The effect of acute beetroot juice supplementation on the responses to local cooling and endothelial function in cold sensitive individual

Individuals with cold sensitivity have reduced skin blood flow which could be due to an attenuated release of nitric oxide (NO). Beetroot has a high concentration of inorganic nitrate and is thought to benefit cardiovascular health through increased NO-mediated vasodilation. Using a placebo-controlled, double blind, randomised, crossover design, this study tested the hypothesis that acute concentrated beetroot juice (CBJ) supplementation would increase the rate of cutaneous rewarming following a local cold challenge and augment endothelium-dependent vasodilation in individuals with cold sensitivity. Thirteen cold sensitive individuals consumed 140 ml of either CBJ or nitrate-depleted CBJ (Placebo) 90 min prior to testing. Participants completed foot and hand cooling (separately, in 15 °C water for 2 minutes) with spontaneous rewarming in 30 °C air. Endothelial function was assessed at the forearm, finger and foot by iontophoresis of 1% w/v acetylcholine using laser Doppler flowmetry. Resting blood pressure and the skin temperature during and following cooling (Figure 1) were the same in CBJ and Placebo. CBJ did not affect the maximum response to acetylcholine in the forearm, finger or foot (2.0 [1.0] vs 2.3 [0.7] flux.mmHg^-1, 3.3 [1.6] vs 3.1 [1.5]flux.mmHg^-1, 1.2 [0.8] vs 1.0 [0.7] flux.mmHg^-1; all P>0.05). Acute CBJ supplementation did not improve extremity rewarming, endothelial function or lower blood pressure in individuals with cold sensitivity.