Effects of Supplementation with Selenium, as Selenized Yeast, in a Healthy Male Population from New Zealand

Abstract

Selenium (Se) supplementation was tested in a group of healthy men from Auckland, New Zealnd with selenized yeast (Selplex, 200 μg/day) as the supplementation mode. A set of biomarkers, including DNA damage levels and seleno-antioxidant enzyme levels, were evaluated at pre- and postsupplementation time points. Supplementation produced significant increases in serum Se levels, red blood cell (RBC) thioredoxin reductase (TR) activity and peroxide-induced DNA damage, when the mean baseline serum Se level was 110 ng/ml. Those with higher baseline serum Se levels gained less serum Se and showed a significant reduction of RBC glutathione peroxidase (GPx) activity by supplementation. The optimum benefits of supplementation on DNA stability are observed when the serum Se level reaches between >120 and <160 ng/ml. However, the most significant observation was that those with highest baseline DNA damage benefit the most from Se supplementation, whereas those having lower baseline DNA damage are disadvantaged. A dose of 200 μg/day selenized yeast was also shown to be a safer supplementation option compared to a similar dose of selenomethionine (SeMet). This study highlights the requirement for prestratification of a population by standing serum Se level and baseline DNA damage level, before any Se supplementation is carried out.

ACKNOWLEDGMENTS

The authors are grateful to the Cancer Society of New Zealand for the financial support provided for this study from June 2006 to July 2009. The authors also wish to thank and acknowledge the contributions made by Alltech, Ireland by supplying Se as 200 μg selenised yeast (SELPLEX) capsules for this study. We also wish to thank Prof. Andrew Collins, Professor of Nutrition Biology, University of Oslo, Norway for his suggestions in improving this manuscript. This study was designed by Lynnette R. Ferguson, Nishi Karunasinghe, and Shuotun Zhu. He Duan and Yi-Ju Ko conducted the volunteer recruitment, laboratory procedures and data management. This manuscript was written by Nishi Karunasinghe and Lynnette R. Ferguson with statistical methods and analyses by Dug Yeo Han, in consultation with Christopher M Triggs. Jie-Fu Yu carried out pilot statistical analyses of the data.