Colder Climate, Fatter Microbes In Gut

Tia Ghose, publisher from Live Science, describes how people who live in colder climates tend to have more of the gut microbes associated with obesity, a new study suggests. She writes how researchers have found that people living farther north, colder locales in general, tend to have more of the bacterial group called Firmicutes and fewer of the group Bacteriodes within their guts. Research has shown that people with more Firmicutes bacteria tend to be heavier, while people who are leaner have more Bacteriodes. This doesn't however directly tie with the person's BMI (body mass index), so it doesn't prove how bacterial gut composition affects obesity. Taichi Suzuki, a doctoral candidate in integrative biology at the University of California, Berkeley, say's this study has found an association, not a causal relationship, between gut bacteria and geography. "As a result, it's hard to say whether genetic differences, dietary changes, or some other mechanism is at play. Past work had suggested that people have adapted to colder climates by packing on extra pounds to act as insulation. For instance, some studies have found that Inuits tend to be heavier than African tribesmen." Suzuki said. The relationship between cold and weight isn't clear-cut, however. Spending time in the cold also increases caloric expenditure and that shivering triggers similar muscle responses as exercise. Suzuki and his colleagues looked at studies that describes the gut microbes of 1,020 people from 23 populations around the world, from Sweden to Malawi. Their finding of differences in gut bacteria doesn't appear only in humans. The studies showed that mice captured in northern parts of the United States tend to be heavier than their counterparts in Florida and also have obesity-linked microbes. Even though there is no direct correlation between climate and obesity, the studies suggest that certain gut microbes that only thrive in the cold have a link to being heavier. The author clearly explains the studies, and provides her opinion at the end of the article. She provides evidence given from Taichi Suzuki and also from past studies.

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