Improvement of the human intestinal flora by ingestion of the probiotic strainLactobacillus johnsoniiLa1

Abstract

To exert beneficial effects for the host, for example, improving the intestinal microflora, a probiotic must reach the intestine as a viable strain. These properties must be demonstrated byin vitroas well asin vivomethods. However, only a few well-designed human clinical studies have shown these properties.Lactobacillus johnsoniiLa1 has been shown to give many beneficial effects for the host, but it is unclear whether a viable strain ofL. johnsoniiLa1 has the effect of improving host intestinal microflora. In the present study, a randomised double-blind placebo-controlled cross-over trial was conducted to elucidate the effect ofL. johnsoniiLa1 on human intestinal microflora. Twenty-two young healthy Japanese women were randomly divided into two groups, and either received fermented milk withL. johnsoniiLa1 or a fermented milk withoutL. johnsoniiLa1 (placebo) daily for 21d. Consumption of the fermented milk: (a) increased totalBifidobacteriumandLactobacillus, and decreased lecithinase-positiveClostridiumin the faeces; (b) increased the faecal lactic acid concentrations; (c) decreased the faecal pH; (d) increased the defecation frequency. These changes were stronger than those observed with the placebo.L. johnsoniiLa1 was identified in all subjects only after the consumption of the fermented milk. These results suggest thatL. johnsoniiLa1 can contribute to improve intestinal microflora with probiotic properties.