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Flavonoids of the mediterranean diet
169
Tuesday, 1 June 1999 Mediterranean diet ['HE DIET OF CRETE: PAST AND PRESENT ~,. Kafatos, J. Moschandreas. University of Crete School of Medicine, )epartment of Social Medicine, Preventive Medicine & Nutrition Clinic, '~eraklion, Crete, Greece I'he diet of inhabitants of the Greek island of Crete has long been hailed Ls a prime example o f the Mediterranean diet with all its cardioprotective )enefits. The present paper investigates the changes in this diet over the last "our decades by reviewing data from previous investigations and presenting he latest findings on dietary trends in recent years. Dietary intake is ;stimated using dietary records and adipose fat measurements, the latter )eing a biochemical marker reflecting the long-term dietary fat intake. The thirty seven year follow-up of the Cretan Seven Countries cohort has ~rovided evidence of changes in dietary habits even in deeply rural areas of Me island, in 1960, 8% o f the total energy intake was from saturated fats ~¢hereas by 1998 (157 men), this had risen to 1 I%. Adipose fat comparisons 3f 112 surviving cohort members in 1997 with a sample of 200 Cretan men ~n 1962 indicated that certain of the saturated fatty acids were slightly higher in the 1997 Cretan cohort eg mean myristic acid 1.7% in 1997 cf 1.2% in Se 1962 subjects. The total saturated fat percentage in the 1962 subjects was 18.8% compared with 20.7% in 1997. The linoleic acid content was less in the 1997 sample (8.0% cf 10.4%). Adipose fat estimates in 56 rural males aged 40 to 60 in 1997 indicated that in these younger men, differences since 1960 were even more evident. The adipose saturated fats contributed 21.6% of the total fatty acids. The adipose 3 in these 40 to 60 year old rural males were 1.2%, whereas the 6 were 9.9% In the elderly the corresponding percentages were 1.1% and 8.9%. When considering the urban population of Crete, it can be seen that dietary intake patterns are less favourable than those observed in Cretan villages, in a study of practising urban lawyers, adipose saturated fat levels were at 24% for both males (85 subjects) and females (59 subjects). The adipose 3 fatty acids were 1.1%, whereas the 6 were I 1.9% in the male lawyers and for the female lawyers the corresponding values were 1.0% and 12.8%. Further evidence of the gradual abandonment of the traditional Cretan diet is apparent in dietary intake data and the adipose fat composition of primary school children in Crete. In 1998, a sample of the control group aged II to 12 years in a health intervention program (91 children) had a total fat contribution to energy intake o f 42.1 En%, and a dietary saturated fatty acid contribution to energy intake of 14.4 En%. Preliminary data from adipose fatty acid 1998 analyses in the health intervention study indicate a saturated adipose fat percentage of 24.4% and a monounsaturated fatty acid (MUFA) percentage of 59.8%. In contrast, a study undertaken in 1982 presented saturated adipose fat percentages in 8 to 16 year old children in urban (18 children) and rural (20 children) Crete of 19.6% and 20.3% respectively and a MUFA percentages of 70.7% and 69.5% respectively. The deterioration of the diet of the Cretan population is reflected in the increasing total serum cholesterol levels and the increasing morbidity and mortality from cardiovascular diseases in the last few decades. "Supported by the International Olive Oil Council CROSS CULTURAL RELATIONSHIP OF DIETARY HABITS AND CORONARY HEART DISEASE IN THE SEVEN COUNTRIES STUDY A. Menotti. Division of Epidemiology, University of Minnesota, Minneapolis, USA: Associazione Ricerca Cardiologica, Rome, Italy The Seven Countries Study was carried out in 12,763 middle-aged men belonging to 16 cohorts in seven countries (USA, Finland, the Netherlands, Italy, former Yugoslavia, Greece and Japan). Baseline surveys were carried out between 1958 and 1964 and a number of individual characteristics were measured, while dietary information was collected in sub-samples using the weighed record method. Follow-up for vital status and causes of death was complete for 25 years. Since the first 5 years of follow-up strong association were found between some nutrients, such as saturated fatty acids, and incidence and mortality from coronary heart disease (CHD). More recenlty a recoding of nutritional data allowed to identify 18 different food groups and to study their relationship with coronary heart disease long-term mortality.
Large differences in food group consumption were seen, with high consumption of dairy products in Northern Europe, meat in the United States, vegetables, legumes, fish and wine in Southern Europe, and cereals, soya products and fish in Japan. Population death rates from CHD showed large differences, ranging from 268 per 1000 in East Finland to 25 per 1000 in Crete, Greece. Animal food groups were directly correlated, while vegetable food groups (except potatoes) as well as fish and alcohol were inversely correlated with CHD mortality. Univariate analysis showed significant positive correlation coefficients for butter (R =0.887), meat (R = 0.645), pastries (R = 0.752) and milk (R = 0.600) consumption and significant negative correlation coefficients for legumes (R = -0.822), oils (R = -0.571), and alcohol (R = -0.609). Combined vegetable foods (excluding alcohol) were inversely correlated (R = -0.519), whereas combined animal foods (excluding fish) were directly correlated (R = 0.798) with CHD death rates. Multivariate stepwise analysis selected butter, lard+margarine and meat as significant predictors and produced an R square of 0.922. These findings were confirmed by factor analysis with high correlation coefficients between factor scores, identifying cohort dietary patterns, and 25-year CHD mortality. These cross-cultural analyses are consistent with the hypothesis that dietary patterns are important determinants of differences in population CHD death rates, and confirm the opposite effects on apparent risk o f animal and vegetable foods. FLAVONOIDS OF THE MEDITERRANEAN DIET A. Ferro-Luzzi, G. Maiani, G. Catasta. National Institute of Nutrition,
Rome, Italy The Mediterranean diet is universally recognised as being endowed of healthpromoting attributes. It has been associated with lower risks for cardiovascular disease and for cancer of diverse sites. There is still uncertainty, however, relative to the specific mechanism or mechanisms by which this protective action is carried out. General agreement exists o n the role o f the plant component of the diet, which constitutes a larger proportion of total diet than any other "western" diet. Although several other plausible mechanisms are thought to concur, such as the fatty acid profile, the lower total fat content, and the higher fibre content, the focus of the attention has been directed recently on the nutrient antioxidlmts present in fruits and vegetables, such as vitamin C and beta-carotene. It became soon evident that these alone could explain only a fraction of the beneficial health effects of the Mediterranean diet, and a good deal o f new scientific evidence has started to accumulate on the potentially crucial role of a large class of nonnutrient bio-active compounds that are present in all vegetable products: the flavonoids. Plausible protective mechanisms have been identified, that have spurred large numbers o f studies and provided a sound basis for further investigations. The full understanding of this area of research however is currently hampered by three major limitations: the difficulty o f defining with precision what the "Mediterranean diet" was or is; the lack o f data banks on the flavonoids content o f relevant food commodities and their very large natural variability; the scanty knowledge on their bioavailability in man and on the various factors interfering with it. A source o f detailed information on the nature o f the fruits and vegetables consumed in Europe in the early "60s - the EURATOM survey - offers a unique opportunity to examine in detail not only the influence of latitude but also the amplitude of seasonal variations in the consumption of individual and well identifiable vegetables and fruits. The results of this analysis reveal the profound geographic and seasonal differences characterising national dietary habits o f those years. The implications for health of the seasonal alternation in food choices have not been investigated and - regretfully such detailed dietary surveys are rarely carried out. However, it is reasonable to infer, on the basis o f indirect evidence, that much o f these differences and seasonal fluctuations have now disappeared, due to many factors such as societal organization changes, evolution of the agricultural sector, wider commercial availability o f products, better storage conditions and longer shelf-life of perishable products. Thus, the Mediterranean diet - whatever that was in the years when its health-promoting qualities were revealed - might be well on its way to become a thing of the past. A review of the time trend in the fooddisappearance data in several European countries shows in fact that there has been a consistent decline - between the '60s and the 90's - of the plant-based moiety of national diets, with a decrease of cereals, potatoes
71st EAS Congress and Satellite Symposia
C
170
Post-congress, Kos Meditet~'anean diet
and vegetables, and a reciprocal increase in animal-based products and added fats and sugars. However, further comparisons with more recent food consumption survey data suggest that - while attenuated - some of the main North-South differences in the choice of the individual types of fruits and vegetables entering in the diets of present-day Europeans may still persist. The content of flavonoids o f the diet is difficult to calculate, as appropriate tables of food composition are not yet available. An analysis of reconstructed dietary duplicates has provided the first insight in the quantity of five selected flavonoids that were consumed by the Dutch cohort of the 7-Country Study. No such analytical data are available for the Italian or Greek cohort, but a calculation has been made of selected flavonoid intakes of the 16 cohorts participating in the study. The results do not show a consistent trend towards higher intakes of flavonoids in the cohort of Southern Europe, despite their much higher vegetable and fruit intake. However, even the interpretation of chemical analytical data of actual flavonoid content of individual foods and dietary duplicates should be viewed with some caution, similarly to the calculations based on currently available food composition data banks. In fact, the flavonoid composition of plants and fruits is controlled by a large number of external factors, many of which are likely to have evolved over recent years, particularly agricultural practices, food processing technologies and storing facilities. Thus, for example, vegetables produced under green-house conditions a practice much more widespread now than forty years ago - might lead to a lower content of flavonoids. Also other agricultural practices can modulate the phenolic profile and concentration in plants. Even the cultivars currently used in agro-industrial systems of production may differ from those cultivated in the '60s, in the home orchards. Furthermore, flavonoid bioavailability from foods may be promoted by current food-processing technologies ( e.g. lycopene in tomato sauces ) or interfered with ( by matrix of foods or presence of proteins) or their amount reduced by technological processes such as blanching and heating, or domestic cooking (oxidative degradation or leaching into the cooking water). All these uncertainties are further compounded by the ample variations that exist in the flavonoid and anthocyanine content o f foods identified under the same botanical name (onions for example, the yellow skin Salisbury variety containing several times the amount contained in the white skinned variety), wines ( red wines being richer but also highly variable depending many external factors) and olive oil. In conclusion, while flavonoid intake is undoubtedly of great epidemiological significance and with an important disease-preventing potential, we are unable to provide at present a reasonably accurate estimate of the flavonoids of the pristine Mediterranean diet. It is also unlikely that a reliable and representative estimate of the flavonoid intake of current dietary trends in countries with a dominating "Mediterranean" style of eating can be obtained.
FISH AND THE MEDITERRANEAN DIET M.J. Gibney. Department of Clinical Medicine. Trinity College Medical School St. James's Hospital Dublin 8, Ireland The Mediterranean diet is characterized by its inherent features and by its contrast with other dietary patterns in Europe. Most notably, the Mediterranean diet is characterized by a high consumption of olive oil and a high consumption of fruit and vegetables. However, the role of fish in the Mediterranean diet is very dependent on geographic regions e.g. very high fish consumption in the Norther Basque province of Spain compared to the rest of Spain. The role o f alpha-linolenic acid (C18:3 n-3) as a precursor of the n-3 polyunsaturated fatty acid eicosapentaenoic (20:5 n3) is uncertain but given the strong plant-based origins of the former its contribution is likely to be reasonably significant. While the conversion of CI8:3 n-3 to C20:5 n-3 is low, probably about 7%, chronic exposure to low doses of n-3 PUFA such as C18:3 n-3, probably confer an advnatage to the Mediterranean diet. This paper will largely focus on a recent EU-funded study which examined the tong term (16 weeks) dose response (0.003, 06, 09g/d n-3 PUFA) in healthy human volunteers focussing on incorporation of C20:5 n-3 into platelets, fasting plasma triacylglycerol (TAG), postprandial TAG metabolism postprandial coagulated proteins and aspects of reverse cholesterol transport pathway. By and laarge, the idea of an Institute which serves to create networks o f research on food and nutrition has been very well received by scientists, by the EU Commission and European Parliament officials. The fact that IEFS is co-sponsoring, along with the Greek Ministry and DGV, the major EU initiative on "Dietary and Health Lifestyles", which has a very wide level o f participation, is an indicator of the reputation IEFS has attained.
POSTPRANDIAL LIPAEMIA AND THE MEDITERRANEAN DIET C.M. Williams. Hugh Sinclair Unit of Human Nutrition. University of Reading, Reading RG6 6AP, United Kingdom Increasing recognition of the adverse consequences of elevated triglyceride levels in the postprandial state has led to further attempts to delineate effects of both meal, and background diet, composition on postprandial lipaemia There is particular interest in the possibility that cross cultural differences in the intakes of the major fatty acid classes - saturated, monounsaturated and n-6 and n-3 polyunsaturated fatty acids may contribute to differences in risk of CHD partly through their effects on postprandial lipaemia. There is clear evidence that when added to the background diet, the very long chain n-3 polyunsaturated fatty acids (PUFAs) from fish oil have potent triglyceride-lowering effects resulting in marked reductions in both fasting triglycerides and attenuation of the postprandial response to a standard meal. However, the dietary level at which these fatty acids have been shown to attenuate postprandial lipaemia in short term studies are generally higher than those which exist in the Mediterranean diet. In addition, dietary supplementation or enrichment with the precursor n-3 PUFA, alpha-linolenic acid, has not been shown to result in alteration in either fasting triglycerides or postprandial lipaemia even at very high supplemental intake levels. From these data it would seem unlikely that the cardioprotective effects of the Mediterrranean diet originate from beneficial effects of n-3 PUFA on postprandial lipaemia. In meal studies, substitution of meal saturated fatty acids with monounsaturated fatty acids (MUFAs) up to levels found in olive oil, has not been shown to be associated with attenuated postprandial lipaemia and some studies report an exaggerated postprandial triglyceride response when olive oil is used as the source of fat in the meal. In contrast we compared responses to standard test meals in subjects from Southern and Northern Europe who were habituated to diets of different saturated and monunsaturated fat content. In subjects from Southern Europe, although triglyceride responses were higher in the early postprandial period they were lower in the late postprandial period compared with the Northern Europeans. In a group of Northern European subjects transferred onto a high MUFA diet, the pattern of postprandial response altered towards that seen in the Southern European subjects. We have speculated that the pattern of postprandial triglyceride response observed in Southern Europeans reflects more efficient absorption and clearance o f dietary fat. An efficient fat-catabolising system may be cardioprotective by maintaining low levels of remnant panicles, Io~ activation of factor VII and reduced capacity for neutral lipid exchange and small dense LDL formation in the late postprandial period. The author acknowledges the important contributions of her collaborators at the Universities of Crete, Dublin and Surrey and financial support from the EU and MAFF (UK).
ALPHA-LINOLENIC ACID IN THE CRETAN DIET AND THE PROTECTION OF SUDDEN DEATH S. Renaud, D. Lanzmann. INSERM, Unit 330. University BordeatLr 2 and Centre Jean Theves, Athis-Mons, France Cardiac mortality, especially sudden death, has been rarely prevented in dietary intervention ~ a l s to lower coronary heart disease (CHD). Only trials with an increased level o f n-3 fatty acids (fish or fish oil) (DART Lancet 1989:2:757) have succeeded so far. In Crete, cardiac death as shown by the seven country study is a rare event. In our duplication of the Cretan diet on 600 coronary patients (Lancet 1994:343:1454) we did not observe any sudden death as compared to l0 in the control group with the prudent diet. Like the Crete population (Eur J Clin Nutr 1993:47:20), our subjects with the Cretan diet had a high level of oleic and alpha-linolenic acids in their plasma. Studies have shown that arrhythmia of myocytes in culture, and ventricular fibrillation in dogs and rats are inhibited by n-3 fatty acids (Proc Natl Acad Sei USA 1997:94:4182). In rat reperfusion ventricular fibrillation was inhibited only by the alpha-linolenic acid rich rapeseed oil but not by olive oil. (J Nutr 1995:125:1003) In Crete it seems that it is through the consumption of walnuts, purslane and other greens as well as of snails, that a high intake of alpha-linolenic acid is achieved. Recent prospective studies in USA (Harvard Public Health) and Europe (Euramic) indicate that the only fatty acid apparently inhibiting cardiac mortality in man is alpha-linolenic acid. Thus, alpha-linolenic acid, in addition to regulate the level o f prostaglandins and leukotrienes, may be the main fatty acid protecting from CHD clinical manifestations, especially sudden death.
71st EAS Congress and Satellite Symposia
Tuesday, 1 June 1999 Mediterranean diet ['HE DIET OF CRETE: PAST AND PRESENT ~,. Kafatos, J. Moschandreas. University of Crete School of Medicine, )epartment of Social Medicine, Preventive Medicine & Nutrition Clinic, '~eraklion, Crete, Greece I'he diet of inhabitants of the Greek island of Crete has long been hailed Ls a prime example o f the Mediterranean diet with all its cardioprotective )enefits. The present paper investigates the changes in this diet over the last "our decades by reviewing data from previous investigations and presenting he latest findings on dietary trends in recent years. Dietary intake is ;stimated using dietary records and adipose fat measurements, the latter )eing a biochemical marker reflecting the long-term dietary fat intake. The thirty seven year follow-up of the Cretan Seven Countries cohort has ~rovided evidence of changes in dietary habits even in deeply rural areas of Me island, in 1960, 8% o f the total energy intake was from saturated fats ~¢hereas by 1998 (157 men), this had risen to 1 I%. Adipose fat comparisons 3f 112 surviving cohort members in 1997 with a sample of 200 Cretan men ~n 1962 indicated that certain of the saturated fatty acids were slightly higher in the 1997 Cretan cohort eg mean myristic acid 1.7% in 1997 cf 1.2% in Se 1962 subjects. The total saturated fat percentage in the 1962 subjects was 18.8% compared with 20.7% in 1997. The linoleic acid content was less in the 1997 sample (8.0% cf 10.4%). Adipose fat estimates in 56 rural males aged 40 to 60 in 1997 indicated that in these younger men, differences since 1960 were even more evident. The adipose saturated fats contributed 21.6% of the total fatty acids. The adipose 3 in these 40 to 60 year old rural males were 1.2%, whereas the 6 were 9.9% In the elderly the corresponding percentages were 1.1% and 8.9%. When considering the urban population of Crete, it can be seen that dietary intake patterns are less favourable than those observed in Cretan villages, in a study of practising urban lawyers, adipose saturated fat levels were at 24% for both males (85 subjects) and females (59 subjects). The adipose 3 fatty acids were 1.1%, whereas the 6 were I 1.9% in the male lawyers and for the female lawyers the corresponding values were 1.0% and 12.8%. Further evidence of the gradual abandonment of the traditional Cretan diet is apparent in dietary intake data and the adipose fat composition of primary school children in Crete. In 1998, a sample of the control group aged II to 12 years in a health intervention program (91 children) had a total fat contribution to energy intake o f 42.1 En%, and a dietary saturated fatty acid contribution to energy intake of 14.4 En%. Preliminary data from adipose fatty acid 1998 analyses in the health intervention study indicate a saturated adipose fat percentage of 24.4% and a monounsaturated fatty acid (MUFA) percentage of 59.8%. In contrast, a study undertaken in 1982 presented saturated adipose fat percentages in 8 to 16 year old children in urban (18 children) and rural (20 children) Crete of 19.6% and 20.3% respectively and a MUFA percentages of 70.7% and 69.5% respectively. The deterioration of the diet of the Cretan population is reflected in the increasing total serum cholesterol levels and the increasing morbidity and mortality from cardiovascular diseases in the last few decades. "Supported by the International Olive Oil Council CROSS CULTURAL RELATIONSHIP OF DIETARY HABITS AND CORONARY HEART DISEASE IN THE SEVEN COUNTRIES STUDY A. Menotti. Division of Epidemiology, University of Minnesota, Minneapolis, USA: Associazione Ricerca Cardiologica, Rome, Italy The Seven Countries Study was carried out in 12,763 middle-aged men belonging to 16 cohorts in seven countries (USA, Finland, the Netherlands, Italy, former Yugoslavia, Greece and Japan). Baseline surveys were carried out between 1958 and 1964 and a number of individual characteristics were measured, while dietary information was collected in sub-samples using the weighed record method. Follow-up for vital status and causes of death was complete for 25 years. Since the first 5 years of follow-up strong association were found between some nutrients, such as saturated fatty acids, and incidence and mortality from coronary heart disease (CHD). More recenlty a recoding of nutritional data allowed to identify 18 different food groups and to study their relationship with coronary heart disease long-term mortality.
Large differences in food group consumption were seen, with high consumption of dairy products in Northern Europe, meat in the United States, vegetables, legumes, fish and wine in Southern Europe, and cereals, soya products and fish in Japan. Population death rates from CHD showed large differences, ranging from 268 per 1000 in East Finland to 25 per 1000 in Crete, Greece. Animal food groups were directly correlated, while vegetable food groups (except potatoes) as well as fish and alcohol were inversely correlated with CHD mortality. Univariate analysis showed significant positive correlation coefficients for butter (R =0.887), meat (R = 0.645), pastries (R = 0.752) and milk (R = 0.600) consumption and significant negative correlation coefficients for legumes (R = -0.822), oils (R = -0.571), and alcohol (R = -0.609). Combined vegetable foods (excluding alcohol) were inversely correlated (R = -0.519), whereas combined animal foods (excluding fish) were directly correlated (R = 0.798) with CHD death rates. Multivariate stepwise analysis selected butter, lard+margarine and meat as significant predictors and produced an R square of 0.922. These findings were confirmed by factor analysis with high correlation coefficients between factor scores, identifying cohort dietary patterns, and 25-year CHD mortality. These cross-cultural analyses are consistent with the hypothesis that dietary patterns are important determinants of differences in population CHD death rates, and confirm the opposite effects on apparent risk o f animal and vegetable foods. FLAVONOIDS OF THE MEDITERRANEAN DIET A. Ferro-Luzzi, G. Maiani, G. Catasta. National Institute of Nutrition,
Rome, Italy The Mediterranean diet is universally recognised as being endowed of healthpromoting attributes. It has been associated with lower risks for cardiovascular disease and for cancer of diverse sites. There is still uncertainty, however, relative to the specific mechanism or mechanisms by which this protective action is carried out. General agreement exists o n the role o f the plant component of the diet, which constitutes a larger proportion of total diet than any other "western" diet. Although several other plausible mechanisms are thought to concur, such as the fatty acid profile, the lower total fat content, and the higher fibre content, the focus of the attention has been directed recently on the nutrient antioxidlmts present in fruits and vegetables, such as vitamin C and beta-carotene. It became soon evident that these alone could explain only a fraction of the beneficial health effects of the Mediterranean diet, and a good deal o f new scientific evidence has started to accumulate on the potentially crucial role of a large class of nonnutrient bio-active compounds that are present in all vegetable products: the flavonoids. Plausible protective mechanisms have been identified, that have spurred large numbers o f studies and provided a sound basis for further investigations. The full understanding of this area of research however is currently hampered by three major limitations: the difficulty o f defining with precision what the "Mediterranean diet" was or is; the lack o f data banks on the flavonoids content o f relevant food commodities and their very large natural variability; the scanty knowledge on their bioavailability in man and on the various factors interfering with it. A source o f detailed information on the nature o f the fruits and vegetables consumed in Europe in the early "60s - the EURATOM survey - offers a unique opportunity to examine in detail not only the influence of latitude but also the amplitude of seasonal variations in the consumption of individual and well identifiable vegetables and fruits. The results of this analysis reveal the profound geographic and seasonal differences characterising national dietary habits o f those years. The implications for health of the seasonal alternation in food choices have not been investigated and - regretfully such detailed dietary surveys are rarely carried out. However, it is reasonable to infer, on the basis o f indirect evidence, that much o f these differences and seasonal fluctuations have now disappeared, due to many factors such as societal organization changes, evolution of the agricultural sector, wider commercial availability o f products, better storage conditions and longer shelf-life of perishable products. Thus, the Mediterranean diet - whatever that was in the years when its health-promoting qualities were revealed - might be well on its way to become a thing of the past. A review of the time trend in the fooddisappearance data in several European countries shows in fact that there has been a consistent decline - between the '60s and the 90's - of the plant-based moiety of national diets, with a decrease of cereals, potatoes
71st EAS Congress and Satellite Symposia
C
170
Post-congress, Kos Meditet~'anean diet
and vegetables, and a reciprocal increase in animal-based products and added fats and sugars. However, further comparisons with more recent food consumption survey data suggest that - while attenuated - some of the main North-South differences in the choice of the individual types of fruits and vegetables entering in the diets of present-day Europeans may still persist. The content of flavonoids o f the diet is difficult to calculate, as appropriate tables of food composition are not yet available. An analysis of reconstructed dietary duplicates has provided the first insight in the quantity of five selected flavonoids that were consumed by the Dutch cohort of the 7-Country Study. No such analytical data are available for the Italian or Greek cohort, but a calculation has been made of selected flavonoid intakes of the 16 cohorts participating in the study. The results do not show a consistent trend towards higher intakes of flavonoids in the cohort of Southern Europe, despite their much higher vegetable and fruit intake. However, even the interpretation of chemical analytical data of actual flavonoid content of individual foods and dietary duplicates should be viewed with some caution, similarly to the calculations based on currently available food composition data banks. In fact, the flavonoid composition of plants and fruits is controlled by a large number of external factors, many of which are likely to have evolved over recent years, particularly agricultural practices, food processing technologies and storing facilities. Thus, for example, vegetables produced under green-house conditions a practice much more widespread now than forty years ago - might lead to a lower content of flavonoids. Also other agricultural practices can modulate the phenolic profile and concentration in plants. Even the cultivars currently used in agro-industrial systems of production may differ from those cultivated in the '60s, in the home orchards. Furthermore, flavonoid bioavailability from foods may be promoted by current food-processing technologies ( e.g. lycopene in tomato sauces ) or interfered with ( by matrix of foods or presence of proteins) or their amount reduced by technological processes such as blanching and heating, or domestic cooking (oxidative degradation or leaching into the cooking water). All these uncertainties are further compounded by the ample variations that exist in the flavonoid and anthocyanine content o f foods identified under the same botanical name (onions for example, the yellow skin Salisbury variety containing several times the amount contained in the white skinned variety), wines ( red wines being richer but also highly variable depending many external factors) and olive oil. In conclusion, while flavonoid intake is undoubtedly of great epidemiological significance and with an important disease-preventing potential, we are unable to provide at present a reasonably accurate estimate of the flavonoids of the pristine Mediterranean diet. It is also unlikely that a reliable and representative estimate of the flavonoid intake of current dietary trends in countries with a dominating "Mediterranean" style of eating can be obtained.
FISH AND THE MEDITERRANEAN DIET M.J. Gibney. Department of Clinical Medicine. Trinity College Medical School St. James's Hospital Dublin 8, Ireland The Mediterranean diet is characterized by its inherent features and by its contrast with other dietary patterns in Europe. Most notably, the Mediterranean diet is characterized by a high consumption of olive oil and a high consumption of fruit and vegetables. However, the role of fish in the Mediterranean diet is very dependent on geographic regions e.g. very high fish consumption in the Norther Basque province of Spain compared to the rest of Spain. The role o f alpha-linolenic acid (C18:3 n-3) as a precursor of the n-3 polyunsaturated fatty acid eicosapentaenoic (20:5 n3) is uncertain but given the strong plant-based origins of the former its contribution is likely to be reasonably significant. While the conversion of CI8:3 n-3 to C20:5 n-3 is low, probably about 7%, chronic exposure to low doses of n-3 PUFA such as C18:3 n-3, probably confer an advnatage to the Mediterranean diet. This paper will largely focus on a recent EU-funded study which examined the tong term (16 weeks) dose response (0.003, 06, 09g/d n-3 PUFA) in healthy human volunteers focussing on incorporation of C20:5 n-3 into platelets, fasting plasma triacylglycerol (TAG), postprandial TAG metabolism postprandial coagulated proteins and aspects of reverse cholesterol transport pathway. By and laarge, the idea of an Institute which serves to create networks o f research on food and nutrition has been very well received by scientists, by the EU Commission and European Parliament officials. The fact that IEFS is co-sponsoring, along with the Greek Ministry and DGV, the major EU initiative on "Dietary and Health Lifestyles", which has a very wide level o f participation, is an indicator of the reputation IEFS has attained.
POSTPRANDIAL LIPAEMIA AND THE MEDITERRANEAN DIET C.M. Williams. Hugh Sinclair Unit of Human Nutrition. University of Reading, Reading RG6 6AP, United Kingdom Increasing recognition of the adverse consequences of elevated triglyceride levels in the postprandial state has led to further attempts to delineate effects of both meal, and background diet, composition on postprandial lipaemia There is particular interest in the possibility that cross cultural differences in the intakes of the major fatty acid classes - saturated, monounsaturated and n-6 and n-3 polyunsaturated fatty acids may contribute to differences in risk of CHD partly through their effects on postprandial lipaemia. There is clear evidence that when added to the background diet, the very long chain n-3 polyunsaturated fatty acids (PUFAs) from fish oil have potent triglyceride-lowering effects resulting in marked reductions in both fasting triglycerides and attenuation of the postprandial response to a standard meal. However, the dietary level at which these fatty acids have been shown to attenuate postprandial lipaemia in short term studies are generally higher than those which exist in the Mediterranean diet. In addition, dietary supplementation or enrichment with the precursor n-3 PUFA, alpha-linolenic acid, has not been shown to result in alteration in either fasting triglycerides or postprandial lipaemia even at very high supplemental intake levels. From these data it would seem unlikely that the cardioprotective effects of the Mediterrranean diet originate from beneficial effects of n-3 PUFA on postprandial lipaemia. In meal studies, substitution of meal saturated fatty acids with monounsaturated fatty acids (MUFAs) up to levels found in olive oil, has not been shown to be associated with attenuated postprandial lipaemia and some studies report an exaggerated postprandial triglyceride response when olive oil is used as the source of fat in the meal. In contrast we compared responses to standard test meals in subjects from Southern and Northern Europe who were habituated to diets of different saturated and monunsaturated fat content. In subjects from Southern Europe, although triglyceride responses were higher in the early postprandial period they were lower in the late postprandial period compared with the Northern Europeans. In a group of Northern European subjects transferred onto a high MUFA diet, the pattern of postprandial response altered towards that seen in the Southern European subjects. We have speculated that the pattern of postprandial triglyceride response observed in Southern Europeans reflects more efficient absorption and clearance o f dietary fat. An efficient fat-catabolising system may be cardioprotective by maintaining low levels of remnant panicles, Io~ activation of factor VII and reduced capacity for neutral lipid exchange and small dense LDL formation in the late postprandial period. The author acknowledges the important contributions of her collaborators at the Universities of Crete, Dublin and Surrey and financial support from the EU and MAFF (UK).
ALPHA-LINOLENIC ACID IN THE CRETAN DIET AND THE PROTECTION OF SUDDEN DEATH S. Renaud, D. Lanzmann. INSERM, Unit 330. University BordeatLr 2 and Centre Jean Theves, Athis-Mons, France Cardiac mortality, especially sudden death, has been rarely prevented in dietary intervention ~ a l s to lower coronary heart disease (CHD). Only trials with an increased level o f n-3 fatty acids (fish or fish oil) (DART Lancet 1989:2:757) have succeeded so far. In Crete, cardiac death as shown by the seven country study is a rare event. In our duplication of the Cretan diet on 600 coronary patients (Lancet 1994:343:1454) we did not observe any sudden death as compared to l0 in the control group with the prudent diet. Like the Crete population (Eur J Clin Nutr 1993:47:20), our subjects with the Cretan diet had a high level of oleic and alpha-linolenic acids in their plasma. Studies have shown that arrhythmia of myocytes in culture, and ventricular fibrillation in dogs and rats are inhibited by n-3 fatty acids (Proc Natl Acad Sei USA 1997:94:4182). In rat reperfusion ventricular fibrillation was inhibited only by the alpha-linolenic acid rich rapeseed oil but not by olive oil. (J Nutr 1995:125:1003) In Crete it seems that it is through the consumption of walnuts, purslane and other greens as well as of snails, that a high intake of alpha-linolenic acid is achieved. Recent prospective studies in USA (Harvard Public Health) and Europe (Euramic) indicate that the only fatty acid apparently inhibiting cardiac mortality in man is alpha-linolenic acid. Thus, alpha-linolenic acid, in addition to regulate the level o f prostaglandins and leukotrienes, may be the main fatty acid protecting from CHD clinical manifestations, especially sudden death.
71st EAS Congress and Satellite Symposia