chemistry, biochemistry and applications. Boca Raton: CRC Press; 2006. 12. Haminiuk CWI, Maciel GM, Plata-Oviedo MSV, Peralta RM. Phenolic compounds in fruits
an overview. Int J Food Sci & Technol 2012;47(10):2023
44. 13. Del Rio D, Rodriguez-Mateos A, Spencer JP, Tognolini M, Borges G, Crozier A. Dietary (poly)phenolics in human health: structures, bioavailability, and evidence of protective effects against chronic diseases. Antioxid Redox Signal 2013;18(14): 1818
92. 14. Tsao R, Yang R. Optimization of a new mobile phase to know the complex and real polyphenolic composition: towards a total phenolic index using high-performance liquid chromatography. J Chromatogr A 2003;1018(1):29
40. 15. Ignat I, Volf I, Popa VI. A critical review of methods for characterisation of polyphenolic compounds in fruits and vegetables. Food Chem 2011;126(4):1821
35. 16. Neveu V, Perez-Jimenez J, Vos F, Crespy V, du Chaffaut L, Mennen L, et al. Phenol-Explorer: an online comprehensive database on polyphenol contents in foods. Database (Oxford) 2010;2010 bap024. 17. Nogata Y, Sakamoto K, Shiratsuchi H, Ishii T, Yano M, Ohta H. Flavonoid composition of fruit tissues of citrus species. Biosci Biotechnol Biochem 2006;70(1):178
92. 18. Peterson JJ, Dwyer JT, Beecher GR, Bhagwat SA, Gebhardt SE, Haytowitz DB, et al. Flavanones in oranges, tangerines (mandarins), tangors, and tangelos: a compilation and review of the data from the analytical literature. J Food Comp Anal 2006;19:S66
73. 19. Peterson JJ, Beecher GR, Bhagwat SA, Dwyer JT, Gebhardt SE, Haytowitz DB, et al. Flavanones in grapefruit, lemons, and limes: A compilation and review of the data from the analytical literature. J Food Comp Anal 2006;19:S74
80. 20. Toma´s-Barbera´n FA, Clifford MN. Flavanones, chalcones and dihydrochalcones
nature, occurrence and dietary burden. J Sci Food Agric 2000;80(7):1073
80. 21. Ross SA, Ziska DS, Zhao K, ElSohly MA. Variance of common flavonoids by brand of grapefruit juice. Fitoterapia 2000;71 (2):154
61. 22. El-Seedi HR, El-Said AM, Khalifa SA, Goransson U, Bohlin L, Borg-Karlson AK, et al. Biosynthesis, natural sources, dietary intake, pharmacokinetic properties, and biological activities of hydroxycinnamic acids. J Agric Food Chem 2012;60(44):10877
95.

23. Zhao Z, Moghadasian M. Chemistry, natural sources, dietary intake and pharmacokinetic properties of ferulic acid: A review. Food Chem 2008;109(4):691
702. 24. Ovaskainen ML, Torronen R, Koponen JM, Sinkko H, Hellstrom J, Reinivuo H, et al. Dietary intake and major food sources of polyphenols in Finnish adults. J Nutr 2008;138(3):562
6. 25. Tresserra-Rimbau A, Medina-Remon A, Perez-Jimenez J, Martinez-Gonzalez MA, Covas MI, Corella D, et al. Dietary intake and major food sources of polyphenols in a Spanish population at high cardiovascular risk: The PREDIMED study. Nutr Metab Cardiovasc Dis 2013. [Epub ahead of print]. 26. Cassidy A, O’Reilly EJ, Kay C, Sampson L, Franz M, Forman JP, et al. Habitual intake of flavonoid subclasses and incident hypertension in adults. Am J Clin Nutr 2011;93(2):338
47. 27. Rissanen TH, Voutilainen S, Virtanen JK, Venho B, Vanharanta M, Mursu J, et al. Low intake of fruits, berries and vegetables is associated with excess mortality in men: the Kuopio Ischaemic Heart Disease Risk Factor (KIHD) Study. J Nutr 2003;133(1): 199
204. 28. Sesso HD, Gaziano JM, Jenkins DJ, Buring JE. Strawberry intake, lipids, C-reactive protein, and the risk of cardiovascular disease in women. J Am Coll Nutr 2007;26(4):303
10. 29. Cassidy A, Mukamal KJ, Liu L, Franz M, Eliassen AH, Rimm EB. High anthocyanin intake is associated with a reduced risk of myocardial infarction in young and middle-aged women. Circulation 2013;127(2):188
96. 30. Basu A, Rhone M, Lyons TJ. Berries: emerging impact on cardiovascular health. Nutr Rev 2010;68(3):168
77. 31. Ros E, Tapsell LC, Sabate J. Nuts and berries for heart health. Curr Atheroscler Rep 2010;12(6):397
406. 32. O’Keefe JH, Gheewala NM, O’Keefe JO. Dietary strategies for improving post-prandial glucose, lipids, inflammation, and cardiovascular health. J Am Coll Cardiol 2008;51(3):249
55. 33. Simeonov SB, Botushanov NP, Karahanian EB, Pavlova MB, Husianitis HK, Troev DM. Effects of Aronia melanocarpa juice as part of the dietary regimen in patients with diabetes mellitus. Folia Med (Plovdiv) 2002;44(3):20
3. 34. Lee IT, Chan YC, Lin CW, Lee WJ, Sheu WH. Effect of cranberry extracts on lipid profiles in subjects with Type 2 diabetes. Diabet Med 2008;25(12):1473
7. 35. Qin Y, Xia M, Ma J, Hao Y, Liu J, Mou H, et al. Anthocyanin supplementation improves serum LDL- and HDL-cholesterol concentrations associated with the inhibition of cholesteryl ester transfer protein in dyslipidemic subjects. Am J Clin Nutr 2009;90 (3):485
92. 36. Basu A, Wilkinson M, Penugonda K, Simmons B, Betts NM, Lyons TJ. Freeze-dried strawberry powder improves lipid profile and lipid peroxidation in women with metabolic syndrome: baseline and post intervention effects. Nutr J 2009;8:43. 37. Erlund I, Koli R, Alfthan G, Marniemi J, Puukka P, Mustonen P, et al. Favorable effects of berry consumption on platelet function, blood pressure, and HDL cholesterol. Am J Clin Nutr 2008;87(2):323
31. 38. Naruszewicz M, Laniewska I, Millo B, Dluzniewski M. Combination therapy of statin with flavonoids rich extract from chokeberry fruits enhanced reduction in cardiovascular risk markers in patients after myocardial infraction (MI). Atherosclerosis 2007;194(2):e179
184. 39. Dharmashankar K, Widlansky ME. Vascular endothelial function and hypertension: insights and directions. Curr Hypertens Rep 2010;12(6):448
55. 40. Vita JA. Polyphenols and cardiovascular disease: effects on endothelial and platelet function. Am J Clin Nutr 2005;81(1 Suppl):292S
7S.

7. POLYPHENOLS AND VASCULAR HEALTH

REFERENCES

41. Zuchi C, Ambrosio G, Luscher TF, Landmesser U. Nutraceuticals in cardiovascular prevention: lessons from studies on endothelial function. Cardiovasc Ther 2010;28(4): 187
201. 42. Zhu Y, Xia M, Yang Y, Liu F, Li Z, Hao Y, et al. Purified anthocyanin supplementation improves endothelial function via NOcGMP activation in hypercholesterolemic individuals. Clin Chem 2011;57(11):1524
33. 43. Ostertag LM, O’Kennedy N, Kroon PA, Duthie GG, de Roos B. Impact of dietary polyphenols on human platelet function—a critical review of controlled dietary intervention studies. Mol Nutr Food Res 2010;54(1):60
81. 44. Jennings A, Welch AA, Fairweather-Tait SJ, Kay C, Minihane AM, Chowienczyk P, et al. Higher anthocyanin intake is associated with lower arterial stiffness and central blood pressure in women. Am J Clin Nutr 2012;96(4):781
8. 45. Dohadwala MM, Holbrook M, Hamburg NM, Shenouda SM, Chung WB, Titas M, et al. Effects of cranberry juice consumption on vascular function in patients with coronary artery disease. Am J Clin Nutr 2011;93(5):934
40. 46. Goldberg DM, Dam J, Carey M, Soleas GJ. Cultivar-specific patterns of polyphenolic constituents in wines from the Finger Lakes region of New York State. J Wine Res 2000;11(2):155
64. 47. Xia EQ, Deng GF, Guo YJ, Li HB. Biological activities of polyphenols from grapes. Int J Mol Sci 2010;11(2):622
46. 48. Hernandez-Jimenez A, Gomez-Plaza E, Martinez-Cutillas A, Kennedy JA. Grape skin and seed proanthocyanidins from Monastrell x Syrah grapes. J Agric Food Chem 2009;57(22): 10798
803. 49. Rodrigo R, Miranda A, Vergara L. Modulation of endogenous antioxidant system by wine polyphenols in human disease. Clinica Chimica Acta 2011;412(5
6):410
24. 50. Zern TL, Wood RJ, Greene C, West KL, Liu Y, Aggarwal D, et al. Grape polyphenols exert a cardioprotective effect in preand postmenopausal women by lowering plasma lipids and reducing oxidative stress. J Nutr 2005;135(8):1911
7. 51. O’Byrne DJ, Devaraj S, Grundy SM, Jialal I. Comparison of the antioxidant effects of Concord grape juice flavonoids alphatocopherol on markers of oxidative stress in healthy adults. Am J Clin Nutr 2002;76(6):1367
74. 52. Freedman JE, Parker III C, Li L, Perlman JA, Frei B, Ivanov V, et al. Select flavonoids and whole juice from purple grapes inhibit platelet function and enhance nitric oxide release. Circulation 2001;103(23):2792
8. 53. Keevil JG, Osman HE, Reed JD, Folts JD. Grape juice, but not orange juice or grapefruit juice, inhibits human platelet aggregation. J Nutr 2000;130(1):53
6. 54. Chou EJ, Keevil JG, Aeschlimann S, Wiebe DA, Folts JD, Stein JH. Effect of ingestion of purple grape juice on endothelial function in patients with coronary heart disease. Am J Cardiol 2001;88 (5):553
5. 55. Stein JH, Keevil JG, Wiebe DA, Aeschlimann S, Folts JD. Purple grape juice improves endothelial function and reduces the susceptibility of LDL cholesterol to oxidation in patients with coronary artery disease. Circulation 1999;100(10):1050
5. 56. Feringa HH, Laskey DA, Dickson JE, Coleman CI. The effect of grape seed extract on cardiovascular risk markers: a metaanalysis of randomized controlled trials. J Am Diet Assoc 2011;111(8):1173
81. 57. Polagruto JA, Gross HB, Kamangar F, Kosuna K, Sun B, Fujii H, et al. Platelet reactivity in male smokers following the acute consumption of a flavanol-rich grapeseed extract. J Med Food 2007;10(4):725
30. 58. Williamson G, Carughi A. Polyphenol content and health benefits of raisins. Nutr Res 2010;30(8):511
9.

891

59. Joshipura KJ, Hu FB, Manson JE, Stampfer MJ, Rimm EB, Speizer FE, et al. The effect of fruit and vegetable intake on risk for coronary heart disease. Ann Intern Med 2001;134(12): 1106
14. 60. Joshipura KJ, Ascherio A, Manson JE, Stampfer MJ, Rimm EB, Speizer FE, et al. Fruit and vegetable intake in relation to risk of ischemic stroke. JAMA 1999;282(13):1233
9. 61. Dauchet L, Ferrieres J, Arveiler D, Yarnell JW, Gey F, Ducimetiere P, et al. Frequency of fruit and vegetable consumption and coronary heart disease in France and Northern Ireland: the PRIME study. Br J Nutr 2004;92 (6):963
72. 62. Mizrahi A, Knekt P, Montonen J, Laaksonen MA, Heliovaara M, Jarvinen R. Plant foods and the risk of cerebrovascular diseases: a potential protection of fruit consumption. Br J Nutr 2009;102 (7):1075
83. 63. Yamada T, Hayasaka S, Shibata Y, Ojima T, Saegusa T, Gotoh T, et al. Frequency of citrus fruit intake is associated with the incidence of cardiovascular disease: the Jichi Medical School cohort study. J Epidemiol 2011;21(3):169
75. 64. Cassidy A, Rimm EB, O’Reilly EJ, Logroscino G, Kay C, Chiuve SE, et al. Dietary flavonoids and risk of stroke in women. Stroke 2012;43(4):946
51. 65. Knekt P, Kumpulainen J, Jarvinen R, Rissanen H, Heliovaara M, Reunanen A, et al. Flavonoid intake and risk of chronic diseases. Am J Clin Nutr 2002;76(3):560
8. 66. Benavente-Garcia O, Castillo J. Update on uses and properties of citrus flavonoids: new findings in anticancer, cardiovascular, and anti-inflammatory activity. J Agric Food Chem 2008;56 (15):6185
205. 67. Chanet A, Milenkovic D, Manach C, Mazur A, Morand C. Citrus flavanones: what is their role in cardiovascular protection? J Agric Food Chem 2012;60(36):8809
22. 68. Mulvihill EE, Huff MW. Citrus flavonoids and the prevention of atherosclerosis. Cardiovasc Hematol Disord Drug Targets 2012;12 (2):84
91. 69. Morand C, Dubray C, Milenkovic D, Lioger D, Martin JF, Scalbert A, et al. Hesperidin contributes to the vascular protective effects of orange juice: a randomized crossover study in healthy volunteers. Am J Clin Nutr 2011;93(1):73
80. 70. Demonty I, Lin Y, Zebregs YE, Vermeer MA, van der Knaap HC, Jakel M, et al. The citrus flavonoids hesperidin and naringin do not affect serum cholesterol in moderately hypercholesterolemic men and women. J Nutr 2010;140(9):1615
20. 71. Jung UJ, Kim HJ, Lee JS, Lee MK, Kim HO, Park EJ, et al. Naringin supplementation lowers plasma lipids and enhances erythrocyte antioxidant enzyme activities in hypercholesterolemic subjects. Clin Nutr 2003;22(6):561
8. 72. Rizza S, Muniyappa R, Iantorno M, Kim JA, Chen H, Pullikotil P, et al. Citrus polyphenol hesperidin stimulates production of nitric oxide in endothelial cells while improving endothelial function and reducing inflammatory markers in patients with metabolic syndrome. J Clin Endocrinol Metab 2011;96(5): E782
792. 73. Milenkovic D, Deval C, Dubray C, Mazur A, Morand C. Hesperidin displays relevant role in the nutrigenomic effect of orange juice on blood leukocytes in human volunteers: a randomized controlled cross-over study. PLoS One 2011;6(11):e26669. 74. Reshef N, Hayari Y, Goren C, Boaz M, Madar Z, Knobler H. Antihypertensive effect of sweetie fruit in patients with stage I hypertension. Am J Hypertens 2005;18(10):1360
3. 75. Dow CA, Going SB, Chow HH, Patil BS, Thomson CA. The effects of daily consumption of grapefruit on body weight, lipids, and blood pressure in healthy, overweight adults. Metabolism 2012;61(7):1026
35.

7. POLYPHENOLS AND VASCULAR HEALTH

892

68. VASCULAR PROTECTIVE EFFECTS OF FRUIT POLYPHENOLS

76. Giordano L, Coletta W, Tamburrelli C, D’Imperio M, Crescente M, Silvestri C, et al. Four-week ingestion of blood orange juice results in measurable anthocyanin urinary levels but does not affect cellular markers related to cardiovascular risk: a randomized crossover study in healthy volunteers. Eur J Nutr 2012;51(5):541
8. 77. Hyson DA. A comprehensive review of apples and apple components and their relationship to human health. Adv Nutr 2011;2(5):408
20. 78. Knekt P, Jarvinen R, Reunanen A, Maatela J. Flavonoid intake and coronary mortality in Finland: a cohort study. BMJ 1996;312(7029):478
81. 79. Hertog MG, Feskens EJ, Hollman PC, Katan MB, Kromhout D. Dietary antioxidant flavonoids and risk of coronary heart disease: the Zutphen Elderly study. Lancet 1993;342(8878):1007
11. 80. Avci A, Atli T, Erguder IB, Varli M, Devrim E, Turgay SA, et al. Effects of apple consumption on plasma and erythrocyte antioxidant parameters in elderly subjects. Exp Aging Res 2007;33(4):429
37. 81. Ko SH, Choi SW, Ye SK, Cho BL, Kim HS, Chung MH. Comparison of the antioxidant activities of nine different fruits in human plasma. J Med Food 2005;8(1):41
6. 82. Maffei F, Tarozzi A, Carbone F, Marchesi A, Hrelia S, Angeloni C, et al. Relevance of apple consumption for protection against oxidative damage induced by hydrogen peroxide in human lymphocytes. Br J Nutr 2007;97(5):921
7. 83. Lotito SB, Frei B. The increase in human plasma antioxidant capacity after apple consumption is due to the metabolic effect of fructose on urate, not apple-derived antioxidant flavonoids. Free Radic Biol Med 2004;37(2):251
8. 84. Chai SC, Hooshmand S, Saadat RL, Payton ME, BrummelSmith K, Arjmandi BH. Daily apple versus dried plum: impact on cardiovascular disease risk factors in postmenopausal women. J Acad Nutr Diet 2012;112(8):1158
68. 85. Ravn-Haren G, Dragsted LO, Buch-Andersen T, Jensen EN, Jensen RI, Nemeth-Balogh M, et al. Intake of whole apples or clear apple juice has contrasting effects on plasma lipids in healthy volunteers. Eur J Nutr 2012. Epub ahead of print. 86. Auclair S, Chironi G, Milenkovic D, Hollman PC, Renard CM, Megnien JL, et al. The regular consumption of a polyphenolrich apple does not influence endothelial function: a randomised double-blind trial in hypercholesterolemic adults. Eur J Clin Nutr 2010;64(10):1158
65. 87. Bondonno CP, Yang X, Croft KD, Considine MJ, Ward NC, Rich L, et al. Flavonoid-rich apples and nitrate-rich spinach augment nitric oxide status and improve endothelial function in healthy men and women: a randomized controlled trial. Free Radic Biol Med 2012;52(1):95
102. 88. Weichselbaum E, Wyness L, Stanner S. Apple polyphenols and cardiovascular disease
a review of the evidence. Nutrition Bulletin 2010;35(2):92
101. 89. Egert S, Bosy-Westphal A, Seiberl J, Kurbitz C, Settler U, Plachta-Danielzik S, et al. Quercetin reduces systolic blood pressure and plasma oxidised low-density lipoprotein concentrations in overweight subjects with a high-cardiovascular disease risk phenotype: a double-blinded, placebo-controlled cross-over study. Br J Nutr 2009;102(7):1065
74. 90. Tsang C, Higgins S, Duthie GG, Duthie SJ, Howie M, Mullen W, et al. The influence of moderate red wine consumption on antioxidant status and indices of oxidative stress associated with CHD in healthy volunteers. Br J Nutr 2005;93(2):233
40. 91. Fraga CG, Actis-Goretta L, Ottaviani JI, Carrasquedo F, Lotito SB, Lazarus S, et al. Regular consumption of a flavanol-rich chocolate can improve oxidant stress in young soccer players. Clin Dev Immunol 2005;12(1):11
7.

92. Edwards RL, Lyon T, Litwin SE, Rabovsky A, Symons JD, Jalili T. Quercetin reduces blood pressure in hypertensive subjects. J Nutr 2007;137(11):2405
11. 93. Conquer JA, Maiani G, Azzini E, Raguzzini A, Holub BJ. Supplementation with quercetin markedly increases plasma quercetin concentration without effect on selected risk factors for heart disease in healthy subjects. J Nutr 1998;128(3):593
7. 94. Janssen K, Mensink RP, Cox FJ, Harryvan JL, Hovenier R, Hollman PC, et al. Effects of the flavonoids quercetin and apigenin on hemostasis in healthy volunteers: results from an in vitro and a dietary supplement study. Am J Clin Nutr 1998;67 (2):255
62. 95. Freese R, Vaarala O, Turpeinen AM, Mutanen M. No difference in platelet activation or inflammation markers after diets rich or poor in vegetables, berries and apple in healthy subjects. Eur J Nutr 2004;43(3):175
82. 96. Ferretti G, Bacchetti T, Belleggia A, Neri D. Cherry antioxidants: from farm to table. Molecules 2010;15(10):6993
7005. 97. McCune LM, Kubota C, Stendell-Hollis NR, Thomson CA. Cherries and health: a review. Crit Rev Food Sci Nutr 2011;51 (1):1
12. 98. Traustadottir T, Davies SS, Stock AA, Su Y, Heward CB, Roberts II LJ, et al. Tart cherry juice decreases oxidative stress in healthy older men and women. J Nutr 2009;139 (10):1896
900. 99. Kelley DS, Rasooly R, Jacob RA, Kader AA, Mackey BE. Consumption of Bing sweet cherries lowers circulating concentrations of inflammation markers in healthy men and women. J Nutr 2006;136(4):981
6. 100. Ataie-Jafari A, Hosseini S, Karimi F, Pajouhi M. Effects of sour cherry juice on blood glucose and some cardiovascular risk factors improvements in diabetic women: a pilot study. Nutrition and Food Science 2008;38(4):355
60. 101. Martin KR, Bopp J, Neupane S, Vega-Lopez S. 100% Tart cherry juice reduces plasma triglycerides and CVD risk in overweight and obese subjects. FASEB J 2010;24 (Meeting Abstract Suppl):722.14. 102. Donovan JL, Meyer AS, Waterhouse AL. Phenolic composition and antioxidant activity of prunes and prune juice (Prunus domestica). J Agric Food Chem 1998;46(4):1247
52. 103. Kimura Y, Ito H, Kawaji M, Ikami T, Hatano T. Characterization and antioxidative properties of oligomeric proanthocyanidin from prunes, dried fruit of Prunus domestica L. Biosci Biotechnol Biochem 2008;72(6):1615
8. 104. Wu X, Beecher GR, Holden JM, Haytowitz DB, Gebhardt SE, Prior RL. Lipophilic and hydrophilic antioxidant capacities of common foods in the United States. J Agric Food Chem 2004;52 (12):4026
37. 105. Tinker LF, Schneeman BO, Davis PA, Gallaher DD, Waggoner CR. Consumption of prunes as a source of dietary fiber in men with mild hypercholesterolemia. Am J Clin Nutr 1991;53 (5):1259
65. 106. Basu A, Penugonda K. Pomegranate juice: a heart-healthy fruit juice. Nutr Rev 2009;67(1):49
56. 107. Stowe CB. The effects of pomegranate juice consumption on blood pressure and cardiovascular health. Complement Ther Clin Pract 2011;17(2):113
5. 108. Aviram M, Dornfeld L. Pomegranate juice consumption inhibits serum angiotensin converting enzyme activity and reduces systolic blood pressure. Atherosclerosis 2001;158(1):195
8. 109. Aviram M, Rosenblat M, Gaitini D, Nitecki S, Hoffman A, Dornfeld L, et al. Pomegranate juice consumption for 3 years by patients with carotid artery stenosis reduces common carotid intima-media thickness, blood pressure and LDL oxidation. Clin Nutr 2004;23(3):423
33.

7. POLYPHENOLS AND VASCULAR HEALTH

REFERENCES

110. Esmaillzadeh A, Tahbaz F, Gaieni I, Alavi-Majd H, Azadbakht L. Concentrated pomegranate juice improves lipid profiles in diabetic patients with hyperlipidemia. J Med Food 2004;7(3):305
8. 111. Rosenblat M, Hayek T, Aviram M. Anti-oxidative effects of pomegranate juice (PJ) consumption by diabetic patients on serum and on macrophages. Atherosclerosis 2006;187(2):363
71. 112. Sumner MD, Elliott-Eller M, Weidner G, Daubenmier JJ, Chew MH, Marlin R, et al. Effects of pomegranate juice consumption on myocardial perfusion in patients with coronary heart disease. Am J Cardiol 2005;96(6):810
4. 113. Mathew AS, Capel-Williams GM, Berry SE, Hall WL. Acute effects of pomegranate extract on postprandial lipaemia, vascular function and blood pressure. Plant Foods Hum Nutr 2012;67(4):351
7. 114. Burton-Freeman B. Postprandial metabolic events and fruitderived phenolics: a review of the science. Br J Nutr 2010;104 (Suppl 3):S1
14. 115. Vauzour D, Rodriguez-Mateos A, Corona G, Oruna-Concha MJ, Spencer JP. Polyphenols and human health: prevention of disease and mechanisms of action. Nutrients 2010;2(11):1106
31. 116. Manach C, Williamson G, Morand C, Scalbert A, Remesy C. Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies. Am J Clin Nutr 2005;81 (1 Suppl):230S
42S. 117. van Dam RM, Naidoo N, Landberg R. Dietary flavonoids and the development of type 2 diabetes and cardiovascular diseases: review of recent findings. Curr Opin Lipidol 2013;24 (1):25
33. 118. Fraga CG, Galleano M, Verstraeten SV, Oteiza PI. Basic biochemical mechanisms behind the health benefits of polyphenols. Mol Aspects Med 2010;31(6):435
45. 119. Mann GE, Bonacasa B, Ishii T, Siow RC. Targeting the redox sensitive Nrf2-Keap1 defense pathway in cardiovascular disease: protection afforded by dietary isoflavones. Curr Opin Pharmacol 2009;9(2):139
45. 120. Steffen Y, Schewe T, Sies H. (2)-Epicatechin elevates nitric oxide in endothelial cells via inhibition of NADPH oxidase. Biochem Biophys Res Commun 2007;359(3):828
33. 121. Wallace TC. Anthocyanins in cardiovascular disease. Adv Nutr 2011;2(1):1
7. 122. Schewe T, Steffen Y, Sies H. How do dietary flavanols improve vascular function? A position paper. Arch Biochem Biophys 2008;476(2):102
6. 123. Sies H, Schewe T, Heiss C, Kelm M. Cocoa polyphenols and inflammatory mediators. Am J Clin Nutr 2005;81(1 Suppl):304S
12S. 124. Schnorr O, Brossette T, Momma TY, Kleinbongard P, Keen CL, Schroeter H, et al. Cocoa flavanols lower vascular arginase activity in human endothelial cells in vitro and in erythrocytes in vivo. Arch Biochem Biophys 2008;476(2):211
5. 125. Anter E, Thomas SR, Schulz E, Shapira OM, Vita JA, Keaney Jr. JF. Activation of endothelial nitric-oxide synthase by the p38 MAPK in response to black tea polyphenols. J Biol Chem 2004;279(45):46637
43. 126. Galleano M, Pechanova O, Fraga CG. Hypertension, nitric oxide, oxidants, and dietary plant polyphenols. Curr Pharm Biotechnol 2010;11(8):837
48. 127. Fisher ND, Hughes M, Gerhard-Herman M, Hollenberg NK. Flavanol-rich cocoa induces nitric-oxide-dependent vasodilation in healthy humans. J Hypertens 2003;21(12):2281
6. 128. Heiss C, Dejam A, Kleinbongard P, Schewe T, Sies H, Kelm M. Vascular effects of cocoa rich in flavan-3-ols. JAMA 2003;290 (8):1030
1. 129. Gonzalez-Gallego J, Garcia-Mediavilla MV, Sanchez-Campos S, Tunon MJ. Fruit polyphenols, immunity and inflammation. Br J Nutr 2010;104(Suppl 3):S15
27.

893

130. Speciale A, Canali R, Chirafisi J, Saija A, Virgili F, Cimino F. Cyanidin-3-O-glucoside protection against TNF-alpha-induced endothelial dysfunction: involvement of nuclear factor-kappaB signaling. J Agric Food Chem 2010;58(22):12048
54. 131. Gonzalez R, Ballester I, Lopez-Posadas R, Suarez MD, Zarzuelo A, Martinez-Augustin O, et al. Effects of flavonoids and other polyphenols on inflammation. Crit Rev Food Sci Nutr 2011;51 (4):331
62. 132. Leiherer A, Mundlein A, Drexel H. Phytochemicals and their impact on adipose tissue inflammation and diabetes. Vascul Pharmacol 2013;58(1
2):3
20. 133. Kanner J, Gorelik S, Roman S, Kohen R. Protection by polyphenols of postprandial human plasma and low-density lipoprotein modification: the stomach as a bioreactor. J Agric Food Chem 2012;60(36):8790
6. 134. Galleano M, Calabro V, Prince PD, Litterio MC, Piotrkowski B, Vazquez-Prieto MA, et al. Flavonoids and metabolic syndrome. Ann NY Acad Sci 2012;1259:87
94. 135. Williamson G. Possible effects of dietary polyphenols on sugar absorption and digestion. Mol Nutr Food Res 2013;57 (1):48
57. 136. Stangl V, Dreger H, Stangl K, Lorenz M. Molecular targets of tea polyphenols in the cardiovascular system. Cardiovasc Res 2007;73(2):348
58. 137. Rimbach G, Boesch-Saadatmandi C, Frank J, Fuchs D, Wenzel U, Daniel H, et al. Dietary isoflavones in the prevention of cardiovascular disease—a molecular perspective. Food Chem Toxicol 2008;46(4):1308
19. 138. Kroon PA, Clifford MN, Crozier A, Day AJ, Donovan JL, Manach C, et al. How should we assess the effects of exposure to dietary polyphenols in vitro? Am J Clin Nutr 2004;80 (1):15
21. 139. Auclair S, Milenkovic D, Besson C, Chauvet S, Gueux E, Morand C, et al. Catechin reduces atherosclerotic lesion development in apo E-deficient mice: a transcriptomic study. Atherosclerosis 2009;204(2):e21
27. 140. Chanet A, Milenkovic D, Deval C, Potier M, Constans J, Mazur A, et al. Naringin, the major grapefruit flavonoid, specifically affects atherosclerosis development in diet-induced hypercholesterolemia in mice. J Nutr Biochem 2012;23(5):469
77. 141. Mauray A, Felgines C, Morand C, Mazur A, Scalbert A, Milenkovic D. Bilberry anthocyanin-rich extract alters expression of genes related to atherosclerosis development in aorta of apo E-deficient mice. Nutr Metab Cardiovasc Dis 2010;22 (1):72
80. 142. Pujos-Guillot E, Hubert J, Martin J-F, Lyan B, Quintana M, Claude S, et al. Mass spectrometry-based metabolomics for the discovery of biomarkers of fruit and vegetable intake: citrus fruit as a case study. J Proteome Re 2013. [Epub ahead of print]. 143. Kay CD, Hooper L, Kroon PA, Rimm EB, Cassidy A. Relative impact of flavonoid composition, dose and structure on vascular function: a systematic review of randomised controlled trials of flavonoid-rich food products. Mol Nutr Food Res 2012;56(11):1605
16. 144. Perez-Jimenez J, Neveu V, Vos F, Scalbert A. Systematic analysis of the content of 502 polyphenols in 452 foods and beverages: an application of the phenol-explorer database. J Agric Food Chem 2010;58(8):4959
69. 145. Koponen JM, Happonen AM, Mattila PH, Torronen AR. Contents of anthocyanins and ellagitannins in selected foods consumed in Finland. J Agric Food Chem 2007;55(4):1612
9. 146. Gil MI, Tomas-Barberan FA, Hess-Pierce B, Holcroft DM, Kader AA. Antioxidant activity of pomegranate juice and its relationship with phenolic composition and processing. J Agric Food Chem 2000;48(10):4581
9.

7. POLYPHENOLS AND VASCULAR HEALTH