Bananas commonly cause indigestion if they are consumed raw before they have fully ripened. The ripening process is necessary to convert the indigestible starch in the fruit into digestible sugar. Bananas also contain high amounts of fiber, which can cause indigestion in those who do not regularly consume high-fiber foods.
People often suffer from indigestion after eating bananas because they have mistakenly consumed bananas that were not ripe enough to be eaten raw. When bananas are green and uncooked, they are high in resistant starch, which the body cannot digest or absorb. Consumption of this starch causes excess fermentation in the gut, leading to increased toxin and gas production.
To avoid indigestion and reap the highest energy and antioxidant benefits from bananas, the fruit should be eaten when completely yellow with some brown or black spots, according to Don Bennett, a Disease Avoidance Specialist. The resistant starch in the fruit converts into digestible sugar by the time bananas ripen to this stage.
People who do not consume many high-fiber foods may also find that bananas cause gas and bloating. The solution to this form of indigestion is to gradually increase the amount of fiber in the diet, slowly acclimating the digestive system to more fiber-rich foods.