Catalyzes the NAD-dependent oxidation of all-trans-retinol and its derivatives such as all-trans-4-hydroxyretinol and may participate in retinoid metabolism (PubMed:15369820, PubMed:16787387). In vitro can also catalyzes the NADH-dependent reduction of all-trans-retinal and its derivatives such as all-trans-4-oxoretinal (PubMed:15369820, PubMed:16787387). Catalyzes in the oxidative direction with higher efficiency (PubMed:16787387). Has the same affinity for all-trans-4-hydroxyretinol and all-trans-4-oxoretinal (PubMed:15369820). all-trans-retinol + NAD(+) = all-trans-retinal + H(+) + NADH all-trans-4-hydroxyretinol + NAD(+) = all-trans-4-hydroxyretinal + H(+) + NADH all-trans-4-oxoretinol + NAD(+) = all-trans-4-oxoretinal + H(+) + NADH Binds 2 Zn(2+) ions per subunit. Dimer of identical or non-identical chains of three types; alpha, beta and gamma. Three alleles are known: ADH1B*1 (ADH2*1) corresponding to variant beta-1, ADH1B*2 (ADH2*2) corresponding to variant beta-2, ADH1B*3 (ADH2*3) corresponding to variant beta-3. The sequence shown is that of allele ADH1B*2. The ADH1B*2 allele frequency in orientals is approximately 75%, whereas it is less than 5% in most Caucasian populations. The ADH1B*2 allele is associated with a lower risk of alcoholism. ADH1B variations have been associated with protection against alcohol dependence and alcohol-related aerodigestive tract cancer [MIM:103720]. There are 7 different ADH's isozymes in human: three belongs to class-I: alpha, beta, and gamma, one to class-II: pi, one to class-III: chi, one to class-IV: ADH7 and one to class-V: ADH6. Belongs to the zinc-containing alcohol dehydrogenase family.