Comparison of the impact of trans fatty acids from ruminant and industrial sources on surrogate markers of cholesterol homeostasis in healthy men

Scope: Mechanisms by which trans fatty acids (TFA) from industrial (iTFA) and ruminant (rTFA) sources alter cholesterol homeostasis are virtually unknown. We compared the impact of dietary iTFA and rTFA on surrogate markers of cholesterol absorption (beta-sitosterol and campesterol) and synthesis (lathosterol) in healthy men. Methods and results: In a randomized, controlled double-blind crossover study, 38 healthy men consumed three experimental isoenergetic diets for 4wk each. The three diets were (i) high in iTFA (10.2 g/2500 kcal), (ii) high in rTFA (10.2 g/2500 kcal) and (iii) control diet low in TFA from any source (2.2 g/2500 kcal). The sum of plasma beta-sitosterol and campesterol concentrations was significantly reduced after the iTFA diet compared with the control diet (-12%, p=0.050). The reduction in combined b-sitosterol and campesterol levels was larger in magnitude after the rTFA diet (-29% versus the control diet and -20% versus the iTFA diet, p<0.0001). The TFA-rich diets had no impact on plasma lathosterol concentrations. Conclusions: Very high intakes of rTFA and iTFA decrease cholesterol absorption but have no impact on cholesterol synthesis. Consumption of rTFA reduces cholesterol absorption to a greater extent than iTFA, but this difference does not ultimately affect plasma cholesterol concentrations.