Whole wheat is high in fiber — but refined wheat contains almost none.The fiber content of whole-grain wheat is 12–15% of the dry weight. As they’re concentrated in the bran, fibers are removed during the millig process and largely absent from refined flour.The main fiber in wheat bran is arabinoxylan (70%), which is a type of hemicellulose. The rest is mostly made up of cellulose. Most wheat fiber is insoluble, passing through your digestive system almost intact and adding bulk to stool. Some fibers also feed your gut bacteria.What’s more, wheat contains small amounts of soluble fibers, or fructans, that may cause digestive symptoms in people with irritable bowel syndrome (IBS). By and large, though, wheat bran may have beneficial effects on gut health.