Trace mineral selenium is one of the nutrients that we need in small amounts every day. It is actually a paradoxical element – if we are deficient in it, we can experience many deficiency symptoms, but if we get more than we need either from food or supplements, we can experience symptoms of toxicity.
Functions of selenium and its benefits for health
Trace mineral selenium has many functions, and researchers are finding more of its roles everyday. First of all, selenium works like an antioxidant and slows down the biochemical process of aging, that is, the loss of youthful elasticity. This process is enhanced by vitamin E, another important antioxidant.
The antioxidant effect of selenium also supports the cardiovascular system and protects against cancer. Did you know that low levels of selenium in soil are associated with higher risk of cancer? The soil is important here because the vegetables that we eat only have adequate amounts of selenium if they are grown in selenium rich soils. Other studies have found that low soil levels of selenium are associated with higher risk of heart disease. One study about angina found that, when patients took 1 mg of selenium together with 200 IU of vitamin E, almost 100% of patients experienced reduced symptoms. The group on a placebo did not experience much benefit. (Source – Staying Healthy with Nutrition by Elson M. Haas, MD).
Keshan disease, that comes about because of severe selenium deficiency, was discovered in Keshan, China. People with this disease, usually children and women, suffer from enlarged heart and cardiovascular inefficiency. People in Keshan treat this condition with a herb named astralagus, which concentrates selenium from the soil.
Selenium also protects us from toxic effects of heavy metals and other chemicals. People who get adequate levels of selenium in their diet (for adults, this is between 55 and 200 mcg of selenium per day), experience less toxic effects from smoking, alcohol, oxidized fats, and mercury.
Men need a lot more selenium then women because this element is important in male fertility.
However, scientists are still not sure if selenium actually causes infertility – but they do know it can prevent it.
Selenium is also needed for making the most active form of thyroid hormone. That is why anyone with thyroid problems should consider if their selenium levels are low – that is, do they get enough selenium in their daily food?
What are the food sources of selenium?
As mentioned above, the amount of selenium in food depends on the soil where the food was grown. This differs in different regions and from country to country. Also, lots of selenium is lost when the food is refined, for example, in white flour. It can also be found in some water sources. Breast milk contains a few times more selenium that cow milk.
The following products are considered to be abundant in this important trace mineral:
- Brazil nuts
- Sunflower seeds
- Onions and garlic
- Rye bread
- Nutritional yeast
If you want to make sure you get enough selenium in your diet, it is important to eat a variety of fresh foods. If for some reason you can’t do that, hold a bowl of some Brazil nuts on your counter and eat 1-2 (no more) of these nuts a day. One Brazil nut has about 50 mcg of selenium, an amount that is recommended for the maintenance of adult health.
What is the best supplement for selenium?
If you are looking for a selenium supplement, make sure you get organic selenium (selenocysteine or selenomethione forms). Make sure to take it with vitamin E since the antioxidant effects of selenium and E are synergistic.
If you get sodium selenite form, make sure you take it in the absence of vitamin C, since it seems to combine with this form of selenium and make the selenium made by this interaction less absorbable and even (possibly) more toxic.
There are good brands available on iherb.com and the prices are at least 30% less than in local health foods stores. (Just make that if you are ordering from Canada, select the cheapest shipping option if you do not want to pay custom fees at the door.)
How much selenium is too much?
With respect to selenium toxicity, research have shown that taking about 1 mg (1000 mcg) of selenium daily for extended period of time did not show any negative effects. It is really possible that in our current environment we need more than 100 mcg to get its antioxidant, anticarcionogenic, and immune boosting benefits.
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