It has previously been reported that the introduction of a new issue (D1) of a stock diet (D0) caused a significant decrease in voluntary ethanol consumption in rats of our UChA (low ethanol consumer) and UChB (high ethanol consumer) strains, and that, after changing to a diet lacking in animal products (D3), ethanol consumption reached the previous level attained in UChB rats and exhibited a bimodal distribution in UChA rats in such a way that about one-third of these consumed more than 2 ml of a 10% (v/v) ethanol solution per 100 g of body weight, as did UChB rats. When UChA rats exhibiting high ethanol consumption and also UChB rats were fed on the D3 diet with a brewer's yeast supplement, a significant decrease in ethanol intake was observed. Since significant correlations of voluntary ethanol intake to blood acetaldehyde levels, and to hepatic and brain aldehyde dehydrogenase (AldDH) activities, have been reported, the effects on these parameters of diet D1 and of supplements of brewer's yeast or disulfiram were studied. Results showed that rats of both strains fed on a D1 diet exhibited a significant increase in blood acetaldehyde level after ethanol administration, concomitant with an inhibition of hepatic and brain AldDH activities and a significant decrease in ethanol intake. Thus, this effect could be related to a disulfiram-like activity. The decrease in ethanol intake induced by brewer's yeast was not accompanied by changes of blood acetaldehyde level after ethanol, nor by inhibition of hepatic AldDH activity in either strain.(ABSTRACT TRUNCATED AT 250 WORDS)