Association of caffeine, green tea and coffee consumption with mortality and disability among older adults

Several epidemiological studies have shown that consumption of coffee and green tea is inversely associated with risks of death and disability; however, the relationship between caffeine consumption and these outcomes remains unclear. We examined these associations in Japanese older adults. This was a prospective study of 7708 adults (aged ≥ 65 years) recruited from the Kyoto-Kameoka study. Dietary intake was estimated using a validated FFQ. Caffeine consumption was classified into four categories. Disability and mortality data were collected between 15 February 2012 and 30 November 2016. Hazard ratios (HR) and 95 % CI of outcomes were calculated using multivariable Cox proportional hazard models. During the median 4·75-year follow-up period, a total of 593 deaths and 1379 disability incidents were recorded. After adjusting for confounders, caffeine consumption was inversely associated with the incidence of disability (< 100 mg/d: reference; 100-149 mg/d: HR, 0·91 (95 % CI 0·80, 1·04); 150-199 mg/d: HR, 0·84 (95 % CI 0·72, 0·99); ≥ 200 mg/d: HR, 0·75 (95 % CI 0·63, 0·89), P_{for trend} = 0·001) but not all-cause mortality. High coffee consumption was inversely associated with mortality (≥ 3 cups/d: HR, 0·62 (95 % CI 0·43, 0·88)) and disability (≥ 3 cups/d: HR, 0·81 (95 % CI 0·65, 0·99)) compared with non-consumption. However, green tea consumption was not associated with mortality or disability. Caffeine and coffee consumption was inversely associated with disability and/or mortality. Further research is needed to clarify whether high caffeine intake is safe and effective for older adults.