Fiber2026-05

Interindividual Variation in Adult Gut Microbiome Composition in Two Rural Communities in Japan: Associations With Energy and Nutrient Intakes.

Sekiya Sae, Masuda Momoka, Mizuno Yuki, Naka Hiroaki et al. — American journal of human biology : the official journal of the Human Biology Council

Summary

This study investigated how the traditional Japanese diet influences the gut microbiome in rural communities. Researchers found that consuming foods rich in fiber, omega-3s, and vitamin D, like seafood, rice, and vegetables, was linked to a more diverse and potentially healthier gut bacteria profile. Conversely, higher intake of alcohol and fat was associated with less gut diversity.

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Key points

Eating foods common in the traditional Japanese diet, like seafood, rice, and vegetables, was linked to a more diverse gut microbiome.
Nutrients such as dietary fiber, omega-3 fatty acids, and vitamin D were associated with greater gut bacteria diversity.
Higher intake of alcohol and fat was connected to less diversity in gut bacteria.
The study was conducted in two rural communities in Japan, focusing on adults.

What the study looked at

This study explored the connection between the traditional Japanese diet and the variety of bacteria living in people's guts. Researchers wanted to understand if the specific nutrients consumed by adults in rural Japan might influence the diversity and composition of their gut microbiome. This was a cross-sectional study involving 263 adults, aged 20 and older, from two rural Japanese communities. Participants completed questionnaires about their food intake, had their height and weight measured, and provided stool samples. These samples were then analyzed to identify the types and amounts of bacteria present in their gut. The study found that individuals who ate more foods characteristic of the traditional Japanese diet, such as seafood, rice, and vegetables (which provide nutrients like vitamin D, omega-3 fatty acids, carbohydrates, and dietary fiber), tended to have a greater diversity of gut bacteria. In contrast, higher consumption of alcohol and fat was linked to less diverse gut microbiomes. The specific mix of gut bacteria also varied significantly with the intake of several nutrients, including various fibers, omega-3s, and calcium.

Dietary takeaway

This research suggests that a diet rich in fiber from vegetables, rice, and seafood may promote a more diverse and potentially healthier gut microbiome. Choosing a variety of these traditional Japanese foods could be beneficial for your gut health, as they provide essential nutrients including dietary fiber. However, remember that this is just one study, and more research is needed to confirm these findings definitively.

Abstract

OBJECTIVES: The "Japanese diet" has long been regarded as a key factor contributing to the remarkable life expectancy of the Japanese population. Given that the gut microbiome is thought to mediate the link between diet and health, this study investigated energy and nutrient intake among rural populations in Japan, who are presumed to adhere closely to the traditional "Japanese diet," and examined their association with gut microbiome diversity and composition. METHODS: A cross-sectional study of 263 individuals aged ≥ 20 years was conducted in two rural communities in Japan, in July and August 2022. Participants completed a food frequency questionnaire, and we measured weight and height and collected fecal samples. The diversity and composition of the gut microbiome were assessed using 16S ribosomal RNA analysis. The associations between energy and nutrient intakes and alpha diversity metrics, beta diversity metrics, and the relative abundance of bacteria at the genus level were assessed. RESULTS: Individuals who consumed more nutrients characteristic of seafood, rice, and vegetables (vitamin D, omega-3 highly unsaturated fatty acids, carbohydrates, total dietary fiber, and insoluble dietary fiber) had significantly higher gut microbiome diversity, while those who consumed more alcohol and fat had significantly lower microbiome diversity. Energy intake from alcohol, as well as intakes of cholesterol, iron, vitamin B1, vitamin C, carbohydrates, soluble dietary fiber, omega-3 highly unsaturated fatty acids, and calcium were significantly associated with beta diversity metrics (p < 0.05), indicating that gut microbiome composition varied with these nutrient intakes. CONCLUSION: Nutrient intakes may influence the interindividual variation in the gut microbiome seen in two rural populations in Japan. Future research should focus on elucidating the interactive effects between the "Japanese diet" and the gut microbiome.

View on PubMed →DOI: 10.1002/ajhb.70274