Nutrition Update
Lewis A. Barness MD1
1 Professor of Pediatrics, University of South Florida College of Medicine, Tampa, FL.
Recommendations for improved nutrition have been somewhat modified in the past decade, as evidence clarifies the physiology of digestion, the relation of activity to nutritional requirements, the possible relation of early nutrition to later diseases, the re-evaluation by the American Academy of Pediatrics (AAP) Committee on Nutrition of the use of whole milk in early life, and the recommendations of the USDA of a healthy diet. Breastfeeding continues to be the recommended feeding for infants.
Digestive Processes
Swallow, digestive, and metabolic processes are well developed in the term infant at birth. Fetal swallowing of amniotic fluid occurs at 16 to 17 gestational weeks; at 30 to 34 gestational weeks, infants develop the ability to suck. At birth, development of the lower esophageal sphincter is incomplete and gastroesophageal reflux is demonstrable; reflux is common up to about 4 months.
At birth, the rooting reflex propels the infant to the food source, that is, the mother's or an artificial nipple. The swallowing reflex enables material from the posterior reaches of the mouth to progress to the esophagus, and peristalsis moves the food through the digestive tract. The extrusion reflux, present for up to 2 to 3 months, pushes material out from the anterior part of the mouth, perhaps as a protective mechanism.
