HIV attacks the body’s CD4 cells, or T cells – a type of white blood cell that plays a major role in helping the immune system fight infection. Antiretroviral therapy aims to control HIV and restore immune function, but the effectiveness of HIV treatment in adults may be hampered by low levels of vitamin D.

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Without treatment, HIV continues to invade immune cells and use their machinery to replicate itself.

This was the conclusion of a new study published in the journal Clinical Nutrition.

First author Amara Ezeamama, an assistant professor of epidemiology and biostatistics at the University of Georgia in Athens, says:

“With antiretroviral drugs, people with HIV are beginning to live longer lives. Our goal was to understand whether vitamin D deficiency limits the amount of immune recovery benefit for persons on HIV treatment.”

Without treatment, the HIV continues to attack and destroy the CD4 cells in the immune system. HIV hijacks CD4 cells and uses their machinery to make copies of itself and spread throughout the body.

As the HIV infection worsens, the person’s immune system gets weaker and weaker and they become more prone to opportunistic infection.

The most important lab indicator of how well the immune system is working, and the strongest predictor of HIV progression, is the CD4 cell count. This normally improves with antiretroviral therapy.

The CD4 count of an uninfected adult who is generally in good health ranges from 500 cells/mm3 to 1,200 cells/mm3. A very low CD4 count (less than 200 cells/mm3) is one of the ways to find out if the HIV infection has progressed to full-blown AIDS.

There are an estimated 33 million people infected with HIV worldwide – 1.2 million of them in the US. The advent in 1996 of highly active antiretroviral therapy (HAART) – a combination of different classes of medications taken daily – means that for many patients who have access to the medication, what was once a fatal diagnosis can now be managed as a chronic disease.

For their study, Prof. Ezeamama and colleagues examined 18 months of data for 398 HIV-positive adults on HAART.

The data included a measure of participants’ vitamin D levels at the start of the trial (baseline) and their CD4 cell counts at months 0, 3, 6, 12 and 18.

In their analysis, the researchers looked at how the changes in CD4 cell counts related to the baseline levels of vitamin D over the study period.

They found that participants with sufficient levels of vitamin D at baseline recovered more of their immune function than participants with vitamin D deficiency.

The average difference in CD4 cell count between the two groups was as much as 65 cells at one point. This effect seemed to be stronger in younger and underweight participants.

The researchers conclude that vitamin D supplementation may help HIV-positive adults on HAART to recover immune function more quickly, but they note this needs to be tested with a study specifically designed to look at the effect.

Prof. Ezeamama says we are in an era of hope for persons with HIV, and:

We know that HIV treatment works, and now people can live for several decades with HIV. We can further delay the progress of the disease and maintain survivors on a higher quality of life if we understand the factors that limit the effectiveness of HIV treatment.”

Earlier this year, Medical News Today learned that a class of drugs already being tested for the treatment of cancer can suppress dormant HIV in patients on antiretroviral therapy and may hold the key to complete eradication of the virus.