Age-dependent associations of smoking and drinking with non-high-density lipoprotein cholesterol

Serum high-density lipoprotein (HDL) cholesterol levels are influenced by habitual smoking and drinking. Non-HDL cholesterol is known to be a potent predictor of cardiovascular disease. However, it remains to be determined whether the associations of non-HDL cholesterol with smoking and drinking differ with age. The objectives of this study were to investigate relationships among smoking, drinking, and non-HDL cholesterol and to investigate interactions of age with smoking and drinking regarding serum non-HDL cholesterol levels. Subjects (54,020 Japanese men aged 20-69 years) were divided into drinkers and nondrinkers or into smokers and nonsmokers and were further divided into 5 age groups with 10-year intervals. Subjects in each age group were divided into 3 subgroups according to alcohol or cigarette consumption. The mean levels of serum non-HDL cholesterol calculated after adjustment for age and body mass index were compared among the groups. In nondrinkers, non-HDL cholesterol levels of subjects in their 40s or older were significantly higher in heavy smokers than in nonsmokers, whereas non-HDL cholesterol levels of subjects in their 20s and 30s were not significantly different among non-, light, and heavy smokers. In drinkers, non-HDL cholesterol levels of subjects in all age groups were not higher in light and heavy smokers than in nonsmokers. In nonsmokers, non-HDL cholesterol in subjects in their 30s or older was significantly lower in light and heavy drinkers than in nondrinkers, whereas this difference was not observed in subjects in their 20s. In smokers, non-HDL cholesterol levels of subjects in all age groups were significantly lower in light and heavy drinkers than in nondrinkers, and the differences in non-HDL cholesterol between drinkers and nondrinkers tended to increase with advance of age. The difference in non-HDL cholesterol between drinkers and nondrinkers tended to be greater in smokers than in nonsmokers. Thus, the associations of non-HDL cholesterol with smoking and drinking were modified by drinking and smoking, respectively. Smoking is associated with high non-HDL cholesterol in nondrinkers, and drinking is associated with low non-HDL cholesterol in nonsmokers; these associations are shown at middle and elderly ages but not at young ages.