The aim of the study is to examine the effects of probiotics intervention on choline metabolites and intestinal microbiota composition using a randomized double blind clinical trial. Also, we proposed to explore the real-time change of choline metabolites after probiotics intervention through a PC challenge test. Our study will clarify the biochemical pathway involved in metabolic diseases and hope to provide a new targeted-preventive and therapeutic strategy for chronic metabolic diseases.

Dietary choline (mainly refer to phosphatidylcholine, PC) produce trimethylamine (TMA) through the action of gut flora in vivo. TMA then readily absorbed into systemic circulation and oxidized by hepatic flavin monoxygenases (FMO3) to trimethylamine-N-oxide (TMAO). The elevated levels of circulating TMAO is identified as a risk factor for the prevalence and development of metabolic diseases such as cardiovascular diseases and nonalcoholic fatty liver diseases. Targeting gut flora for reducing TMAO may be a promising approach for preventing chronic metabolic diseases. Recent studies found that some strains representing two different phyla (Firmicutes and Proteobacteria) are capable of producing TMA from choline in vitro. On the other hand, TMA intervention can change the structure of intestinal flora, reducing the abundance of bifidobacterium and lactobacillus. Probiotics can improve the ecological balance of the gut flora, which might be beneficial to human health and disease prevention. However, whether probiotics could inhibit the TMA-producing bacterias and reduce the TMA and TMAO levels through balancing the gut flora was unclear.

In order to explore whether probiotics can reduce the TMA and TMAO levels, we are proposed to recruit 50 volunteers aged from 18-30 years old to participate in the randomized double-blind trial. The volunteers are randomized allocated into different intervention groups. The probiotics intervention group is provided once daily orally-taken powder in a sachet, which contains 4 strains of probiotics. The non-probiotic control is provided with a powder without probiotics , but has same look, color, taste, flavor and weight as the probiotics intervention group. A PC challenge test will be hold before and after the 4 weeks intervention. The blood and fecal sample will be collected before and after the trial and analyzed by appropriate method. The dietary assessment is assessed by a 3-day dietary record.The statistic analysis is by SPSS 23.0.

Inclusion Criteria:

• Healthy males at 18 to 30 years old;
• Free from antibiotics and probiotic products for at least 1 month;
• Willing to participate in the study, consume the test product and perform all measurements.

Exclusion Criteria:

• Sever physical diseases;
• Intolerance to probiotics or eggs