Selenium is an essential trace mineral that occurs naturally in the soil and is absorbed by plants and crops, from where it enters the human food chain. New Zealand soils have long been low in selenium which in turn affects its content in foods and which transfers to a low serum (blood) level in the general New Zealand population. While an increase in the selenium content of our food supply - largely due to imported selenium-enriched foods, and supplemental animal feeds - has improved our collective selenium status, many people may still benefit from paying attention to their selenium intake.
Why do we need selenium?
We use selenium to make approximately 25 different types of selenoproteins; complexes made up of the mineral selenium and the amino acid cysteine ( to form selenocysteine). There are about 25 different selenocysteine-containing selenoproteins in human tissues. One of the best-known actions of these compounds is their role in maintaining cellular health and supporting the body's natural antioxidant systems. Selenium contributes to the normal functioning of antioxidants like glutathione peroxidase, which plays a part in neutralising free radicals and supporting the activity of other antioxidant nutrients, including vitamins C and E.
In addition to its antioxidant role, selenium supports:
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Normal thyroid hormone metabolism
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Healthy immune system function
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The body’s natural ability to manage oxidative stress
Natural Sources of Selenium
Selenium is readily available in the following foods:
- Brazil nuts - these are the best source of selenium and just eating few of these daily will keep your levels topped up.
- Seafood- including crab, lobster, tuna
- Poultry and red meat
- Eggs
- Organ meats- Kidney and liver
- Vegetables- including onions, garlic, broccoli, tomatoes and mushrooms
Remember that that selenium content in food will be governed by soil quantities of selenium.
How much selenium do we need?
In New Zealand a safe upper limit for selenium intake is set at of 400 micrograms daily, however most supplements contain a maximum of 150mcg daily as most people will be getting selenium from various dietary sources. While 400mcg is considered a safe intake that will not produce toxicity in the majority of the population, there is evidence that selenium supplementation may be not be recommended for those people who already have an adequate selenium status. Evidence suggests that smokers may require a higher intake of selenium, however always check with a health professional if you want to take a higher dose of selenium than is recommended in any dietary supplement.
Selenium may be a trace mineral, but it plays a significant role in maintaining everyday wellbeing—from supporting antioxidant activity and immune health to assisting with normal thyroid function. Including selenium-rich foods as part of a varied diet can be one of the simplest ways to support your body’s daily needs.
