Benefits
Antioxidant defense support
Selenium from high-selenium yeast supplies the body with the building blocks for selenium-dependent enzymes such as glutathione peroxidases, which help neutralize free radicals. In men with lower baseline selenium status, high-selenium yeast has been shown to support reductions in markers of oxidative stress, helping maintain cellular balance against everyday oxidative load.
Healthy immune function
Adequate selenium status helps maintain normal immune cell activity and the body's antioxidant protection of immune tissues. Selenoproteins contribute to balanced inflammatory and immune responses, so maintaining sufficient selenium intake supports the immune system's everyday readiness and resilience.
Normal thyroid metabolism
The thyroid gland is one of the most selenium-rich tissues in the body. Selenium-dependent deiodinase enzymes help convert thyroid hormone into its active form, and selenoproteins protect thyroid tissue from oxidative byproducts. Supplying organically bound selenium helps maintain normal thyroid hormone metabolism.
Food-form bioavailability
As an organically bound, yeast-derived selenium source, SelenoExcell® delivers selenium primarily as selenomethionine, the same form found in selenium-rich foods. This food-form selenium is well absorbed and readily incorporated into the body's protein pool, helping build and maintain robust selenium reserves over time.
Maintains healthy selenium status
Many adults have suboptimal selenium intake depending on regional soil levels. Supplementing with a standardized high-selenium yeast helps raise and maintain plasma and tissue selenium to adequate levels, supporting the wide range of selenoproteins the body relies on for antioxidant, immune, and metabolic functions.
Mechanism of action
Glutathione peroxidase synthesis
Selenium is incorporated as selenocysteine into glutathione peroxidase enzymes. These enzymes reduce hydrogen peroxide and lipid peroxides, forming a frontline antioxidant defense that protects cell membranes and DNA from oxidative damage.
Selenomethionine protein incorporation
Yeast-derived selenomethionine is non-specifically incorporated into body proteins in place of methionine, creating a selenium reservoir. This stored selenium is gradually released and used to synthesize functional selenoproteins as the body requires them.
Thyroid deiodinase activity
Selenium-containing iodothyronine deiodinases convert thyroxine (T4) into the metabolically active triiodothyronine (T3). Sufficient selenium supports normal activity of these enzymes and helps protect the thyroid from peroxide generated during hormone synthesis.
Redox signaling and thioredoxin support
Selenoproteins such as thioredoxin reductase help regulate the cell's redox state and support normal cell-signaling and repair processes, contributing to balanced responses to oxidative and inflammatory stress.
Clinical trials
Multicenter, double-blind, randomized, placebo-controlled trial; 200 µg/day selenium as high-selenium (selenized) yeast; mean follow-up ~6–7 years.
1,312 older adults from the eastern United States with a history of nonmelanoma skin cancer.
Selenized yeast did not reduce the primary endpoint of basal or squamous cell skin cancer; in fact, later analysis found a modest increase in squamous cell and total nonmelanoma skin cancer. Secondary analyses suggested lower total cancer incidence and lower prostate and colorectal cancer rates, especially in men with low baseline selenium, but these were exploratory findings that later trials did not confirm.
Randomized, double-blind, placebo-controlled trial; SelenoExcell® selenium yeast at 200 or 285 µg/day vs. L-selenomethionine 200 µg/day vs. placebo; 9 months supplementation plus 3-month washout.
69 healthy adult men.
The higher-dose selenium yeast group showed significant reductions in oxidative stress markers (urinary 8-OHdG down ~34% and 8-iso-PGF2alpha down ~28%), with the greatest effect in men who started with lower selenium levels. Selenomethionine alone did not significantly change these markers. No changes in PSA or blood glucose were observed.
Large randomized, double-blind, placebo-controlled trial using L-selenomethionine 200 µg/day (not selenium yeast), with or without vitamin E; planned 7–12 years, stopped early.
35,533 generally healthy men aged 50–55+ in the US, Canada, and Puerto Rico.
Selenium as selenomethionine did not reduce prostate cancer risk and showed a small non-significant signal toward increased type 2 diabetes. Because this trial used pure selenomethionine rather than multi-species selenized yeast, it does not directly test SelenoExcell®, and its null result helped temper earlier selenium cancer-prevention enthusiasm.