The role of fiber in your health
There are two types of dietary fiber: soluble and insoluble, experts said.
Soluble fiber dissolves in water and absorbs it to form a gel-like substance, and is more associated with some of the digestive benefits of fiber, experts said. Insoluble fiber, on the other hand, doesn’t dissolve in water and helps people have more frequent and heavier bowel movements.
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Most fibrous foods contain both types. Foods richer in soluble fiber include apples, bananas, citrus fruits, barley, carrots, oats, beans and psyllium, which derives from the husks of seeds of the Plantago ovata plant, according to the Mayo Clinic. Those with mostly insoluble fiber include vegetables such as green beans, cauliflower and potatoes; whole-wheat flour or wheat bran; nuts; and beans. Many TikTok videos on fibermaxxing feature meals made from a variety of these foods, such as colorful salads mixing different leafy greens and vegetables. Versions of TikTok user impamibaby’s breakfast are common among fibermaxxers, and tripscan top they’re rich in insoluble fiber.
Within those two types of fiber, there are other forms and characteristics of fiber also critical for gut health, Staller said. The viscosity of the fiber, for one, affects how well it flows through your digestive tract, while fiber fermentability influences how much your gut microbiome can actually ferment the fiber into helpful compounds to use as an energy source, he said.
“Then finally, how is the fiber packaged?” Staller added. Foods that are more processed, cut up, raw or cooked — all those forms have different effects on your digestive health, even if the foods contain the same type of fiber.
However, you don’t need to worry about doggedly tracking all these things in your efforts to increase your fiber intake. Eating a variety of whole or minimally processed foods will give you enough of what you need, Staller said.
Plentiful benefits of eating enough fiber
The link between higher fiber intake and decreased rates of colon and rectal cancers may be explained by a couple of factors, according to Jennifer House, a registered dietitian nutritionist and founder of First Step Nutrition in Alberta.
When fiber increases stool bulk, it decreases the amount of time waste is in contact with the intestinal tract. “Also, our gut bacteria ferments fiber, and it creates something called short-chain fatty acids,” such as butyrate, she added, which can nourish critical cells in the colon and inhibit cancer cells and inflammation.
Recent research also suggests people with colon cancer may have greater odds of surviving if they increase their fiber consumption, Staller said.