The scientific evidence does not say that fiber treats all forms of constipation with the same strength. In the same analysis, it was found that increasing dietary fiber increased the frequency of bowel movements in constipated people, but it did not clearly improve all other symptoms, such as stool consistency, pain during defecation, or the need for laxatives. This is important because constipation may have more than one cause, and is not always due to a lack of fiber alone.
Therefore, the practical advice is to view fiber as an important basis for prevention and improvement, not a sole treatment for all cases. If constipation is mild, or related to a lack of vegetables, fruits and whole grains, increasing fiber may be enough to make a noticeable difference.
However, if the constipation is severe, or accompanied by severe pain, blood in the stool, unexplained weight loss, or started suddenly after an advanced age, it is not enough to modify the diet, but a doctor should be consulted.
