Dietary nitrate improves skeletal muscle microvascular oxygenation in HIV-infected patients receiving highly active antiretroviral therapy: a randomized, double-blind, cross-over, placebo-controlled study

Human immunodeficiency virus-1 (HIV-1) proteins and highly active antiretroviral therapy (HAART) have been associated with microvascular endothelial dysfunction. Although nitrate-rich beetroot juice (NR-BJ) consumption has been shown to improve endothelial function in clinical population, its effects in the HIV-infected patients has not been addressed. We investigated the effect of a single dose of NR-BJ on muscle oxygen saturation parameters in response to a handgrip exercise in HIV-infected patients. Fifteen HIV-infected patients received NR-BJ or nitrate-depleted beetroot juice (ND-BJ) in a double-blind cross-over design. Near-infrared spectroscopy was utilized to assess muscle oxygen saturation parameters during rhythmic handgrip exercise after NR-BJ or ND-BJ supplementation. A significant faster muscle oxygen desaturation rate during exercise (-7.97±5.00 vs -5.45±3.94 %.s-1; p=0.005) and the muscle oxygen resaturation rate during exercise recovery (0.43±0.24 vs 0.28±0.24 %.s-1; p=0.030) after NR-BJ ingestion was found. However, no significant difference in exercise time until fatigue was observed. Salivary nitrite and urinary nitrate concentration were analysed after NR-BJ or ND-BJ. A significant increase in salivary nitrite and urinary nitrate in NR-BJ condition compared to ND-BJ was observed (p<0.05). Our findings suggest that NR-BJ consumption may acutely improve muscle oxygen saturation during exercise and exercise recovery in HIV-infected patients undergoing HAART, individuals who are expected to present microvascular damage. Thus, future studies investigating the chronic effect of NR-BJ are warranted to delineate a better nutritional strategy based on nitrate-rich foods.

Keywords: Beetroot; human immunodeficiency virus; microcirculation; muscle oxygenation.