A low allergen diet may help breastfeeding mothers with colicky babies

Research question Does a maternal diet low in allergens calm breastfed babies with colic?

Answer In a randomised trial, babies whose mothers ate a low allergen diet cried less than babies whose mothers ate wheat, peanuts, soy, and dairy products.

Why did the authors do the study? Infantile colic is common and can be distressing and exhausting for new mothers. There's some evidence that maternal diet might be to blame for some cases in breastfed infants. These authors wanted to test this theory formally in a prospective randomised trial. They particularly wanted to focus on the role of dietary allergens such as wheat and dairy products.

What did they do? They recruited 107 healthy breastfeeding women whose babies had colic. Most of the babies were less than 6 weeks old, the age at which colic tends to peak, and they were crying or fussing for more than 5 hours each day. The participants, who were recruited from well infant clinics in Melbourne, Australia, were randomised to a low allergen or a control diet for one week. Women on the low allergen diet excluded dairy products, soy, wheat, eggs, peanuts, tree nuts, and fish. Control women did not. Instead, they were asked to include one portion of wheat and peanuts each day, one chocolate covered cereal bar, and a trial drink containing soya and milk. The women recorded their babies' distress on validated charts for two days before the diet began and for two days at the end of the week. The authors compared the proportion of babies in each group who showed at least 25% improvement during the week.

What did they find? Ninety babies completed the study. Three quarters (74%, 35/47) of those in the low allergen group were at least 25% better by the end of the week, compared with only 37% (16/43) of babies in the control group. That's an absolute risk reduction of 37% (95% CI 18% to 56%, P < 0.001) for the low allergen diet. Overall, the diet reduced babies' crying by about one and a half hours a day on average, although a similar proportion of mothers in both groups reported a subjective improvement in their baby's behaviour (29/42 in the low allergen group and 22/39 in the control group). In general, the women stuck to the diet they were given, although 17 of the 41 women in the control group had started to exclude potentially allergenic foods by the end of the trial.

What does it mean? This small trial suggests that allergens in the maternal diet have at least something to do with infantile colic in young babies who are exclusively breast fed. Excluding major allergens such as wheat seemed to reduce crying by enough to make a difference to most women—about one and a half hours a day. However, the women knew which diet they were following and reported their own babies' distress using charts, so bias is always possible. We still don't know exactly what causes colic. For some women, a hypoallergenic diet may help, at least in the short term. Diet is unlikely to be the full story, however. Two thirds of the babies in this trial still had significant colic at the end of the week, regardless of their mothers' intake of dietary allergens.