Fat and fatty acids intake of adults in eastern Croatia

Nutrition Research 23 (2003) 1453–1461 www.elsevier.com/locate/nutres

Fat and fatty acids intake of adults in eastern Croatia Lj. Primoraca,*, M.L. Mandic´a, T. Klapeca, K. Folivarskib, A. Perla, D. Kenjeric´a a

Faculty of Food Technology, Kuhaceva 18, pp 709, HR-31107 Osijek, Croatia b Saponia, Inc., HR-31000 Osijek, Croatia

Received 19 January 2003; received in revised form 9 July 2003; accepted 11 July 2003

Abstract The objective of this work was to determine dietary intake of total fat and fatty acids in adults in eastern Croatia. Thirty nine participants (25 women and 14 men) took part in a duplicate diet study. Total fat was extracted from the duplicated portions using a method by Bligh and Dyer, and fatty acids were determined using a GC analysis after methylation with boron trifluoride. Mean fat and fatty acids intakes for all subjects expressed as percentage of daily energy intake (% E) were: 33.4%, 9.9%, 11.8%, 9.0%, and 0.7% for total fat, saturated, monounsaturated, polyunsaturated, and trans fatty acids, respectively. The differences between sexes were not significant when expressed as % E. Also, a very low intake of linolenic acid (0.5% E), and a high linoleic acid/linolenic acid ratio (17.1), were noted. Because of the health implications of such an imbalance, further research on the prevalence of this in general population is warranted. Nevertheless, these results indicate a need for a more aggressive education of the public on health benefits of n-3 fatty acids and on their dietary sources. © 2003 Elsevier Inc. All rights reserved. Keywords: Duplicate diet study; Fat intake; Fatty acids intake; n-6/n-3 ratio

1. Introduction Amount and quality of dietary fat is associated with several disorders and diseases, such as coronary heart disease, stroke, obesity, and certain types of cancer [1– 6]. A remarkable increase in the intake of fat, which is a trend not limited to developed countries, has been

* Corresponding author. Tel.: ⫹385-31-224-323; fax: ⫹385-31-207-115. E-mail address: [email protected] (Lj. Primorac). 0271-5317/03/$ – see front matter © 2003 Elsevier Inc. All rights reserved. doi:10.1016/S0271-5317(03)00154-4

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noted over the last thirty years, with percentage of energy intake (% E) contributed by fat exceeding the recommended upper margin of 30% [7]. Aggressive campaining by public health authorities in most Western countries effected a moderate decrease in the intake of saturated fat, but in most instances it is still above the recommended 10% E [7]. At the same time, a higher intake of vegetable oils rich in linoleic acid (e.g. from corn, sunflower seed, safflower seed, cottonseed, and soybean), and a concomitant decreased consumption of fish, resulted in alterations of the n-6/n-3 fatty acid ratio [6]. The objective of reducing saturated fat and cholesterol intake has also made trans fatty acids more common in human nutrition. However, evidence of adverse health effects of trans fatty acids has appeared [2], prompting research into means of decreasing their presence in hydrogenated fat products [8]. According to food inventory data, an average intake of fat in Croatian adults is 38-39% E [9], with hardly any data on the intake of fatty acids available. Recent findings of high intake of total and saturated fat were obtained in samples of school children and adolescents [10,11]. The aim of this work was to investigate the intake of total fat and the fatty acid pattern in adult population. The setting was an urban center of eastern Croatia, part of the country traditionally inclined toward foods rich in saturated fatty acids.

2. Methods and materials 2.1. Subjects and collection of samples Thirty nine volunteers participated in the study, of which 25 were women (21-48 yrs, body mass index (BMI) 22.6⫾2.7), and 14 men (19-48 yrs, BMI 25.0⫾3.6). All subjects had 12 (high school) or more (university) years of education. The subjects collected in duplicate all food and drink consumed during a day. They were also asked to simultaneously record all consumed items and their weights and/or measures using the forms we provided. All subjects also filled in a questionnaire with some personal and other information which was instrumental in the interpretation of the results. The collection of duplicates was carried out over a period of seven consecutive days during February and March 1996. To prevent the effect of underreporting and/or undercollecting biases on the aim of the study, the weights of daily duplicates were checked against the weights of daily records, and causes of any significant differences were discussed with subjects and removed. 2.2. Chemical analysis of total fat and fatty acids The following nutrients were quantified: total fat, saturated fatty acids (SFA): C6-C24; monounsaturated fatty acids (MUFA): C14:1 n-5, C16:1 n-7, C18:1 n-9 (OA), and C20:1 n-9; polyunsaturated fatty acids (PUFA): C18:2 n-6 (LA), C18:3 n-3 (LNA), C20:4 n-6; and trans fatty acids (TFA): C18:1 and C18:2 trans isomers. Of the nutritionally important fatty acids only EPA and DHA were not analyzed, but considering the low consumption of fish in this group of subjects, their contribution to total PUFA is dispensable. Total fat was extracted according to a procedure by Bligh and Dyer [12], and fatty acids were determined using gas chromatography analysis after methylation with boron trifluoride [13]. Details on

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preparation of samples and the used methods for total fat and fatty acid determination have been described elsewhere [14]. 2.3. Determination of daily energy intake Daily energy intakes of subjects were determined from quantities of fat, protein and carbohydrates in duplicates, by means of Atwater factors [15]. The contents of protein and carbohydrates were calculated using the formula: dry matter ⫺ ash ⫺ crude fiber ⫺ total fat. Dry matter of samples was determined by drying to constant weight at 101-105°C in an oven, and samples were ashed at 525°C in a muffle furnace. Crude fiber was determined using a Fibertec apparatus, according to an AOAC method [13]. 2.4. Data analysis Differences in mean values between men and women were examined using t-test. Association between variables was evaluated using the Pearson correlation coefficient. All statistical calculations were performed using computer programs Excel 2000 (Microsoft Corp.) and Statistica 6.0 (Statsoft Inc.)

3. Results The calculated daily intakes of energy, total fat and main fatty acid groups are presented in Table 1. Fractions of individual fatty acids in total fatty acid intake for the combined (both men and women) group, are presented in Fig. 1. A wide individual variation was observed in the intake of energy, total fat and fatty acid groups. Men had higher mean intakes of total fat and fatty acid groups (in g/d) compared to women, but this was expected considering their greater mean body weight, and a greater intake of energy (p⬍0.01) (Table 1). Connected to this, a strong correlation between total fat intake and daily energy intake was established for the combined (both men and women) group (r⫽0.91, p⬍0.001). Statistically significant differences between sexes were found for PUFA and total fat mean intakes, given in g/d (Table 1). When the intakes were calculated as % E, the statistical significance of differences disappeared (Table 1). The influence of BMI on the results must also be considered since there was a significant difference (p⬍0.05) between men and women in present study. If the BMI value of 25 is taken as an upper margin for obesity, 31% of subjects were overweight, i.e. 16% of female subjects and 57% of male subjects. The average BMI in the female group is very similar to the recommended range of 20-22 [16]. However, since there were only minor differences between sexes in fatty acid pattern or contribution of fat to energy intake, the BMI and the weight status obviously did not imply qualitative variation in food intake in this group of subjects. The mean total fat intake (Table 1) in the investigated sample of population is high compared to recommendations (up to 30% E [9,16 –19]). Sixty-nine percent of all subjects had a fat intake above 30% E, and 33% had an intake of total fat higher than 35% E. The mean SFA intake was at the recommended maximum intake (9.9% E, for all subjects)

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Table 1 Daily dietary intake of energy, total fat and main fatty acid groups in eastern Croatia Parameters

Men

Women

P

All

Energy (MJ) Energy (Kcal) Total fat (g/day) Total fat (E%) Saturated fatty acids (SFA) (g/day) (E%) Monounsaturated fatty acids (MUFA) (g/day) (E%) Polyunsaturated fatty acids (PUFA) (g/day) (E%) Linolenic acid (LNA) (g/day) (E%) Trans fatty acids (TFA) (g/day) (E%) MUFA/SFA PUFA/SFA LA/LNA

8.33 ⫾ 1.58 1990 ⫾ 378 74.2 ⫾ 20.4 33.4 ⫾ 4.9

6.63 ⫾ 1.78 1583 ⫾ 426 59.3 ⫾ 20.4 33.4 ⫾ 4.9

⬍0.01 ⬍0.01 ⬍0.05 ns

7.24 ⫾ 1.88 1729 ⫾ 450 64.7 ⫾ 21.4 33.4 ⫾ 4.8

20.7 ⫾ 7.7 9.6 ⫾ 2.3

17.2 ⫾ 5.9 10.1 ⫾ 2.0

ns ns

18.5 ⫾ 6.7 9.9 ⫾ 2.1

24.7 ⫾ 8.4 11.5 ⫾ 2.6

20.3 ⫾ 7.9 11.9 ⫾ 2.6

ns ns

21.9 ⫾ 8.2 11.8 ⫾ 2.6

20.3 ⫾ 4.9 9.7 ⫾ 2.1

14.8 ⫾ 5.8 8.7 ⫾ 1.8

1.1 ⫾ 0.4 0.5 ⫾ 0.1

1.0 ⫾ 0.6 0.6 ⫾ 0.2

ns ns

1.0 ⫾ 0.5 0.5 ⫾ 0.2

1.4 ⫾ 0.5 0.7 ⫾ 0.3 1.2 ⫾ 0.2 1.1 ⫾ 0.4 18.5 ⫾ 5.9

1.3 ⫾ 0.7 0.7 ⫾ 0.2 1.2 ⫾ 0.2 0.9 ⫾ 0.3 16.4 ⫾ 5.3

ns ns ns ns ns

1.3 ⫾ 0.6 0.7 ⫾ 0.3 1.2 ⫾ 0.2 1.0 ⫾ 0.4 17.1 ⫾ 5.5

⬍0.01 ns

16.8 ⫾ 6.0 9.0 ⫾ 1.9

ns-difference not significant.

(Table 1), with one half of subjects having an intake higher than 10% E. On the other hand, the intake of PUFA was very high (9.0% E, for all subjects). LA was the principle PUFA in this study, contributing 92% to the PUFA intake. An extremely low fraction of LNA (1.0 g/day or 0.5% E for the combined group) (Table 1) was found. Thirty-eight percent of all subjects had a LNA intake less than 0.5% E. The resulting LA/LNA ratio, for the whole group, was 17.1 (Table 1), with only 13% of subjects having the ratio lower than 10. Major fatty acids in the diet of all participants were OA (35.0 wt %), LA (27.0 wt %), and palmitic acid (17.8 wt %) (Fig. 1).

4. Discussion The determined high total fat intake in the investigated group indicates an increased risk for development of obesity, especially since most of the subjects in this urban sample keep a sedentary occupation. Thirty-one percent of the subjects are already overweight, as mentioned above. The results of a large cross-sectional study in Croatia pointed to an even greater prevalence of obesity in general adult population (79.2% of males and 49.9% of females) [20]. Obesity is among the most important health problems in the world today. It has been suggested that in developed countries, obesity is more common in people of lower socioeconomic status and in those living in rural communities [7]. Considering the above-

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Fig. 1. Mean fatty acid profile of diet in eastern Croatia.

mentioned prior results on obesity prevalence and the fraction of overweight subjects in this study of urban setting, the transitional Croatia could be categorized as a developed country in which obesity is associated with lower socioeconomic status. The established means of PUFA and SFA intakes were somewhat surprising for this group of subjects regarding the strong influence of traditional diet in the area with lard, pork, and a range of pork based products as staple foods. Naturally, for subjects from an urban center and a level of education including at least high school, it had been anticipated that some deviation from such a diet, generally recognized as ‘unwholesome’, would occur. Similar methodology yielded 12.7% and 4.3% E for SFA and PUFA, respectively, in the Netherlands [21]. The low mean intake of SFA probably results from the abovementioned education level (a quarter of participants with high school, and the rest with university education) and awareness of the negative health impact of excessive intake of saturated fat. There are equivocal reports in the literature on the effect of education level on saturated fat and cholesterol intake [22,23]. Nonetheless, several other socioeconomic factors can also influence food choice [24,25]. Apparently, subjects’ efforts to curb their SFA intake have resulted in a more extensive use of plant oils, especially sunflower oil on account of its availability and dominant position on the local market (eastern Croatia is a major sunflower growing and processing area of the country). A high PUFA/SFA ratio of 1.0 was determined in this work (Table 1). The ratio is still used as an indicator of quality of nutrition in view of fat intake, although it is becoming generally accepted that the ratio is inadequate for this purpose because it neglects different metabolic effects of n-6 and n-3 PUFA [1]. Over the course of evolution, human diet mostly contained equal amounts of these two groups of unsaturated fatty acids, while the n-6/n-3 ratio of 10-20, or even 25, is a feature of modern age diet, common for populations in industrialized countries [26,27]. This may also explain the

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accumulating scientific evidence on the relationship between a high n-6/n-3 ratio and etiologies of cancer, cardiovascular and other chronic diseases [6,27,28]. Another measure of n-6 and n-3 fatty acid intakes is the LA/LNA ratio, which was very high (17.1 for the combined group; Table 1). Considering the low mean fish intake in this group of subjects (14 g/d for the combined group), which makes the lack of information on EPA and DHA content dispensable, as well as the mean intake of another major n-6 fatty acid, i.e. arachidonic acid (0.26 g/d for the combined group), the calculated LA/LNA ratio is almost equivalent to the n-6/n-3 ratio in these subjects. The determined value for this factor (Table 1) is higher than all recommendations. The FAO/WHO Joint Committee has recommended a ratio of LA to LNA between 5 and 10 [17], while an n-6/n-3 of 5 is also considered desirable in several European countries [29]. Current Dietary Reference Intakes in Japan include a recommended n-6/n-3 ratio of 4, but Japan Society for Lipid Nutrition deems the ratio too high and deficient in sound scientific backing, advocating to reduce the goal ratio to 2 or less [28]. The unfavorable LA/LNA ratio established in this work is a consequence of the region-specific extensive use of sunflower oil which has a very high LA/LNA ratio, often beyond 100. According to Croatian standards [30] sunflower oil should contain between 48-74% LA, and up to 1% LNA. Actual analyses revealed mean levels of 62.1% LA and 0.22% LNA (Croatian Institute of Public Health, unpublished data). To meet recommendations for the n-6/n-3 ratio, a decrease of n-6 fatty acid intake and an increase of n-3 fatty acid intake (i.e. LNA and long chain PUFA) is necessary. European Consensus on Coronary Prevention [18] and EURODIET project [19] recommend 200 mg/d of fatty acids from fish (i.e. ⬎20 g/d fish), and a group of leading experts on the nutritional aspects of polyunsaturates propose 650 mg/d EPA ⫹ DHA (0.3% E) as an adequate intake [31]. The estimated intakes of EPA ⫹ DHA in the U.S. (which might be considered a typical Western style diet) is between 100 and 200 mg/d [32,33], as opposed to Norway where fish consumption is much more common (around 67 g fish/d), and an average intake of very long chain fatty acids is 0.9 g/d or 0.4% E [34]. Japanese consume around 80 g of fish and shellfish per day ingesting 1-2 g of n-3 PUFA [35]. The mean intake of LNA for all subjects was two times lower than the values recommended for prevention of coronary heart disease (i.e. 2 g/d [18]), also lower than the adequate intake (2.2 g/d or 1% E), as suggested by the expert group [31]. The mean intake of LNA in this group of subjects was low in its own right, regardless of the high LA intake. LNA can be converted to long chain n-3 PUFA in the body, thereby substituting for fish/cod liver oil consumption. However, the efficiency of this conversion, as well as the amount of long chain n-3 PUFA needed for beneficial effects, depend on the intake of LA and some other fatty acids [27]. The most important nutritional sources of LNA are rapeseed and soybean oil, in addition to some nuts, vegetables, legumes, and grains [18]. Availability of rapeseed and soybean oil has been increasing in Croatia over the last couple of years. Previously, these oils have only been marketed as a mixture called ‘plant oil’. The fraction of soybean and rapeseed oil in all sold plant oils in Croatia (for June/July 2002) is 4.1% and 1.1%, respectively, with an even poorer share of the market in eastern Croatia, i.e. 0.7% and 3.8%, respectively.(Source: MEMRB Puls Panel trgovina d.o.o on a sample of 705 retail stores in Croatia, for a period of June/July 2002). Nevertheless, the market share of the ‘plant oil’ is significantly greater, making 34.4% of all plant oils in Croatia, but again less in eastern part of the country, with only 13.5%. The latest ‘Croatian Food Guidelines for Adults’ advise

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on the use of plant oils, with an emphasis on olive oil [9]. Significance of soybean and rapeseed oils for a better provision with n-3 fatty acids is obvious in Japan where these represent main dietary oils, and are major contributors to the relatively high level of consumption of n-3 PUFA [35]. Between 1985 and 1994 an almost sixfold increase in canola oil use took place in the U.S., effecting a reduction in the n-6/n-3 ratio from 12.4 to 10.6 [33]. The mean MUFA contribution to daily energy intake in this study was 11.8% (Table 1). The quantity of OA as the most abundant fatty acid in the diet (Fig. 1), reflects its ubiquitous occurrence in fats and oils (e.g. lard, 45%, chicken fat, 42%, etc.) [36]. Acquired food preference and cost are probably among the most important reasons for a lesser presence of olive oil in the diet in eastern Croatia. For instance, in the coastal region of Croatia (Dalmatia), 73.8% of population consume olive oil more than twice a week vs only 3.4% in the continental eastern Croatia [20]. Similarly, in other (e.g. Mediterranean) countries where olive oil is a staple food, MUFA make 18% E, as opposed to Western European countries with 9-12% contribution of MUFA to energy intake [37]. Dietary guidelines usually do not restrict intake of MUFA [16,17]. The mean intake of TFA (C18:1 and C18:2 isomers) for the investigated sample of population was low (0.7% E, Table 1). Numerous metabolic and epidemiologic studies have shown that TFA enhance the risk of coronary heart disease [38]. The WHO proposition of reducing TFA presence in human nutrition [17] induced a prompt reaction from producers/ food industry, which introduced different methods of reducing TFA content in final products [8]. The current intakes of TFA in most countries range from 0.5% E (Greece, Italy) to 2.1% E (Iceland) [37], or 0.7% E in Japan [38]. Such intakes are not associated with an unfavorable serum lipid profile [39]. Comparison with present results should take into account that not all common TFA were determined here, as well as the fact that the applied methodology differs between studies. Relatively low intake in this study is most likely connected with the type of fat subjects used for preparing their meals (vegetable oils and lard being the most common in Croatia). In some countries (UK, The Netherlands, Norway, US) hydrogenated fats are more commonly used in cooking and food production which results in increase in total TFA intake but also in a greater contribution of these to total TFA intake. For example, TFA originating from hydrogenated products make 64% of total TFA in the UK, 80-90% in the US, and less than 50% in the Mediterranean countries [37,40]. The problem of a high n-6 to n-3 fatty acid ratio identified in this group of subjects is, in all probability, not limited to this small sample of population of eastern Croatia, and further research into this is warranted. In the meantime, a more aggressive education of the public on health benefits of n-3 PUFA and on their dietary sources is needed.

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