A consistent diet of a few key components is the easiest way to prevent diarrhea in a baby. These foods include, but are not limited to, bananas, rice, applesauce, toast and yogurt, according to WebMD. All are safe to feed any baby over the age of 1 with the ability to chew solid or mashed-up foods.
A baby's stomach takes time to adjust to foods other than breast milk, formula or cow's milk. Slowly introduce bland, low-fiber fruits, breads and other non-acidic foods to a baby's diet, notes the American Academy of Family Physicians. None of these foods should bring about any measurable amount of gastrointestinal bloating, discomfort or diarrhea. Yogurt in small quantities gives a baby a healthy bacteria that helps break down and process foods, softening stool in a gentle way. Rice and breads help to solidify stool and prevent diarrhea while a baby tries more adventurous foods like tomatoes, mangoes, berries and plums. Applesauce gives the gastrointestinal tract a break, since the mush breaks down easily and is not acidic or alkaline.
These suggestions form the basis of the BRAT diet, which has received praise and criticism for both its ability to regulate a child's digestive system and its lack of variety and complete nutrition, according to WebMD. To that end, it offers an excellent way to prevent diarrhea in the face of impending illness or while introducing new foods, but it is not a recommendation for an overall and permanent diet.