QUEBEC—Natural trans fats produced by ruminant from dairy and beef cattle has no significant effect on low-density lipoprotein (LDL), but may be associated with a reduction in plasma high-density lipoprotein (HDL) cholesterol concentrations, particularly in overweight women, according to a study published in the American Journal of Clinical Nutrition.
Ruminant trans fat is naturally-occurring, found in meat and dairy foods. Industrial produced trans fat is a component of partially hydrogenated vegetable oils that have been associated with cholesterol and coronary heart disease.
Researchers at Laval University investigated the effects of a butter naturally enriched in ruminant trans fats (rTFAs), of which vaccenic acid is the predominant isomer, on plasma lipid concentrations among healthy women. In a double-blind, randomized, crossover controlled study, 61 healthy women ages 19 to 70 years were fed two isoenergetic diets lasting four weeks each. The two diets were defined as moderately high in rTFAs (3.7 g/d, 1.5% of daily energy) and control (0.9 g/d, 0.3% of daily energy).
They found no significant effect of the rTFA diet was found on total plasma cholesterol, LDL cholesterol, apolipoprotein B, apolipoprotein A-I, and triglyceride concentrations compared with the control diet. There was a small yet statistically significant reduction in plasma HDL-cholesterol concentrations with the rTFA diet (−2.8%; P = 0.004), which was significant (P for the BMI × treatment interaction = 0.006) among women with a BMI (in kg/m2) ≥25 (-5.2%; P = 0.004; n = 18) but not among women with a BMI <25 (-1.2%; P = 0.13; n = 43).
The results suggest that an increase in dietary rTFAs equivalent to ∼1% of daily energy has no significant effect on LDL but may be associated with a reduction in plasma HDL-cholesterol concentrations, particularly in overweight women.
