Regional cerebral effects of ketone body infusion with 3-hydroxybutyrate in humans: Reduced glucose uptake, unchanged oxygen consumption and increased blood flow by positron emission tomography. A randomized, controlled trial.
Level 2 - randomized trial
Individual randomized crossover trial in humans
PubMed 29489818 · doi:10.1371/journal.pone.0190556
What was done
Nine healthy human subjects were studied in a randomized crossover design on two separate occasions: once with and once without a continuous infusion of 3-hydroxybutyrate. Positron emission tomography (PET) was used to measure regional cerebral glucose utilization, oxygen consumption, and cerebral blood flow across parietal, occipital, temporal, frontal, and cortical grey regions.
What was found
During 3-hydroxybutyrate infusions, blood concentrations reached 5.5 ± 0.4 mmol/l. In all measured brain regions, cerebral glucose utilization decreased by 14% and cerebral blood flow increased by 30%. Cerebral oxygen consumption remained unchanged, accompanied by a decrease in oxygen extraction.
Why it matters
This study provides direct quantitative PET evidence in humans that acute elevation of ketone bodies reduces brain glucose uptake and boosts cerebral blood flow without compromising cerebral oxygen metabolism.
Limits
The sample size was very small (n = 9) and restricted to healthy volunteers. Findings reflect acute intravenous ketone infusion rather than diet-induced ketosis or chronic exposure, and clinical outcomes in neurological disease populations were not evaluated.
Cited by
- supports Ketone bodies increase cerebral blood flow by 30% to 40%.