Can the Microbiome Cause Obesity? Interview with Eran Segal PhD, Microbiome Expert

Sure. My name is Eran Segal. I'm a professor at the Weizmann Institute of Science and for the past 15 years have been studying the gut microbiome as it relates to health and disease. My lab has been following very large cohorts of over 10,000 individuals, tracking their lifestyle, history of disease, gut microbiome, and other related factors over the long-term.

Many years ago, we saw studies showing tremendous effects for the microbiome in obesity. That attracted me to studying the microbiome, and taking a more holistic view of looking not just at obesity, but looking at the microbiome, in general, in its relation to health and disease.

We’ve been studying the microbiome in obesity for a very long time and in very large populations of people. We found that even if you have the exact same bacterial species in your gut, but it differs by a few nucleotides, that can make a huge difference in being associated with leanness or obesity. And, we believe that giving the right probiotics to people who are overweight, can actually help them in reducing and lowering their weight.

I believe that the microbiome can cause obesity. We've shown that in animal models. We are now beginning to test this in humans by looking at bacteria that are found in lean individuals and giving them to people who are overweight. The genetics of some microbes in lean people could actually help with reducing weight because some of these bacteria can give propensity to obesity.

Bacteria form a very large ecosystem, and they're involved in pretty much almost every aspect of our life. Gut microbes produce a lot of important molecules that eventually even reach our bloodstream and even the brain.

We are beginning to understand the signatures of the microbiome that relate to disease. By testing someone’s microbiome, we can see if they are at a higher risk of developing disease. We believe the microbiome may also have a causal role in disease, so it’s possible that various ways to alter their gut microbiome could reduce the risk factors for disease.

When we analyze one's microbiome, we're looking at billions of different base pairs of DNA - that's too much information for anybody to comprehend. So, we use tools from machine learning and artificial intelligence to make sense of even a single person's microbiome. And, of course, we also use those tools to understand the microbiome of many individuals and associate all of that with the state of health and disease.

Part of it has to do with your blood glucose levels. We’ve shown in the past that every person has a different blood glucose response to food, and the gut microbiome is part of the reason why. By using the microbiome data, we can predict in advance how an individual will respond to food and therefore tailor diets to individuals, and by that balance their blood sugar levels. This can help people with prediabetes or diabetes improve their disease symptoms.

The first step is to test your microbiome so that we can see which bacteria you have. Once we know that, we use algorithms that associate clinical parameters to foods. This allows us to prescribe a personalized diet that can balance blood sugar levels.

About a decade ago, we showed that consumption of artificial sweeteners can actually alter gut microbiome composition. If you take the microbiome composition of a person who consumed artificial sweeteners, even for one week, and you transplant them into mice, those mice can develop symptoms of diabetes and obesity. Basically, artificial sweeteners can alter composition of the microbiome in a way that can cause both obesity and symptoms of diabetes.

I think one area that has been under explored in the gut microbiome is its relation to neurodegeneration through the gut-brain axis. We know that the gut microbiome can create many molecules, some of which reach the brain, and as a result the area of neurodegenerative disease is a promising area for study.

A few years back, we learned that consumption of red meat can actually cause heart disease through the microbiome. This is because one of the pathways that converts molecules in red meat can eventually also clog arteries.