A recent study found that both high and low vitamin D levels are related to increased risk of mortality among both HIV-infected and HIV-exposed infants in Tanzania.
There are approximately 35 million people currently living with HIV. Although people are affected by HIV all around the world, 68% of new cases are in sub-Saharan Africa. HIV is a sexually transmitted infection, but it can also spread from mother to child during pregnancy, childbirth, or breastfeeding.
When a person is infected with HIV, their immune system becomes weaker, causing them to become more susceptible to infections and cancer. Since vitamin D plays an important role in the immune system, researchers have become interested in whether it plays a role in HIV.
Research has primarily focused on the relationship between vitamin D and HIV in adult populations, with one study suggesting a relationship between vitamin D deficiency and increased mortality.
In an effort to investigate the role of vitamin D status in HIV during infancy, researchers analyzed data from 253 HIV-infected infants and 948 HIV-exposed infants. They wanted to determine whether vitamin D status was related to morbidity and mortality among the infants.
The researchers collected data from a randomized controlled trial that evaluated the effects of multivitamins (not including vitamin D) on HIV-exposed and HIV-infected infants. During this trial, mothers and infants were followed-up through monthly clinic visits and quarterly clinical exams for two years. Vitamin D levels were measured when the infants were five to seven weeks of age.
The researchers wanted to first examine the relationship between vitamin D status and morbidity.
Here is what they found after adjusting for potential confounding factors:
The researchers then looked to see if there was a relationship between vitamin D levels and mortality. Here is what they found after adjusting for potential confounding factors:
The researchers created a graph to illustrate the relationship between vitamin D status and mortality among HIV-infected infants.
The data forms a U-shaped curve, showing that both low and high vitamin D status is associated with an increased risk for mortality among HIV-infected infants.
The researchers concluded,
“In this prospective cohort study of Tanzanian infants born to HIV-infected mothers, the relation between 25(OH)D concentrations at 5–7 weeks of age and mortality appeared to be U-shaped for both HIV-infected and HIV-exposed infants.”
They went on to offer possible explanations for their surprising results,
“Infants who are exposed to the outdoors and sun during infancy may also be at high risk of exposure to mosquitos, malaria, and other pathogens that produce malaria-like symptoms.”
The researchers emphasized that these results do not prove causation, but merely display an association. Randomized controlled trials are needed to evaluate the effects of healthy vitamin D levels on morbidity and mortality among both HIV-infected and HIV-exposed infants.
Sudfeld C. et al. Vitamin D Status Is Associated with Mortality, Morbidity, and Growth Failure among a Prospective Cohort of HIV-Infected and HIV-Exposed Tanzanian Infants. The Journal of nutrition, 2015.