Infantile colic is defined as extended periods of excessive crying that is distinguishable from “normal” crying. The crying is often accompanied by facial flushing, flatulence and stooling difficulties. Colic usually resolves by about five months of age. Parents often attempt to treat colic by changing the infant's formula, although this method is not well supported in the literature. Some studies have shown that certain dietary modifications may cause a reduction in colic symptoms, but the studies had methodologic flaws. Lucassen and colleagues conducted this randomized, double-blind trial to determine if a whey hydrolysate formula could successfully treat infantile colic.

Infants younger than six months of age were included if their parent complained (either spontaneously or in response to direct questioning) about the infant's amount of crying. Infants had to be thriving, to be taking at least one formula feeding daily, to have never had a hypoallergenic formula feeding trial and to have no history of allergy to cow's milk. For the one-week qualification period, the parents were instructed to complete a daily questionnaire to determine if the infant met the colic definition (i.e., crying for at least three hours per day for at least three days per week for at least three weeks). Various behaviors were recorded during the one-week trial: fussing, feeding, playing and sleeping. If the child met the colic criterion of crying for more than three hours per day, he or she was randomized to receive a cow's milk formula or a hypoallergenic whey hydrolysate formula. An identical diary was maintained during the intervention week. The difference in the reduction of crying between the qualification week and the intervention week was the primary outcome measure.

Thirty-eight infants met the qualifications and completed the study; 20 infants were randomized to receive the whey hydrolysate formula and 18 received the cow's milk formula. In the entire group, mean crying plus fussing time during the qualification week was 368 minutes per day, with a mean crying/fussing duration of 4.8 weeks. Babies receiving the hypoallergenic formula had a decrease in crying of 77 minutes per day more than the cow's milk group. When confounding factors (gender and qualification-period crying duration) were taken into account, there was a decrease of 47 additional minutes per day in the whey hydrolysate group versus the standard formula group. Forty percent of the children in the whey hydrolysate group no longer met criteria for infantile colic at the end of the intervention week compared with 28 percent of the standard formula group.

The authors acknowledge that the small sample size of the study may limit the conclusions that can be drawn from it. However, they suggest that substituting a whey hydrolysate formula for a cow's milk formula in an infant younger than six months who presents with colic can lead to a decrease in crying of about one hour per day.

editor's note: Other evaluations of treatments for colic (e.g., Garrison MM, Christakis DA. A systematic review of treatments for infant colic. Pediatrics 2000;106:184–90) have found similar effects in colicky infants who were fed a hypoallergenic formula. Unfortunately, it is difficult to achieve adequate blinding in these studies, and there will always remain some subjective component to analysis of these infants, regardless of how strictly the researchers define their terms. It may be reasonable to switch an infant who seems truly colicky from a cow's milk formula to a whey hydrolysate formula (which is cheaper and reported to taste better than a casein hydrolysate formula). For the mother who is breast-feeding and is atopic, some studies show that avoidance of cow's milk may improve the infant's symptoms. For the breast-feeding mother without atopy, there is some evidence that a diet without milk, egg, wheat or nut products may lessen the duration of the infant's symptoms. Repeated switching between formulas is not likely to reduce the infant's symptoms.—g.b.h.