Selenium is an essential trace mineral. You only need a small amount, but it plays important roles in the body.

Selenium is built into special proteins called selenoproteins as the amino acid selenocysteine. These include the glutathione peroxidases, which help protect cells from oxidative damage, and the iodothyronine deiodinases, which convert thyroid hormone from its inactive to active form. Selenium from food or supplements is absorbed mainly in the small intestine. Organic forms such as selenomethionine (found in foods and selenium yeast) are absorbed very efficiently, while inorganic forms such as sodium selenite are absorbed well but handled differently by the body. The selenium content of Australian foods depends on the soil where crops are grown, and Brazil nuts are a particularly rich source. The body regulates selenium carefully, and too much can be harmful (NIH Office of Dietary Supplements).

• Helps maintain thyroid function as part of a healthy diet
• May help support antioxidant defences
• Helps maintain healthy hair and nails
• Helps maintain normal immune system function
• Helps relieve selenium deficiency when dietary intake is inadequate

How much selenium do I need?

Adults need only a small amount each day, and many people get enough from a varied diet. A couple of Brazil nuts can supply a lot, so check your total intake before adding a supplement.

Can you take too much selenium?

Yes. The gap between enough and too much is fairly narrow, and long-term excess can cause brittle hair and nails, a garlic-like breath odour and stomach upset. Stick to the label dose and count the selenium in any other supplements you take.

Do not exceed the label dose. Excess selenium over time can be harmful. Speak to your health professional if you are pregnant, breastfeeding, have a thyroid condition or take other supplements containing selenium.

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