A new line of research suggests that one small molecule released during exercise could play a big role in keeping our brains sharp as we age.
Aging is a major driver of cognitive decline, dementia, and neurodegenerative disease, yet effective interventions remain limited.
Aerobic exercise stands out as one of the most powerful lifestyle tools we have, improving memory, mood, sleep, and slowing neurological decline in older adults and animal models.
Scientists now know that during exercise, our muscles, liver, and even neurons release signalling molecules called exerkines that help coordinate beneficial changes throughout the body.
One exerkine in particular, β-hydroxybutyrate (BHB), is emerging as a key player linking physical activity to better brain health.
Meet β‑Hydroxybutyrate: The “Exercise Ketone”
BHB is the most abundant ketone body made in the liver from fats during fasting, low-carbohydrate intake, or aerobic exercise, when blood glucose is relatively low. Both the brain and muscles can use BHB as an efficient fuel, and it has been studied for potential benefits in conditions like neurodegenerative disease, heart failure, and liver disorders because of its anti-inflammatory and neuroprotective properties.
In a new study published in the Journal of Sport and Health Science, researchers from Shanghai University of Sport showed that a single one-hour treadmill session in 19‑month‑old mice (roughly human age 60) more than doubled circulating BHB three hours after exercise, before returning to baseline within 24 hours.
These findings confirm that even in older organisms, aerobic exercise robustly raises BHB levels.
Exercise more than doubles circulating levels of β-hydroxybutyrate. Old mice that underwent an hour of exercise (blue line) exhibited more than doubled circulating β-hydroxybutyrate compared to non-exercised old mice (red line).
Exercise, BHB, and Better Memory
To test whether this surge in BHB actually mattered for the brain, the researchers put older mice on a 16‑week aerobic program—running one hour a day, five days per week.
After the training period, the animals performed better on memory tests, confirming that long‑term aerobic exercise enhances cognition in aging brains.
The team then asked a critical question: could BHB alone mimic these benefits? They injected old mice with BHB five times a week for 16 weeks at a dose of 200 mg per kg of body weight. Supplementation nearly tripled circulating BHB within 15 minutes and, remarkably, produced similar improvements in memory assessments to those seen with exercise.
In a follow‑up experiment, mice were genetically modified to lack an enzyme needed to produce BHB, and these animals failed to gain the same cognitive boost from exercise as normal mice. This suggests BHB is not just a by‑product, but a necessary mediator of at least part of exercise’s brain-protective effects.
What This Could Mean for Human Brain Aging
Human studies show that boosting ketone availability through fasting, ketogenic diets, or exogenous ketones can enhance brain network stability in younger adults, hinting at a protective effect that may also apply to aging brains.
Researchers believe BHB could help guard against age-related cognitive decline, mild cognitive impairment, and possibly Alzheimer’s disease, but clinical trials in older adults are still needed.
For now, the most proven strategy remains regular aerobic exercise, which naturally raises BHB and provides many other systemic benefits.
However, for people interested in “hedging their bets,” BHB supplements—often sold as ketone powders—are already commercially available, typically costing around $30–$45 for a month’s supply.
Anyone considering supplementation should remember that the exciting data so far come primarily from animal studies, not large human trials.
Combining consistent exercise, a nutrient-dense diet, good sleep, and, where appropriate, physician-guided use of BHB supplements may offer a promising, science-informed path toward maintaining a sharper, healthier brain with age.
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