The headline in Science Daily about a new Duke study says it all: “It doesn’t matter much which fiber you choose — just get more fiber!”
That huge array of dietary fiber supplements in the drugstore or grocery aisle can be overwhelming to a consumer. They make all sorts of health claims too, not being subject to FDA review and approval. So how do you know which supplement works and would be best for you?
A rigorous examination of the gut microbes of study participants who were fed three different kinds of supplements in different sequences concludes that people who had been eating the least amount of fiber before the study showed the greatest benefit from supplements, regardless of which ones they consumed.
“The people who responded the best had been eating the least fiber to start with,” said study leader Lawrence David, an associate professor of molecular genetics and microbiology at Duke University.
The benefit of dietary fiber isn’t just the easier pooping that advertisers tout. Fermentable fiber — dietary carbohydrates that the human gut cannot process on its own but some bacteria can digest — is also an essential source of nutrients that your gut microbes need to stay healthy.
“We’ve evolved to depend on nutrients that our microbiomes produce for us,” said Zack Holmes, former PhD student in the David lab and co-author on two new papers about fiber. “But with recent shifts in diet away from fiber-rich foods, we’ve stopped feeding our microbes what they need.”
When your gut bugs are happily munching on a high-fiber diet, they produce more of the short-chain fatty acids that protect you from diseases of the gut, colorectal cancers and even obesity. And in particular, they produce more of a fatty acid called butyrate, which is fuel for your intestinal cells themselves. Butyrate has been shown to improve the gut’s resistance to pathogens, lower inflammation and create happier, healthier cells lining the host’s intestines.
I eat a lot of whole grains, so I probably don’t need a supplement. But I might start one just in case.