Format

Send to

Choose Destination
J Cereb Blood Flow Metab. 2017 Jul;37(7):2485-2493. doi: 10.1177/0271678X16669366. Epub 2016 Jan 1.

Inverse relationship between brain glucose and ketone metabolism in adults during short-term moderate dietary ketosis: A dual tracer quantitative positron emission tomography study.

Author information

1
1 Research Center on Aging, Sherbrooke, Université de Sherbrooke, Québec, Canada.
2
2 Department of Pharmacology & Physiology, Université de Sherbrooke, Sherbrooke, Québec, Canada.
3
3 Department of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada.

Abstract

Ketones (principally β-hydroxybutyrate and acetoacetate (AcAc)) are an important alternative fuel to glucose for the human brain, but their utilisation by the brain remains poorly understood. Our objective was to use positron emission tomography (PET) to assess the impact of diet-induced moderate ketosis on cerebral metabolic rate of acetoacetate (CMRa) and glucose (CMRglc) in healthy adults. Ten participants (35 ± 15 y) received a very high fat ketogenic diet (KD) (4.5:1; lipid:protein plus carbohydrates) for four days. CMRa and CMRglc were quantified by PET before and after the KD with the tracers, 11C-AcAc and 18F-fluorodeoxyglucose (18F-FDG), respectively. During the KD, plasma ketones increased 8-fold ( p = 0.005) while plasma glucose decreased by 24% ( p = 0.005). CMRa increased 6-fold ( p = 0.005), whereas CMRglc decreased by 20% ( p = 0.014) on the KD. Plasma ketones were positively correlated with CMRa (r = 0.93; p < 0.0001). After four days on the KD, CMRa represented 17% of whole brain energy requirements in healthy adults with a 2-fold difference across brain regions (12-24%). The CMR of ketones (AcAc and β-hydroxybutyrate combined) while on the KD was estimated to represent about 33% of brain energy requirements or approximately double the CMRa. Whether increased ketone availability raises CMR of ketones to the same extent in older people as observed here or in conditions in which chronic brain glucose hypometabolism is present remains to be determined.

KEYWORDS:

Metabolism; acetoacetate; glucose; ketogenic diet; ketone; neuroimaging

PMID:
27629100
PMCID:
PMC5531346
DOI:
10.1177/0271678X16669366
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center