Impact of overall diet quality on association between alcohol consumption and risk of hypertension: evidence from two national surveys with multiple ethnics

Background/objectives: Alcohol is commonly consumed around mealtimes. This study hypothesized that the association between alcohol and hypertension was influenced by overall diet quality. This study aims to test the hypothesis that overall diet quality influenced associations between alcohol and risk of hypertension across different ethnicities. Subjects/methods: Using nationally representative data from National Health and Nutrition Examination Survey(NHANES 03–12), China Health Nutrition Survey (CHNS), and an independent population-based study, 43,914 adults were included. Subgroup analysis included 6984 adults from CHNS with a 14-year follow-up. Light alcohol consumption was defined as <7standard drinks/week, moderate as 7–21 drinks/week, and heavy as >21 drinks/week. Alternative healthy eating index and diet balance index were calculated as indicators of diet quality. Results: There were 3968 hypertensives in Caucasians (N = 11,325), 1976 in Africans (N = 5010), 1907 in Hispanics (N = 7274) and 5267 (N = 20,305) in Chinese. In context of high diet quality, light alcohol consumption was significantly associated with decreased risk of hypertension in Caucasians, and the risk of hypertension was not significantly increased with increasing in alcohol consumption in Caucasians, Chinese, and Hispanics (all Pfor trend > 0.05). On the contrary, in context of low diet quality, the risk of hypertension was significantly increased with increasing in alcohol consumption in Caucasians (Pfor trend = 0.005), Chinese (Pfor trend = 0.001) and Hispanics (Pfor trend = 0.022). Associations between alcohol consumption and risk of hypertension significantly varied by diet-quality scores in Caucasians, Hispanics, and Chinese (all Pfor interaction < 0.01) showing gradually changing from nonsignificant increasing trend to linear association. Conclusions: This study firstly demonstrated that overall diet quality influenced associations between alcohol and risk of hypertension across different ethnicities, emphasizing that when examining health effects of alcohol on blood pressure, diet quality should be considered.