Penn State Milton S. Hershey Medical Center researchers are trying to compare the effects of two different forms of selenium (selenium yeast and selenomethionine) on blood selenium levels and biomarkers of oxidative stress as primary endpoints. One in six men are at risk of getting prostate cancer in their lifetime. Participants will be asked to take over-the-counter selenium yeast supplements and selenomethionine or a placebo for nine out of twelve months.

We will conduct a double-blind, randomized, placebo-controlled clinical study of selenium supplementation in the form of L-selenomethionine (SM)(200 µg/day) and selenium-enriched yeast (SY) (200 µg/day and 285 µg/day) for 9 months; the 285 µg/day SY is selected to deliver an equivalent selenium as in 200 µg/day SM to healthy men. The variability of SM in SY that will be used here is less than 3% and it accounts for 70.5% of the SM content in SY. As primary endpoints, we will determine the effects of these two forms of selenium on plasma levels of selenium and its metabolites as well as biomarkers of oxidative stress at several time points. As a secondary endpoint, the effect of these two forms of selenium on plasma PSA levels will be examined.

Inclusion Criteria:

• No history or evidence of diabetes
• Male between the ages of 20-79
• PSA levels ≤ 4.0 ng/mL
• Not taking >50 µg/day selenium as a dietary supplement including multi- vitamins
• Non-smoker
• No concurrently participating or have participated in any other clinical trial within at least 30 days of registration
• Health male

Exclusion Criteria:

• Evidence of prostate cancer
• Evidence of liver or kidney disease