Acute ketone monoester ingestion lowers resting cerebral blood flow: a randomized cross-over trial.

Exogenous ketone monoester (KME) supplements rapidly increase plasma beta-hydroxybutyrate (β-OHB) and may impact cerebral blood flow (CBF). However, it is currently unknown how acute KME ingestion impacts resting CBF and whether differences in KME dose have differential effects on CBF regulation. The purpose of this study was to investigate the effect of two separate KME doses on resting CBF in young adults. On separate days and in a double-blind, placebo-controlled, cross-over design, 20 participants (10 females; aged 23 ± 3 years) ingested either: (1) High-KME (0.6 g kg-1 β-OHB); (2) Low-KME (0.3 g kg-1 β-OHB); or (3) placebo drink, and quietly rested for 120 min. Global CBF (gCBF) was assessed using duplex ultrasound of the internal carotid and vertebral arteries, and transcranial Doppler ultrasound was used to assess middle cerebral artery blood velocity at baseline, 45 min and 120 min post-ingestion. End-tidal CO2 (