GLOSSARY

Selenoproteins are proteins incorporating selenocysteine, including roles in antioxidant defense and thyroid metabolism.

Selenium enters specific proteins as selenocysteine, including enzymes in antioxidant defense and thyroid-hormone metabolism. A selenoprotein is not simply any protein located beside selenium. Essential cellular functions do not guarantee a recovery benefit from supplements. In an adequately supplied athlete, distinguish evidence of biological function from evidence that extra intake improves outcomes, and consider the overall dietary context as well.

Fish, meat, eggs, grains and some nuts supply selenium, with soil and growing region affecting amounts. Brazil nuts can be rich and variable, so a fixed nut count is not a precise dose across products. Blood and functional protein markers require context. An antioxidant claim does not replace adequacy assessment, and combination supplements also contribute to total exposure rather than being nutritionally negligible.

Selenium deficiency occurs with inadequate supply or particular conditions, but excess can cause selenosis. Hair and nail changes, digestive symptoms or unusual breath odor can occur in toxicity and are not specific. Combining rich foods and supplements for immunity can produce unsuitable exposure. Safety limits depend on the reference framework and circumstances; essentiality must not be confused with harmlessness at any amount.