Ketone monoester (KME) supplements are one exogenous ketone intervention which has demonstrated benefits to multiple facets of brain health, including cerebral blood flow (CBF) and cognition. However, it is unknown how KME impact CBF and cognition acutely, and whether the size of KME dose differentially impacts these outcomes. Higher KME doses lower blood pH and arterial CO2 (PaCO2), which are important regulators of CBF. We hypothesized that high-dose KME ingestion would lower CBF via acidosis-induced compensatory reductions in PaCO2, whereas low-dose KME ingestion would enhance CBF, mirroring past findings from other exogenous ketone interventions. Changes in cognitive function were also hypothesized to parallel CBF responses. Twenty young adults (age=23±3 years; BMI=23.4±2.2 kg/m2) participated. In a double-blinded, counterbalanced, crossover design, participants completed 3 separate conditions: 1) high-dose KME (0.6 g/kg); 2) low-dose KME (0.3 g/kg); or 3) placebo. Outcome measures were assessed at fasting baseline, 45-, and 120-min post-ingestion. CBF was assessed using Duplex ultrasound of the internal carotid and vertebral arteries. End-tidal CO2 (PETCO2) was measured using a gas analyzer, to approximate PaCO2. Hippocampal-dependent function was assessed using the lure discrimination index (LDI) and recognition memory score (REC) from the mnemonic similarity task. Over a 2-hour period post-ingestion, low- and high-dose KME lowered CBF to a different extent relative to baseline (45-min (low-dose, high-dose): ∆10.4%, ∆14.0%; 120-min (low-dose, high-dose): ∆6.2%, ∆18.6%; P < 0.001). These reductions were mirrored by dose-dependent reductions in PETCO2 and changes in CBF were positively correlated with changes in PETCO2 (P < 0.001, R2 = 0.219). Despite reductions in CBF, both LDI (P = 0.619) and REC (P = 0.651) were unchanged in the KME conditions. These findings provide a foundational characterization of the acute effects of KME dose on CBF and cognition, which will inform potential therapeutic recommendations on KME for brain health. / Thesis / Master of Science (MSc) / In addition to being an alternative energy source used during fasting or when consuming low amounts of carbohydrates, ketone bodies may act as signals that impact various aspects of brain health. Recent studies suggest that supplementating with a drink that contains ketones is an alternative way to increase ketones in your blood, without dietary modifications. We investigated whether one-time ingestion of a ketone supplement (KME) affects brain blood flow and cognition, as well as whether the size of KME dose differentially impacts these outcomes. Our results show that KME ingestion lowers brain blood flow, to a different extent depending on the dose that was ingested. Despite this, there was no change in memory performance from taking this ketone supplement. These findings were important in demonstrating how KME ingestion impacts the brain, and will inform future guidelines on its potential use for protecting and/or improving brain health.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/30243 |
| Date | January 2024 |
| Creators | Rourke, Aedan |
| Contributors | Walsh, Jeremy, Kinesiology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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