You are what you eat? Think again – you are what eats what you eat.
A growing body of evidence is demonstrating that gut microbes, which aid digestion, also play key roles in human metabolism, weight gain and obesity.
Recent studies indicate that gut microbes from lean people may help prevent obesity, that people living in cold, northern climates have more gut bacteria linked with human obesity, and that even the methane levels of our breath can indicate our relative gut health.
“Further research will demonstrate that many aspects of human metabolic health are closely linked to the relative balance of the microbes residing in our intestines,” said Michael Puff, MD, board-certified gastroenterologist with Spectrum Health Medical Group.
Throughout human evolution, certain microbes that help digest plant and other material developed the niche of performing this task in the human digestive system– a relatively safe and nutritious environment.
“The number of microbes residing in the human body outnumbers human cells 10 to 1,” Dr. Puff said. “The wrong mix of such microbes can help predispose a person to obesity, diabetes and other serious health conditions.
“As we move ahead, the goal of those studying this complex environment will be to shape and cultivate it in ways that can delay, prevent or possibly even treat such conditions.”
Consider these outcomes:
- In 2012, researchers from the University of Maryland Medical Center identified 26 species of bacteria in the human gut that appear to be linked to obesity and related complications including insulin resistance, high blood sugar levels, increased blood pressure and high cholesterol.
- Researchers from the Washington University School of Medicine had previously showed that obese human twins have less diverse bacterial species in their gut than their lean counterparts. In 2013, they introduced microbes from four sets of human twins into mice models. Mice given microbes from a lean twin stayed slim, whereas those given microbes from an obese twin quickly gained weight.
- An analysis of gut bacteria in more than 1,000 people published in 2014 by researchers from the University of California, Berkeley, showed that people in cold, northern regions of the world have more gut bacteria linked with obesity than those in warm, southern areas.
- Researchers from the Cedars-Sinai Medical Center reported in 2013 that people with high levels of hydrogen and methane in their breath are more likely to have a higher body mass index and proportion of body fat due to the presence of certain bacteria in the gut that cause it to extract more calories from food.
More recent work is attempting to tie gut microbes to autoinflammatory diseases, food allergies, autism and even brain function.
“The jury is still out on much of the ongoing studies,” Puff said. “But a growing body of work suggests our gut make up can affect many different systems in the body, which lends itself to an alternative and complementary approach to disease and overall health.”