Modulation by lactic-acid bacteria of the intestinal ecosystem and plasma cholesterol in rabbits fed a casein diet

The effect of lactic acid bacteria on the serum cholesterol levels and the cecal microflora in rabbits fed dietary casein has been examined. A control group was fed a soybean protein diet, three other groups a casein diet; two of tho groups given casein were also given lyophilised resting cells of lactic acid bacteria: Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus to one group and Lactobacillus acidophilus to the other. After 42 d of the experimental diets the cecal content Nas subjected to microbiological analysis: there was no modification of microflora composition with regard to genera, however there were differences in cecal SCFA production and the frequency of the Bacteroides and Clostridium species. Moreover the high serum cholesterol levels found in the rabbits fed the casein diet were decreased after the administration of lactic acid bacteria, revealing the positive role of such bacteria. Our microbiological data underline the importance of diet on the growth and activity of the different bacteria species present in the intestinal ecosystem, and confirm the utility of lactic acid bacteria in restoring microflora balance. (C) 2000 Elsevier Science Inc.