Will metamucil help with diarrhea. You Are Here: Discover the causes of nocturnal diarrhea and how to treat it. Avoid giving babies any cow's milk products. Eat some high potassium foods, such as bananas, potatoes without the skin, and fruit juices. Water is best. Certain ingredients speed up the rate of digestion, causing food to pass rapidly through the colon. Both types can occur at the same time. You may experience temporarily increased gastrointestinal discomfort when you first use the product because of the sudden increase of fiber in your diet. For example:.