Whey from cultured skim milk decreases serum cholesterol and increases antioxidant enzymes in liver and red blood cells in rats

Abstract

The study was carried out to examine the effect of whey from bovine skim milk fermented with bifidobacteria and lactic acid bacteria on plasma cholesterol and antioxidant enzymes in rats. Rats were maintained for 6 wks on a purified diet (reference diet) and on the purified diet supplemented milk whey or whey from cultured skim milk with Bifidobacterium longum (B. longum), Lactobacillus acidophilus (L. acidophilus) or Streptococcus salivarius subsp. thermophilus (S. thermophilus). Diets containing the product with S. thermophilus resulted in the lowest concentration of plasma cholesterol. The activity of superoxide dismutase (SOD) in red blood cells (RBC) and the activity of catalase in liver were elevated on cultured product-diets compared with the reference diet; in addition, the activity of glutathione peroxidase (GSHPx) in RBC was higher on the L. acidophilus diet compared with the reference diet. Although there were no significant differences in the concentrations of thiobarbituric acid-reactive substances and α-tocopherol in plasma, plasma d<1.063 g/ml lipoprotein fractions prepared from rats fed on the B. longum- and L. acidophilus-diets were resistant to the oxidative stress induced by a transition metal ion when compared with those from rats fed on the reference diet. The non-fermented whey diet was not as effective in lowering plasma cholesterol and in increasing antioxidant enzymes as were the fermentation product diets. These results therefore suggest that wheys from cultured milk may exert spesific effects on hypercholesterolemia and oxidative stress.