What Is Selenium?

Selenium is a trace mineral, which is essential to good health. However, it is only needed in small amounts.

Some of the functions of selenium include, protecting our cells from free radical damage. It also helps to regulate thyroid function. And, plays a role in the immune system.

The selenium content of plant foods in our diet, is directly related to the soil concentration of selenium where the food was grown.

Selenium Deficiency

Selenium deficiency is rare, but it may be seen in countries where the soil concentration of selenium is low, for example China.

A prolonged and severe selenium deficiency may lead to Keshan disease, which can be prevented by increasing selenium intake. Another disease, called Kashin-Beck’s disease, has been identified, where selenium deficiency is the primary cause.

For the most part, cases of selenium deficiency are associated with severe gastrointestinal problems, for example Crohn’s disease. Or, following surgical removal of part of the stomach.

Research also suggests that people with an iodine deficiency may benefit from selenium supplementation. This is because a selenium deficiency may worsen the effects of iodine deficiency on thyroid function.

What Foods Contain Selenium?

Celine Massa

As I said, the selenium content of food is quite variable, depending on soil conditions. This doesn’t only effect plants, but animals, too, since animals depend on plants in their own diet.

When animals eat grains or plants grown in selenium-rich soil, they will have higher levels of selenium in their muscle tissue.

Brazil nuts are actually the most highly concentrated source of selenium.

In one study, researchers found that eating one Brazil nut per day proved to be a better source of selenium than taking it as a dietary supplement.

Other sources of selenium, include:

  • Cod
  • Shrimp
  • Tuna
  • Halibut
  • Salmon
  • Scallops
  • Chicken
  • Eggs
  • Shiitake mushrooms
  • Lamb
  • Barley
  • Turkey
  • Oats

Bread and pasta may also contribute some selenium to your diet. However, milling of grains removes much of the selenium content.

What Is The Recommended Intake Of Selenium?

The Institute of Medicine, at the National Academy of Sciences, have set the Recommended Dietary Allowances (RDA) for selenium, as follows:

Selenium RDA For Men

0-6 months: 15 micrograms (adequate intake)
6-12 months: 20 micrograms (adequate intake)
1-3 years: 20 micrograms
4-8 years: 30 micrograms
9-13 years: 40 micrograms
14 years and older: 55 micrograms

Selenium RDA For Women

0-6 months: 15 micrograms (adequate intake)
6-12 months: 20 micrograms (adequate intake)
1-3 years: 20 micrograms
4-8 years: 30 micrograms
9-13 years: 40 micrograms
14 years and older: 55 micrograms
Pregnant females: 60 micrograms
Lactating females: 70 micrograms

A tolerable upper limit (UL) for selenium has been set at 400 micrograms per day for men and women 19 years and older.

Are Selenium Supplements Needed?

Most people do not need to take selenium in supplement form.

As I’ve said before, the nutrients in your diet should come primarily from foods. This is the form that your body recognizes most, and can gain most benefit from.

Getting your selenium from food also means that you are less likely to experience problems with toxicity.

A dietary supplement may be necessary in specific circumstances. It is, however, best to get the advice of your doctor regarding this.

This article is part of a series of short nutrition 101 articles (what is ironwhat is magnesium, what is zinc, what is vitamin D) — please let me know if there’s something you would particularly like me to discuss in this series :-)

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About Melanie
Melanie is a Registered Dietitian who started Dietriffic in March 2007. Her aim is to make good health attainable and sustainable, without guilt and torture, making her approach popular with those who desire a level-headed approach to good health. Have you got your copy of her free book yet?


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{ 12 comments… read them below or add one }

Cathy in NZ January 6, 2012 at 4:25 am

selenium mineral is not in NZ soils either…but I advocate as much as possible (i.e. able to forget) at least a Brazil Nut a day :-)

Reply

Melanie January 10, 2012 at 8:23 pm

That’s interesting Cathy. Is it standard advice in NZ to take a Brazil nut a day, or just something you do yourself?

Reply

Cathy in NZ January 10, 2012 at 8:58 pm

no not standard advice…I just read somewhere about a Brazil nut a day. I don’t know if it has any real affect though…

Reply

Melanie January 11, 2012 at 11:40 am

I think it’s a good thing to do :-)

Reply

Michelle January 12, 2012 at 3:17 pm

I am always interested in the effect vitamins and minerals have on health. I noted your comment on the role selenium has in Chron’s Diseases and will investigate that further. Thanks for sharing this post.

Reply

Melanie January 19, 2012 at 6:25 pm

You’re welcome, Michelle.

Reply

Mark February 21, 2013 at 1:57 am

Good article, Great site, Whish i found it a month ago. Anyway, going to DL your EBook. thanks for the info.

Reply

Selenium Supplement July 30, 2013 at 8:53 pm

Selenium supplements ARE necessary!

You forgot to mention that selenium is consumed in protein form, and as we all know, our bodies takes in a very small portion of the nutrients/vitamins in proteins.

Reply

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