A pilot study on the effect of Lactobacillus casei Zhang on intestinal microbiota parameters in Chinese subjects of different age

Ageing of the population is an imminent global problem. Lactobacillus casei Zhang (LcZ) was isolated from Inner Mongolian fermented milk, koumiss. LcZ possesses numerous probiotic properties in in vitro tests and in animal models. However, it has never been tested in any human trial. In the current study, the impact of oral consumption of LcZ on different age groups was tested. Chinese subjects, including 10 young, 7 middle-aged and 7 elderly volunteers (with mean age of 24.3, 47.6 and 64.7, respectively), were recruited. Each subject took 10.6 log10 cfu LcZ daily for a continuous period of 28 days. Several parameters, including the amounts of LcZ and four selected groups of bacteria, change of bacterial diversity, short chain fatty acids (SCFA) and total bile acids (TBA), were monitored in faecal samples collected from the subjects before starting, during and after stopping oral LcZ consumption. The consumption of LcZ exhibited beneficial effects to the subjects by modulating faecal microbiota in a temporal manner with a prolonged elevation of SCFA and reduction of TBA. The potentially harmful Pseudomonas and Acinetobacter genera were suppressed by the probiotic administration. Furthermore, a moderately divergent response was observed in the indigenous gut populations of Bifidobacterium and Bacteroides fragilis group in different age subjects. Taken together, the current study has provided proof on the positive effect of probiotic consumption and crucial insights into the design and application of probiotic-based products to users of different age segments.