The Crazy Thing Meat Does To Your Belly

It's official: You are what you eat. As scientists learn more about your stomach’s microbiome—the accumulated bacteria and other living organisms that inhabit the lining of your gut—that statement has never been more true. But while most of the research has focused on diet additions (like probiotics) that could boost the health of your microbiome, new research from two American universities suggests that the everyday foods you consume, from burgers to Brussels sprouts, could rapidly and significantly change the microbial makeup of your gut—and not necessarily for the better.
Researchers from Harvard University and the University of California, San Francisco asked men and women to stick to one of two specialized diets for 5 days. One diet was “plant-based” and consisted almost entirely of grains, legumes, fruits, and vegetables. The other “meat-based” diet was animal-centric, and heavy on beef and pork, eggs, and dairy foods like cheese.
After just one day, the study team had already observed significant changes to the microbial composition of the dieters’ guts. Specifically, the levels of bile-resistant bacteria—including a type that animal research has linked to colon inflammation—became elevated among the meat-centric eaters. The plant-based diet had different but similarly rapid effects on the gut microbiome, though previous studies suggest these types of plant-based changes may be good for your gut health, explains study coauthor Lawrence David, PhD, now of Duke University.
What does all this mean? “As researchers, we’re becoming increasingly aware that your gut microbiome is sensitive to diet, and hopefully in the near future, we’ll have a better sense of what foods will help or inhibit certain components of gut health,” Dr. David says.
What’s not clear is whether an animal-product-heavy diet could cause hazardous changes to your microbiome, Dr. David says. “We certainly did associate the growth of a bacteria associated with inflammation to an animal-based diet.” But, he adds, the research is too preliminary to make any diet recommendations.
Also, the people in the study who ate the meat-based diet ate bacon and eggs for breakfast, pork ribs and brisket for lunch, and salami and prosciutto with cheese for dinner. In between meals, they snacked on salami and string cheese. Dr. David says he and his colleagues were trying to find out how quickly extreme diet shifts could affect gut composition. But more study is needed to find out what levels of meat (or plant) consumption are safe and ideal for the health of your stomach.