Explain changes in gastrointestinal tract of infants?

A full term baby has the ability to digest simple proteins, carbohydrates and emulsified fats. In first 3-4 months, the production of starch-splitting enzymes is not satisfactory.  The usual yardstick to introduce starchy foods to infants is when their weight doubles, which, in most well-nourished population, is around 4 months of age. The disaccharidases, including lactase, are secreted adequately at birth. Some infants have inadequate lactase activity and can develop lactose intolerance. Milk protein intolerance is also seen in infants. You will learn more about this later in GIT disorders.