Using MCTs to Support Brain Functioning – And Push Back Against Brain Aging
by Nils Osmar
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One recent finding in Alzheimer’s research (which is not well known by the general pulic) is that the aging brain often struggles to use glucose for long before any cognitive symptoms appear. This glucose hypometabolism, as researchers call it, can show up on brain scans decades before memory problems begin.
In short, our brains can be having difficulty utilizing glucose — but our ability to use ketones for fuel remains intact.
This has led researchers to explore whether providing ketones as an alternative energy source could help address this energy gap in the aging brain.
Medium-chain triglycerides (MCTs), particularly caprylic acid (C8), are uniquely suited for this purpose. Unlike other fats, they’re rapidly converted to ketones in the liver and can cross the blood-brain barrier to fuel neurons directly.
Some Interesting New Research
A 2024 systematic review published in the Journal of Nutrition and Metabolism examined 21 studies on MCT supplementation in people with Alzheimer’s disease and mild cognitive impairment.
The researchers found that MCT supplementation substantially increased plasma ketone levels and brain metabolic rates.
In Alzheimer’s disease, beta-amyloid proteins appear to damage mitochondrial function and glucose transporters, leading to insulin resistance in the brain — sometimes called “type III diabetes.” Ketones provide a way to bypass this dysfunction entirely.
Research from the University of Sherbrooke in Canada, summarized by the Metagenics Institute, demonstrated that providing 30g/day of MCTs to Alzheimer’s patients partially compensated for the brain energy deficit, reducing it from 13% to 10%.
Interestingly, cardiovascular markers remained normal throughout the study, suggesting that inducing mild ketosis through MCT supplementation is safe and tolerable in elderly patients.
The Normal Aging Brain Also Shows Glucose Decline
The possible benefits of MCT fats for the aging brain are not just relevant for those with cognitive impairment. A 2022 study published in Frontiers in Systems Biology used mathematical modeling to show that even healthy adult brains experience an 8% decrease in cerebral glucose metabolic rate with normal aging (compared with to the 20-40% decline seen in Alzheimer’s patients).
The researchers found that MCT supplementation increased acetyl-CoA levels (a key energy molecule) in both healthy adults and those with cognitive impairment. In their model, the 38% drop in acetyl-CoA caused by glucose hypometabolism was reduced to just 12% with 30g of MCT supplementation.
Timing Matters: the Best Time to Take MCTs
Perhaps the most actionable finding comes from a March 2025 study published in PNAS (Proceedings of the National Academy of Sciences). Researchers found that brain aging doesn’t follow a linear pattern — instead, it shows distinct transition points where metabolic stress can be detected before symptoms appear.
The study of 101 participants showed that ketones have robust effects in restabilizing brain networks, with these effects maximized between ages 40 and 60. The researchers specifically identified this as a “midlife critical window” for early metabolic intervention.
This suggests that waiting until cognitive decline is noticeable may be waiting too long. The best time to consider supporting brain energy metabolism may be in midlife, when intervention appears to have the greatest impact.
I Take MCTs Without Carbs. Here’s Why
A 2021 review in Frontiers in Nutrition examined the factors that influence how effectively MCTs produce ketones.
The researchers offered some specific recommendations: If our goal is optimal brain health, MCTs should be consumed after an overnight fast, ideally without an accompanying meal or with a low-carbohydrate meal.
Their suggested protocol:if you finish dinner at 8 p.m., consume your MCTs about 12 hours later at 8 a.m., not in addition to breakfast but as a breakfast substitute. If you eat breakfast, avoid carbohydrates. (If you have eggs for breakfast, skip the toast.) Wait until lunch to break the carbohydrate fast. This maximizes the time under mild ketosis.
A Swedish study with healthy older adults (ages 65-73) confirmed that combining C8 MCT supplementation with time-restricted carbohydrate intake can be effective in helping people achieve mild ketosis. Each intercention appears to help on its own, and combining them appears to amplify the benefits.
The practical takeaway: adding MCTs to coffee in the morning while keeping carbohydrates low appears to optimize ketone production. Adding sugar to that same coffee would negate these benefits and significantly reduce the ketogenic response.
C8 vs. Other MCTs
Not all MCTs are created equal when it comes to ketone production. Coconut oil, for example, is about 7% C8 (caprylic acid), while standard MCT oil is around 12% C8. For those who would like to maximize ketone production, pure C8 oil offers additional benefits.
Interestingly, C8 and C10 (capric acid) appear to work somewhat differently in the brain. Research indicates that C8 primarily stimulates ketogenesis, while C10 increases glycolysis in astrocytes, leading to lactate production — which neurons actually prefer as a fuel source. This suggests a C8/C10 blend may have complementary benefits.
Most clinical studies showing cognitive benefits have used doses in the range of 20-30g daily, typically as a 60/40 or 55/35 blend of C8 and C10.
My Thoughts
The evidence for MCTs supporting brain energy metabolism is becoming increasingly solid.
We can’t yet prove that supplementing with MCTs will translate into preserved cognitive function over decades. (It will take a few decades to be sure.) But the mechanisms by which it may do so are well-understood, the intervention appears safe (as long as we avoid combining MCTs with carbohydrates), and the “critical window” research suggests earlier may be better than later.
What strikes me most is the consistency of the finding that brain ketone metabolism remains intact even as glucose metabolism declines. This isn’t speculative — it’s been demonstrated repeatedly across multiple research groups using PET imaging to directly measure brain fuel uptake.
There is strong evidence to suggest that adding MCT oil (ideally C8-rich) to morning coffee while keeping carbohydrates low or nonexistent in the first few hours after waking to be a reasonable approach based on current evidence.
Summing Up: What I’m Doing
I add about a tablespoon of MCT (rich in C8) to my morning coffee while I’m fasting. My goal is to maintain healthy brain function as the years go by. Adding MCT is one way that I’m trying to build a foundation for this.
My timing aligns with the Frontiers protocol: MCTs in the morning after an overnight fast, then lunch if you are later. I will often add some carbohydrates during lunch. For example, I might have a approaching meal with some wild blueberries on the side, sometimes with a little unsweetened yogurt. I move in and out of ketosis; when I’m eating a ketogenic diet, the timing might matter or less; when I am including some carbohydrates, I make sure to time the MCT so that I’m taking them when they are most useful to my brain. This way, I’m not just adding fats and calories, I’m adding a specific fat that many studies suggest can be beneficial for brain health.
Some people might experience digestive discomfort when they add MCT’s; when I started adding MCT powder to my coffee, I started with one or 2 teaspoons. I literally increased it to one or 2 tablespoons.
Related Studies
Meer et al. (2024). Medium-Chain Triglycerides (MCTs) for the Symptomatic Treatment of Dementia-Related Diseases: A Systematic Review. Journal of Nutrition and Metabolism. Read the study
PNAS (2025). Brain aging shows nonlinear transitions, suggesting a midlife “critical window” for metabolic intervention. Proceedings of the National Academy of Sciences. Read the study
Frontiers in Systems Biology (2022). Modelling the Effects of Medium-Chain Triglycerides on Cerebral Ketone Body Metabolism. Read the study
Metagenics Institute. Ketogenic MCTs Increase Brain Energy Metabolism in Alzheimer’s Disease. Read the summary
Frontiers in Nutrition (2021). The Ketogenic Effect of Medium-Chain Triacylglycerides. Read the study
More About Anti-Aging:
- Longevity Youtube channel Pathways to Longevity
- Longevity Facebook group: Anti-Aging and Life Extension
My Other Websites:
- Personal Website: Nils Osmar
- Exploring possible consciousness in LLMs: AI Consciousness
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