| Trans fatty acids (TFA) can be naturally formed by ruminal hydrogenation of polyunsaturated fatty acids, or chemically produced by partial hydrogenation of liquid vegetable oils. Recent studies have shown that high intake of TFA has detrimental effects on plasma lipoprotein profile and contributes to the risk of coronary heart disease. Objectives of this study were to estimate long-term TFA intake in free-living, healthy adults and examine variables of lipoprotein metabolism in low and high TFA consumers. Among 332 people screened by food frequency questionnaires, forty two men and women were qualified based on TFA intake; cut-off values were 8 g/d for the high intake (HI) and <3 g/d for the low intake (LI). Mean intake of TFA in entire data set was 4.69 g/day (0.2 g/day--40.7 g/day). The estimate of TFA in men was significantly higher than in women (4.3 g/day vs. 5.3 g/day). Compared to LI, serum concentrations of total cholesterol (TC), triglyceride (TG), and low density lipoprotein cholesterol (LDL-C) tended to be higher in HI. However, serum high density lipoprotein cholesterol (HDL-C) and the ratios of TC to HDL, LDL to HDL, and (TC-HDL) to HDL before gender adjustment was significantly lower (46.1 +/- 3.3 mg/dL vs. 54.3 +/- 2.4 mg/dL) and higher in HI relative to LI, respectively. Serum lipoprotein (a) levels and low density lipoprotein receptor (LDL-R) mass in mononuclear cell tended to be lower in HI relative to LI. Both lecithin:cholesterol acyltransferase (LCAT), and cholesteryl ester transfer protein (CETP) activities were higher in HI than in LI. Compared to LI, the serum level of elaidic acid was significantly higher in HI. Stronger correlations between body mass index and ratios of TC to HDL, LDL to HDL, and (TC-HDL) to HDL were observed (r = 0.51--0.54, p =< 0.001/0.001) than those between TFA intake and the ratios (r = 0.33--0.35, p = 0.024--0.035). In conclusion, high TFA consumers tended to eat more of other dietary variables including saturated, monounsaturated, and polyunsaturated fats, total energy, and vitamin E. Although TFA may modulate HDL-C via a putative effect on CETP and LCAT activities, the higher intake of all dietary fats by HI may confound the results. |
