There’s an entire universe of bacteria that make their home in your gut. This bacteria ecosystem, made up of about 100 trillion bacterial cells, is referred to as the microbiome. Far from being passive players taking up space in your intestinal tract, these bacteria help with nutrient absorption and help maintain a healthy digestive tract. Just as importantly, these bacteria that make up your internal ecosystem make up more than 70% of your immune system.
The full range of functions these bacteria carry out has only begun to be explored. Research has even linked gut bacteria with obesity, along with a number of other health problems associated with aging, including type 2 diabetes. Some studies show obese people have a different bacterial composition in their gut relative to normal-weight people and have a less diverse group of bacteria. When gut bacteria from obese mice are placed into mice of normal weight – the normal-weight mice quickly gain body fat. Now, a new study has identified a new link between exercise and gut bacteria.
Can Exercise Change Your Gut Bacteria?
Researchers in Ireland looked at blood and fecal samples from forty professional rugby players. The researchers also studied a control group of men of similar size, weight and age that were not professional athletes. Some men in the control group had a healthy BMI while others had a BMI that placed them in the overweight or obese category. Since diet influences gut bacteria composition, they closely followed the diet of the athletes and used food frequency questionnaires to study the diet of the control group.
After comparing fecal samples between the two groups, researchers discovered the athletes had a more diverse array of gut bacteria compared to the non-athletes. Plus, they had more bacteria associated with metabolic health. The difference was most pronounced between the athletes and sedentary controls that were overweight or obese.
Can you conclude from this study that exercise is key to a healthy gut ecosystem? Not just yet. This study doesn’t prove cause and effect. The athletes ate a healthier diet – more fruits and vegetables and more protein – relative to the control group. Diet has a big influence on the type of gut bacteria that live in your gut. For example, the protein composition of the athletes’ diet was 22% compared to 15 to 16% for the control group. It’s possible a combination of diet and exercise could account for the difference in gut bacteria composition. It’s an exciting finding but one that needs more research. Hopefully, future studies will control better for diet so the effects of exercise alone can be identified.
Factors That Shape Your Gut Ecosystem
What you eat is one of the most important factors that shape your gut microbiome. You’re first exposed to gut bacteria early in life – at birth. As babies move through the birth canal, they become colonized with mom’s bacteria. When babies are delivered by caesarian section, they miss out on this bacterial inoculation. Instead, they pick up bacteria in their surrounding environment, the hospital or delivery room, immediately after birth, creating a different bacterial composition. After birth, the composition of bacteria in a baby’s intestinal tract is influenced by whether a mom chooses to breastfeed or not. Breastfeeding has been linked with a more favorable composition of gut bacteria.
Some research suggests that these early bacteria influence a baby’s health later in life. For example, some research shows babies born by caesarian section have a higher risk for asthma and allergies during childhood. Exposure to bacteria early in life helps shape a baby’s immune system and how it responds to the outside environment. Growing evidence also suggests gut bacteria and diet together influences a child’s risk of obesity.
Diet and Gut Bacteria
Even if you didn’t end up with a healthy composition of bacteria at birth, you have a second chance. What you eat throughout life impacts the type and diversity of bacteria you’re colonized with. For optimal health, you want a wide diversity of gut bacteria. In animals, a diet rich in processed foods is linked with a less diverse population of gut bacteria.
Even more exciting is the fact that changing your diet very quickly changes your gut bacteria – within a day according to a study carried out at Harvard. In this study, participants that switched from a plant-based diet to a meat-based one experienced changes in gut bacteria in as little as 24 hours. Unfortunately, the meat-based diet was linked with bacterial species that cause inflammation.
Even the amount of calories you consume may have an impact on your gut microbiome. Some research shows consuming a high-calorie diet changes the type of gut bacteria that make their home in your gut. In response to a high-calorie diet, you may develop a population of bacteria that are more capable of absorbing the higher nutrient content you’re exposing your gut to. In other words, the more calories you consume, the more you absorb.
What’s the Best Diet for a Healthy Gut Ecosystem?
Based on current research, plant-based diets rich in fiber seem to be most favorable for maintaining a healthy and diverse composition of gut bacteria. A fiber-rich diet selects for gut bacteria that could protect against health problems like colon cancer, obesity, type 2 diabetes, and some autoimmune disorders, although more research is needed. Supplementing your diet with yogurt with active cultures and fermented foods also help create a more diverse population of gut bacteria. As the most recent study suggests, the role exercise plays in creating bacterial diversity needs to be further explored. In the meantime, keep working out and eating a fiber-rich diet and enjoy the many health benefits a healthy diet and exercise offer.
References:
Medical News Today. “Gut Bacteria Diversity Improves with Exercise, Study Shows”
Eur Rev Med Pharmacol Sci. 2013 Feb;17(3):323-33.
The Connecticut Center for Health. “Intestinal Bacteria in the Newborn Baby”
WebMD. “C-Section May Disrupt ‘Good’ Bacteria in Babies”
Nature. “Diet rapidly and reproducibly alters the human gut microbiome”
Today’s Dietitian Vol. 15 No. 6 P. 46. (2013)
Science Daily. “Dietary fiber alters gut bacteria, supports gastrointestinal health”
Nutr Clin Pract. 2012 Apr;27(2):201-14. doi: 10.1177/0884533611436116. Epub 2012 Feb 24.
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