The effects of dietary niacin and riboflavin on voluntary intake and metabolism of ethanol in rats

Abstract

The effects of dietary deficiency and excess of niacin and riboflavin on voluntary drinking of 10% (v/v) ethanol were studied in male rats. The effectiveness of dietary deficiency and excess of both niacin and riboflavin on tissue levels of these vitamins was demonstrated by measurements of urinary N 1-methylnicotinamide and blood glutathione reductase (EC 1.6.4.2) activity. A high-niacin diet containing 75 mg niacin/kg food decreased ethanol intake by about 36% compared to the control diet containing 15 mg niacin/kg. Niacin or riboflavin deficiency and a high-riboflavin diet containing 40 mg riboflavin/kg did not affect significantly ethanol drinking. Changes in dietary levels of niacin or riboflavin did not influence on ethanol elimination rate or levels of blood acetaldehyde during ethanol oxidation. Therefore, blood acetaldehyde was not responsible for the decreased ethanol intake of rats fed with a high-niacin diet. It was concluded that the increased ethanol intake caused by dietary deprivation of B-vitamin complex found in earlier studies is not a result of deficiency of niacin or riboflavin but niacin may be involved in the decrease in ethanol drinking, which follows dietary B-vitamin complex supplementation.