Scientists are discovering that the trillions of microbes in your gut may directly influence your metabolism, weight gain, and insulin sensitivity. But what exactly is gut microbiome and why does it matter? Let’s find out in this post.
What Is Gut Microbiome?
Gut microbiome is the entire ecosystem of microbes (bacteria) that live in your intestines. Did you know that we host up to six pounds of microbes in our gut alone? In our whole body we are composed of about 10 trillion human cells. These human cells comprise about 100 trillion bacterial cells, making us only 10% human and 90% microbial.
What is even more impressive is that the genetic material of the bacterial cells outstrips our human genes. As humans, we are the product of 20,000 human genes, but we carry up to 2 million microbial genes inside our gut. Our microbial DNA to human DNA is actually in the ratio of 150:1. We have about 1100 common species of bacteria in our body.
Types of Gut Bacteria
There are two dominant types of gut bacteria that populate our gastrointestinal tract:
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Bacteroidetes – involved in protein and carbohydrate breakdown
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Firmicutes – promote absorption of fat
These bacteria need to be in just the right ratio to promote ideal weight and health. However, over the last 30 years the ratios of these bacterial communities have drastically changed. They now mirror the global spikes in obesity and diabetes, as well as allergic and inflammatory disorders.
Basically, the diversity of the microbiome has decreased, with a progressive change in density from Bacteroidetes to Firmicutes. Keep in mind that these are not causations, only associations. Nonetheless, we must wonder what we are doing to change these bacteria.
Are Antibiotics Disrupting Your Metabolism?
One major suspect of these changes is the rampant use of antibiotics. Dr. Robert Ratner, Chief Medical Officer of the American Diabetes Association, notes that antibiotics change gut flora in two key ways:
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Directly altering the composition of bacterial communities, even with short-term use
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In early life, antibiotics can change fat metabolism for a lifetime, despite only temporarily altering the microbiome
Gut Diversity and Type 1 Diabetes
In studying those who developed type 1 diabetes through the Type 1 Diabetes Prediction and Prevention Project (DIPP), data has consistently shown that those developing type 1 diabetes have significantly lower diversity in their gut flora. Type 1 Diabetes is considered to be an autoimmune disease, and the risk of autoimmunity increases up to 20 times with certain species of Bacteroides. Again, this is not causation, but association.
Can Gut Bacteria Cause Insulin Resistance?
New evidence suggests that we can show causality, when it comes to our microbiome driving the course of diabetes and obesity. We know that some microbes produce an endotoxin called lipolysaccharides (LPS). When they cross the mucosal barrier in the intestine and enter the interstitial space, they set up an inflammation that impacts the fat cells and the liver, which then can lead to insulin resistance.
Dr. Ratner admits that it does now appear that our microbes are actually controlling our metabolism. Unpublished data from the laboratory of Dr. Martin Blaser at New York University, shows that a specific bacterium in mice can cause diabetes, and removing it cures the disease.
Mice that were engineered as a model of prediabetes consumed the live gram-negative pathogen Ralastonia (a pathogen that contaminates drinking water). The results showed that the mice gained much more weight. They also developed insulin resistance and hyperglycemia, compared with controls. When these same mice were given an antibody of Ralstomia, they lost weight and their hyperglycemia resolved.
How Bariatric Surgery Impacts the Gut Microbiome
We know that bariatric surgery leads to weight loss, and diabetes resolution in some people. Dr. Randy Seeley, Ph.D. of the University of Michigan, Ann Arbor believes that there is more going on during post surgical weight loss than just food restriction and malabsorption. He studies how weight loss surgery affects the microbiome and theorizes that the physical manipulation of the gut changes the gut microbiome. Enteroplasticity is induced with the physical manipulation of the gut.
Enteroplasticity refers to a fluid adaptation of both the gut's structure and its bacterial communities to the altered physical and chemical environment. After bariatric surgery, it has been recognized that a firmicute, "Roseburia intesinalis" increases and that this bacteria is also found to be deficient in people who have diabetes.
In an article coauthored by Dr. Seeley, it was discovered that after mice underwent vertical sleeve gastectomy, there was an increase of Roseburia and other firmicutes, thus another link for weight loss surgery repairing the microbiome.
Can You Repair Your Gut Microbiome Without Surgery?
The good news is that we don't have to have weight loss surgery to repair our gut microbiome. We can easily determine the BUG composition of our microbiome through simple stool testing. We can also correct the imbalances in our bacterial communities through good gut health. This is exciting health news that can transform diabetes care.
FAQs about Gut Microbiome
What is the gut microbiome?
The gut microbiome refers to the trillions of microorganisms and their genetic material living in your gastrointestinal tract. These bacteria play a key role in digestion, immune function, and metabolism.
Can antibiotics cause obesity or diabetes?
There is growing evidence that early-life or excessive antibiotic use can alter the gut microbiome in ways that affect fat metabolism and insulin sensitivity.
How can I improve my gut health naturally?
You can support a healthy microbiome through diet (e.g., high-fiber, prebiotic-rich foods). Probiotics, stress management, regular exercise, and avoiding unnecessary antibiotics also help.
About the Author
Cheryl Winter is a board-certified family nurse practitioner and registered dietitian with advanced training in diabetes and weight management.
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