Selenium Supplements May Cause Premature Death

Recent research suggests that supplementing with selenium can increase your cholesterol levels by almost 10%, leading to an increased risk of coronary heart disease.

Selenium is an essential mineral, which people normally obtain from foods such as vegetables, meat and seafood. However, there have been many claims over the past few years that over-working of the soil has led to a depletion of its selenium content, and to a corresponding drop in selenium levels within food.

Selenium and Chronic Disease

Given that some chronic health conditions, especially those related to the thyroid such as hypothyroidism, have been linked to selenium deficiency, this has led to an increase in the number of people taking selenium supplements. The efficacy of selenium has not been in doubt, whereas its deficiency has been mentioned as causing a number of problems, so the news on selenium all seemed positive, as noted in this recent article from the UK medical journal, The Lancet:

• "Selenium is needed for the proper functioning of the immune system, and appears to be a key nutrient in counteracting the development of virulence and inhibiting HIV progression to AIDS. It is required for sperm motility and may reduce the risk of miscarriage. Deficiency has been linked to adverse mood states. An elevated selenium intake may be associated with reduced cancer risk." (1)

Selenium Supplements and Cholesterol Increase

In late 2009, a team of researchers at the University of Warwick's Medical School (UK) discovered something surprising: high levels of selenium are associated with higher levels of cholesterol, which significantly increases the risk of heart disease. The research team examined the association between levels of selenium in the blood (plasma selenium) with those of fats in the blood (blood lipids), and found that in people with higher plasma selenium (over 1.20 µmol/L) there was an increase in the average total cholesterol level of 8%. Researchers also noted a 10% increase in the "bad" (non-HDL) cholesterol levels – these lipoproteins, such as LDL, VLDL and IDL are associated with heart attacks and angina (chest pain).
Almost half of the 1042 study participants with the highest selenium levels admitted that they took dietary supplements regularly.
Dr. Saverio Stranges, leader of the study team, said that although high selenium levels were not always caused by people taking supplements, the use of them had risen considerably in recent years, and he felt this was largely due to the belief that selenium can reduce the risk of cancer and other diseases.
In an apparent contradiction of the earlier article (quoted above) in The Lancet, Dr. Stranges said that selenium supplementation "has spread despite a lack of definitive evidence on selenium supplements efficacy for cancer and other chronic disease prevention. The cholesterol increases we have identified may have important implications for public health. In fact, such a difference could translate into a large number of premature deaths from coronary heart disease.
"We believe that the widespread use of selenium supplements, or of any other strategy that artificially increases selenium status above the level required is unwarranted at the present time. Further research is needed to examine the full range of health effects of increased selenium, whether beneficial or detrimental." (2)
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References:

1. "The importance of selenium to human health", Margaret Rayman, D Phil; The Lancet, Vol 356, Issue 9225, pp.233–241, 15 July 2000.
2. University of Warwick