Ketone supplement altered brain insulin responses in older men
In a crossover trial of 18 older men with overweight, the supplement lowered blood flow responses to insulin in ten brain areas compared with placebo.
Our read
Interventions- Studied:
- Randomized trial in 18 older men with overweight, against taste-matched placebo (Double-blind, placebo-controlled)
- What changed:
- Ketone supplementation lowered blood flow responses to insulin in ten brain areas compared with placebo
- The catch:
- Blood flow responses served as a proxy for brain insulin responsiveness
- In the record:
- The 15th paper on ketone monoester with results in people; 19 on record in all.
Editor of record: Boris Djordjevic · AgingResearch.News
Eighteen men with overweight, averaging 70.2 years old, took ketone monoester or a taste-matched placebo in a randomized, double-blind crossover trial. The supplement raises blood ketones, molecules the body can use for fuel. The dose was 395 milligrams per kilogram of body weight.
Brain scans measured blood flow responses to insulin given through the nose. Compared with placebo, the supplement lowered these responses in ten brain areas. It also shortened reaction time by 9 milliseconds, a modest improvement in attention and the speed of responding. It did not affect memory or executive function, the skills used to plan and manage tasks. Resting whole-brain blood flow also fell. The supplement was well tolerated.
Why it matters
The trial explored brain responses to insulin as a possible link between nutritional ketosis—a state of raised blood ketones—and cognitive performance in older age.
Caveats
The trial measured short-term blood flow and test performance, not whether cognitive decline was prevented. All 18 participants were older men with overweight, limiting application to women or other age and weight groups.
The paper
Maastricht University
Metabolism, Jun 9, 2026, Open access
doi.org/10.1016/j.metabol.2026.156672PubMed 42263845
Corrected, Oct 1, 2026
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