Influence of dietary ascorbic acid on cholesterol 7 alpha-hydroxylase activity in the rat.

An experiment was carried out to determine whether dietary excess of ascorbic acid inhibits cholesterol 7 alpha-hydroxylase activity and elevates cholesterol levels in the rat, as previously observed in the guinea pig. Male, weanling Sprague-Dawley rats were fed a cereal-based diet supplemented with 0, 0.5, 10.0, or 20.0 g ascorbate/kg for 45 days. Ascorbate supplementation did not alter plasma ascorbate levels in the rat, but did increase hepatic ascorbate at the highest dietary intakes (10.0 and 20.0 g ascorbate/kg diet). Ascorbate supplementation had no effect upon plasma and liver cholesterol levels or cholesterol 7 alpha-hydroxylase activity. Under the experimental conditions employed, the rat appears resistant to ascorbate-induced alteration of sterol metabolism.