Impact of Bifidobacterium animalis subsp. lactis BB-12 and, Lactobacillus acidophilus LA-5-containing yoghurt, on fecal bacterial counts of healthy adults

This randomized, placebo-controlled, double blind, parallel dose–response study investigated the impact of 4-week commercial yoghurt consumption supplemented with Bifidobacterium animalis subsp. lactis (BB-12) and Lactobacillus acidophilus (LA-5) on fecal bacterial counts of healthy adults. Fifty-eight volunteers were randomly assigned to three different groups: 1. placebo (no probiotic, no starter and no green tea extract); 2. Yoptimal (109 cfu/100 g of BB-12 and LA-5 and 40 mg of green tea extract) and 3. Yoptimal-10 (1010 cfu/100 g of BB-12, 109 cfu/100 g of LA-5 and 40 mg of green tea extract). These yoghurt products also contained Lactobacillus delbrueckii subsp. bulgaricus (107 cfu/100 g) and Streptococcus thermophilus (1010 cfu/100 g). The quantitative PCR (qPCR) results showed that there were significant increases (P = 0.02) in bifidobacteria counts with the Yoptimal treatment as compared to baseline. The fecal numbers of B. animalis subsp. lactis and LA-5 significantly increased in the two probiotic treatments compared to the placebo treatment. Viable counts of fecal lactobacilli were significantly higher (P = 0.05) and those of enterococci were significantly lower (P = 0.04) after the intervention when compared to placebo. No significant difference was observed between treatments in volunteers' weight, waist girth, blood pressure, fasting plasma triglyceride and HDL-C concentrations, as well as cholesterol/HDL-cholesterol ratio. However, a significant increase in plasma cholesterol levels was observed in the placebo group (P = 0.0018) but the levels remained stable in the two probiotic yoghurt groups. These results show that probiotic strains supplemented in the form of yoghurt remain active during gut transit and are associated with an increase in beneficial bacteria and a reduction in potentially pathogenic bacteria. This trial was registered at clinicaltrials.gov as NCT00730626.

Research Highlights
► Validation that BB-12 and LA-5 (dose of 109 cfu/100 g of yoghurt) can survive the intestinal transit.
► Significant impact of beneficial bacteria (bifidobacteria and lactobacilli).
► Significant reduction in potentially pathogenic bacteria such as enterococci.
► No negative alteration of enteric microbiota in healthy subjects (no intestinal flora imbalance).