Maintaining a healthy brain depends not only on diet but also on regular physical activity. While many people assume that exercise can fully counteract the effects of junk food, new research suggests the reality is more nuanced. A recent study from University College Cork led by Professor Yvonne Nolan, reveals that running can protect mental health and improve mood, even for individuals consuming a typical Western diet high in fat and sugar. The study highlights how exercise positively influences brain function through gut health, hormones, and chemical balance, offering biological proof that physical activity can help regulate mood and reduce anxiety. These findings suggest that while diet is crucial for long-term brain health, incorporating regular running or aerobic exercise can significantly mitigate the mental health risks posed by processed foods.

To explore the combined impact of diet and exercise on the brain, researchers studied adult male rats for over seven weeks. One group consumed a standard healthy diet, while the other ate a “cafeteria diet” consisting of high-fat, high-sugar foods and ultra-processed meals. Within each diet group, half the rats were given access to a running wheel to exercise voluntarily.

The results were striking. Even rats on the unhealthy cafeteria diet experienced antidepressant-like effects from running. Regular physical activity improved mood regardless of diet, suggesting that exercise can partially offset some of the mental health risks associated with poor nutrition.While the cafeteria diet did not severely impair the rats’ learning or memory, exercise slightly improved their navigation skills. Researchers also observed mild anti-anxiety effects from running, which occurred regardless of dietary intake. This indicates that physical activity alone can enhance mental health, helping to regulate mood and reduce stress, even in the context of a high-fat, high-sugar diet.

One of the key findings of the study was the effect of diet on the gut’s chemical environment. The unhealthy cafeteria diet disrupted the production of gut metabolites, altering 100 out of 175 chemical compounds analysed in the rats’ caecum (part of the large intestine).Exercise played a restorative role by increasing levels of three critical metabolites—anserine, indole-3-carboxylate, and deoxyinosine, all of which are associated with mood regulation. This demonstrates that running supports mental health through gut-brain interactions, helping to counteract some of the chemical imbalances caused by processed foods.

The study also explored adult hippocampal neurogenesis, which is the growth of new brain cells in the hippocampus, a region crucial for memory and emotion. Rats on a healthy diet experienced significant increases in neurogenesis through exercise.However, rats consuming the cafeteria diet did not see the same benefit. This indicates that while running improves mood regardless of diet, a poor diet may prevent the brain from fully reaping the deeper, cellular-level advantages of exercise. In other words, exercise can help mood and mental health, but it cannot entirely reverse the structural brain effects of chronic junk food consumption.

The study offers reassuring insights for people who struggle to maintain a perfectly healthy diet. It shows that even when consuming processed or high-sugar foods, regular exercise such as running or other aerobic activities, can provide measurable mental health benefits. Physical activity helps reduce symptoms similar to depression, lowers anxiety, and promotes overall well-being.Importantly, the research highlights the role of gut health in regulating mood. Exercise positively influences gut metabolites and hormones, which in turn support brain function and emotional resilience. While a balanced diet remains essential for optimal cognitive health, incorporating regular physical activity is a practical and effective way to protect mental health, even when eating habits are less than ideal.While this study focused on male rats and a short exercise period, future research should include females and longer-term activity. Still, the findings highlight that regular running can improve mood, reduce anxiety, and support gut-brain health. Although exercise can’t fully reverse all the effects of a poor diet, it remains a proven way to protect brain function and maintain mental well-being in today’s fast-food-heavy world.

Disclaimer: This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.