Low vitamin D levels in people with HIV were not associated with any particular antiretroviral (ARV) medication, nor with signs of bone loss, according to a study presented Wednesday, July 21, at the XVIII International AIDS Conference (IAC) in Vienna.

Vitamin D is critical to good health. People with low vitamin D levels—which typically occur in people living in more extreme latitudes during the winter months—have been associated with cardiovascular disease, bone mineral loss and several cancers. Of concern, studies presented over the last several years increasingly find that low vitamin D levels are common in people with HIV, particularly African Americans, men and people who are overweight.

At this year's IAC, several studies found high rates of vitamin D deficiency, including one from the United States that found low vitamin D levels in 66 percent of an HIV cohort, with 38 percent of those having extremely low vitamin D levels. What's more, several previously published studies have suggested that some ARV drugs might increase the risk of vitamin D loss, particularly efavirenz (found in Sustiva and Atripla).

To determine the association between ARV drugs, bone mineral loss and low vitamin D levels, Emma Devitt, MD, from the Chelsea and Westminster College in London, and her colleagues examined medical records from 312 HIV-positive people seen at their London HIV clinic. Most of the study participants were male and had been living with HIV for an average of 12 years. All were taking ARV medication.

Devitt reported at IAC that 35 percent of the participants had low vitamin D levels and 21 percent had very low levels. Women and ethnic minorities were more likely to have low levels. Devitt and her colleagues did not find, however, any association between vitamin D levels and ARV drugs. This included efavirenz, which 28 percent of the cohort was taking.

Also contrary to previous studies, Devitt's team found no significant association between signs of mild to moderate bone loss. People with low vitamin D levels were not more likely to have increases in alkaline phosphatase—an enzyme that signals bone mineral loss—nor were they more likely to have actual bone loss, as diagnosed with bone scans.

“More analysis is required in order to fully grasp why such large proportions of these patients are indeed deficient and whether there is an underlying pathological pathway or whether there is an external cause that can be identified,” Devitt said.

She concluded: “Ultimately, optimization of vitamin D level is essential in HIV-positive patients, in particular, females and those from ethnic minorities.”