Contribution oftrans-18∶1 acids from dairy fat to european diets

Twelve commercial samples of French butter, purchased in October–November, and 12 other samples, purchased in May–June, were analyzed with particular attention to theirtrans-octadecenoic acid contents. The isomeric fatty acids were quantitated by a combination of gas-liquid chromatography (GLC) of total fatty acids as isopropyl esters on a polar capillary column (CPSil 88) and of silver nitrate-impregnated thin-layer chromatography followed by GLC of the pooled saturated (used as internal standards) andtrans-octadecenoic acid fractions. Autumn butters contained 3.22±0.44%trans-octadecenoic acids (relative to total fatty acids), whereas those collected during the spring contained 4.28±0.47% (P<0.01). Minimum and maximum values for the two sets of butters were 2.46 (autumn) and 5.10% (spring), respectively. The annual mean value for thetrans-octadecenoic acid content in all butter samples was 3.8% of total fatty acids (ca. 2% for thetrans-11 18∶1 acid). This value allows calculation of the daily individual intake oftrans-octadecenoic acids from dairy products by populations of member states of the European Economic Community (EEC). It varies from 0.57 g (Portugal) to 1.66 g (Denmark). The mean value for the twelve countries of the EEC is 1.16 g/person/d, which is close to data published for the United States. In France, the consumption oftrans octadecenoic acids from dairy fat is higher than that from margarines (ca. 1.5 vs. 1.1 g/person/d).