Abstract / Summary
Abstract Green tea is a familiar part of everyday life in Japan, and our previous cross-sectional study found a positive association between green tea consumption and happiness, partly explained by social network size. We examined this Green tea–Social network–Happiness framework longitudinally among 6,701 community-dwelling older Japanese adults from the Japan Gerontological Evaluation Study, followed from 2016 to 2019. Green tea consumption was categorized as < 1, 1, 2–3, or ≥ 4 cups/day; social network size was the number of friends met per month; and happiness was rated on an 11-point scale. After adjustment, baseline green tea consumption was not significantly associated with social network size (P = 0.245) or happiness (P = 0.328) in 2019. In contrast, social network size in 2019 was strongly associated with concurrent happiness (P < 0.001; ≥10 vs 0 friends/month: β = 0.533, 95% CI 0.368–0.698) and showed substantial within-person persistence: 59.9% of participants with ≥ 10 friends/month in 2016 remained in that category in 2019, and 54.6% with no friends in 2016 remained in the zero category. These findings indicate that the cross-sectional Green tea–Social network–Happiness pattern was not reproduced as a simple prospective pathway over three years, whereas the continuity of social connectedness and its association with happiness remained prominent.