Differential effects of cigarette smoking and alcohol consumption on the plasma levels of carotenoids in middle-aged Japanese men

Although several studies have reported that cigarette smoking and alcohol consumption are inversely associated with the plasma level of beta-carotene even after adjustment for dietary carotene intake, their effects on other carotenoids have not been examined extensively. The authors examined the associations of smoking and alcohol with plasma levels of the five principal carotenoids (beta-carotene, alpha-carotene, lutein, lycopene, and zeaxanthin). The subjects were 634 apparently healthy men aged 40-49 years who were sampled randomly from five areas in Japan with varying rates of mortality from gastric cancer. Multiple linear regression analysis controlling for age, serum total cholesterol, serum triglycerides, body mass index, and consumption frequencies of green vegetables, yellow vegetables and fruit, showed that both smoking and alcohol had a significant inverse association with the plasma levels of beta-carotene and alpha-carotene; only smoking reduced the level of lutein, and neither smoking nor alcohol significantly affected the level of lycopene or zeaxanthin. With regard to the reduction of beta-carotene and alpha-carotene, the effect of smoking was smaller in drinkers than in nondrinkers, and the effect of alcohol was smaller in smokers than in nonsmokers, and significant interactions between smoking and alcohol were observed (P=0.034 for beta-carotene and 0.026 for alpha-carotene). The results indicate that the differential effects of smoking and alcohol should be considered when the health effects of plasma carotenoids are examined.