The Effect of Dietary Nitrate on Nocturnal Sleep-Disordered Breathing and Arterial Oxygen Desaturation at High Altitude

Patrician, Alexander, Harald Engan, David Lundsten, Ludger Grote, Helena Vigetun-Haughey, and Erika Schagatay. The effect of dietary nitrate on nocturnal sleep-disordered breathing and arterial oxygen desaturation at high altitude. High Alt Med Biol 19:21-27, 2018.-Sleep-disordered breathing and fluctuations in arterial oxygen saturation (SaO₂) are common during sleep among lowlanders ascending to high altitude. Dietary nitrate (NO₃^-) supplementation has been shown to lower the O₂ consumption in various conditions. Our objective was to investigate whether dietary NO₃^- could reduce sleep-disordered breathing and SaO₂ desaturation during sleep at altitude. Cardiorespiratory responses during sleep were measured in 10 healthy lowlanders at 330 m and then again in the Himalayas at 3700-4900 m. Each subject received two 70 mL shots of either beetroot juice (BR; ∼5.0 mmol NO₃^- per shot) or placebo (PL: ∼0.003 mmol NO₃^- per shot) in a single-blinded, weighted order over two consecutive nights at altitude. At 2.5-4.5 hours into sleep at altitude, BR increased the SaO₂ desaturation drop (4.2 [0.1]% with PL vs. 5.3 [0.4]% with BR; p = 0.024) and decreased the SaO₂ desaturation duration (14.1 [0.9] seconds with PL to 11.1 [0.9] seconds with BR; p = 0.0.041). There was a reduction in breaths with flow limitation (p = 0.025), but no changes in Apnea-Hypopnea Index (AHI), mean and minimum SaO₂. The study suggests BR supplementation does not improve AHI or oxygenation, but may increase fluctuations in arterial O₂ saturation during sleep at altitude in native lowlanders.