Probiotics modulate gut microbiota and health status in Japanese cedar pollinosis patients during the pollen season

Background Japanese cedar pollinosis (JCP) is a challenging public health problem in Japan. Altered gut microbiota is associated with several diseases, including allergic diseases. However, only a few studies have focused on JCP and the underlying mechanisms for probiotic effects remain unclear. In addition, this study is the first observation of the correlation between the gut microbiota and blood lipid in JCP. Methods Faecal samples from JCP subjects were collected before and after treatment with ( n = 14) and without ( n = 11) LGG–TMC0356-fermented milk for 10 weeks. Gut microbiota composition was characterized from faecal DNA using sequencing of 16S rRNA genes. Results 16S rRNA-based operational taxonomic unit clustering of the microbiota revealed that LGG–TMC0356-fermented milk significantly altered gut microbiota after 10 weeks of milk consumption, and eight dominant genera of microbes were detected. During the JCP season, the Bacteroidetes / Firmicutes ratio, when compared to baseline, was significantly decreased in subjects at end of the study. Bacteroidetes showed positive correlation with LDL- and HDL-cholesterol levels, whereas Firmicutes showed negative correlation with total cholesterol, LDL- and HDL- cholesterol. Conclusions The altered gut microbiota through supplementation of fermented milk containing the study probiotics may be a prospective target for protection against JCP, with beneficial effects on blood lipid levels.