Selenium is an essential trace mineral incorporated into selenoproteins including glutathione peroxidase (antioxidant), thioredoxin reductase, and iodothyronine deiodinase (thyroid hormone conversion). The thyroid has the highest selenium content per gram of any organ, making adequate selenium essential for thyroid health and antioxidant defence.
Selenium deficiency impairs antioxidant defence, thyroid hormone metabolism, and immune function. Status in Australia is generally adequate but can be low with restricted diets or malabsorption.
FAQs
How many Brazil nuts for selenium?
1-2 per day provides 70-150 mcg, meeting the daily recommended intake. Eating large quantities is not recommended due to selenosis risk.
Does selenium help Hashimoto's thyroiditis?
Yes. Selenium supplementation (200 mcg/day) reduces anti-TPO antibodies in Hashimoto's thyroiditis over 3-6 months, most pronounced in deficient individuals.
Blood selenium or RBC GPx - which is better?
Blood selenium reflects recent intake. RBC glutathione peroxidase (GPx) activity reflects functional selenium status over 3-4 months and is the better long-term marker.
Can selenium cause toxicity?
Yes. Selenosis occurs above 400 mcg/day, causing hair loss, brittle nails, and neurological effects. Supplements should be kept at 100-200 mcg/day maximum.
