Selenium 150mcg

Selenium is one of the few supplements where taking it without a reason can do you harm. These are the questions our naturopaths ask in store before they recommend one.

A good fit if

• A blood test has shown your selenium is low
• You eat little seafood, poultry or eggs and haven't replaced them
• Your practitioner has asked you to take it as part of a thyroid or fertility plan
• You'd like a single-ingredient tablet you can count, rather than selenium hidden in a blend

Check with us first if

• You already take a multivitamin, thyroid formula, antioxidant blend or male fertility formula, because each one may contain selenium and the 150 µg cap is per product.
• You're pregnant or breastfeeding, when the RDI is 65 and 75 µg and any supplement should be guided by a practitioner.
• You already eat a selenium-rich diet, as the evidence for adding a supplement on top of good levels isn't favourable.
• You have type 2 diabetes or are at risk of it, because randomised trials have shown a small signal of more diabetes with selenium supplements.
• You've had melanoma or another skin cancer, because trials at low risk of bias suggested a higher risk of melanoma.
• Prostate health is your reason for buying, because in men whose selenium levels were already highest, supplements were linked to more high-grade prostate cancer.
• You take any prescription medicine. We haven't found checked studies on selenium and medicine interactions, so it's worth a chat rather than a list.

• Selenomethionine (item 4487). Best known for: Raising blood selenium and keeping it up for the longest. Absorption: Blood selenium rose 93% over 9 months at 200 µg/day, the biggest rise of the three forms tested. Typical use: The single-ingredient tablet form, and the one the SELECT trial used.
• High selenium yeast / selenium-enriched yeast (item 2561). Best known for: The only form that changed markers of oxidative damage in a direct comparison trial. Absorption: Blood selenium rose 54% at 200 µg/day and 86% at 285 µg/day over 9 months. Typical use: It's made from Saccharomyces cerevisiae (yeast), so it's not for anyone avoiding yeast.
• Sodium selenite and its pentahydrate (items 4636, 4637). Best known for: A common inorganic form, and the usual one inside multivitamins. Absorption: Inorganic, so it tops up the selenium your enzymes use rather than building a store in your tissues. Typical use: Correcting a shortfall where a long-term reserve isn't the goal.
• Sodium selenate and its decahydrate (items 4634, 4635). Best known for: The one inorganic form that raised platelet glutathione peroxidase within a week. Absorption: Raised blood selenium less than the organic forms over one week. Typical use: Used the same way as selenite; less common on Australian shelves.
• Selenocysteine (item 4486). Best known for: The amino acid at the working centre of every selenoprotein. Absorption: We hold no human trial of it. Typical use: Allowed in Schedule 1 but rare in stores.

Reference values. The NHMRC Recommended Dietary Intake is 70 µg a day for men 19 and over and 60 µg for women, rising to 65 µg in pregnancy and 75 µg while breastfeeding. Children aged 1 to 3 need 25 µg and 4 to 8 need 30 µg. Boys and girls aged 9 to 13 need 50 µg. Infants have an Adequate Intake of 12 µg up to 6 months and 15 µg from 7 to 12 months.

Typical supplemental range. Australian single-ingredient tablets range from about 26 µg up to 150 µg of elemental selenium, and 150 µg is the legal maximum in one daily dose. You take selenium in micrograms, not milligrams. Most overseas trials used 200 µg a day, and some went to 285 or 300 µg. So the dose most studies used isn't one an Australian listed medicine can provide. We'd rather say that plainly than suggest the tablet matches the trial, and doubling up on products to reach 200 µg isn't the answer.

Upper level. The NHMRC Upper Level is 400 µg a day for adults, from food and supplements combined. It's much lower for children: 90 µg from 1 to 3, 150 µg from 4 to 8 and 280 µg from 9 to 13. So an adult 150 µg tablet is more than the whole day's Upper Level for a 1 to 3 year old.

Worth knowing. The 150 µg cap applies to each product, not to you. Selenium turns up in multivitamins, thyroid formulas, antioxidant blends and male fertility formulas, so add up every label before you add another product. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Seafood: named by the NHMRC as a main Australian and New Zealand source; no per-serve figure published there
• Poultry: named as a main source; no per-serve figure published
• Eggs: named as a main source; no per-serve figure published
• Other muscle meats: A smaller contribution than seafood, poultry and eggs
• Cereal products: varies with the source, because plant selenium tracks the selenium in the soil the grain grew in

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• Everyone. Every selenium medicine taken by mouth in Australia must warn that selenium is toxic in high doses and that 150 micrograms a day from dietary supplements should not be exceeded.
• Everyone. The NHMRC Upper Level is 400 µg a day for adults, and it counts food as well as supplements.
• Children. The Upper Level is 90 µg from 1 to 3 years, 150 µg from 4 to 8 and 280 µg from 9 to 13. Never give an adult selenium tablet to a young child.
• Babies. The Upper Level is 45 µg up to 6 months and 60 µg from 7 to 12 months.
• Pregnancy. The RDI is 65 µg a day and the Upper Level is 400 µg. Only take it with a practitioner's guidance, not as something you choose yourself.
• If you already have enough selenium. In the SELECT trial, men with the highest starting selenium levels had a higher risk of high-grade prostate cancer when they took supplements.
• Melanoma. Cochrane reported that well-designed randomised trials suggested a higher risk of melanoma.
• Type 2 diabetes risk. Cochrane reported that randomised trials showed a slightly higher risk of type 2 diabetes with supplements.
• Hair and skin. In SELECT, the trial Cochrane pooled, selenium increased hair loss and mild dermatitis. Worth knowing, since selenium is also sold for hair.
• Avoiding yeast. High selenium yeast and selenium-enriched yeast are made from Saccharomyces cerevisiae; choose selenomethionine or a selenite or selenate salt instead.
• Taking more than one product. The 150 µg limit applies to each medicine, not to you, so three products containing selenium can take you over the Upper Level without any single label being exceeded.
• Medicine interactions. We hold no verified studies of selenium interactions with medicines, so we don't list the interactions that are commonly repeated.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.