Hyperhomocysteinemia Induced by Guanidinoacetic Acid Is Effectively Suppressed by Choline and Betaine in Rats

Rats were fed 25 % casein (25C) diets differing in choline levels (0–0.5%) with and without 0.5 % guani-dinoacetic acid (GAA) or 0.75 % L-methionine for 7 d to determine the effects of dietary choline level on experimental hyperhomocysteinemia. The effects of dietary choline (0.30%) and betaine (0.34%) on GAA-and methionine-induced hyperhomocysteinemia were also compared. Dietary choline suppressed hyperhomo-cysteinemia induced by GAA, but not by methionine, in a dose-dependent manner. GAA-induced enhancement of the plasma homocysteine concentration was sup-pressed by choline and betaine to the same degree, but the effects of these compounds were relatively small on methionine-induced hyperhomocysteinemia. Dietary supplementation with choline and betaine significantl