Two functional genetic polymorphisms, ADH1B rs1229984 and ALDH2 rs671, play key roles in ethanol metabolism and are especially prevalent in East Asian populations. The rs1229984 variant accelerates the conversion of ethanol to acetaldehyde, whereas rs671 reduces enzymatic activity for converting acetaldehyde into acetic acid. These variants affect alcohol use disorder risk and have been implicated in various systemic conditions.

To investigate the broader associations of ADH1B rs1229984 and ALDH2 rs671 with habitual alcohol use in large, unselected populations.

We analysed data from 146 374 Taiwanese adults (aged 20–90 years) enrolled in the Taiwan Biobank.

Both variants showed clear associations with habitual alcohol use. The ADH1B rs1229984 CC genotype was associated with a higher prevalence of drinking, indicating a substantial contribution to alcohol-related behaviour. The ALDH2 rs671 A allele was linked to markedly reduced drinking, reflecting known intolerance among carriers rather than implying a uniformly larger effect than ADH1B. Beyond alcohol use, rs671 showed a protective association with gout, whereas rs1229984 was not significantly associated with chronic diseases after correction.

In this large population sample, both ADH1B rs1229984 and ALDH2 rs671 demonstrate meaningful, genotype-dependent effects on habitual alcohol use. Their combined effects underscore the importance of evaluating gene–gene interactions rather than attributing disproportionate influence to a single locus.