How does fiber prevent constipation?
Fiber helps prevent constipation in two main ways. The first is insoluble fiber, which is abundant in wheat bran, whole grains, and the peels of some fruits and vegetables. This type adds bulk to the stool, making its presence inside the colon more visible to the intestinal wall, thus stimulating the natural movement that pushes waste out.
The second method is soluble fiber, such as that found in oats, legumes, apples, chia seeds, and psyllium husks. This fiber absorbs water and forms a gel-like substance, making stool softer and easier to pass. Therefore, fiber alone is not enough if a person does not drink enough fluids, because an important part of its effect depends on the presence of water inside the intestines.
and statistical analysis of randomized trials, published in the American Journal of Clinical Nutrition, reported that fiber supplements can improve chronic constipation in adults, and that psyllium in particular was among the most beneficial, especially when using doses exceeding 10 grams per day for at least 4 weeks. However, the researchers also noted that there was variation between the studies, meaning that the response may differ from person to person.
