Lack of lactobezoars in infants given predominantly whey protein formulas.

Lactobezoars have been reported with increasing frequency in low-birth-weight infants. The etiology of a lactobezoar is not well understood and is probably multifactorial. During a 2 1/2-year period, 29 of 442 infants weighing less than 2,000 g who were fed casein-predominant formulas had lactobezoars. During the subsequent 14-month period, 223 infants weighing less than 2,000 g were fed a whey-predominant formula, and none had lactobazoars. There have been no reports of lactobezoars in infants fed human milk or whey-predominant formulas. It would appear that the presence of casein as the predominant protein is necessary for the development of a lactobezoar.