Exogenous ketosis attenuates acute mountain sickness and mitigates normobaric high-altitude hypoxemia

Fourteen healthy male participants completed two 29-hour protocols at a simulated altitude of 4,000 to 4,500 m in a randomized crossover design, receiving ketone ester or placebo at regular timepoints. The protocol was ended early if severe acute mountain sickness (Lake Louise Score of 10 or more) developed. Ketone ester kept d-beta-hydroxybutyrate near 3 mM while placebo stayed below 0.6 mM. Protocol duration increased by 32 percent on average with ketone ester and doubled in participants who developed severe acute mountain sickness (n = 9). Ketone ester also inhibited progressive hypoxemia and increased cerebral oxygenation, while inducing mild metabolic acidosis, hyperventilation and relative sympathetic dominance.