More people are focusing on their gut health, as fibermaxxing goes mainstream, colorectal cancer rises among young adults and personalized gut microbiome treatments become increasingly popular.
Now, a generation- and culture-spanning way of preserving food is in the spotlight: fermentation. The federal government’s latest dietary guidelines specifically encourage Americans to eat more fermented food.
The foods have been further popularized by followers of Health Secretary Robert F. Kennedy Jr.’s Make America Healthy Again movement. And while other diet fads championed by MAHA have been questioned by health experts — like unproven claims about raw milk and seed oils — there’s some science behind the benefits of eating fermented foods.
Fermented foods go back thousands of years in human history, to the days when we needed to keep food from spoiling but didn’t have refrigerators. Many cultures have traditional fermented foods: yogurt, kimchi, sauerkraut, South Indian idli and dosa.
Dietitians and doctors say they’re a great addition to almost anyone’s diet, but they warn against new, mass-produced products.
Here’s what to know.
Fermentation is a process by which naturally occurring microbes including bacteria and yeast break down and preserve food.
The foods are a hot research topic, though many of their health benefits are already clear, experts say.
“We’ve been doing this for ages and we just found out more recently that it’s actually helped our gut health,” said Dr. Lisa Ganjhu, a gastroenterologist with New York University Langone Health.
Still, it doesn’t automatically mean something is healthy if it’s fermented.
“Beer and wine are fermented foods, but they’re not necessarily probiotics,” she said. “If anything, they influence our own microbiome in more of a negative way.”
Barbara Olendzki, director the University of Massachusetts Chan Medical School’s Center for Applied Nutrition, said she recommends people focus on “whole fermented foods” like fermented beets or green beans in addition to foods like yogurt, kefir, kimchi, sauerkraut and tempeh.
The microbes in fermented foods help predigest it, breaking it down and changing the compounds available in it. The bacteria themselves also help keep the gut in balance, by competing with other bacteria — some of them less beneficial — already in your intestines.
“What is it that makes the fermented foods so healthy? The answer is we’re still working on it,” said Dalia Perelman, a Stanford University research dietitian.
Some fermented foods, like yogurt, give you the live probiotics while you’re eating them. Others, like sourdough bread, give you few, if any, because they’ve been baked or otherwise processed in ways that kill the microbes. But there’s evidence that some fermented foods are beneficial even without the live microbes, Perelman said.
