Love Brazils? Beware Potential Selenium Overload!

I got a shock the other day. I have been vegetarian for 40 years and was confident I was never short of any essential vitamins or minerals. I paid attention to what I ate, rarely ate junk food and took supplements when I felt the need. All tests have always come back normal. Since becoming vegan a year ago, I have researched which areas of my diet may need more rigorous attention and apart from a B12 supplement, I decided it was far better to eat a balanced, plant-based diet than to buy expensive supplements that I may or may not need and may or may not absorb on the off-chance that I may become slightly deficient.

 I had read that a good source of Selenium for vegans was Brazil nuts. Fantastic, I thought, I love Brazil nuts. They became my favourite morning snack. I would eat at least 6 and maybe 10 a day.

When I decided to research and write a series of posts on essential vitamins and minerals, I read about Selenium in a little more detail. That’s when I got the shock.

The BDA – the association of British Dieticians – recommends eating only 1-2 Brazil nuts a day and no more than 3-4 due to the possibility of Selenium toxicity!

The Adult RDA for Selenium is 55mcg (micrograms) with an upper limit of 400mcg.

I was consuming about 30g of Brazil nuts, which is approximately 575mcg of Selenium per day!


(100g of Brazil nuts per month provides the requisite amount).

Selenium is required for healthy thyroid function, to strengthen the immune system, protect cells from damage, and reduce the risk of cancer and heart disease. The amount of Selenium in our foods has depleted due to poor quality soil and contaminated water and varies considerably according to where you live.

However, studies conducted on vegans in the UK, Germany, US and New Zealand (the latter has very low levels of selenium in the soil) showed that the majority were taking adequate amounts of Selenium.

Symptoms of Selenium toxicity include:

Hair loss, fatigue, irritability, white spots on nails, gastrointestinal disorders and neurological damage.

Stopping the excess Selenium and drinking lots of water usually reverses the damage.

Fortunately, I seem to have avoided these problems but I will miss my favourite snack.

Sources of Selenium:

Brazil  Nuts: 30g = 575mcg

Wholewheat Spaghetti 215g = 56mcg

Couscous: 140g = 39 mcg

Shitake Mushrooms 85g = 21 mcg

Wholewheat Flour 30g = 20mcg

Sunflower Seeds 30g = 16mcg

Sources: The Vegan Society

Rich Vegan Foods

Copyright: Chris McGowan

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