Effect of wheat bran and wheat germ on the intestinal uptake of oleic acid, monoolein, and cholesterol in the rat.

The effects of fiber-rich wheat bran and wheat germ on the intestinal absorption of dietary cholesterol, free fatty acids, and monoglycerides were studied. Rats were given a test meal containing [(14)C]oleic acid, [(14)C]monoolein, and [(3)H]cholesterol. After a 1-hour digestion period, wheat bran or wheat germ (10% of meal solids) did not significantly modify the gastric emptying of lipids. No effect of wheat bran was evidenced on the amounts of lipids and cholesterol in the intestinal content or the mucosal segments, whereas wheat germ significantly increased the cholesterol in the small intestine content, decreasing its intestinal absorption. Both fractions only slightly influenced the levels of absorbed lipids and cholesterol in the plasma and liver. In vitro binding measurements showed that the wheat fractions bind only 7% to 15% of both lipids and cholesterol. Results indicate that wheat bran has no direct effect on the mucosal uptake process, whereas wheat germ might decrease the uptake of dietary cholesterol by an as yet unknown mechanism.