Can your diet and exercise seriously affect your brain?

I think we are all aware of the threat that our diet has on our brain and general health. Chemicals and additives in junk food have an impact on our gut and this really does affect our whole body.  Especially, depressive and hormonal effects that we are less aware of. Additionally, our gut-brain axis is a particularly key area of study due to the ever-growing detrimental effects that are being discovered. However, there has been evidence which states that running, or any aerobic exercise, can literally reverse some of the effects. It restores metabolites in the gut which are tied to mental wellbeing and balancing vital hormones like insulin and leptin.

Details of the study

There have been researchers in the University College Cork investigating the differences between rats fed on a western-style processed diet versus a standard chow diet. Half the animals in each group were given access to a running wheel. As a result, there were multiple effects shown regarding the caecal contents, hormonal changes and neurogenesis, based on the different diets and the effects of exercise.

Effects on the gut metabolism

To start with, the gastrointestinal tract (gut) has a steady rate of production of metabolites and proteins for survival and emotional regulation. The caecal contents are these metabolites and proteins produced at the start of the large intestine. Following the study, western style diet has been proved to negatively affect 100/175 metabolites. Some examples, amongst many more, of these metabolites are: anserine, indole-3-carboxylate and deoxyinosine. These all play a role in mood regulation and how we deal with emotions. Interestingly, a subset of the metabolites affected by the western diet were partially restored when the individuals engaged with the running wheel, giving evidence for aerobic exercise reversing some effects of western diet.

Effects on hormone production

Blood sample analysis from the western- style diet, also showed how hormonal changes mirrored behavioural outcomes. Some hormonal changes included reductions in insulin and leptin levels. Insulin is needed for cells to take up glucose for energy and leptin is key in regulating appetite and controlling when the body has enough energy. Specifically, reductions in these will affect ATP (energy) production which is vital for all aspects of survival and emotional regulation. Beyond that, Glucagon- like peptides also decreased with the western style diets, which have a similar effect to the lack of leptin. Again, this reinforces the negative effect of the components of western diets. In the exercising group of rats, peptide YY levels increased which is a compensatory hormone which stabilises the metabolism: exercise allows the body to make up for the low diet quality.

Effects on the brain

Neurogenesis is formation of new neurons, allowing us to regulate emotions, learn skills, retain knowledge and maintain musculoskeletal movement. The hippocampal area is the area of the brain which is involved in regulation of emotion and memory. A key finding: with a western diet, adult hippocampal neurogenesis was prevented. Via the gut-brain axis, this shows the debilitating impact of the diet on the brain. Again, exercise was proved to improve some navigational and regulatory mechanisms in both groups of rats, proving the adverse effects.

Limitations of the study

The detrimental effects of bad diet and benefits of exercise are obvious in these studies; however these experiments have only been done on male rats. Male and females have physiological differences which can greatly affect each sex’s hormones, neurology and gut metabolism. Furthermore, the duration of these experiments was 7 weeks therefore not showing the effects of chronic long-term exposure. However, these experiments will show some effective biomarkers for future therapies involving gut brain axis and conditions like diabetes and other nutritional based disorders.

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