Prebiotics help to improve the gut health and immunity of the baby. Along with the breastmilk you can give curd, oats khichdi, mashed banana

Prebiotics act as food for the good bacteria present in the baby's intestine. This helps the bacteria grow. When the good bacteria grows it inhibits the growth of bad/pathogenic bacteria and thus boost the baby's immunity. With this it also promotes softer stools in babies. Prebiotics also help reduce the incidence of allergy in children who are suseptible to developing allergies. Studies indicate prebiotics to be helpful in reducing the incidence and severity of diarrhea and illness, especially cold, cough and fever in babies.