There are trillions of reasons to eat healthy.
Credit: Illustration: Sarah Wilkins

OK, so maybe the words "gut biome" were not what you expected to see on, but try thinking of the microbiome as your own intestinal Game of Thrones. The occasional gross bits are overshadowed by an epic tale of microbial heroes and villains, with struggles and interconnections and plot twists and subplots being uncovered daily by researchers such as Rob Knight, a professor and researcher at the University of Colorado, Boulder. Knight's American Gut Project is collecting samples from volunteers around the world to gather data on how diet and lifestyle influence the makeup of the bacterial multitudes we carry within.

We've known for a long time that bacteria live in and on our bodies, but it's only been in the last few decades that scientists have begun to appreciate the complexity of our relationship with our bacterial occupants. Everyone's guts are colonized with both helpful and harmful bacteria. The beneficial bacteria help digest food, absorb nutrients, and maintain the delicate inner lining of the intestines. The bacterial bad guys, on the other hand, have been linked to diseases ranging from diabetes to depression and appear to play a critical role in obesity. A number of studies have shown that transplanting gut bacteria from obese to thin subjects causes weight gain, and that inoculating obese subjects with bacteria from lean ones assists with weight loss.

Short of swapping gut bacteria with your skinny cousin, what can you do to build a healthier inner you? Knight cautions that microbiome research is in its early days, and there's still much work to be done before anyone can tell us exactly which foods to eat to build the ideal bacterial balance. Meanwhile, though, the data Knight has been collecting suggest that many of the habits and foods we already associate with healthy weight and good health are also associated with a robust and diverse microbiome. Exercise, getting enough sleep, and eating a diverse diet (leafy green vegetables, brightly colored fruits, and yogurt) low in saturated fat are good for you and appear to be good for your bacterial occupants as well.