It matters what you feed your gut

Carolyn O’Neil is a registered dietitian and author of “The Slim Down South Cookbook.” Email her at

If you’ve ever had the feeling that there’s more to eating well than calories and cholesterol, then you really should trust your gut.

Research on our gastrointestinal tract shows that the mixture of microbes in the gut can make or break the body’s overall health. Referred to as the microbiome, the population of friendly bacteria that live in the gastrointestinal tract aid digestion, help absorption of nutrients and boost immune function.

“It’s the control center for human biology,” said Justin Sonnenburg, co-author of “The Good Gut” and researcher at Stanford University’s School of Medicine. Sonnenburg and his co-author wife, Erica Sonnenburg, also at Stanford, are leading the charge to place the microbiome at the center of the discussion about optimal health today.

“We have more bacteria than cells in our bodies. We are more microbial than we are human,” Justin Sonnenburg said.

So, what does a good gut look like? According to the Sonnenburgs and other researchers focused on intestinal health, the quantity and variety of bacteria is key.

A poor diet lacking in dietary fiber can wreck the microbiome’s health, because fiber is what they feed on.

When they don’t get their “food” from what we consume, the bacteria can eat away at the mucosal lining of the intestinal tract and, eventually, perish.

“Low fiber intake leads to reduced bacterial diversity in the gut,” Erica Sonnenburg said. “It’s diet-induced extinction of the gut bacteria.”

The average American consumes about 15 grams of dietary fiber a day. The recommended amount for good health is between 25 and 35 grams per day.

“You have to feed your bugs, not just your body,” said registered dietitian Regan Jones. “It’s yet another reason to eat more fruits and vegetables and whole grains.”

Fermented dairy foods with live active cultures, such as yogurt and kefir, as well as fermented foods such as sauerkraut and kimchi, help add good bacteria to the gut.

“There’s an explosion of probiotics foods and beverages in the dairy aisle with beneficial live microbes,” Erica Sonnenberg said. “But, keep in mind that probiotic supplement pills are unregulated and are often mislabeled. And what might work for one person might not work for others. It’s highly personalized.”

Here’s another note of caution for fans of “detox” regimens, including colonics that “flush out” the gastrointestinal tract: “Colonic irrigation is not safe or effective for the health of the microbiome,” Justin Sonnenberg said.