No Benefit of Ingesting a Low-Dose Ketone Monoester Supplement on Markers of Cognitive Performance in Females

Exogenous ketones have shown potential to mitigate cognitive decrements in states of fatigue, but studies in females are limited. Following a familiarization session and a baseline session without a mental fatiguing protocol (MF), 12 females completed two experimental sessions, consisting of a battery of cognitive tests (psychomotor vigilance test (PVT), task-switching, incongruent flanker) performed before (PRE) and after (POST) MF. In a counter-balanced crossover design, a R-beta HB (R)1,3-butanediol ketone monoester (KME, similar to 188 mg center dot kg(-1) body mass) or placebo (PLA) was ingested before MF. Markers of cognitive performance (speed and correct responses per second), blood beta-hydroxybutyrate, glucose, and lactate, and subjective markers of perceived cognitive load and fatigue were collected at PRE and POST. From baseline measures, KME ingestion significantly increased blood beta-hydroxybutyrate (P < 0.001; similar to 1.8 mM), decreased glucose (P < 0.001; similar to 0.6 mM), and attenuated a similar to 34% rise in lactate compared to PLA (P = 0.04) during POST testing. MF significantly increased perceived cognitive workload and fatigue for both experimental trials in comparison to the control (P < 0.05) but did not impair any of the cognitive variables assessed (all P > 0.05). Although changes in blood markers are similar to those observed in previous KME investigations, compared with PLA, KME ingestion did not affect cognitive performance following a MF protocol in females.