HIV-positive people who have deficient zinc levels should consider supplements, says a study in the June 15 Clinical Infectious Diseases. It's especially true for those whose viral loads don't stay undetectable with HIV meds. Adequate zinc levels support good immune function.

In the 18 months of the study, daily zinc supplements (women got 12 mg; men, 15) boosted immune function and significantly cut diarrhea. The U.S. National Institutes of Health generally recommends 8 mg for women and 11 mg for men.

More than half of all HIV-positive people could use some extra zinc, so ask your doctor for a simple blood test to determine if you should head for the supplements aisle.