The Nested Study on the Intestinal Microbiota in GENKI Study with Special Reference to the Effect of Brown Rice Eating

Abstract

Purpose: Brown rice eaters are healthy and have good bowel movement, which suggests a good intestinal environment and good composition of microbiota. However, knowledge about the normal variation of the intestinal microbiota of these people still remain limited. Subjects and Methods: A nested study on the intestinal microbiota was carried out among the GENKI study participants. Metagenomic analysis of 109 samples were carried out with a questionnaire asking about dietary changes from a baseline survey. Results and Discussion: 109 healthy subjects (18 males, 90 females, unknown 1) provided stools for analysis. The average age was 50.1 ± 15.1 years old in males and 55.8 ± 13.8 years old in females. Average body mass index (BMI) of males was 20.9 ± 2.3 kg/m2 and 20.2 ± 2.2 kg/m2 in females. Common bacterial profiles at phylum level were Firmicutes 44.3 ± 9.9%, Bacteroides 20.7 ± 8.8%,, Actinobacteria 8.3 ± 6.3%, Proteobacteria 1.7 ± 2.7% and Verrucobacteria 1.2 ± 4.2% (max 39.4%). At the genus level, Bacteroides (12.7%), Blautia (8.3%), Faecalibacterium (7.9%), Bifidobacterium (6.3%), Prevotella (5.3%), Eubacterium (4.9%), Ruminococcus (3.8%), Fusicatenibacter (2.6%), Collinsella (1.9%), Streptcoccus (2.4%), Subdoligranulum (2.1%), Anaerostipes (1.7%), Akkermansia (1.2%), and Roseburia (1.7%) occupied more than 1%. The difference between the brown rice and white rice eaters by microbiota profile was high butyrate producing bacteria and low fusobacterium. High prevalence of Faecalibacterium prausnitzii (5.28%) suggested the benefit on butyrate production, and Blautia wexlerae (3.67%) suggested the control on intestinal immunity. Conclusion: Habitual rice eaters showed Faecalibacterium and Blautia dominant profile of intestinal microbiota. Brown rice eaters showed additional benefits by high prevalence of Fermicutes and low prevalence of Fusobacterium. These profiles could lead to integrated healty life.