Objectives: This study aimed to determine the relationship between objective chewing ability and the nutritional status of Japanese community-dwelling elders. Design: A cross-sectional study. Participants: A total of 509 community-dwelling elders living in the Tokyo metropolitan area participated in a comprehensive survey conducted in October 2013. Measurements: The basic characteristics were sex, age, and body mass index. Undernutrition was examined through serum albumin levels. Chewing ability was examined through color-changeable xylitol gum by evaluating the color changes in chewing gum. Nutritional intake was examined using the semi-quantitative food frequency questionnaire. Results: In the poor chewing ability group, all nutrient intake levels were significantly low, except for carbohydrates, and intake levels for all food groups were significantly low, except for cereals, confectionery, sugars, seasonings, and spices. Additionally, after adjusting for covariates for sex, age, Tokyo Metropolitan Institute of Gerontology-Index of Competence (TMIG-IC) score, Mini-Mental State Examination (MMSE) score, body mass index (BMI), stroke, number of functional teeth, energy intake, and protein intake, chewing ability was found to be significantly associated with undernutrition. Conclusion: We concluded that chewing ability was closely associated with nutrient and different food groups’ intake, as well as undernutrition, among Japanese community-dwelling elders. Thus, to ensure comprehensive nutritional management, nutritionists and dentists should collaborate when treating the same patients.

Social isolation is a particular problem among older people and social participation may reduce future isolation. However, it is unclear which types of activities and which level of participation are effective. This study examines the relationship between social participation and isolation among Japanese older people by employing a 3-year longitudinal study. A mail survey was sent to 3,518 community-dwelling older people in an urban area in 2014 (baseline: BL). We then conducted follow-up mail survey on respondents who were non-isolated at BL in 2017 (follow-up: FL), with isolation being defined as being in contact with others less than once a week. An analysis was carried out on 1,070 subjects (398 men and 672 women). Social participation is defined by participation in group activities (community, senior club, hobbies, sports, volunteering, politics, industry, and religion). A logistic regression analysis was conducted to determine the association between the types of social participation and the number of organization types at BL, and isolation at FL. At FL, 75 men (18.8%) and 59 women (8.8%) were considered to be isolated. Among the men, participation in a hobby group and sports group both significantly reduced the degree of isolation. Moreover, participation in two organizations and three or more organizations significantly lowered the risk of isolation when compared to non-participants. Among women, there were no significant associations among particular types of social activities and isolation. On the other hand, participation in one organization and three or more organizations significantly reduced their isolation when compared to non-participants. There was a significant linear trend between the number of types of organizations and isolation, regardless of gender. Participation in social activities reduces future isolation in older people. Encouraging participation in social activities could help reduce negative health outcomes associated with social isolation later in life.