The Role of Vitamin D Deficiency in the Pathogenesis of Osteoporosis and in the Modulation of the Immune System in HIV-Infected Patients

The Potential Protective Role of Vitamin D Supplementation on HIV-1 Infection

HIV infection remains a global and public health issue with the incidence increasing in some countries. Despite the fact that combination antiretroviral therapy (cART) has decreased mortality and increased the life expectancy of HIV-infected individuals, non-AIDS conditions, mainly those associated with a persistent inflammatory state, have emerged as important causes of morbidity, and mortality despite effective antiviral therapy. One of the most common comorbidities in HIV-1 patients is Vitamin D (VitD) insufficiency, as VitD is a hormone that, in addition to its physiological role in mineral metabolism, has pleiotropic effects on immune regulation. Several reports have shown that VitD levels decrease during HIV disease progression and correlate with decreased survival rates, highlighting the importance of VitD supplementation during infection. An extensive review of 29 clinical studies of VitD supplementation in HIV-infected patients showed that regardless of cART, when VitD levels were increased to normal ranges, there was a decrease in inflammation, markers associated with bone turnover, and the risk of secondary hyperparathyroidism while the anti-bacterial response was increased. Additionally, in 3 of 7 studies, VitD supplementation led to an increase in CD4+ T cell count, although its effect on viral load was inconclusive since most patients were on cART. Similarly, previous evidence from our laboratory has shown that VitD can reduce the infection of CD4+ T cells in vitro. The effect of VitD supplementation on other HIV-associated conditions, such as cardiovascular diseases, dyslipidemia or hypertension, warrants further exploration. Currently, the available evidence suggests that there is a potential role for VitD supplementation in people living with HIV-1, however, comprehensive studies are required to define an adequate supplementation protocol for these individuals.

Vitamin D deficiency and altered bone mineral metabolism in HIV-infected individuals

Although patients with HIV infection are living decades longer than before with the advent of combination antiretroviral therapy, they have an increased rate of co-morbidities associated with chronic HIV, such as osteoporosis, cardiovascular disease, and immune dysfunction. Many of these complications are known to be affected by vitamin D status in the general population. Thus, the high rate of vitamin D deficiency among HIV-infected patients is alarming. Many observational and cohort studies have demonstrated that vitamin D deficiency is associated with these HIV-related complications, but randomized, placebo-controlled trials are limited. This paper reviews recent data on vitamin D deficiency in HIV infection.

Habitual nutrient intake in HIV-infected youth and associations with HIV-related factors

Few studies have evaluated habitual nutrient intake among HIV-infected youth in the United States, even though diet may influence disease progression and risk of comorbidities. This study determined habitual micronutrient and macronutrient intake in HIV-infected youth. HIV-infected subjects and healthy controls 1-25 years old were prospectively enrolled. Nutrient intake was assessed via 24-h dietary recalls performed every 3 months for 1 year and compared to recommended intake from the U.S. Dietary Reference Intakes (DRIs) and Acceptable Macronutrient Distribution Ranges (AMDRs). Subjects with two or more food recalls were analyzed (175 HIV(+) and 43 healthy controls). Groups were similar in age, race, sex, body mass index, and kilocalorie intake. In both groups, intake of several micronutrients was below the DRI. In addition, HIV(+) subjects had a lower percentage DRI than controls for vitamins A, D, E, pantothenic acid, magnesium, calcium, folate, and potassium. HIV(+) subjects' percentage caloric intake from fat was above the AMDR and was higher than controls. Caloric intake was negatively correlated with current and nadir CD4 count. Zinc, riboflavin, and magnesium percentage DRI were positively associated with current CD4 count. In HIV(+) subjects not on antiretroviral therapy, HIV-1 RNA levels were negatively correlated with protein intake. HIV(+) youth have an inadequate dietary intake of several essential nutrients and poorer dietary intake compared to controls. Intake of some nutrients was associated with important HIV-related factors. Further investigation is warranted to determine the impact of dietary intake of specific nutrients on HIV progression and chronic complication risk in this population.

Vitamin D and HIV infection: a review of the clinical evidence

The positive effects of vitamin D in different acute and chronic diseases (e.g., bone and renal disorders, acute and chronic respiratory tract infections, and diabetes mellitus), and regulation of immune system function have been shown. In this review vitamin D status and the effects of its supplementation alone or in combination with other bone-modifying substances like calcium and bisphosphonates on the different aspects of human health have been investigated in HIV+ individuals. Three scientific electronic databases have been investigated for extracting related articles. Searching only PubMed yielded 59 results with ‘HIV OR AIDS’ and ‘Vitamin D’ keywords. Because many of the studies in this field are observational or cross-sectional, designing comprehensive and eligible randomized clinical trials has been recommended by several authors in order to develop evidence-based clinical practice guidelines to determine the best regimen of vitamin D supplementation in HIV-infected patients.