Fibers found in food are a motley bunch: some are long and straight, others branched and broad. They can have opposite charges and varied solubilities, and our foods contain them in assorted combinations and dosages. Despite this diversity, researchers often lump them together into one group—“dietary fiber”—which can muddy each fiber’s individual effects on the human body.
Researchers at Stanford University School of Medicine have started to untangle this figurative fiber jumble: they investigated the medical impact of two purified fibers in a randomized, longitudinal, crossover study in 18 volunteers published online April 27 in Cell Host & Microbe. The team found that various fibers have different, sometimes opposing effects on human health and uncovered some of the mechanisms that explain why.
Dietary fibers are carbohydrates from plants that humans cannot digest. Gut bacteria, however, can ferment them into short-chain fatty acids. The same bacteria also produce vitamins such as ...
