Dietary differences with green tea intake among middle-aged Japanese men and women

Although several epidemiologic investigations have suggested a protective role of green tea against cardiovascular diseases and cancer, few studies examined how consumption of green tea was associated with intake of other dietary factors.

In the winters of 1989-1991, 880 men ages 40-49 years were randomly sampled from the general populations of five Public Health Center districts of Japan. Response rate was 72% (n = 634). A convenience sample of 373 spouses also consented to participate. They were interviewed on the frequency of consumption of green tea and 37 food items. A 3-day weighed food record was collected from a subgroup of the subjects (207 men and 164 women) to calculate daily intake of 22 nutrient variables. Consumption of the foods and nutrients was compared with three levels of green tea intake (< 1, 1-4, and > 4 cups/days) after adjustment for potential confounders.

Among men, green tea was associated significantly with consumption of 10 foods (P < 0.05) and at borderline significance with 4 nutrients (P < 0.1). These foods and nutrients included fruits (apple, orange juice), vegetables (green, yellow, and pickled), total lipid, cholesterol, and carotene. Among women, green tea was associated with 6 foods and total energy.

The results indicate that consumption of green tea is associated with diets that could modify the risks of cardiovascular diseases and cancer, especially among men. When the health effects of green tea are examined by observational epidemiologic studies, potential confounding and effect modification by other dietary factors should be controlled thoroughly.