Folate Metabolism in the Ethanol-Fed Rat

Abstract

The effect of long-term ethanol supplementation on folate metabolism was studied in McCollum rats receiving approximately 30% of their caloric intake as ethanol. Ethanol did not significantly affect hepatic or plasma total folate levels. The net hepatic uptake and metabolism of a labeled folate dose to polyglutamate forms were unimpaired by ethanol administration. In fact, the ethanol-fed animals metabolized hepatic pteroylmonoglutamates to polyglutamate forms, predominantly the pentaglutamate, at a slightly faster rate than the control animals, and the net hepatic uptake of the labeled dose was higher than in the controls. Tetrahydrofolate derivatives were the predominant one-carbon form of folate in the livers of ethanol-fed and control animals, although the proportion of folate in the 5-methyltetrahydrofolate form was slightly increased after ethanol supplementation. Although hepatic metabolism of folate appears to be unimpaired in the ethanol-fed rat, an increased rate of pteroylpolyglutamate synthesis, with a resulting increase in the tissue storage of folate, might be a contributing factor to the low serum folate levels reported in alcoholics.ethanol folate folylpoly-γ-glutamates