Impact of whole wheat flour and its milling fractions on the cecal fermentations and the plasma and liver lipids in rats.

The aim of the present work was to evaluate the cholesterol-lowering potency of the different milling fractions of whole wheat flour, by investigating the effects of these wheat fractions (white flour, whole flour, and bran) on digestive fermentations and lipid metabolism in Wistar rats. Compared to the control, which was fiber-free, the different cereal fractions did not affect the daily food intake or weight gain. The white flour and whole flour diets markedly enlarged the cecum and elicited acidic fermentations (pH approximately 6.2), whereas bran was less effective. It appears that white flour rather promoted propionate-rich fermentations (+62%), whereas bran favored butyrate-rich fermentations (+178%). White flour or bran did not significantly affect total steroid excretion, but whole flour was effective (+41%). Both white flour and whole flour decreased cholesterol in the d < 1.040 fraction, but only whole flour significantly lowered cholesterolemia. However, all the cereal diets significantly decreased liver lipids, whole flour being the most potent (-54%). In conclusion, the totality of the wheat grain is important for cholesterol- and triglyceride-lowering effects, and the splitting up of the grain alters its health effects.