Plasma, Prostate and Urine Levels of Tocopherols and Metabolites in Men after Supplementation with a γ-Tocopherol-Rich Vitamin E Mixture

The vitamin E forms gamma- and delta-tocopherols (T) inhibit carcinogenesis in animal models; nevertheless, their cancer preventive activities in humans are uncertain. As an initial step to address this issue, we conducted a pilot phase 0 trial to determine the levels of tocopherols and their metabolites in prostate cancer patients undergoing radical prostatectomy. The patients were randomized to no supplementation or two capsules of a gamma-T-rich vitamin E mixture daily for 7 or 14 day prior to prostatectomy. Blood and urine samples were collected before supplementation and on the day of surgery, along with prostate tissue, for analysis of tocopherols and their metabolites. Estimated blood loss during surgery was not significantly different across treatment arms and there were no reported adverse events. Prostate tissue levels of gamma-T and delta-T were increased after 14 day of supplementation. Their side-chain degradation metabolites (CEHCs and CMBHCs) were significantly elevated in plasma, prostate and urine samples after supplementation for 7 or 14 day. In conclusion, supplementation with gamma-T-rich vitamin E increased the prostate levels of gamma-T and delta-T. The use of pure gamma-T, delta-T or tocopherol mixtures with higher ratio of gamma-T or delta-T to alpha-T is recommended for future studies.

Automated summary

Gamma- and delta-tocopherols in vitamin E have been shown to inhibit carcinogenesis in animal models, but their effects in humans remain uncertain. This pilot study found that supplementation with gamma-T-rich vitamin E increased levels of gamma-T and delta-T in prostate tissue, suggesting potential benefits for cancer prevention.