Can bacteria in the gut influence body type?

Can bacteria in the gut influence body type?

Recently the science/health news has been abuzz with interesting results demonstrating that the bacteria in the gut can influence body type, specifically obesity.

( The bacteria present in the gut varies between lean and obese people. Further, in a mouse model, bacteria transplanted from an obese person actually causes more obesity than bacteria transplanted from a lean person. We are learning that these little bacteria in our gut influence health and disease in important ways.

To learn more about this, researchers put mice colonized with bacteria from lean people and mice colonized with bacteria from obese people in the same cage. Mice eat poop, thereby ‘auto-transplanting’ the bacteria from their partner mouse into their own gut. What happened when the bacteria promoting obesity met the bacteria promoting leanness? The ‘lean’ bacteria won (depending on dietary conditions). Bacteria from the mice colonized with ‘lean’ bacteria changed the bacterial profile of their partner mouse and the partner mouse, even though they started out with the ‘obese’ bacteria, gained less weight (depending on the diet consumed). Some of the recent news headlines have described these findings that bacterial transplants may control obesity and stopped there. Like many other news items, we are left with the impression that maybe we are just around the corner from controlling obesity with a pill or procedure (in this case a bacterial colony pill or procedure that is some equivalent to a poop transplant).

But this idea really misses a crucial point, in my opinion. The mice were fed either a diet low in saturated fat and richer in plant components or a diet with more saturated fat and less plant components. These diets represented a ‘healthy’ human diet or the ‘unhealthy’ human diet. Guess what? The only animals that showed a benefit from the bacterial transplant were those animals who were fed the healthy human diet, with low saturated fat and more healthy plant components. The animals that got the high saturated fat, low plant component diet had full weight gain despite eating the ‘lean’ bacteria. The trump card? Diet. Researchers from this group had earlier published results showing that the bacterial composition of the gut can change significantly within a single day of eating a high fat, high sugar unhealthy diet.

This research is tremendously exciting. It appears that the world of bacteria in our gut has very important ramifications for our health. I have no doubt this type of research will yield significant new understandings, new approaches, and new treatments for our more common maladies. Though we have much to learn I also suspect that this world of human-bacteria interaction will prove to be yet another world of mechanisms by which we show diet is likely the single greatest master of our health and that optimal nutrition comes from plant-based diets (as supported by this research).

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