Brain-derived neurotrophic factor, or BDNF, is a protein involved in neuron survival and the changes in connections between neurons that support learning and memory. It is often promoted as something we should “boost,” but the science requires an important distinction: increasing BDNF measured in blood does not necessarily result in more BDNF in the brain or improved cognition. Blood measurements are affected by platelets, sample handling, and sample timing.
Among lifestyle approaches, exercise has the strongest human evidence. Claims about particular foods, fasting, and other “BDNF hacks” deserve more caution.
Make aerobic exercise a regular habit
Research supports aerobic exercise as a way to increase circulating BDNF, particularly immediately after a workout. Repeated training can also increase resting levels, although results vary between studies and individuals. A meta-analysis examining exercise programs lasting at least two weeks found an overall increase in resting peripheral BDNF, with clearer evidence for aerobic training than resistance training. This does not establish one ideal workout or guarantee a permanent increase.
Walking, cycling, swimming, or another sustainable aerobic activity offers a practical starting point. Consistency matters more than trying to reproduce the largest laboratory spike.
Evidence also extends beyond blood tests. In a randomized trial involving 120 older adults, one year of aerobic exercise increased anterior hippocampal volume by approximately 2%. Changes in hippocampal volume were associated with changes in serum BDNF. However, that association does not prove BDNF caused the brain changes.
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Consider harder intervals, but understand the limits
A small experimental study involving 12 participants compared fasting, prolonged light cycling, and brief high-intensity cycling. The intense cycling intervals produced substantially larger increases in circulating BDNF than light exercise. This suggests intensity can influence the immediate response. However, these findings should be interpreted cautiously. The minuscule sample of healthy, physically active participants limits how well the results generalize to other populations.
The study did not demonstrate that a few minutes of intense exercise prevents dementia, produces lasting BDNF increases, or improves memory. Intervals are an option for people whose health and fitness allow them; they are not a necessary starting point.
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Treat dietary claims as preliminary
A Mediterranean-style diet has been studied specifically for BDNF, but the findings are more modest than many headlines suggest. In an analysis involving 243 participants, average plasma BDNF was higher in the Mediterranean-diet groups after three years, but the overall differences were not statistically significant. The nut-supplemented group showed some favourable findings, including a lower likelihood of very low BDNF; a subgroup with depression also showed a benefit. These results do not establish a reliable BDNF increase for everyone.
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Do not assume fasting raises BDNF in humans
Animal findings do not necessarily translate to people. In the 12-participant cycling study, fasting for 20 hours increased ketones but did not increase BDNF. That experiment cannot settle every fasting regimen, but it directly challenges the claim that entering a fasted state necessarily boosts BDNF.
The most defensible action is regular, manageable aerobic exercise. Beyond its potential effects on BDNF, aerobic exercise has well-established benefits for cardiovascular health, mood, sleep, and overall physical functioning. Even if exercise does not produce lasting increases in BDNF, these broader health benefits make it a valuable habit. Rather than focusing on a single biomarker, its value should be measured through meaningful improvements in health, fitness, and well-being.
Further reading
- A meta-analytic review of the effects of exercise on brain-derived neurotrophic factor
- The effect of physical exercise on circulating brain-derived neurotrophic factor in healthy subjects: A meta-analysis of randomized controlled trials
- Exercise and circulating BDNF: Mechanisms of release and implications for the design of exercise interventions
- The effect of acute exercise on serum brain-derived neurotrophic factor levels and cognitive function
