Dietary exposure to trans-fatty acids (TFA) is likely to be high among Canadian Inuit; yet no data are available on the physiological effects of TFA in this population. The purpose of the present study was to assess the association between TFA and plasma lipid profiles in Inuit men and women living in Nunavik (Québec, Canada). In a cross-sectional, population-based survey, a total of 795 Nunavik Inuit eligible participants gave a blood sample. Exposure to TFA was assessed by their relative proportion in erythrocyte membrane. We performed multiple regression analysis using plasma lipids or their linear combinations as the dependent variables and TFA as the main predictor, adjusting for potential confounders. The associations varied markedly between the sexes and according to age. In men (n 357, aged 36·3 (sd 14·3) years, TFA 1·24 (sd 0·54) %), TFA tended to be negatively associated with HDL-cholesterol (HDL-C), apoA1 and LDL particle size, and positively associated with non-HDL-C, LDL-cholesterol (LDL-C), apoB100, the apoB100:apoA1 ratio and the ratios of total cholesterol (TC), LDL-C and TAG to HDL-C. No such trends were observed in women (n 438, aged 37·0 (sd 14·1) years, TFA 1·16 (sd 0·54) %), except for HDL-C and apoA1 in women aged 50 years and more. These results suggest that TFA could raise the risk of CHD in Inuit men at least through their physiological effects on plasma lipids. The differential associations reported in pre- and postmenopausal women need to be reproduced in other populations and in experimental studies addressing the influence of sex hormones in response to dietary fats.

The aim of the present study was to investigate the potential nutritional and metabolic impact of trans (t) fatty acids (FA) on an appropriate experimental dietary model. Since previously reported experimental designs have been matter of concern, we developed a dietary model to compare the effect of t isomers and/or the saturation of FA independently of other variables. Wistar rats were fed diets containing identical amounts of nutrients and high levels of dietary fats (200 g/kg) for 30 d. Dietary fat rich in t-FA was compared with fat rich in saturated (s) FA or rich in cis (c) FA, maintaining the same length of C chain of the FA. The fats were obtained through isomerization or hydrogenation of the c-FA present in the control fat. Apparent fat absorption, energy efficiency and triacylglycerol levels in serum and liver were different in rats fed t-FA or s-FA than c-FA. The apparent fat absorption was (%): s-FA 85·7 (SD 3·4)<T-FA 93·1 (sd 0·4)<c-FA 96·7 (sd 1·1) (P<0·05). The efficiency of energy utilization was lower in t-FA (11·7 %) and s-FA (18·5 %) diets, reaching statistical significance only between s-FA and c-FA. A striking finding was the change in the lipid profile in serum and liver. Serum and hepatic triacylglycerol levels were greater for t-FA and s-FA diets than in c-FA; however, the increases on serum triacylglycerol concentrations were greater with the s-FA diet and the increases on hepatic triacylglycerol content were greater with t-FA. Knowledge of the t-FA effects on this kind of experimental dietary model could contribute to determine the potential risk of t-FA intake for man.

We have compared the effects on lipoproteins and haemostatic variables of two hard margarines with similar functional properties, one traditional margarine containing partially hydrogenated fish oil (PHFO), and one experimental margarine based on vegetable oil (VO). Both were all-purpose cooking margarines with nearly identical functional properties. Trans fatty acids from PHFO in the traditional margarine were replaced mostly by saturated, monounsaturated and trans fatty acids of vegetable origin in the new formulation. Both test margarines contained approximately the same amount of cis polyunsaturated fatty acids. Sixteen female normolipidaemic students consumed each diet with the two test margarines for 14 d in random order (crossover design). The amount of fat was 31 % energy in the PHFO diet and 32 % energy in the VO diet. The test margarines provided approximately 26% energy in both diets. In the PHFO diet 7.8 % of the energy was derived from trans fatty acids and 9.2 % from saturated fatty acids (12:0, 14:0 and 16:0) while in the VO diet, 1.1 % energy was derived from trans fatty acids and 13.3% from saturated fatty acids (12:0, 14:0 and 16:0). The natural content of cholesterol in PHFO was deliberately not balanced by addition of cholesterol to the VO diet, thus the PHFO diet contained 215 mg and the VO diet 86 mg cholesterol per 8.5 MJ. LDL-cholesterol concentration was 19 % higher in subjects on the PHFO diet compared with the VO diet (P < 0.01). The ratio LDL-cholesterol:HDL-cholesterol was 12.6 % higher in subjects on the PHFO diet compared with the VO diet (P < 0.01). The level of apolipoprotein (apo)A-I was 6 % lower in subjects on the PHFO diet compared with the VO diet (P < 0.01). The ratio apoB:apoA-I was 10.4 % higher in subjects on the PHFO diet than on the VO diet (P < 0.01). There were no significant differences in total cholesterol, HDL-cholesterol, triacylglycerols, apoB, lipoprotein(a) and haemostatic variables between the diets. Our results demonstrate that PHFO, with its unfavourable effects on plasma lipids, can be replaced by vegetable oils in margarine without appreciable loss of functional properties but with significant improvement in the effects on plasma lipoproteins.