Complementary feeding: Should baby be leading the way?

The introduction of solid foods and drinks other than milk (complementary feeding) is a key developmental milestone that exerts powerful changes in terms of functional changes to the gastrointestinal tract, the immune system and metabolic processes. Diversification of the diet exposes the infant to a greater range of fatty acids and proteins, and these, as well as associated micronutrients, must be absorbed from a more varied food matrix containing complex carbohydrates, and a following meal‐based pattern of feeding. Successful complementary feeding must ensure that the requirements of the infant for nutrients are met by the dietary supply because milk is a poor source of iron, zinc, vitamin D and vitamin A, all of which are essential for the maintenance of normal growth and function. The introduction of solid foods also serves to stimulate the development of the reflexes that coordinate biting and chewing with swallowing of food. The World Health Organization has set out guidelines advising parents that all babies should be exclusively breastfed for the first 6 months of life, with no introduction of complementary foods prior to this time. At 6 months, nutritionally adequate complementary foods should be introduced, with continuation of breastfeeding to 2 years of age. The UK Department of Health generally advocates this approach, although their guidelines suggest flexibility by wording the advice as delay until “around 6 months. ” It has been suggested that babies who can sit up and hold their head steady, have good hand‐eye coordination, have lost the tongue thrust reflex and are growing at a rapid rate may benefit from introduction of solids at between 4 and 6 months. The timing of the introduction of complementary feeding is of considerable importance and so confusion among parents as a result of imprecise guidelines is unfortunate. Late introduction (after 6 months of age) puts infants at risk of malnutrition because their stores of nutrients that have carried over from fetal life will become depleted. Early introduction of solids carries a risk of choking, as well as a risk of overwhelming the capacity of the kidneys and gastrointestinal tract to handle solutes and nitrogenous waste (leading to dehydration), and also elevates the risk of gastroenteritis and allergic sensitisation. Preterm infants represent a special case and the introduction of complementary foods should be based upon their developmental stage rather than their chronological age. Early weaning is more likely in this group of infants and there may be ongoing consequences of doing so. A study of 108 preterm infants in Brazil found that use of inappropriate foods for weaning was also a problem and early introduction of ultra‐processed foods, cows milk and wheat‐based foods was associated with lower weight‐for‐age z‐scores at age 2 years. The introduction of complementary foods should be accomplished gradually and the full process of weaning will typically take 6 months. Throughout that time, milk should remain a key part of the diet. Feeds of breast milk or appropriate infant formula should continue, with both later being used for drinks and mixing with solid foods. The World Health Organization strongly promotes breast milk and considers that commercial follow‐on or growing‐up milks are unnecessary. Importantly, formula milks targeted at infants older than 6 months of age are not regulated in the same way as milks for younger children. This enables open marketing and, globally, their use is increasing. Although such products are able to maintain intakes of iron and other micronutrients, when infants are transitioning to solid foods, they increase the risk of waterborne infection and exposure to contaminants, and also commit families to an unnecessary cost. Their use is growing particularly quickly in areas such as the Asia‐Pacific region.