Listen to Your Gut

For every cell that makes up your body, there are just as many, if not more, microorganisms that inhabit you. The ones that live in your digestive tract — such as yeast, viruses and bacteria — make up the gut microbiome, and they can have a big impact on your health. The question is how?

“We have a pretty good gist of the regular players,” microbiologist Ben Willing says of gut microbes. “[But] we definitely don’t have a clear idea of what they’re all doing.” 

Willing, an associate professor in the Department of Agricultural, Food & Nutritional Science, is one of the U of A researchers working to understand how different bacteria in the gut function and the role they play beyond digestion. 

Here are five things research can tell us about how the tiny microbes in your gut contribute to the big picture of human health.

Bacteria can be harnessed

Once researchers understand the role each microbe plays, they may be able to treat people for various ailments by manipulating the microbiota. This is known as microbial therapeutics, and it has already shown promise in a U of A study in improving insulin sensitivity in severely obese patients. 

Willing and his team have been looking at the role of Parasutterella bacteria, a core component of the human microbiome, to better understand its therapeutic potential. In an experiment, they colonized mice with a complex microbiota that did not include Parasutterella and then added it to see what changed. They discovered the bacteria could play a role in controlling bile acid production and reducing some carcinogenic molecules, which may explain some of the associations of this bacteria with colonic and liver health.

Your gut is a battlefield

Anything we put into our bodies can also affect the health of our gut. In some cases, that means too much of a good thing. Willing and his team did an experiment to discover how taking large amounts of vitamin B12 affected the gut microbiota.

“There’s actually a competition dynamic that occurs in the gut for B12,” says Willing. While some microbes in the gut produce B12, others — including harmful pathogens — absorb it and vie for any that enters the digestive tract. Ideally the microbes with which we have a symbiotic relationship will out-compete the bad guys.

But Willing and his team found that an excess of B12 means there’s no longer a need to compete, which allows pathogens to thrive. In Willing’s experiment, the mice that received extra B12 developed infections more quickly — and more severely — than mice in the control group. 

The immune system is open to suggestion

Our gut microbiota help shape our immune system — not only by training it to recognize beneficial microorganisms but also by producing molecules that affect our cells’ behaviour. The presence, or absence, of certain microbes in the gut may even play a role in childhood allergies.

Anita Kozyrskyj, a professor in the Department of Pediatrics, and her team have linked “persistently low levels of gut Bacteroides” — a genus of bacteria found in the intestine — with childhood peanut allergies. They’ve also found that babies from families with pets — especially dogs — showed higher levels of two bacteria linked with lower risks of childhood allergic diseases, such as asthma and eczema, and reduced obesity.

You are what you eat

The gut and the brain communicate along what is called the gut-brain axis. Studies have shown that the composition of gut microbiota can affect the brain in ways that impact development and behaviour.

One such study, conducted by Kozyrskyj, found that boys with an abundance of Bacteroides in their gut at age one achieved higher cognitive and language development scores at age two. Another study, by pharmacologist Anna Taylor and her team, found a difference in the composition of the gut microbes of mice who had and hadn’t been exposed to morphine. They also found that when the gut microbiota were altered with antibiotics, the mice were more likely to develop symptoms of opioid dependence. 

A healthy gut may reduce disease 

Studies suggest that imbalances in gut microbiota could contribute to diseases such as asthma, diabetes, obesity and inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis, as well as neurological diseases and mental illnesses.

“There are lots of interesting studies going on that are looking at linking the microbiome, and the composition and the function of the microbiome, to our mental health as well as looking at neurological disease,” Willing says.

He is working on a study with Christopher Power, a professor of neurology in the Department of Medicine, to see if they can trigger microbes in the gut to produce anti-inflammatory molecules in patients with multiple sclerosis to help them stay in remission longer.