Catalase is most highly expressed in the liver, kidney and erythrocytes. The enzyme is responsible for the rapid conversion of hydrogen peroxide to water and oxygen, where one molecule of this enzyme can catalyse more than 1 million hydrogen peroxide molecules per second! Decreased CAT activity leads to increased concentrations of hydrogen peroxide, hence leading to increased oxidative stress.
Compared to the CC genotype, individuals with the T allele (CT genotype) have been associated with decreased CAT activity. Ensure a polyphenol-rich diet with a high intake of vegetables. Decrease dietary and environmental carcinogen exposure (pollution, pesticides, smokes foods and nitrates used as a food preservative). Cessation of smoking should be strongly encouraged.
If you have a medium to high impact variation on this gene, you can 'add in' choices that better support it biochemical and functional pathway.