For years, people with HIV have swallowed selenium to boost their health. But questions remained: How useful is this dietary supplement, and what notable side effects might it cause? When Archives of Internal Medicine reported good results of a clinical trial earlier this year, news of selenium’s established efficacy and safety as a complementary therapy for HIV raced through discussion groups and treatment hotlines. More recently, however, doubts about the study have surfaced, along with information suggesting a link between long-term selenium use and diabetes.

Selenium is a trace mineral—meaning you don’t need a lot of it. The National Institutes of Health’s Office of Dietary Supplements says we need about 55 micrograms of the stuff a day. Selenium originates in soil and makes its way into our bodies through food—notably meat, fish and eggs.

Low blood levels of selenium usually result from inadequate agricultural soil and poverty, but deficiencies have also been found in people with HIV. Studies suggest that this can increase HIV’s virulence, retard natural killer cells, encourage some AIDS-related infections and generally speed HIV progression. Meanwhile, test-tube studies show that selenium slows HIV replication in immune system cells. In HIV-negative people, selenium has been said to decrease the risk of various cancers without provoking significant side effects.

“I envision selenium as a lion tamer in a zoo,” says Barry Hurwitz, PhD, professor of psychology and behavioral medicine at the University of Miami. “The effect of it is to tame the virus, make it more docile.” Hurwitz is the lead author of the Archives placebo-controlled study, published on January 22, showing a link between selenium supplementation and lower HIV viral loads.

The study enrolled 262 south Florida HIV-positive residents, most of whom were black or Hispanic. More than 30 percent were women. Approximately 25 percent of the 141 people randomized to get selenium were not taking HIV meds, compared to 28 percent of the 121 people randomized to placebo.

Nutrition 21’s Selenomax-brand selenium was used because, Hurwitz says, it is an easily absorbed form of the supplement.

The trial focused on differences in viral loads and CD4 counts after nine months of selenium or placebo treatment. Hurwitz and his team concluded that, “daily selenium supplementation can suppress the progression of HIV viral load and provide indirect improvement of CD4 count.”

The results, however, seem to have raised more questions than answers, at least among some experts.

David A. Ross, PhD, a professor and epidemiologist at the London School of Hygiene and Tropical Medicine, says the results can’t be called decisive because of the way the data were analyzed. The trial, Ross says, didn’t answer the question, “Did the people who got selenium have slower disease progression than those who didn’t?”

That’s because the researchers divided the selenium-taking group into two subdivisions before counting their CD4 cells and viral loads. Instead of comparing all selenium takers to those who took placebo, Hurwitz’s team conducted a more selective analysis of the data involving the patients who actually experienced higher blood levels of the mineral versus those who did not (including placebo participants). 

Injecting yet another question, Ross, in a response to the Hurwitz study published six months later in the July 23 issue of Archives, wonders if other factors might explain the viral load and CD4 differences. For instance, he suggests, if the people who responded to selenium did so because they adhered to the dosing, while non-responders skipped some pills, that could affect results. It could be that the responders also took all their HIV meds, while non-responders missed doses of HIV meds along with selenium.

George M. Carter, director of the Foundation for Integrative AIDS Research (FIAR)—a group that sponsors and promotes clinical trials of herbal and nutritional treatments for people with HIV, AIDS and hepatitis—doesn’t have such questions. “I think the data indicates that it makes sense to use a selenium supplement,” Carter says. He counts the Hurwitz study among several providing mounting evidence that people with HIV should use selenium.

The debate over the efficacy of dietary supplements, Carter says, is really about economics, not science: Higher profits are made from HIV drugs than from mineral supplements. “If it’s not a patentable intervention, nobody’s interested—there’s no money in it,” says Carter, explaining his analysis of the doubts on selenium’s efficacy. “I don’t think there’s a big selenium cartel out there trying to push selenium,” he adds.

But while dietary supplements may not match the capital garnered by pharmaceuticals, they are a $20 billion industry, according to the American Dietetic Association. And Nutrition 21, based in Tarrytown, New York, only began wide distribution of Selenomax after the Hurwitz study was published, according to a promotional video housed on their website. Selenomax packages also prominently display the Hurwitz findings.

But the implications don’t end with debates over dollars. While the Hurwitz study did not report any significant side effects among those taking selenium for nine months, high-dose supplementation can produce a variety of adverse effects, including hair loss, mangled fingernails and toenails, neurological damage and an enlarged spleen.

Even people using standard doses of selenium for long periods of time may face some health risks. While the National Academy of Sciences sets the tolerability level of selenium at 400 micrograms daily for humans, a recent study published in Annals of Internal Medicine found that 200 micrograms daily—the same dose used in the Hurwitz study—increased the risk of diabetes when used for an average of 7.7 years. 

Despite the criticisms of his study, Hurwitz suggests that selenium supplementation should be viewed as a safe and effective therapy to be used in combination with HIV drug regimens.

Carter calls selenium one of many supplements necessary for people with HIV. “No matter how much food one eats, gut dis-regulation [disruption of digestive absorption caused by HIV] means there will be an inadequate uptake of nutrients. So it makes sense to take some supplements—at least a multivitamin.”