Plasma lipid and lipoprotein responses of rats to starch and sucrose diets with and without brewer's yeast.

The effect of starch and sucrose diets, with and without brewer's yeast, on plasma total cholesterol and triglyceride concentration and on the lipoprotein distribution in plasma was studied in male rats. The rats were fed a cereal based stock diet, a starch or a sucrose diet, plus or minus brewer's yeast, for 4 weeks. The plasma cholesterol concentration increased to similar levels in rats fed the starch or the sucrose diets but remained unchanged in rats fed the stock diet. The plasma triglyceride level increased in rats fed stock diet, but was unchanged in those fed starch or sucrose diets. Brewer's yeast did not modify the cholesterol value in any of the three groups but reduced the triglyceride level in rats fed the stock and the starch diets. In rats fed the starch diet there was a reduction in the relative amount of prebeta lipoproteins, but no significant alterations in the beta, prealpha and alpha fractions, as compared with rats fed stock diet. Rats fed the sucrose diet had lower prebeta, beta and alpha lipoprotein percentages and a much higher prealpha percentage than rats fed the stock diet. Brewer's yeast had no consistent effects on the lipoprotein distribution. The results support the contention that there might be a dissociation between dietary effects on the plasma lipid level and on the lipoprotein distribution.