Inside your gut (the collection of organs involved in digestion, such as the mouth, stomach, intestines) are trillions of bacteria. It’s estimated each of us have more bacterial cells than human cells. And this can include up to 1000 different bacterial species alongside viruses, fungi and other microbes. Together, they make up your microbiome.

Now before you start running for an antibiotic, without the microbiome, it would be pretty hard to survive. And a greater diversity in the types of bacteria, appears to be better. Your microbiome is the result of thousands of years of evolution and is crucial to help digest food, regulate metabolism and support the immune system. For example, bacteria in the small and large intestines are needed to digest dietary starches and fibres. As a result, the microbiome may be important in preventing diseases such as diabetes, heart disease, cancer and mental health.

While as infants you get your initial microbiome from your birth mother, the microbiome isn’t static. It can change based on environment exposures and many behaviours. In particular, your microbiome is affected by what you eat, how much you exercise, sleep patterns and stress.

You Are What You Eat and So Is Your Microbiome

Given your microbiome is in your gut, and mostly your intestines, it’s probably no surprise that what you eat can greatly affect it. In one of the more robust studies looking at diet and the microbiome, the results clearly indicate the connection between the two. A healthy diet pattern of plant-based foods, or animal-based foods (eggs, fish) was associated with bacteria that may reduce risk factors for a variety of diseases.

One of the dietary factors that’s been associated with diversity of the microbiome is fibre. In mice, restricting fibre weakened the gut to disease resistance. Research in the Hazda population of hunter-gatherers in Tanzania has found their high-fibre diet to be associated with more types of gut bacteria. In addition, this diversity decreased as seasonal fibre intake decreased. And a randomized study found a diet focused on fibre improved how the microbiome functioned.

In contrast, a diet high in processed foods and refined sugar may decrease the diversity in your microbiome. Eating more processed foods is associated with less types of bacteria in the gut. This may be due to the high levels of sugar and lack of fibre in processed foods. In addition, the use of artificial sweeteners has been linked to a disruption of the microbiome and may impair glucose tolerance.

Your Microbiome Needs Exercise Too

How much exercise and activity you do can also affect your microbiome. Athletes tend to have a microbiome associated with muscle function and improved health. But not just in athletes, women meeting the minimum guidelines for physical activity also had a different microbiome compared to women who weren’t active. And those women who sat less and took breaks from sitting, also had a greater diversity in their microbiome.

The good news is that it doesn’t take long to improve your microbiome. Just six weeks of exercise in sedentary people was enough to result in favourable changes. However, six-weeks of inactivity reversed these changes. In those with obesity, the microbiome was different to start with and a longer exercise program was needed for changes to occur. This is supported by study of a 12-week program, which improved the microbiome in children with obesity. It’s not quite certain how exercise affects your microbiome. Much of it may have to do with exercise resulting in changes to your intestine associated with a more favourable environment for bacteria.

While these studies suggest being active can change your microbiome for the better, some bacteria may actually boost motivation for exercise. In a study of mice, certain bacteria improved running performance by enhancing the pleasurable response to exercise. When this pathway was blocked, the mice fatigued much sooner. Whether this applies to you and me, however, needs to be studied.

Sleep, Stress and Depression

Sleep is something many people don’t get enough of. And this cannot only affect you, it may also have an effect on your microbiome. While not studied as much as diet and exercise, early research in mice suggests a connection between sleep quality and the microbiome. Chronic sleep deprivation in mice over four weeks led to increased inflammation and poor metabolic function. Studies in people have found sleep quality to be associated with greater microbiome diversity, while sleep deprivation over two days resulted in microbiome changes associated with insulin resistance.

There is some suggestion your microbiome may also be implicated in mental health and wellness. A study in university students found bacteria amount went down during exam week, when stress was high. Depression may also alter the microbiome. In a large study, people with depressive symptoms had a higher number of specific types of bacteria and less of others, reducing diversity.

If you’re interested in improving (or maintaining) the health of your microbiome, healthy nutrition, regular exercise, good quality sleep and stress management may be the way to go. Besides helping out the trillions of organisms in your body, you’ll also get benefits yourself.

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