How to tell if your baby is allergic to proteins in your breast milk.

Does Your Diet While Breast-Feeding Affect Your Kid?

Does Your Diet While Breast-Feeding Affect Your Kid?

Advice for parents
April 11 2013 12:40 PM

A Dairy Dilemma

Can changing your diet calm your breast-feeding baby?

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There is, however, some research suggesting that a limited diet could make difficult babies easier—hence my warning that the research literature is complex. In a randomized, controlled clinical trial from 2005, Australian researchers told a group of 47 nursing moms with colicky 3-to-9-week-old babies to stop eating cow’s milk, eggs, peanuts, tree nuts, wheat, soy, and fish for seven days. They told a second group of 43 nursing moms to specifically eat these foods. Both groups were told that they were testing the effectiveness of diets that had previously been shown to improve colic. All the moms kept detailed journals of when and how long their babies cried or fussed during the first two days and the last two days of the trial, and the researchers decided that the intervention would be deemed effective if it reduced the infants’ crying or fussiness by at least 25 percent. At the end, they found that nearly three-quarters of the babies of moms who cut out the foods achieved this benchmark, but only a little more than one-third of the babies of the free-eating moms did.

Yet there are other aspects of the study to keep in mind. Like the fact that one-third of the babies in the free-eating group cried or fussed significantly less at the end of the trial. This is probably because they passed their fussy “peak,” which often happens right around six weeks of age, the average age of the infants in this trial. Colic (and general fussiness) resolves on its own, which makes it difficult to confirm cause and effect when interventions seem to work. If you cut out dairy on Tuesday and your baby cries less on Friday, is it because of what you’re not eating, or is it because your baby is naturally becoming more agreeable? Another issue with the study is that it was not blinded: The moms knew what they were eating, and those who might have heard from friends that dietary restriction can reduce crying might have subconsciously evaluated their babies’ behavior differently at the end of the trial. (The free-eating moms may have had similar ascertainment biases if, for instance, they had preconceived notions that their “diet” wasn’t going to work.)


The other thing that’s interesting about the trial is that there was no significant difference in how well the two groups of moms thought the interventions worked. More than one-half of the moms in both groups said that their diets reduced their babies’ crying or fussing. This finding helps to illustrate just how tough it can be for people—and especially desperate, exhausted moms who really need things to get better—to objectively assess whether interventions work. People often feel better or report improvements based on the very fact that they are being treated, even if the pill or regimen doesn’t really do anything. This powerful phenomenon is known as the placebo effect, and some scientists believe it is, over time, getting stronger.

It’s likely, then, that many nursing mothers give up foods without needing to—yet many will swear that it helps, in part because of the tricks our brains play on us when we attempt to evaluate interventions we desperately hope will work. That said, for the small percentage of babies who suffer from food allergies or intolerances, yes, cutting out the trigger foods as a breastfeeding mom may help. And, really, if it seems to help, “if a mother is still eating a well-balanced diet, and she's thinking that her baby has less colic when she eats X rather than Y, then go ahead,” says Michael Kramer, scientific director of the Institute of Human Development, Child and Youth Health at McGill University. Believe me, if ditching dairy had turned my son into a cooing machine—or even if it didn’t but I truly believed it did—I sure as hell would have kept doing it. But if you’re really missing that yogurt you gave up three weeks ago and your baby never had serious gastrointestinal or allergic symptoms anyway, consider allowing yourself to indulge again. Sometimes, as moms, we blame ourselves or our choices for things that, well, just are. Babies cry—it’s a fact of life and it’s one that is probably not our fault.

Melinda Wenner Moyer is a science writer based in Cold Spring, New York, and is Slate’s parenting advice columnist. Follow her on Twitter.