AIDS Treatment Update, Issue 61-62, January-February 1998

The report has led to suggestions that taking selenium supplements could have a significant impact on disease progression. However, newspaper reports suggesting that selenium represents an amazing new treatment that costs less than 50p per day are certainly exaggerated.

Dr Will Taylor, an associate Professor of Medicinal Chemistry at the University of Georgia, suggests that low levels of selenium may be caused by HIV replication. However, he also believes that selenium deficiency may boost HIV replication. Higher levels of selenium may help to damp down replication rates, and also help the immune system maintain optimum responses.

"Selenium isn't so much food for the virus, more a birth control pill. The viruses don't need selenium for survival so much as for growth regulation. When selenium levels are too low we not only have a weakened immune system, but the viral birth control is reduced and the virus replicates at higher levels".

Dr Taylor argues that HIV, like some other viruses he has investigated, uses selenium as a key means of judging how it should respond to changes in its environment. Low selenium levels may be a sign that a cell is about to die, through a `suicide' process known as apoptosis or `programmed cell death'. "The virus may only be triggered into replication when there is an external threat signalled by falling selenium levels, indicating that it is time to get replicating."

But how does this translate into practice? The only controlled study to date, conducted in France, found no benefits to selenium supplementation when people with HIV took 100 micrograms/day for one year.

"I think 100 micrograms/day is too low, considering that even asymptomatic HIV infected people apparently have impaired absorption of micronutrients", argues Dr Taylor. "200 micrograms/day would be probably be a more appropriate dose to study. Deficiencies of other micronutrients may also have an effect; for example, vitamin B6 is required as a co-factor for conversion of dietary selenium into selenoproteins [the form in which immune cells store selenium]. So if one is B6-deficient, taking selenium alone may be much less effective. Also, this study took place in patients with advanced disease. I suspect selenium will be most effective when given as an early intervention."

Despite these hunches, the fact remains that at present there is no hard evidence of any benefits from taking selenium supplements. Dr Taylor is now working with researchers in the US to design research to look at the potential benefits of selenium supplementation.

However, as Professor Brian Gazzard of the Chelsea & Westminster Hospital points out, it is "crucial to understand that the presence of selenium deficiency among people with a poor prognosis may simply be a symptom of their ill-health, rather than the cause. If it is a symptom, it is obviously unlikely that treating it will produce any change in overall prognosis."

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