Leaky gut mystery may be explained by microbe evolution

The topic of beneficial gut bacteria has been ubiquitous among health advocates for some time now. However, gut bacteria are also linked to autoimmune disorders such as inflammatory bowel disease. The “leaky gut” hypothesis is often used to explain harmful bacteria. This theory states that dangerous bacteria migrate from the gut and cause inflammation in the body.

“But one mystery has been how potentially pathogenic bacteria can exist in healthy people for decades with no apparent health consequences,” said Noah Palm, a professor of Immunobiology at Yale University.

In an attempt to understand the leaky gut phenomenon, Yale researchers analyzed the behavior and genetics of potentially pathogenic microbes in mice and discovered that the bacteria split into two unique populations. 

One population of pathogenic bacteria was similar to the original bacteria, but another strain mutated in a way that allowed them to thrive in the mucosal linings of the intestine and migrate to the lymph nodes and liver after exiting the gut. These are the bacteria that cause inflammation and disease.

What’s insidious about these bacteria is that, unlike traditional pathogens, they can temporarily evade the immune system by hiding in organs. Eventually, the microbes can trigger autoimmune diseases. This finding helps to explain why people with these potentially pathogenic bacteria can appear healthy but are more likely to become sick as they age. 

The researchers say environmental factors play a role. For example, those who consume a healthy diet will develop a diverse gut biota. With this diversity, there is more competition between bacteria and less probability for the potentially harmful bacteria to develop and exit the gut. However, if there is a lack of bacterial diversity in the gut, the gut environment is ripe for developing dangerous gut bacteria variants. 

The researchers, including study lead author Yi Yang, expect that the knowledge gained from this study will help develop new treatments for several diseases linked to “leaky gut.”

The study is published in the journal Nature.

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By Erin Moody , Earth.com Staff Writer