There are more microbes living in your gut right now than all humans that have ever existed on this earth. Known as your gut microbiota, these microbes perform countless life-sustaining functions and fundamentally they distinguish whether you have good overall health or lingering bad health. For example, without diversity in your gut microbe population, your gut lining integrity can become compromised, in turn influencing malabsorption, fatigue, depression and disease.
It is well known that your gut health is strongly determined by your diet, but research is finding that exercise may be just as important. Like a comfy bed influences a good night’s sleep, exercise promotes your gut health through numerous mechanisms at both a physical and metabolic level. For instance, a recent study that involved 32 sedentary adults found that exercise for just 30 to 60 minutes, three times per week for six weeks, resulted in an increase in microbes that produce short-chain fatty acids (SCFAs), specifically butyrate. Butyrate is the primary energy source for your gut cells, meaning it is required to both strengthen and repair your gut lining.
Further to this, butyrate has been shown to reduce inflammation within the gut, which in turn reduces your risk of inflammatory bowel disease, insulin resistance, weight gain and diabetes. Interestingly, when these 32 adults returned to their sedentary lifestyle, their butyrate-producing microbes declined, resulting in poorer gut health.
Dysbiosis refers to a reduction in the diversity of your good (commensal) bacteria and an overgrowth of unfavourable microbes. It has been associated with many conditions, including inflammatory bowel disease, diabetes, colon cancer, allergies, asthma, eczema and autism. Although it remains unclear whether dysbiosis is a cause or a consequence of these conditions, it has been found that prebiotic and/or probiotic therapy can ameliorate symptoms in some of these diseases, indicating that manipulation of your gut microbiota could be a viable therapeutic strategy. Accordingly, there are many factors that both contribute to and modulate your gut microbiota profile including genetics, diseases, drugs, smoking, lifestyle, stress and, of course, dietary factors.
And yes … you guessed it, exercise, or a lack of, also plays a role in dysbiosis. Studies have found that a decrease in the Bacteroidetes to Firmicutes ratio (dysbiosis) is related to obesity, suggesting that the normalisation of this ratio may prevent weight gain and obesity-associated diseases.
Interestingly, a study conducted by Evans et al. found that exercise resulted in an increase in the Bacteroidetes to Firmicutes ratio. It has also been found that R. hominis, A. muciniphila and F. prausnitzii (bacterial species) are significantly higher in active women than in their sedentary peers. This was found in a study that looked at the effects of three hours of light exercise a week on 40 pre-menopausal women. It concluded that exercise modulates your microbiota profile. In particular, it found that physical activity performed at low doses and continuously (weekly exercise compared to monthly) can increase the abundance of health-promoting bacteria, including Bifidobacterium spp, R. hominis, A. Muciniphila and F. prausnitzii.
As previously mentioned, butyrate is a very beneficial SCFA for good gut health. Both R. hominis and F. prausnitzii produce beneficial butyrate. F. prausnitzii also produces metabolites that deliver anti-inflammatory actions. The bacteria A. muciniphila has been linked with a lower body mass index, whereas low levels have been linked to metabolic disorders, including obesity and diabetes.
Furthermore, exercise has been shown to help A. muciniphila stick to your gut wall lining. This is important as it promotes mucus production, which is essential for good gut health. In addition, A. muciniphila has been found to reverse weight gain from a high-fat diet.
In another area of research, scientists looked at differences between mice which performed exercise and those that were sedentary. The researchers found that fit mice had significantly higher amounts of lactobacillus bacteria. Lactobacillus bacteria produce lactic acid, which lowers the pH level in your gastrointestinal tract (GIT). A lower pH level is favourable in your intestinal tract as it inhibits the growth of pathogenic microbes, promotes the growth of good microbes, and enhances your absorption of certain minerals, including magnesium, calcium and iron.
As mentioned earlier, it has been found that exercise promotes the growth of A. muciniphila. This beneficial bacteria has been shown to increase endocannabinoids. These are cannabis-like molecules that your body naturally makes. In relation to gut health, your endocannabinoids are involved in regulating gut inflammation as well as your gut barrier integrity. Endocannabinoids are also involved in your eating patterns. For instance, when you are hungry, specific endocannabinoids are released. And when you are full, particular endocannabinoids are released into your gut. Notably, it has been found that the endocannabinoid system is overactive in obese people. In addition, research has also found that more endocannabinoids are produced in the blood of athletes, which in turn provides them with pain relief and improves mood.
The athlete’s gut
In May 2020, an article published in the International Journal of Sports Nutrition and Exercise Metabolism concluded that the cluster of athletic components, including exercise, associated dietary factors and body composition, promote a more “health-associated” gut microbiota. This is characterised by a higher abundance of health-promoting bacterial species, increased microbial diversity, health-promoting functional pathways, mucosal immunity and improved gut barrier function. In comparison, those who are sedentary have reduced gut health and in turn reduced overall health. However, don’t despair as there is hope. The study also noted that if those who are sedentary start exercising and maintain a healthy exercise regime, they can positively modulate the composition and metabolic capacity of their gut microbiota, consequently improving their overall health.
Exercise and diet often go hand in hand, with evidence showing that an active lifestyle is frequently associated with a higher consumption of fruits, vegetables and overall fibre. A sedentary lifestyle, however, is often associated with a higher consumption of fatty, energy-dense and low-fibre foods. Therefore, not only is exercise an important habit that influences other healthier lifestyle activities such as diet choices, it most likely also has a direct modulating effect on your gut microbiota health.
5 tips for exercising your way to better gut health
- Focus on consistency rather than type or intensity — even if it’s just a half-hour walk each day.
- Embrace the morning. Exercise is a keystone habit, meaning it influences you to make healthier choices after it, such as better food choices.
- Exercise is an opportunity, not a task. There are people stuck in hospital beds and prison cells. Get out there and enjoy moving.
- The best exercise is the one you like. Rather than conforming to gym classes or marathons (unless these are your thing), find exercises that you like.
- Do it for your gut microbes, not just your body fat. Remember, good gut health promotes better digestion, an improved mood and reduces your risk of chronic disease.
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Josh is the founder of Reed Nutrition, Byron Bay. He is a consultant dietitian, health writer and the author of the plantbasedguidebook.com. Josh specialises in gut health, food intolerance, plant-based nutrition and Aboriginal health.