Link Between Changing Gut Flora and Obesity

Marc Bomhof would like to amend the old saying, You Are What You Eat, to be more accurate. Perhaps something like: You Are What You and Your Gut Microbiota Eat.

“It’s estimated that there’s about 100 trillion bacteria living in our digestive tract,” explains Bomhof. “We have about 10 trillion human cells versus 100 trillion bacterial cells and so we’re essentially 10% human and 90% bacteria. These things obviously have a very significant effect on our host physiology.”

Bomhof, a PhD candidate in Raylene Reimer’s lab, was recently announced as the winner of a prestigious Killam Pre-Doctoral Scholarship. The Scholarship pays $33,000 for 12 months, along with a research allowance of $3,000. Since Bomhof and his wife Tara had their first son in June, the funding will be particularly welcome in allowing him to stay focused.

“I’m extremely grateful for this funding and deeply honoured by it,” he says. “The financial support is awesome and it allows me to stay really dedicated, and answer the questions that I really want to answer.”

Linking Gut Bacteria to Obesity

Like many researchers in his field, the questions that Bomhof wants to answer revolve around the growing problem of obesity in our society. Bomhof believes obesity rates may be partly due to a change in the bacteria in our gut. Specifically, he believes that what we eat affects the type of bacteria that take up residence.

Our modern, high-sugar, low-fibre, processed way of eating invites the wrong characters, and starves the most beneficial bacteria. “Historically we’ve had a diet that’s been very, very high in complex carbohydrates, and it’s estimated our ancestors ate about 100 grams of fibre a day. Now our food environment is almost void of fibre,” says Bomhof.

“We have a lot of processed foods where a lot of the fibre has been removed from the foods and the high-fat, high-sugar diet is thought to really impact that gut microbiota so it’s taken on a different profile which has a negative effect on our body, the host metabolism,” he says. “It might be increasing inflammation, it might be increasing energy extraction, it might be changing the various metabolites that are absorbed by the body and that’s what’s causing the negative effects on the health.”

Feeding the Good Bacteria

One of the research solutions pursued by Bomhof and the Reimer lab is to ‘feed’ the good bacteria, using prebiotics. Reimer’s lab has been using a specific prebiotic fibre called oligofructose to feed the gut bacteria of overweight subjects in several trials, and so far they’ve seen some interesting results.

“We’re looking at the different metabolic changes that are happening at a cellular level with the oligofructose,” he says. “Prebiotic fibre, for whatever reason, really seems to reduce adipose tissue. It might not necessarily decrease weight, but it has an effect on reducing [fat]. We’re still trying to figure out the mechanism of what’s mediating that reduction.”

The hope is that by feeding the good bacteria in our guts using prebiotics we can change our metabolism, kind of a ‘gut makeover’ project, which Bomhof says might be more effective than simply eating live bacteria probiotics which don’t seem to have as big an effect.

Bomhof, who also holds a Natural Sciences and Engineering Research Council of Canada (NSERC) and an Alberta Innovates – Health Solutions scholarship, became viscerally interested in the relationship between diet and health, during his career as a professional cyclist competing with a team based in Toulouse, France.

In a sport plagued with performance-enhancing drug scandals, he became interested in finding an ethical way to maintain a competitive edge that focused on how proper nutrition could be used to fuel the body for optimal health and performance. This interest led him to the Nutrition and Food Science program at the University of Alberta and a dietetics degree.

Driven to Relieve the Burden of Chronic Disease

While working as a clinical dietitian at the Sturgeon Community Hospital in St. Albert, Bomhof counselled individuals on the management and prevention of chronic diseases through nutrition, and provided nutrition support services to patients in intensive care, cardiology, nephrology, internal medicine, and gastrointestinal surgery units. He says that this clinical experience gave him a strong appreciation for the impact and burden of chronic diseases like diabetes on his patients and became the motivational force for his research career, which he pursued at the University of Calgary.

Bomhof isn’t naïve, however, and he emphasizes that the lab’s research is only part of the obesity puzzle. “Obesity is a very, very, very complex disease. We know with weight loss that most people can lose weight in the short term but sustaining that weight loss is extremely difficult,” he says. “Now the reason for that is your underlying biology is protecting the set point your previous weight and your body is resisting that downwards movement in your body weight.

“It’s always trying to draw it back up through powerful physiological mechanisms. It’s not just because of a lack of willpower or being lazy. It’s a fact that it’s very, very hard to maintain weight loss. We’re trying to target those underlying physiological reasons the biological reasons that make it hard to maintain that weight loss.”

Bomhof says that’s where prebiotic fibre comes in. “If we can make it a little bit easier for people to maintain a weight loss by increasing the satiety, by decreasing the feelings of hunger in the brain, then perhaps that can just be one tool in the toolbox for people to utilize to maintain a healthy weight in the long term and fend off different metabolic diseases like type 2 diabetes or non-alcoholic fatty liver disease.”

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Don McSwiney, University of Calgary
First published in the Inside Tract® newsletter issue 192 – 2014
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