名古屋文理大学

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.

Freshwater clams (Corbicula spp.), commonly known as shijimi in East Asia, have long been valued for their functional and nutritional properties. In this review, we summarise the physiological effects of hot water extracts derived from Taiwanese freshwater clams (FCE), particularly in relation to metabolic syndrome and other lifestyle-related disorders. Traditionally, shijimi has been used to alleviate hepatic dysfunction and symptoms associated with alcohol consumption. FCE significantly suppresses galactosamine-induced increases in serum aspartate aminotransferase and alanine aminotransferase. In addition, FCE reduces alcohol-induced hepatic lipid accumulation and lowers hepatic cholesterol levels. FCE also influences alcohol metabolism: animals receiving FCE exhibit lower blood alcohol concentrations and a faster rate of alcohol clearance following ethanol administration. These findings suggest that shijimi may protect against alcohol- or drug-induced liver damage, potentially by enhancing alcohol metabolism. Beyond its role in liver protection, shijimi has been associated with the alleviation of jaundice, possibly through increased bile secretion linked to improved cholesterol homeostasis. Supporting this, studies using models of exogenous hypercholesterolemia show that FCE lowers both serum and hepatic cholesterol levels in a dose-dependent manner. Overall, traditional claims regarding the hepatoprotective effects of shijimi are increasingly supported by mechanistic and molecular evidence. This is the first clarified review of the various effects of shijimi.

Social relationships are vital for health. We studied residents of the Ojika Islands in Japan to examine how social ties relate to diet and health. Our results showed that, despite strong social bonds and frequent food exchanges compared to urban Japan, some residents are less socially engaged than others. This was confirmed by a cluster analysis of individual data on close relationships and food sharing: 105 adults were divided into the socially Active (n = 50) and Less Active (n = 55) groups. Considering both the material (nutritional) and non-material (behavioral or psychological) benefits of close relationships and food sharing, we hypothesized that the Active group would have a more nutritious diet and better health outcomes than the Less Active group. As expected, the Active group had lower sodium intake and fewer cases of high blood pressure. Surprisingly, the Less Active group consumed higher levels of four beneficial nutrients—calcium, iron, riboflavin, and vitamin C. These findings suggest that social relationships can influence the diet and health of island residents in both positive and negative ways.