Selenium is an essential trace mineral that is a core component of selenoproteins, which function as powerful antioxidant enzymes (e.g., glutathione peroxidases). These enzymes protect cells from oxidative damage, a key driver of aging. It also plays a vital role in thyroid hormone metabolism and immune function, making its sufficiency critical for systemic health.
Verdict
Ensure adequacy through diet; supplement cautiously only if deficient.
HEALTHSPAN IMPACT
Moderate
RISK LEVEL
Low
EVIDENCE GRADE
B
MONTHLY COST
$2 - $7
Protocol
- Supplementing with 50-200 mcg daily, often as selenomethionine, to ensure adequate levels without exceeding the upper limit.
Flags
- U-shaped mortality curve: both deficiency and excess are associated with increased mortality.
- The SELECT trial linked 200 mcg/day supplementation to an increased risk of high-grade prostate cancer in some men.
- High intake may increase the risk of developing type 2 diabetes.
- Toxicity (selenosis) can occur with chronic intake above the 400 mcg/day tolerable upper limit.
- Dietary sources like Brazil nuts can have highly variable and potentially excessive selenium content.