The effect of consumption of milk fermented by Lactobacillus casei strain Shirota on the intestinal microflora and immune parameters in humans

Abstract

Objective: To determine the effect of consumption of milk fermented by Lactobacillus casei strain Shirota (L. casei Shirota) on the composition and metabolic activities of the intestinal microflora, and immune parameters in humans. Subjects: Twenty healthy male subjects aged 40–65 years were selected. Design:A placebo-controlled trial was performed in which 10 subjects were randomly assigned to a control and 10 to a treatment group. During the first and last two weeks of the 8-week study the subjects received a strictly controlled diet without fermented products. The same controlled diet was given during the intermediate 4-week test period but then the treatment group received three times daily 100 ml of fermented milk containing 10⁹ CFU L. casei Shirota/ml, whereas the same amount of unfermented milk was given to the subjects in the control group. Results: In comparison to the control group, the consumption of L. casei Shirota-fermented milk resulted in an increase of the Lactobacillus count in the faeces in which the administered L. casei Shirota was predominant at the level of 10⁷ CFU/g wet faeces. This was associated with a significant increase in Bifidobacterium counts (PClostridium; however the differences were not statistically different between the treatment and the control groups. The β-glucuronidase and β-glucosidase activities per 10¹⁰ bacteria decreased significantly (PL. casei Shirota-fermented milk. Furthermore, the consumption of the fermented milk product resulted in a slight but significant increase in the moisture content of the faecal samples (PL. casei Shirota-fermented milk is able to modulate the composition and metabolic activity of the intestinal flora and indicate that L. casei Shirota-fermented milk does not influence the immune system of healthy immunocompetent males. Sponsorship:The study was financially supported by Yakult Honsha Co. Ltd, Tokyo, Japan.