Catalyzes the NADPH-dependent reduction of a wide variety of carbonyl-containing compounds to their corresponding alcohols (PubMed:9565553, PubMed:18087047, PubMed:12732097, PubMed:19013440, PubMed:19563777). Displays strong enzymatic activity toward all-trans-retinal, 9-cis-retinal, and 13-cis-retinal (PubMed:12732097, PubMed:18087047). Plays a critical role in detoxifying dietary and lipid-derived unsaturated carbonyls, such as crotonaldehyde, 4-hydroxynonenal, trans-2-hexenal, trans-2,4-hexadienal and their glutathione-conjugates carbonyls (GS-carbonyls) (PubMed:19013440, PubMed:19563777). Displays no reductase activity towards glucose (PubMed:12732097). all-trans-retinol + NADP(+) = all-trans-retinal + H(+) + NADPH 9-cis-retinol + NADP(+) = 9-cis-retinal + H(+) + NADPH 13-cis-retinol + NADP(+) = 13-cis-retinal + H(+) + NADPH allyl alcohol + NADP(+) = acrolein + H(+) + NADPH (E)-4-hydroxynon-2-en-1-ol + NADP(+) = (E)-4-hydroxynon-2-enal + H(+) + NADPH a 4-hydroxynonen-1-ol + NADP(+) = a 4-hydroxynonenal + H(+) + NADPH NADP(+) + prenol = 3-methyl-2-butenal + H(+) + NADPH (E)-hex-2-en-1-ol + NADP(+) = (E)-hex-2-enal + H(+) + NADPH (E,E)-2,4-hexadien-1-ol + NADP(+) = (E,E)-2,4-hexadienal + H(+) + NADPH (E)-4-oxonon-2-en-1-ol + NADP(+) = (E)-4-oxonon-2-enal + H(+) + NADPH 4-methylpentan-1-ol + NADP(+) = 4-methylpentanal + H(+) + NADPH Retinaldehyde reductase activity is inhibited by tolrestat. kcat is 640 min(-1) for glyceraldehyde as substrate (PubMed:12732097). kcat is 185 min(-1) for pyridine-3-aldehyde as substrate (PubMed:12732097). kcat is 116 min(-1) for acrolein as substrate. kcat is 103 min(-1) for 3-methyl-2-butenal as substrate. kcat is 97 min(-1) for(E)-2-hexenal as substrate. kcat is 82 min(-1) for (E,E)-2,4-hexadienal as substrate. kcat is 120 min(-1) for 4-hydroxynonenal as substrate. kcat is 3 min(-1) for GS-acrolein as substrate. kcat is 70 min(-1) for GS-3-methyl-2-butenal as substrate. kcat is 71 min(-1) for GS-(E)-2-hexenal as substrate. kcat is 147 min(-1) for (E,E)-2,4-hexadienal as substrate (PubMed:19563777). kcat is 35 min(-1) for D,L-glyceraldehyde as substrate. kcat is 27 min(-1) for all-trans-retinal as substrate. kcat is 1 min(-1) for 9-cis-retinal as substrate (PubMed:18087047). kcat is 43 min(-1) for 4-hydroxynon-2-enal (PubMed:19013440). kcat is 40 min(-1) for (E)-4-oxonon-2-enal (PubMed:19013440). kcat is 25 min(-1) for 4-methylpentanal (PubMed:19013440). Cofactor metabolism; retinol metabolism. Secreted through a lysosome-mediated non-classical pathway. Found in many tissues. Highly expressed in small intestine, colon and adrenal gland. Overexpressed in certain types of cancers, including hepatocellular carcinoma and lung cancer associated with tobacco smoking. Has no counterpart in murine and rat species. Belongs to the aldo/keto reductase family.