Low Vitamin A Levels May Indicate Infectivity in HIV Patients

Low Vitamin A Levels May Indicate Infectivity in HIV Patients

SEATTLE--Researchers at the University ofWashington believe they have discovered a possible explanation for disparitiesbetween observational studies and randomized trials of vitamin A for HIVinfection. According to their study in the October issue of the Journal ofAcquired Immune Deficiency Syndromes (31, 2:243-49, 2002) (www.jaids.com),the common presence of vitamin A deficiency among HIV-infected individuals hasbeen associated with faster disease progression and greater infectivity inobservational studies, although in randomized clinical trials, vitamin Asupplementation has not proven beneficial. According to researchers, this may bebecause serum vitamin A concentration does not accurately reflect vitamin Atissue stores in this population; rather, it is a marker of more active or moreadvanced disease.

"Our results suggest that an acute phase response--theseries of physiologic events that accompany acute and chronic inflammatorystates, including trauma, infection and autoimmune diseases--accompanies moreactive HIV infection and this leads to depressed serum vitamin Aconcentrations," said Jared Baeten, Ph.D., of the University ofWashington's Department of Epidemiology and a study author. "Thus, wehypothesize that low serum vitamin A levels are a consequence of more activeviral replication, and that these low vitamin A concentrations may simply beartificially depressed and are not reflective of true deficiency."

To come to this conclusion, researchers conducted across-sectional study of 400 infected and 200 uninfected women in Mombasa,Kenya. Investigation demonstrated 59 percent of the HIV-positive women had serumvitamin A concentrations reflecting deficiency compared with 29 percent of theHIV-negative women. Researchers noted vitamin A deficiency was independentlyassociated with HIV infection and the acute phase response--of those women withvitamin A deficiency, 55 percent also had an acute phase response, compared with27 percent of those who were not deficient in vitamin A.

After the cross-sectional aspect of the study was completed,researchers conducted a randomized, placebo-controlled trial of vitamin Asupplementation. The 400 HIV-infected subjects were randomly assigned to receiveeither 10,000 IU/d of vitamin A (as retinyl palmitate) or a matching placebo forsix weeks. Researchers found vitamin A supplementation did not increase serumlevels of the vitamin in HIV-infected women having an acute phase response,although supplementation did increase serum levels in HIV-infected women withoutan acute phase response. In cases where deficiency was present at baseline, thisincrease did not bring the women to normal levels.

Researchers concluded that among HIV-infected individuals, it islikely that low serum vitamin A concentrations reflect more active infection andthe acute phase response. Baeten added, "Our results suggest that theobservational findings were simply measuring more active infection, rather thantrue vitamin A deficiency, and thus show why supplementation was notbeneficial."