Common Name: Selenium

Overview:

Selenium is not only a metal but also an essential trace mineral in human nutrition. This mineral is incorporated into proteins and forms selenoproteins. These proteins are important antioxidant enzymes. Selenoproteins help to prevent cellular damage from free radicals (free radicals are natural by products of cellular metabolism) that are ultimately responsible for many chronic diseases such as cancer, heart disease and other illness that become more common as we age.

Selenium is found in plants and animals. The selenium content of plants is dependant on the amount of selenium in the soils where they are grown. The selenium content of animals used as a source of meat is dependant on the selenium content of the plants on which these animals feed. Researchers have found that the soils in Nebraska and the Dakotas are high in selenium. People who live in this region have been found to have the highest selenium intake in the United States.

The soils in some parts of Russia and China have very low levels of this mineral in their soils. In this part of the world, selenium deficiencies are very common. Keshans disease, endemic in China where the soils are selenium poor, is a cardiomyopathy caused by a selenium deficiency. Kashins-Beck or “big joint disease” is a form of osteoarthropathy that is again found in areas of China, Tibet, Siberia, and North Korea. All these areas have soil that is very poor in selenium.

Selenium has antioxidant activity. Studies are showing that selenium may also have anticancer properties, antiatherogenic properties as well as the ability to strengthen the immune system. Selenium may also have the ability to detoxify some metals and compounds that are poisonous to humans.

Benefits

While a deficiency in selenium can lead to: cardiomyopathies, ischemic heart disease, and an increased risk of cancer. Selenium supplements have been shown to:

• Protect against certain forms of cancer. Low dietary intake of selenium has been linked to an increased risk of several types of cancer including lung, colorectal, skin and prostate. Studies in vitro (in the test tube) as well as animals and humans are showing that selenium supplementation protects against some forms of cancer.

Studies to date are showing that low selenium levels are not, in and of themselves, carcinogenic. Instead low selenium levels increase the susceptibility to the development of tumors. Low selenium status has been linked to poorer outcomes in those with cancer has been found in some studies.

A large well-controlled study that took place between 1983 and 1993 investigated the benefits of selenium supplementation. Participants in that study who took 200mcg daily (this was supplied by a brewer’s yeast with a high selenium level) showed a significantly lowered mortality from cancer. The mortality rate in those who took the supplements was 53% less that the control group. Although the rate of basal and squamous skin cell carcinomas was not affected, the incidence of lung, colorectal, and prostate cancers were greatly reduced. A similar study done in China took place over 4 years. The outcome of this study was similar. Those who took 200mcg of selenium had a reduced rate of primary liver cancer (cancer that develops first in the liver).

There has been much speculation that selenium in large doses may effectively tread some established cancers. A large study by the American Cancer Society is now underway.

1. Reduce the risk of cardiovascular disease. Diminished selenium levels have been associated with an increased risk of suffering a heart attack. Because selenium has antioxidant properties, it has shown to be able to protect against free radiacal damage to blood vessels. This damage leads to atheromatous plaque build up and hardening of the arteries. The ability of selenium to prevent the clumping of platelets, inhibit the production of bad cholesterol, and inhibit the formation of the inflammatory producing prostaglandins are also linked to its ability to prevent heart attacks.
2. Be essential in the maintenance of a health immune system. When there is not enough selenium in the body, normally benign (viruses that cause no illness) viruses can transform into ones that can cause disease. Studies have shown that selenium plays an important role in T-cells as well as natural killer cells. The T-cell response to infection is enhanced in the presence of selenium supplementation. The antioxidant properties of selenium protects the cells of the immune system from free radical damage. One study showed that selenium supplements help in the incidence of hepatitis-B-hepatoma (LOOK THIS UP). The level of selenium in the body is predicative of the survival time in those infected with AIDS.
3. Supplemental selenium can help protect against Kashin-Beck Disease, a form of arthritis that is common in selenium deficient areas of China. Preliminary evidence links selenium and vitamin E to the alleviation of the pain and morning stiffness associated with arthritis.
4. Supplemental selenium is helpful in protecting against the adverse side affects of being exposed to UV-radiation. In studies with mice, a significant reduction the development and mortality from skin cancers caused by exposure to UV radiation was seen.

Dietary Sources

	Seafood		Brazil Nuts
	Salmon		Beef
	Pork		Chicken
Brown Rice

Recommended Dosage:

Typical dosage for selenium supplementation range from 50-200mcg (micrograms daily).

Contra-indications

Selenium intake less than 900mcg daily are not likely to cause any adverse reactions. The most common symptoms of selenium toxicity are hair and nail brittleness and loss. Other symptoms include skin rash, a garlic odor to the breath, fatigue, irritability, nausea and vomiting..

Women who are pregnant or breastfeeding should avoid selenium intake greater than 60-70mcg daily and consult a health care provider before using selenium

Drug interactions

There is no known reaction reported with any drugs.

However, taking vitamin C and selenium together may decrease the absorption of selenium while taking selenium with vitamin E may increase the effective of both selenium and vitamin E.

Web References

1. http://dietary-supplements.info.nih.gov/factsheets/selenium.asp
2. http://lpi.oregonstate.edu/infocenter/minerals/selenium/

Printed Reference Material

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