Colic was first mentioned in recorded history by the ancient Greeks (Cirgin Ellett, 2003), yet in 2013 the cause remains somewhat undetermined. Colic is the medical term for excessive, frequent crying in a baby who appears to be otherwise healthy and well fed. It is a poorly understood yet common condition that affects around one in five babies. However, the condition is not harmful and babies with colic continue to feed and gain weight normally. There is no evidence that colic has any long-term effects on a baby’s health (NHS Choices, 2012i). A baby with colic may have several crying outbursts a day and this may occur a few times a week. The crying pattern usually begins within the first few weeks of life but often stops by the time the baby is four months old, by six months at the latest. Typically, a baby with colic will scream and draw up their legs, and may refuse to be comforted. It can be very distressing for parents, especially as the cause of colic remains largely unknown.
While the exact cause is unknown several factors are thought to contribute including poor digestion, lactose intolerance and/or a reaction to cow’s milk proteins. Since the 1970s, numerous studies have indicated that certain components of cow’s milk may lead to colic. In a clinical trial to investigate the effects of cow’s milk whey proteins, 24 out of 27 infants with colic showed no symptoms of colic after whey protein was removed from their diet. In fact crying hours per day dropped from 5.6 hours to 0.7 hours (Lothe and Lindberg, 1989). In order to alleviate the negative effects of cow’s milk whey proteins (and other milk proteins thought to cause colic) some infant formulas are hydrolysed, this means the proteins are broken up. These hydrolysed formulas are called hypoallergenic and have been shown to be effective in the treatment of colic in some infants (Lindberg, 1999; Jakobsson et al., 2000; Lucassen et al., 1998; Lucassen et al., 2000).
Some differences in intestinal flora (the bacteria that inhabit the gut) have been identified in infants with colic (Lehtonen et al., 1994; Savino et al., 2004). Research suggests that altering intestinal flora might help prevent colic in formula-fed infants, who have well-known differences in gut flora compared to breast-fed infants (Newburg, 2000). Other reports that oligosaccharide (prebiotic) supplements in infant formulas may promote gastrointestinal health are inconclusive (Savino et al., 2006). However, a formula specifically developed to simulate the beneficial effects of human breast milk and to reduce some of the common feeding problems of cow’s milk formula-fed infants was tested in infants with colic. It contained partially hydrolysed whey proteins, a mixture of oligosaccharides (90 per cent galacto-oligosaccharides and 10 per cent fructo-oligosaccharides), low lactose, modified vegetable oil with 41 per cent of the palmitic acid in the beta-position and starch. In human milk, palmitic acid is predominantly in the central or betaposition, whereas in cow’s milk and infant formulas, it is mainly in the first and third position and may form calcium-fatty acid complexes which are poorly absorbed in the gut (Savino, 2006). In a previous observational study, within two weeks of feeding with this formula, a significant decrease in the number of colic episodes was observed in the majority of infants tested (Savino et al., 2003). This study was performed to confirm the role of this new formula in infants with colic in a randomised prospective trial. Results showed that infants fed with the formula had a significant decrease in colic episodes after just one week of treatment compared to infants from the control group. The difference in crying time was even more significant after two weeks of treatment. This study provides compelling evidences for the relation between colic and type of feeding. However, the increasingly expensive and elaborate attempts to simulate human breast milk beg the question, why don’t we put a more concerted effort into simply promoting breastfeeding?
In transient lactose intolerance, the enzyme lactase is not produced while there is illness in the gut, but is manufactured again once the gut has recovered. In a review investigating transient lactose intolerance as a cause of colic, a range of studies showed that crying time was reduced when formula or breast milk was incubated with the enzyme lactase (Buckley, 2000). It has been suggested that infant colic has a multiple aetiology; in other words, colic may be caused by a number of different factors including whey proteins, lactose and others.
The fact that the incidence of colic is similar in formula fed and breastfed infants has led scientists to investigate the role of the maternal diet in this condition and many reports now link the maternal intake of cow’s milk to the occurrence of colic in exclusively breastfed infants. The breast milk of mothers who consume cow’s milk and milk products has been shown to contain intact proteins from these foods. To test the possible role of cow’s milk proteins in breast milk, researchers have investigated the effects of eliminating all dairy products from the mothers’ diet. An early report linking cow’s milk proteins in human breast milk to infantile colic date back to a letter published in the Lancet in the late 1970s (Jakobsson and Lindberg, 1978). The letter described how the symptoms of colic disappeared in 13 out of 19 infants whose mothers eliminated cow’s milk from their diet. In a subsequent clinical trial designed by the same researchers, 66 breastfeeding mothers of infants with colic were put on a diet free from cow’s milk. The colic disappeared in 35 of the infants and subsequently reappeared in 23 of them when cow’s milk protein was reintroduced to the mothers’ diet (Jakobsson and Lindberg, 1983). The authors suggest that a diet free of cow’s milk may be useful as a first trial of treatment of infantile colic in breastfed infants.
Researchers at the Washington School of Medicine in Missouri US found that mothers of infants with colic had significantly higher levels of the cow’s milk antibody immunoglobulin G (IgG) in their breast milk than mothers of infants without colic (Clyne and Kulczycki, 1991). The authors of this study suggest that bovine IgG present in breast milk may be involved in the development of colic. This link was confirmed more recently and again it was suggested that the maternal avoidance of milk and dairy products may be an effective treatment for colic in some breastfed infants (Estep and Kulczycki, 2000). A systematic review of nineteen studies and two literature reviews on medical and conventional interventions for infantile colic from 1980 to 2009 found some scientific evidence to support the use of a casein hydrolysate formula in formula-fed infants and a low-allergen maternal diet in breastfed infants with colic. However, they found little scientific evidence to support the use of lactase, additional fibre or behavioural interventions.
They suggested that further research on low-allergenic formulas and maternal diets would be useful (Hall et al., 2012). In a substantial review of 27 controlled trials published in the British Medical Journal, the elimination of cow’s milk protein was deemed to be a highly effective treatment for infantile colic. The reviewers remained uncertain about the effectiveness of low lactose formula milks and the effectiveness of substitution with soya-based formula milks (although no adverse events were reported) while supporting the substitution of normal cow’s milk formula for whey or casein protein hydrolysate (hypoallergenic) formulas, in which the milk protein is partially broken down to ease digestion (Lucassen, 1998).
Interestingly, Dr Benjamin Spock, author of the hugely popular book Baby and Child (over 50 million copies sold worldwide) warns that the proteins in cow’s milk formulas can cause colic (Spock and Parker, 1998). Spock acknowledges that some infants that are allergic to cow’s milk formula may be allergic to soya-based infant formula as well and that these infants are often given expensive hydrolysate formulas. However, he states that soya formulas have an important advantage over cow’s milk formulas in that they contain none of the animal proteins linked with colic (and type 1 diabetes) and are free of lactose.
This said, it should be emphasised to parents who breastfeed, it is a good idea to continue breastfeeding as weaning on to formula milk may make the colic worse. If eliminating cow’s milk and milk products from the maternal diet does not help, cutting out other foods may help. Researchers at the University of Minnesota tested a range of foods including cruciferous vegetables (cabbage, cauliflower, sprouts and broccoli) in an elimination diet in mothers of babies with colic. While the results showed that cow’s milk had the strongest association with colic, other foods more weakly associated included: onions, chocolate, cabbage, broccoli and cauliflower (Lust et al., 1996).
In conclusion, colic is a common cause of maternal distress and family disturbance and more research is needed to develop solid evidence-based recommendations for successful treatment. However, eliminating cow’s milk from the maternal diet (if breastfeeding) and avoiding cow’s milk formula may help.