>> Monday, January 2, 2017
Did you know that you have more bacterial cells inside your intestines than you have human cells in your entire body? Not only that, but they house somewhere between 250 to 800 times more genes than we have human genes in our body. Perhaps it's not so far out, then, for us to learn that these bacteria (called the 'microbiome') play an important role in our metabolism, and are very likely to contribute to the risk of both obesity and type 2 diabetes.
A wonderful Viewpoint article in JAMA (free to read online here) outlines what we know about this topic so far.
The microbiome has many important functions, including the production of important amino acids (protein building blocks) and vitamins, and they also help to degrade toxins. The genes in these bacteria also produce hormones and inflammatory molecules that enter our circulation and effect our health.
These bacteria also play a role in how many calories we absorb from food, because they make enzymes that help us to digest polysaccharides, a type of carbohydrate. Some types of gut bacteria are better at this than others, and studies have shown that people with obesity carry more of the carb-digesting bacteria (called Firmicutes) than people without obesity. Interestingly, some studies have shown that when a person with obesity loses weight, particularly after bariatric surgery, the proportion of 'good' bacteria (called Bacterioides) increases relative to the 'bad' Firmicutes. Overall, the studies suggest that the gut bacteria may be both a cause and a consequence of obesity.
Along with the increased capacity to absorb carbs in people who carry more Firmicutes bacteria, so comes an increased risk of having not only obesity, but also type 2 diabetes. Altered production of short chain fatty acids by gut bacteria, as well as low grade gut inflammation caused by chemicals made by the microbiome, also contribute to insulin resistance and diabetes risk.
So how does this play out in terms of treatment of obesity or diabetes? Well, some studies (mostly done in rodents, but some in humans too) have shown that manipulation of the gut microbiome by way of stool transplants (yep, transplanting poo), or perhaps by other modalities such as change in diet or probiotics, may be able to have an effect on the type of bacteria we have, but we are far from developing concrete treatment approaches. However, as we learn more about our gut bugs and the genes they carry, we come steps closer to learning how we may ultimately be able to incorporate microbiome modification into our treatment options for obesity and metabolic syndrome.
Follow me on twitter! @drsuepedersen
www.drsue.ca © 2017