Obesity Linked to Gut Microbes in Humans Living in Cold Regions

From an evolutionary biology perspective, causes and factors of obesity could be related to adapting to different environmental conditions. A study conducted by researchers at the University of California Berkeley and the University of Arizona Tucson has unveiled relative historical information.

Through in-depth analysis of thousands of gut microbes from people across the world, graduate student Taichi Suzuki of UC Berkeley and Professor Michael Worobey of the University of Arizona have found that people living in northern latitudes possessed more gut bacteria that was linked to obesity. They believe that this could be attributed to generations of adapting to cold weather.

But as unconventional as the study of gut microbes sounds, it's actually a prevalent topic of research in science because of the various types of bacteria in the gut that are related to diabetes, obesity and cancer. The two bacteria that Suzuki and Worobey examined in this study were Firmicutes (which dominates the intestines of obese people) and Bacteroidetes (which dominates the intestines of slim people). The studied data included research from six previous studies that looked at 1,020 people from Africa, Europe, North America, South America and Asia.

They found that Firmicutes are more prevalent in the guts of people in northern latitudes whereas Bacteroidetes were more common in the guts of people in southern latitudes. These numbers were unrelated to sex and age. The authors then associated this trend with Bergmann's rule, which is relative to the genetics of animals where their body size increases with latitude. But research comparing the evidence found in human guts has not yet been scientifically compared to Bergmann's rule.

"People think obesity is a bad thing, but maybe in the past getting more fat and more energy from the diet might have been important to survival in cold places," said Suzuki in this UC Berkeley News Center article. "Our gut microbes today might be influenced by our ancestors."

Suzuki and Worobey hope to conduct follow-up studies with such promising information, but for now, their most recent study can be seen in the journal Biology Letters.