What does a ADH1B genotype mean for lifestyle?

The ADH1B gene encodes alcohol dehydrogenase, an enzyme that catalyzes the first step of alcohol metabolism. A common variant (rs1229984, ADH1B*2) results in significantly higher enzyme activity, causing ethanol to be converted more rapidly to acetaldehyde, a toxic intermediate that produces unpleasant effects such as nausea, facial flushing, and headache. Individuals carrying this variant tend to drink less alcohol on average and have a lower risk of alcohol dependence. However, the increased acetaldehyde exposure also raises the risk of certain cancers (e.g., esophageal cancer), especially with regular alcohol consumption. For lifestyle, this means: genetics is one factor but not deterministic. A DNA test can provide clues but does not replace medical advice. Those with the variant should avoid or minimize alcohol to reduce cancer risk. Even without the variant, alcohol poses general health risks. The evidence is strong (human studies, GWAS), but individual outcomes depend on environment and other genes.