Effects of dietary propionate on carbohydrate and lipid metabolism in healthy volunteers.

Propionate produced in the colon from the fermentation of alpha-amylase-resistant starch and non-starch polysaccharides, is cholesterol lowering and gluconeogenic in animal models. In humans, little is known about the effect of propionate on metabolism. In a double-blind, paired-comparison, placebo-controlled study, the diet of 10 healthy female volunteers, aged 20-22 yr, was supplemented for a period of 7 wk with 7.5 g sodium propionate daily in capsule form, while the diet of the 10 control group members was supplemented with dibasic calcium phosphate in identical capsules as placebo. Propionate supplementation did not lower total serum cholesterol (TC), but increased HDLC (9.5%) (p less than 0.05) and triglyceride levels (16.7%, p less than 0.02) and decreased fasting serum glucose and maximum insulin increments during glucose tolerance tests (p less than 0.05). The results suggest that the improvement in glucose tolerance and insulin sensitivity and the known beneficial effect of dietary fiber on HDL metabolism may in part be mediated through effects of propionate on hepatic carbohydrate metabolism.