Live Up North? Your Gut May Have More 'Fat' Microbes

[Jesus Malverde]

People who live in colder climates tend to have more of the gut microbes associated with obesity, a new study suggests.

Researchers found that people living farther north, in generally colder locales, have more of the bacterial group Firmicutes and fewer of the group Bacteriodes within their guts.

Previous research has shown that people with more Firmicutes bacteria tended to be heavier, while people with leaner bodies had more Bacteriodes. (The new study didn't have information on subjects' body mass indexes, and so couldn't directly tie the bacterial gut composition with obesity.)

Still, the new findings support the hypothesis that certain obesity-associated microbial communities are "too good at digesting food," meaning they break food down in a way that leaves more calories available for a person's body to use, said study co-author Taichi Suzuki, a doctoral candidate in integrative biology at the University of California, Berkeley.

However, the study 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, Suzuki told Live Science.

Read More: http://news.yahoo.com/live-north-gut-may-more-39-fat-39-001612997.html

[scarletwoman]

1. I think it makes sense for a number of reasons.

Disclaimer: I know essentially nothing about the study of gut bacteria, it simply interests me, and when I read or hear something about the subject, I try to pay attention.

Something I heard on an NPR program sometime back (Science Friday?) mentioned the possibility that gut bacteria are passed down through families - not as a proven fact, but as a possibility. It would seem to make sense that a developing fetus in the womb would pick up the bacteria that are present in its mother's body.

For millenia, cold climate survival involved cycles of food abundance and food scarcity. It would seem that natural selection would favor those who could extract the greatest amount of calories from whatever food was available. Therefore, if a certain type of gut bacteria - the Firmicutes referred to in the article - left "more calories available for a person's body to use", it stands to reason that those who could best survive in a cold climate would be those who harbored that particular type of gut bacteria.

And if these bacteria are passed through families the same as other genetic material, then the descendants would continue to host these bacteria - even after their necessity for survival ceased to be a factor.

The diet factor is also interesting. Up until modern times, cold climate survival depended on a diet of meat proteins and fat, and very little plant material - growing seasons are short in the far north. Foraging could be done during the summer, but once winter set in, diets were severely limited. So it may be that having fewer plant sources for food also favors one type of gut bacteria over another - and if the bacteria is inherented, your plant-deprived ancestors set what kind of bacteria you would be born with.

One question this raises, imo, is whether we can change the composition of our gut bacteria.

Thanks for the interesting article!

[mainer]

2. Yet the heaviest people I've seen live in the south

Although I agree that gut flora certainly plays a role