Selenium is a mineral which is essential in human nutrition in very small amounts (larger amounts are toxic). Researchers are finding that selenium deficiency may be involved in many important diseases, including HIV. The fact that this mineral has been the subject of irresponsible promotion as a cure-all must not blind us to the real possibilities that proper supplementation may have value in disease prevention and treatment.
A major literature review published in The Lancet [Rayman MP. The importance of selenium to human health. The Lancet. July 15, 2000; volume 356, pp.233-41] offered an overview of what is known and not known concerning selenium and human health. There appears to be a strong case for more attention to supplementation as a possible treatment – a medical intervention which would cost essentially nothing, so it could be available anywhere in the world.
Concerning immune functions: "Supplementation with selenium, even in 'selenium-replete' individuals, has marked immunostimulant effects, including an enhancement of proliferation of activated T-cells (clonal expansion). Lymphocytes from volunteers supplemented with selenium (as sodium selenite) at 200mcg per day showed an enhanced response to antigen stimulation and an increased ability to develop into cytotoxic lymphocytes and to destroy tumor cells. Natural-killer-cell activity was also increased. Supplementation resulted in a 118% increase in cytotoxic-lymphocyte-mediated tumor cytotoxicity and an 82% increase in natural-killer-cell activity compared with baseline."
Concerning HIV: "Selenium seems to be a crucial nutrient for HIV-infected individuals. It is a potent inhibitor of HIV replication in vitro... More than 20 papers report a progressive decline in plasma selenium in parallel with the on-going loss of CD4 T cells in HIV-1 infection. This decline in selenium occurs even in early stages of disease when malnutrition or malabsorption cannot be a factor. In fact, plasma selenium is a strong predictor of the outcome in HIV infection. Baum and colleagues showed that selenium-deficient HIV patients are nearly 20 times more likely (p<0.0001) to die from HIV-related causes than those with adequate levels... Baum and colleagues showed that low plasma selenium is a significantly greater risk factor for mortality than low helper-T-cell count, by a factor of 16, and confers a more significant risk than deficiency of any other nutrient investigated."
Pancreatitis: "In a small controlled trial in Rostock, Germany, intravenous administration of selenium to patients with acute necrotizing pancreatitis reduced mortality from 89% in controls to zero in the treatment group."
Cancer: Various studies have found more cancer or cancer deaths in persons with low selenium levels. For example, in a prospectively followed cohort of 34,000 men, "those in the lowest quintile [fifth] of selenium status, as measured by toenail selenium, were found to have three times the likelihood of developing advanced prostate cancer as those in the highest quintile (p for trend=0.03). Only cases diagnosed more than 2 years after collection of the samples were counted." [The reason for not counting earlier cases is to avoid confusion due to the possibility that the illness itself might cause the low selenium levels through poor intake, absorption, or metabolism of food.]
Other research has found effects of correcting selenium deficiency on mental status, tiredness, and mood – and possibly on cardiovascular disease, although findings here have been mixed, perhaps because some of the trials included very few people with selenium deficiency.
A study was conducted in an area with low soil-selenium levels. People in this study were given either a placebo or selenium supplements of 200mcg (three times their normal intake) which were made up of selenium enriched yeast, an organic form of selenium as distinguished from most other supplements that are inorganic and may not have the same effect. While the study did not prove what it originally set out to, namely that selenium reduces the risk of skin cancer, it did find that it greatly reduced the risk of many other kinds of cancer. People taking the selenium supplements had 71% fewer prostate cancers, 67% fewer esophageal cancers, 62% fewer colorectal cancers and 46% fewer lung cancers than the people who were taking the placebos.
Deficiency is often indicated by weak muscles and premature ageing.
Selenium is essential for healthy immune functioning. A large-scale study has shown that selenium supplementation reduces the incidence of viral hepatitis in selenium-deficient populations, presumably by enhancing immune function. [Yu S-Y, Li W-G, Zhu Y-J, et al. Chemoprevention trial of human hepatitis with selenium supplementation in China. Biol Trace Element Res 1989;20: pp.15-20]
Dietary consumption of apples and selenium intake (assessed by food frequency questionnaire) were each associated with a reduced risk of asthma in an English study of adults. [Am J Respir Crit Care Med 2001;164(10): pp.1823-28]
Extensive small intestinal resection patients are at risk for developing selenium deficiency due to impaired absorptive capacity.
The availability of selenium for absorption was reduced almost to zero when sodium selenite (a common form of selenium) and 1gm ascorbic acid were taken together well before any meal. [N Z Med J 98(784): pp.627-9, Aug 14, 1985]
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