Bananas that are unripe, or green in color, cause or contribute to constipation. The impact of bananas on constipation is a common source of confusion in part because bananas either contribute to constipation or help relieve it based on the level of ripeness, according to Everyday Health.
Ripe bananas, which are softer and more yellow, actually help relieve constipation, according to Everyday Health. Ripe bananas have high soluble fiber content, which is an aid in moving waste through the bowels. The volume of bananas consumed also plays a role, especially with infants and small children. Jane Morton, M.D. reports that excess applesauce, bananas and cereal constipate babies though cereal is the worst culprit.