Alimentación, nutrición y dietética TRANS FATTY ACIDS PRESENT IN OUR FOOD: WHAT MUST WE REQUEST FROM INDUSTRY?

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1 TRANS FATTY ACIDS PRESENT IN OUR FOOD: WHAT MUST WE REQUEST FROM INDUSTRY? Martijn B. Katan Ph.D. Wageningen Centre for Food Sciences And Division of Human Nutrition and Epidemiology. Wageningen Agricultural University Bomenweg HD Wageningen The Netherlands Trans fatty acids and their effects on health. Until some ten years ago, partially hydrogenated vegetable oils were considered a wholesome and perhaps even beneficial component of foods. Such hydrogenated or hardened fats are rich in trans fatty acids. These are unsaturated fatty acids, but their molecualr structure is slightly different from that of the unsaturated fatty acids that occur naturally in vegetable oils. These differences in structure can be precisely tuned during hydrogenation to yield a fat with a desired melting range, mouthfeel, and stability. Hardening was therefore a way to tailor fats to the needs of a partical industry and a particular product. Until 1990 the conventional wisdom was that trans fatty acids were innocuous, although a few scientists did worry about possible harm 1 2. However, studies in the 1960s and 1970s by Keys and coworkers 3 and by the Unilever research laboratory 4 had shown only a modest cholesterol-elevating effect of partially hydrogenated fats on total serum cholesterol levels, while a study from the laboratories of Procter and Gamble 5 showed no effect at all. As total cholesterol was considered the major intermediary between dietary fats and coronary heart disease, this seemed to give trans fatty acids a clean bill. Two papers were instrumental in changing this view. The first one, by Mensink and Katan 6, showed that the modest rise in cholesterol induced by trans fatty acids concealed a large rise in LDL combined with a fall in HDL; the authors therefore concluded that the effect of trans fatty acids on the serum lipoprotein profile was as least as unfavorable as that of the cholesterol-raising saturated fatty acids. The second paper, by Willett and coworkers, reported a direct association between trans fatty acids intake and subsequent coronary heart disease in a large cohort of women 7, and suggested that the practice of partially hydrogenating vegetable oils contributed to the occurrence of coronary heart disease. In 1994, Willett and Ascherio 8, stated the message regarding the adverse effects of trans fatty acids more forcefully by publishing a calculation that greater than 30,000 deaths per year in the US might be due to consumption of partially hydrogenated vegetable fat. This statement caused much controversy even though the calculation was straightforward, and indeed fairly conservative. The only debatable assumption was that the association between low HDL levels and coronary heart disease is causal, and that therefore a fall in HDL caused by consumption of trans fatty acids will increase coronary heart disease mortality. Although the evidence for this is less complete than that for changes in LDL, the assumption is plausible: the association between low HDL levels and coronary heart disease is consistent and strong, and drugs that raise HDL lower the incidence of coronary heart disease in randomized clinical trials. 9 64

2 Apart from the dramatic presentation in terms of number of deaths, the controversy over the paper of Willett and Ascherio 8 stemmed mostly from the fact that in the US margarines had long been advanced as the healthy alternative to butter. As most US margarines contained a high proportion of trans fatty acids, scientists and health educators to say nothing of industry faced a painful about-turn if the adverse effects of trans were to prove true. The situation in Europe and elsewhere was somewhat easier. Soft margarines high in polyunsaturated fatty acids had been positioned as heart-healthy in Europe from the late 1960s on but these margarines contained little or no trans fatty acids not because of health concerns but for purely technical reasons. Such margarines are made of a mixture of a liquid oil with small amounts of a hard fat, the socalled hardstock. The hard fat can be a tropical fat such as palm oil which has saturated but no trans fatty acids, or a partially hydrogenated oil such as hardened soybean oil. Partially hydrogenated oils are high in trans fatty acids but because the proportion of hardstock in heart healthy margarines is much lower than the proportion of unhardened oil the final trans fatty acids content was low even in European countries that did use hardened oil as a hardstock. However, the regular brands of margarine in Europe were often high in trans fatty acids derived form partially hydrogenated vegetable and fish oil, and these margarines were affected by the new findings. Partially hydrogenated edible oils are a major commodity world wide, and the controversy about their health effects spawned a large number of studies (e.g. 10.) Together these have led to a consensus that trans fatty acids raise the bad LDL cholesterol as strongly as saturated fatty acids, and that in addition they depress the good HDL cholesterol which saturated fatty acids do not. Trans fatty acids also cause a small elevation of lipoprotein(a) and an increase in fasting serum triglycerides 11 The effects of trans fatty acids on blood lipids and lipoproteins form "a sound basis on which to make a strong recommendation to the general public and to food manufacturers to emphasize the use of vegetable oils in their natural state and after minimal hydrogenation", to quote Lichtenstein et al 10. This statement forms part of a broadening consensus on the adverse effects of trans fatty acids. This in turn has recently prompted the US Food and Drug Administration (FDA) to propose a requirement that the amount of trans fatty acids in a food be included in the Nutrition Facts panel of food labels in America 12 Food sources of trans fatty acids Food manufacturers in Europe, Canada and elsewhere had already removed trans fatty acids from most of their retail margarines and other retail fats 4-5 years ago when the deleterious effects of trans fatty acids first became clear 13. Trans-free margarines are now also available in the US. However, margarines were never the major source of trans fatty acids in the US in the first place. The reason why attention in that country focused so much on margarines was perhaps that the findings on trans were in such stark contrast with the health claims made for margarines earlier on. However, the largest dietary source of trans fatty acids both in the US and elsewhere is actually the hard fats which are used for industrial food preparation and which are called shortenings. In 1997, US per capita consumption of fat from margarines was 9.9 pounds per year (12 g/d) as opposed to 20.9 pounds per year (26 g/d) from vegetable shortenings 14. The rapid growth of away-from-home eating will make the difference even larger, because shortenings typically go into the foods that hurried consumers eat "on the go" such as baked goods and sweets, and vegetable shortenings are used extensively for deep-fat frying in the food service industry. Such shortenings are made from partially hydrogenated vegetable oils, and they contain 11 to 34% trans fatty acids 15 As a result a medium helping of French fries contains 5-6 gram, a doughnut 2 gram and an ounce of crackers 2 gram of trans fatty acids

3 What must we request from industry? Can manufacturers replace these high-trans shortenings by better fats? Yes, they can, but they need the support from governments. Lichtenstein et al 10 recommended that food manufacturers emphasize the use of vegetable oils in their natural state. For margarines and cooking fats this can be done, and in most European countries it has in fact been alrgely achieved for retail fats bought by consumers. Substitution of unhydrogenated for partially hydrogenated oils in cookies, crackers, pastries and other baked goods is more difficult because it may degrade mouthfeel and shelf life, and unhydrogenated oils are also less stable upon deep fat frying. Technology could probably overcome these problems, but the investment required is huge. In addition to cost, manufacturers might be reluctant to invest in fast foods with less trans fatty acids because unlike retail margarine, food eaten away from home usually does not carry a nutrition label. Costly efforts to reduce trans fatty acid content and improve the health value of fast foods might therefore go unnoticed by consumers and bring no profit to the producer. Therefore governments and the Commission of the European Union need to step in and provide regulations (see table) TABLE 1. WHAT MUST WE REQUEST...? Fat producers: FROM INDUSTRY Reduce the proportion of trans and saturated fatty acids in table spreads and cooking fats sold to consumers Food producers: Clearly label the type of fatty acids present in retail foods Develop technologies for using oils low in trans and saturated fatty acids in cookies, crackers, pastries and other baked goods Food service and fast food industry: Tell consumers what kind of fat you use in food preparation Provide fast foods prepared with unhardened oils WHAT MUST WE REQUEST FROM GOVERNMENTS AND EU Demand that foods are labelled so that consumers can decide whether these foods are healthy Require the food service, fast food, and restaurant industry to provide information on the health value of the foods sold Give industry more room to make health claims for foods Have such claims regularly checked by independent experts Thus there is still a long way to go in replacing trans fatty acids by more healthy fats. However, the enterprise is worthwhile because it can have a marked impact on coronary heart disease risk, because it requires no effort from the consumer (though a major effort from the producer) and because the largest consumers of foods rich in trans fatty acids are often the poor, the young and the less educated who have the least healthy lifestyle and are not easily reached by nutrition education efforts. 66

4 Wider implications of the trans fatty acids story What happened in the field of trans fatty acids over the past 10 years has some implications that go beyond margarines and shortenings. First, it confirmed the strength of the scientific approach to public health controversies. In a plea for the application of rational science to complicated health issues, Borst has said: "The greatest strength of the scientific approach is always that it can yield compelling data that are highly counter-intuitive" 16. Ten years ago it seemed highly counter-intuitive that partially hydrogenated soybean oil could be as bad for the lipoprotein risk profile as butter, but compelling data have forced us to rethink the issue, all to the benefit of the health of consumers. Second, the agreement between findings from scientists around the globe has been remarkable. A Sounding Board paper in the New England Journal of Medicine reviewed the effects of trans fatty acids on the LDL/HDL ratio. It found that the outcomes of studies performed around the world over the past 10 years lie closely around a straight line that relates the intake of trans with the elevation of the LDL/HDL ratio 17. Thus this type of empirical study can yield results of general validity even though the mechanism through which fatty acids affect blood lipoprotein levels remain unclear. Finally, entire populations can evidently eat food components that increase disease risk without that being noticed for many years. Foodstuffs are often considered safe and wholesome if large populations have eaten them for a long time without apparent harm, but the validity of this approach has never been critically evaluated. Outcrops of rare diseases will soon catch the eye of an attentive doctor: thus AIDS was quickly recognized as a new disease because it caused Kaposi's sarcoma, which until then was a highly uncommon disease. But factors that increase the occurrence of more common diseases can go unrecognized for a long time. The cholesterol-raising factor from coffee beans is an example 18. Scandinavian populations have for ages consumed large amounts of boiled coffee rich in cafestol that markedly raises cholesterol and the risk of coronary heart disease. However, nobody noticed the association between this particular technique of brewing coffee and the risk of coronary heart disease in Finland and Norway until systematic epidemiological and experimental studies made the conclusion inevitable. The same happened with partially hydrogenated fats, which have been a major food ingredient for most of the past century. Thus only painstaking quantitative research can teach us whether a food is healthy or not. Hard data are also indispensible to convince the food industry to change its products, because the investments required are huge and cannot be made frivolously. In the case of trans fatty acids, the system has worked, even though there is much left to be done. 67

5 REFERENCE LIST 1. Kummerow FA. Nutrition imbalance and angiotoxins as dietary risk factors in coronary heart disease. Am J Clin Nutr 1979; 32: Enig MG, Munn RJ, Keeney M. Dietary fat and cancer trends - a critique. Fed Proc 1978; 37: Anderson JT, Grande F, Keys A. Hydrogenated fats in the diet and lipids in the serum of man. J Nutr 1961; 75: Vergroesen AJ. Dietary fat and cardiovascular disease: possible modes of action of linoleic acid. P Nutr Soc 1972; 31: Mattson FH, Hollenbach EJ, Kligman AM. Effect of hydrogenated fat on the plasma cholesterol and triglyceride levels of man. Am J Clin Nutr 1975; 28: Mensink RP, Katan MB. Effect of dietary trans fatty acids on high-density and low- density lipoprotein cholesterol in healthy subjects. New Engl J Med 1990; 323: Willett WC, Stampfer MJ, Manson JE, Colditz GA, Speizer FE, Rosner BA, et al. Intake of trans fatty acids and risk of coronary heart disease among women. Lancet 1993; 341: Willett WC, Ascherio A. Trans fatty acids: are the effects only marginal? Am J Public Health 1994; 84: Rubins HB, Robins SJ, Collins D, Fye CL, Anderson J, Elam MB, et al. Gemfibrozil for the secondary prevention of coronary heart disease in men with low levels of high-density lipoprotein cholesterol. New Engl J Med 1999; 341: Lichtenstein AH, Ausman LM, Jalbert SM, Schaefer EJ. Effects of different forms of dietary hydrogenated fats on serum lipoprotein cholesterol levels. New Engl J Med 1999; 340: Katan MB, Mensink RP, Zock PL. Trans fatty acids and their effect on lipoproteins in humans. Annu Rev Nutr 1995; 15: U.S.Department of Health and Human Services. FDA Proposes New Rules for Trans Fatty Acids in Nutrition labeling, Nutrient Content Claims, and Health Claims. HHS News visited 12 Nov Katan MB. Exit trans fatty acids. Lancet 1995; 346: U.S.Department of Agriculture. Sanford S, Allshouse J. Have we turned the corner on fat consumption? FoodReview 1998; 21: visited 16 June U.S.Department of Agriculture. Agricultural Research Service USDA. Nutrient Database for Standard Reference, Release 13, Nutrient Data Laboratory Home Page, visited 10 Nov Borst P. Geluk in de Wetenschap [in Dutch]. University Press, (no editor) 17. Ascherio A, Willett WC, Katan MB, Zock PL. Trans Fatty Acids and Coronary Heart Disease. New Engl J Med 1999; 340: Urgert R, Katan MB. The cholesterol-raising factor from coffee beans. Annu Rev Nutr 1997; 17:

Alimentación, nutrición y dietética SUPLEMENTOS POLIVITAMÍNICOS Y POLIMINERALES. SU PAPEL EN LA SITUACIÓN ACTUAL

Alimentación, nutrición y dietética SUPLEMENTOS POLIVITAMÍNICOS Y POLIMINERALES. SU PAPEL EN LA SITUACIÓN ACTUAL SUPLEMENTOS POLIVITAMÍNICOS Y POLIMINERALES. SU PAPEL EN LA SITUACIÓN ACTUAL Miriam Becker Food Chemist and Technical Marketing Manager Merck KGaA, Darmstadt, Germany. The presentation will give an overview