Excessive vitamin C loss via renal leak more common in women living with HIV

Women living with HIV (WLWH) lose more vitamin C through abnormal urinary excretion of the vitamin—i.e., a renal leak–than do HIV-negative women, potentially leading to vitamin C deficiency independent of diet, a U.S. study has found.

About This Study

“Vitamin C Urinary Loss and Deficiency in Human Immunodeficiency Virus (HIV): Cross-sectional Study of Vitamin C Renal Leak in Women With HIV” was published online on June 2, 2023, in Clinical Infectious Diseases. The lead authors are Ifechukwude Ebenuwa, M.D., M.HSc., and Pierre-Christian Violet, Ph.D., of the Molecular and Clinical Nutrition Section in the Digestive Diseases Branch of the Intramural Research Program at the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health in Bethesda, Maryland.

Key Research Findings

In this cross-sectional study, researchers analyzed matched fasting blood and urine samples of 96 women, 40 of whom are living with HIV, to determine renal leak prevalence and vitamin C concentrations. Renal leak was defined as exhibiting impaired renal reabsorption of vitamin C that resulted in abnormal or increased urinary loss.

Demographic characteristics differed substantially by serostatus: 84% of WLWH were Black and older (mean age 53 years) compared to the control group, which was 48% Black with a mean age of 37 years.

Seventy-three percent of WLWH had a renal leak compared to 14% of HIV-negative controls. Mean vitamin C concentrations in plasma were lower among WLWH than controls (14μM versus 50μM) and vitamin C deficiency was more common among WLWH than controls (43% versus 7%, respectively). These associations held independently of potential confounders, including demographic differences.

Among WLWH, renal leaks were not associated with CD4 count or HIV viral load. However, 91% of the group had a suppressed viral load and 97% had a CD4 counts above 300 cells/mm3. Being on antiretroviral treatment (ART), which 86% of WLWH were, was a predictor of renal leaks, as were Black race and older age.

Discussion Highlights and Implications for Practice

The researchers discussed several potential mechanisms to explain the findings. One explanation is that ART may induce renal tubular dysfunction or that renal leaks may be mediated by ART-induced metabolic complications. Additional research into the association between ART and vitamin C deficiency is needed, they wrote.

The study authors also noted that while older age is consistent with other findings on renal leak, the association with race/ethnicity has not been reported previously. That result may have been affected by the disproportionately higher enrollment of Black PLWH in this study; they also offered that, perhaps, “HIV- and/or ART-induced vitamin C dysregulation exerts a disproportionately more severe nutritional and metabolic pathophysiology in Black individuals compared with other racial groups.”

Meanwhile, the authors urged providers to check the vitamin C levels of their patients who were living with HIV and to recommend supplementation, if necessary. Dietary guidelines that consider higher intake requirements for people with chronic diseases, including HIV, are also needed, they wrote.

By Barbara Jungwirth