Dietary trans fatty acids: effects on plasma lipids and lipoproteins of healthy men and women.

Effects of cis and trans monounsaturated fatty acids (TFA) and saturated fatty acids were assessed in 29 men and 29 women consuming controlled diets. Subjects ate each diet for 6 wk in a Latin square design. The diets, each with 39-40% of energy as fat were: 1) high oleic (16.7% of energy as oleic acid), 2) moderate TFA (3.8% of energy as TFA), 3) high TFA (6.6% of energy as TFA), 4) and saturated (16.2% of energy as lauric+myristic+palmitic acids). Compared with the oleic diet, LDL cholesterol increased 6.0%, 7.8%, and 9.0% after moderate TFA, high TFA, and saturated diets, respectively. HDL cholesterol was unchanged after moderate TFA, but was slightly lower (2.8%) after high TFA. HDL cholesterol after the saturated diet was 3.5% higher than after the oleic diet. Changes in apolipoproteins B and A-I corresponded with changes in the lipoprotein cholesterols. Thus, compared with oleic acid, dietary TFAs raise LDL cholesterol, but to a slightly lesser degree than do saturates, and high TFA concentrations may result in minor reductions of HDL cholesterol.