Abstract 3279: Very High Intakes of Conjugated Linoleic Acid, a Trans Fat From Milk and Meat, Raise LDL and Lower HDL Cholesterol in Humans
Background Trans fatty acids in the diet are produced either by industrial hydrogenation or by biohydrogenation in the rumens of cows and sheep. Industrial trans fatty acids lower HDL, raise LDL, and increase the risk of coronary heart disease. The effects of trans fatty acids from milk and meat of ruminants are less clear. Cis-9,trans-11-conjugated linoleic acid (CLA) is a trans fatty acid unique to ruminant fats. We fed volunteers controlled diets high in CLA or industrial trans fatty acids, and measured blood lipids.
Methods Sixty-one healthy men (n=25) and women (n=36) were sequentially fed each of 3 diets for 3 weeks, in random order, for a total of 9 weeks. Diets were identical except for 7% of energy (18.9 g in a diet of 10 MJ/day) which was provided either by oleic acid, by industrial trans fatty acids, or by cis-9,trans-11 CLA.
Results Mean (±sd) serum LDL rose from 104 ± 24 mg/dL (2.68 ± 0.62 mmol/L) on oleic acid to 117 ± 26 mg/dL (3.02 ± 0.66 mmol/L) on industrial trans fat (change 13 mg/dL, p<0.001), and to 113 ± 27 mg/dL (2.92 ± 0.70 mmol/L) on CLA (change 9 mg/dL, p<0.001). HDL cholesterol was 2 mg/dL (0.04 mmol/L) lower on industrial trans (p=0.014) and 2 mg/dL (0.06 mmol/L) lower on CLA (p<0.001).
Conclusion A very high intake of cis-9,trans-11 CLA raises LDL- and lowers HDL-cholesterol in humans. Our data suggest that ruminant and industrial trans fatty acids have similar effects on blood lipids. Table 1⇓: Serum lipids (± sd) and apoB in 61 subjects fed diets high in cis-monounsaturates (oleic acid), industrial trans fatty acids, and cis-9,trans-11 CLA