Acute exogenous ketone monoester supplementation decreases cardiac vagal modulation in a dose-dependent manner

Exogenous ketone supplementation can elevate heart rate (HR) but the effects on cardiac autonomic modulation remain unclear. HR variability was analyzed from 18 healthy adults (23 {+/-} 3 yrs; n=10 females) ingesting 0.3 (low-dose) or 0.6 g/kg (high-dose) ketone monoester or placebo in a randomized crossover, double-blind design. Compared to placebo, both ketone doses increased capillary {beta}-hydroxybutyrate and reduced the percentage of successive R-R intervals that differ by [≥]50-ms (pRR50) and the root mean square of successive differences (RMSSD) at 45- and 120-min post-ingestion (all p<0.05). Acute ketone ingestion decreases HR variability measures associated with reduced cardiac vagal modulation.