Down-Regulation of Oxidative DNA Lesions in Human Mononuclear Cells After Antioxidant Supplementation Correlates to Increase of Gamma-Tocopherol

The protective effect of vitamin E supplements has been questioned, possibly because they often contain only α-tocopherol, and recent studies indicate that γ-tocopherol also has important properties. The aim of this study was to investigate whether the levels of DNA lesions in middle-aged, overweight males could be reduced by consumption of low doses of an antioxidant supplement for six weeks, designed to imitate a balanced diet. The participants (n = 60) were randomly divided into: placebo, single-, and double-dose groups. Genotoxic and oxidative DNA lesions in mononuclear cells were measured with the Comet assay, before and after supplement administration. Furthermore, a cell study was performed to investigate if pre-incubation of a human lung cell line (A549) with α- and γ-tocopherol (5 and 50 μM for 23 hours) could protect against induced oxidative DNA lesions as measured by the Comet assay. The level of oxidative DNA lesions in the double-dose group was significantly lower than in the control group. Oxidative DNA lesions correlated only to changes in serum γ-tocopherol, and not α-tocopherol. In the cell study, only γ-tocopherol protected cells against induced oxidative DNA lesions. We therefore hypothesize that γ-tocopheol rather than α-tocopherol is involved in reducing oxidative DNA lesions.