NQO1 encodes for the NAD(P)H dehydrogenase [quinone] 1 enzyme and is involved in the detoxification of potentially mutagenic and carcinogenic quinones derived from tobacco smoke, diet and estrogen metabolism. NQO1 also protects cells from oxidative stress by maintaining your antioxidant levels with ubiquinol CoQ10 and vitamin E.
The variant T allele results in reduced enzymatic activity. Compared with the wild-type CC genotype, the heterozygote variant (CT) has a three-fold decrease in enzyme activity and the TT genotype has only 2%–4% of the quinone reductase activity. Individuals with the CT and TT genotype have been associated with an increased risk for developing certain cancers including breast, colorectal and gastrointestinal cancers, especially when there is exposure to cigarette smoke. The polymorphism has also been linked to benzene toxicity.
If you carry the TT-genotype in this gene then it is recommended that you do not smoke, avoid polycyclic aromatic hydrocarbons (PAHs) found in smoked foods and chargrilled meats. Increase intake of cruciferous vegetables and add in a supplement with sulforaphane (a compound found in broccoli).