April 19, 2019
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Good bacteria, bad bacteria and the bacteria we like to think make us fat

George Danby | BDN
George Danby | BDN

Living within our bodies are trillions of tiny organisms called microbes that compose what has been named the “human microbiome.” Every surface of our bodies has its own microbiome. The gut is the host to different microbes than the mouth, and the mouth houses different microbes than the skin. These microbes are capable of maintaining our health, but they also are capable of eliciting disease.

So what exactly can be found within our bodies? As seniors at the University of Southern Maine, we finished off our semester with a capstone course about the Human Microbiome Project, or HMP. In 2008, this project launched with the goal of identifying the microorganisms found in healthy and unhealthy individuals in order to study how changes in our microbiomes are associated with health and disease. Hopefully in the future, findings from the HMP will enable us to manipulate our microbiota and offer improved and specialized care.

We were surprised to find that with the infancy of the HMP there has been an overwhelming amount of new data in microbial research among the scientific community. But even more surprising may be the attention it has gained over the years in popular culture. The topic has become a regular mainstream, newsworthy contender with headlines such as “ We are Our Bacteria” to “ Invite Some Germs to Dinner” in The New York Times.

But what makes the human microbiome so intriguing to the public? Why do we care so much about it? In our fast-moving culture, most people are reluctant to make long-term lifestyle changes. Everyone seems to be looking for a quick fix, and microbial research has captured the public’s attention in hopes of providing quick and easy alternatives to improving our health.

One theme that has caught the public’s attention is the research linking microbes to obesity, diet and health. Our high-fat “Western” diet has made obesity a growing epidemic here in Maine and the United States, including significant increases in obesity-related health issues including Type II diabetes, hypertension and cardiovascular disease. In Maine, 25 percent of the population is considered obese. There is growing evidence linking the increased abundance of certain bacteria to obesity with certain diets. What still isn’t known is whether there are a specific set of “good” or “bad” microbes that cause obesity. Despite this, the human microbiome has become the latest health fad, with diets and probiotic supplements being promoted as helping to maintain “good” bacteria in your gut.

But are there good bacteria when it comes to obesity? Distinctions of “good” bacteria have been made as bacteria more commonly found in lean, healthy individuals and “bad” bacteria as those abundantly found in obese individuals without considering that many of these studies show correlation and not causation.

As biology students, we are taught to recognize the difference between correlation and causation, because these terms often are used interchangeably when discussing microbiome science and its relation to health. This is where the new science becomes susceptible to being over-hyped and misinterpreted. Jonathan Eisen, a microbiologist at the University of California at Davis, has a blog, Microbiomania, in which he highlights the issue of “overselling the microbiome.” In one case, he gives an award to a news release headlined “ Intestinal flora determines health of obese people.” The research demonstrated that obese people who have less diverse bacteria in their intestines are “more likely” to have health complications in the future, not that their intestinal bacteria “determines” the overall health. This subtle (or not so subtle) misleading with results makes it very difficult for us to interpret the important points behind the research.

So how do we guard against microbiome hype and its impact on our decisions? As a society that suffers from the growing epidemic of obesity, we look to research findings that link microbes to obesity, diet and health in hopes of finding quick and easy alternatives to improving health. Consequently, this makes us more vulnerable to the hype. Before blindly following ads or buying the next “quick fix” probiotic, it is important to do more research on your own, such as going to more reliable, easy-to-read sources of information such as Nutrition Action Newsletter, or even examining the actual research articles to verify whether the results demonstrate causation or correlation. The HMP is a new and exciting field of study, but there is still much that remains to be learned about the complexity between obesity and our gut microbes before conclusions can be made about which bacteria are “good,” which are “bad” and which might make us fat.

Jennifer Suttles and Susan Duong will graduate Saturday from the University of Southern Maine with Bachelor of Science degrees in biology. They were students this semester in Professor Lisa Moore’s senior capstone course on the human microbiome. Moore is a member of the Maine chapter of the national Scholars Strategy Network, which brings together scholars across the country to address public challenges and their policy implications. Members’ columns appear in the BDN every other week.

 



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