Fenech M, Dreosti I, Aitken C
CSIRO Division of Human Nutrition, Adelaide, Australia.
Carcinogenesis. 1997 Feb;18(2):359-64. doi: 10.1093/carcin/18.2.359.
A placebo-controlled double-blind intervention trial was performed using 60 male volunteers aged between 50 and 70 years to test the hypothesis that intake of d-alpha-tocopherol (VITE) above the recommended dietary intake (RDI) level (10.0 mg or 14.9 IU VITE) can protect against DNA damage in human peripheral blood lymphocytes. The intervention consisted of two phases, each of 8 weeks duration: during the initial phase the VITE supplement was 5 x RDI (provided in cereal) and during the second phase the VITE supplement was 30 x RDI (provided in capsules). Blood samples were collected before the initial phase, between phases and at the end of the second phase; the level of VITE was measured in plasma using HPLC and genetic damage rate in peripheral blood lymphocytes was measured using the cytokinesis-block micronucleus assay. The study has shown that cereal supplementation is an effective route for an above RDI intake of VITE; a 5 x RDI supplement resulted in a 22% elevation in the plasma VITE status. By comparison the use of 30 x RDI supplementation with capsules as the route of delivery resulted in an 89% increment in plasma VITE status. The increased VITE status during the intervention, however, had no significant impact on the spontaneous genetic damage rate in human lymphocytes. There was also no correlation between baseline genetic damage frequency and VITE status. However, a 32% (P < 0.007) decrease in the micronucleus index was recorded in both the control and VITE-supplemented groups during the course of the study which could have been due either to seasonal effects or other common components in the diet such as the carrier used for the VITE in the cereal and the capsules. The study has identified a small proportion (3.4%) of apparently healthy individuals who are abnormally sensitive to oxidative stress by hydrogen peroxide and demonstrated that VITE supplementation did not attenuate the impact of the oxidative challenge on genetic damage rate. The above data suggest that supplements in cereal are a viable route for delivering VITE and that supplementation with VITE is unlikely to affect chromosome damage occurring spontaneously or as a result of exposure to oxidative radicals.
