Plasma β-hydroxybutyrate concentrations in young adult females after a high-fat meal under normoxaemia, intermittent hypoxaemia and continuous hypoxaemia: An exploratory analysis.

Hypoxaemia occurs in intermittent forms, such as obstructive sleep apnoea, and in continuous forms, such as at high altitude, and is increasingly recognized as a modulator of cardiometabolic risk. Although hypoxaemia alters postprandial glucose and lipid metabolism, its effects on ketone bodies remain unclear. Using a randomized crossover design, we examined whether 6 h of normoxaemia or intermittent hypoxaemia (15 hypoxaemic cycles/h targeting ∼85% peripheral oxyhaemoglobin saturation with 100% medical-grade nitrogen) alters plasma β-hydroxybutyrate (BHB) concentrations in 12 young adult females (mean [SD]: 21 [3] years) following a high-fat meal (33% of estimated daily energy requirements; 59% of energy from fat). In a follow-up session, a subset (n = 8) completed 6 h of continuous hypoxaemia (fraction of inspired oxygen ∼12.0% in a normobaric chamber). Postprandial data were analysed using baseline-adjusted linear mixed-effects models, with Bonferroni post hoc tests. A time × condition interaction (P = 0.010) indicated that BHB concentrations at 360 min were higher during continuous hypoxaemia (0.247 mmol/L; 95% CI: 0.218-0.275) than normoxaemia (0.176 mmol/L; 95% CI: 0.153-0.200; P