Risques et bénéfices pour la santé des acides gras trans apportés par les aliments. Recommandations

¹ Institut de biologie, EA2993 Nutrition humaine et athérogenèse, Faculté de Médecine, UM-1, 4, Bd Henri IV 34060 Montpellier
² AFSSA, Coordinatrice scientifique

Abstract

The French Food Safety Agency (Agence Française de Sécurité Sanitaire des Aliments, AFSSA) has recently adopted a definite position on risks and benefits of food trans fatty acids (TFA) for human health. After considering available data on origins and biological activities of all types of TFA, including conjugated fatty acids (CLA), it has been proposed a regulatory definition of these fatty acids which is the chemical one : « the trans fatty acids are all unsaturated fatty acids that contain at least one double bond in a trans configuration ». This definition includes the CLA and TFA of animal origin. Daily intakes of TFA (except CLA) in France was found to be 3 g/d in adults, i.e. 1.3 % total energy intake (E %). The male children are the most exposed to high TFA intakes which culminate at 2.5 E % for the 95 th percentile of the 12-14 year-old male children. Consumption of usual foods (not including the consumption of synthetic CLA supplements) leads to a rumenic acid daily intake inferior to 200 mg/d (0.08 E %). The contribution of TFA of animal origin is 60 % in adult (55 % for milk and dairy products) and 55 % (44 %) for male children, showing a higher consumption of TFA of technological origin in the form of bakery products in children than in adults. According to epidemiological data, TFA intakes (except CLA) of 2 E % are associated to a 25 % increased risk of the coronary heard disease. Clinical studies show that the CLA 10t,12c at the dose of 2.6 g/d should be considered potentially proatherogenic. The loss of body fat mass (the anti-obesity effect) with the administration of CLA mixture 9c,11t + 10t,12c (or 10t,12c alone) is obtained at a daily doses ranging from 1.6 to 6.8 g/d (2.6 g/d), but the loss is generally low even in the case of long term administration and adverse effects are observed in particular with 2.6 g/d CLA 10t,12c regarding insuline resistance, insulinemia, C-peptide, glycemia, HDL-C, enzymatic and non enzymatic peroxydations. The main AFSSA’s recommendations (non exhaustive list) are as follows : people should decrease their consumption of bakery products by 30 %, TFA contents of bakery products should not exceed 1 g per 100 g of the commercialized product, TFA contents of every types of margarines bought by the consumer should be lower than 1% of total fatty acids. Because of the prevalence of calcium deficiency particularly in children, declining consumption of dairy products is not recommended, but consumption of (half-)skimmed milk or products elaborated with (half-)skimmed milk should be preferred. Considering the lack of information on the relationship between animal traditional feeding and TFA contents of animal products that people consume, no content upper-limit is proposed for animal (or more specifically dairy) products. AFSSA points out that administration of the synthetic CLA supplement is not justified in humans and animals as well. Information on trans fatty acid in nutrition labeling should be mandatory for contents higher than 0.1 g/100 g in bakery and dairy products, and 0.1% for vegetable oils, margarines and butter. Given the very low levels of CLA in foods usually consumed, the CLA labeling is assumed to be purposeless.