Estimation of caffeine intake in Japanese adults using 16d weighed diet records based on a food composition database newly developed for Japanese populations

Objective: Previous studies in Western populations have linked caffeine intake with health status. While detailed dietary assessment studies in these populations have shown that the main contributors to caffeine intake are coffee and tea, the wide consumption of Japanese and Chinese teas in Japan suggests that sources of intake in Japan may differ from those in Western populations. Among these teas, moreover, caffeine content varies widely among the different forms consumed (brewed, canned or bottled), suggesting the need for detailed dietary assessment in estimating intake in Japanese populations. Here, because a caffeine composition database or data obtained from detailed dietary assessment have not been available, we developed a database for caffeine content in Japanese foods and beverages, and then used it to estimate intake in a Japanese population. Design: The caffeine food composition database was developed using analytic values from the literature, 16 d weighed diet records were collected, and caffeine intake was estimated from the 16 d weighed diet records. Setting: Four areas in Japan, Osaka (Osaka City), Okinawa (Ginowan City), Nagano (Matsumoto City) and Tottori (Kurayoshi City), between November 2002 and September 2003. Subjects: Two hundred and thirty Japanese adults aged 30-69 years. Results: Mean caffeine intake was 256.2 mg/d for women and 268.3 mg/d for men. The major contributors to intake were Japanese and Chinese teas and coffee (47% each). Caffeine intake above 400 mg/d, suggested in reviews to possibly have negative health effects, was seen in 11% of women and 15% of men. Conclusions: In this Japanese population, caffeine intake was comparable to the estimated values reported in Western populations.