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Gut Residents

A citizen science group called the American Gut Project has examined the gut microbes of some 800 people to examine differences in the bacteria living there, writes Katherine Harmon Courage at Scientific American's Observations blog.

While the most common gut bacteria — Firmicutes and Bacteroidetes — were typically present, they were there at different proportions in various people's guts. That, Harmon Courage says, could be linked to diet.

For example, among the participants were Jeff Leach, who eats a paleo diet that avoids dairy, grains, and processed food; author Michael Pollan, who follows a plant-based, though omnivore, diet; and former Mrs. United States Shannon Ford, who eats a gluten-free diet due to her celiac disease. Leach's gut microbiome was about 75 percent Firmicutes while Pollan's was about 50 percent Firmicutes and Ford's was less than 50 percent.

However, Harmon Courage notes that "some of the initial results seem confounding in terms of health impact." For example, people on the paleo diet, she says, appear to have low levels of Proteobacteria, which have been linked to inflammation, but they also have high levels of Firmicutes, which have been associated with obesity. "So, it's not clear that this diet puts the eater on the path of microbial health," she says.

Harmon Courage adds that the results haven't yet been subject to peer review, but says that they "represent a step toward a better understanding of the totality of our health."