Infant feeding practices associated with rates of IgE-mediated food allergies
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Key takeaways:
- 2.9% of exclusively breastfed infants and 1.9% of infants who consumed breast milk and cow’s milk formula developed an IgE-mediated food allergy.
- The most common allergies were milk, sesame, egg and peanut.
Infants who were breastfed through age 2 months developed significantly more IgE-mediated food allergy than infants who exclusively consumed cow’s milk formula, according to a study published in Annals of Allergy, Asthma & Immunology.
Correlations with known risk factors for food allergy did not have any impact on these findings, Idit Lachover-Roth, MD, pediatrician, allergy and clinical immunology unit, Meir Medical Center, and colleagues wrote.
The 1,989 infants in the single-center, prospective, observational Cow’s Milk Early Exposure Trial, or COMEET, included 1,071 (53.8%) who were breastfed exclusively through age 2 months, 616 (31%) who consumed both breast milk and cow’s milk formula and 302 (15.2%) who exclusively consumed cow’s milk formula.
By age 12 months, 43 infants (2.2%) had developed an IgE-mediated food allergy, of which all had been breastfed (P = .002). This included 31 (2.9%) of those who were breastfed exclusively and 12 (1.9%) of those who consumed a combination of breast milk and cow’s milk formula, both of which differed significantly from the exclusive cow’s milk formula group (P = .001 and P = .01, respectively).
The average age of the first allergic reaction was 7.1 ± 2.2 months, with similar timing of introduction to allergenic foods outside of cow’s milk between the groups as well as between infants who did or did not develop a food allergy.
By age 12 months, 98% of the infants were routinely exposed to cow’s milk, sesame, eggs and peanuts. The most common allergies were milk (0.9%), sesame (0.7%), egg (0.7%), peanut (0.4%), tree nut (0.2%), almonds (0.1%) and soy (0.1%).
The 43 infants with food allergy included 11 (25.6%) who developed multiple allergies, specifically eight with allergies to two foods, two with allergies to three foods and one with allergies to four foods.
Specifically, 18 infants had cow’s milk allergy and the other 25 had allergies to other foods. The 18 infants with cow’s milk allergy all had been exclusively breastfed, and the 25 infants with other IgE-mediated food allergy were from the exclusively breastfed and combined breast milk/cow’s milk groups.
The duration of breastfeeding did not affect the prevalence of IgE-mediated food allergy among infants who breastfed exclusively or in combination with cow’s milk formula, the researchers said, with 3.26% of those breastfeeding for at least 6 months and 2.3% of those who breastfed for less than 6 months developing an IgE-mediated food allergy.
There were 771 infants (38.8%) with at least one family member who had an atopic comorbidity and 272 infants (13.7%) with a family member with a current or previous diagnosis of atopic dermatitis, the researchers continued, but there were no significant differences in the prevalence of familial atopic comorbidity based on diet.
However, the infants with an IgE-mediated food allergy had significantly higher prevalence of AD, the researchers said. Infants with at least one family member with AD had a relative risk for IgE-mediated food allergy of 2.4 (95% CI, 1.194-4.653) compared with infants who did not have a family history of AD (P = .03).
Relative risks also were 3.6 (95% CI, 1.428-7.738) when the mother had AD and 4 (95% CI, 1.241-10.808) when the father had AD, the researchers continued, but the presence of food allergy in a sibling did not correlate with food allergy among any of the infants.
The researchers did not have any conclusions as to why infants who were breastfed would develop more IgE-mediated food allergy, although they suggested that allergenic proteins in breastmilk, food diversity in the western world and caffeine consumption among lactating mothers may be factors.
Future studies with larger cohorts, the researchers said, would validate these results and enable physicians to make recommendations to lactating mothers about feeding their infants.
Perspective
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These findings are not surprising or significant. All food allergy prevention guidelines worldwide state that breastfeeding is not associated with a reduction in food allergies. In my own practice, I quote these guidelines.
There are many benefits of breastfeeding outside of food allergy prevention. All clinicians should support breastfeeding and adhere to the WHO guidelines. However, these results help us to reduce the guilt burden from mothers who are unable to breastfeed.
We need to analyze breastmilk content when we look at associations between food allergies and breastfeeding. Breastmilk composition is like fruit salad. Some have a lot of exotic and colored fruits, and some include apples and bananas only. When we understand breastmilk immunomodulatory content vs. food allergy outcomes, we will be in a much better position to draw clear associations.
Perspective
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This is a single-site, observational study done in Israel that evaluated the relationship between breastfeeding, cow’s milk formula feeding and the development of IgE-mediated food allergy. There were several findings that were surprising.
First, the overall prevalence of food allergy at 12 months was low at 2.2%. Second, the authors reported that 98% of infants were routinely exposed to cow’s milk, sesame, eggs and peanuts by the age of 12 months, which seems higher than what I see as a practicing pediatric allergist in the U.S. Third, I found it surprising that all the infants who developed IgE-mediated food allergy were in the breastfed group with no difference between exclusive breastfeeding vs. breastfeeding and cow’s milk formula.
This study did provide some additional information about the relationship between infant feeding and food allergy. However, there were several limitations to this study, including a lack of information about maternal diet or interplay between maternal and infant diet and allergy development.
Furthermore, in a previously published paper from the COMEET study by this group, the authors said that around half of the exclusive breastfeeding group had a protocol deviation, meaning that they had some exposure to formula. In that paper, they concluded that occasional exposure to cow's milk formula might increase the risk for developing allergies.
Additional studies are needed to determine if these findings can be replicated in other populations and, if so, to try to better understand if the increased risk for food allergy in the breastfeeding group was related to something specific to breastmilk vs. the intermittent exposure to cow’s milk formula or some other factor.
As the authors mention, breastfeeding has been shown to have a protective effect, potentially harmful effect or no effect on the development of allergies.
There are numerous benefits to breastfeeding. Providers should be cautious and not over-interpret the findings of this study. Doctors should continue to support breastfeeding mothers, and future, larger studies with additional data are needed prior to changing recommendations for nursing mothers.
The SunBEAm birth cohort is currently underway with a goal of better understanding underlying mechanistic and environmental determinants of food allergy and AD, including maternal diet and breastfeeding, so hopefully we will have more information on this important topic in the near future.
Reference:
Lachover-Roth I, et al. Ann Allergy Asthma Immunol. 2022;doi:10.1016/j.anai.2022.10.013.
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Theresa Bingemann, MD, FACAAI, FAAAAI
This interesting study found higher rates of cow’s milk allergy in those infants who were exclusively breastfed or who received a combination of breastfeeding and cow’s milk formula in the first 2 months of life. However, the best preventive approach is still not clear, given conflicting studies and the numerous benefits of breastfeeding.
In addition, this study did not ask about maternal diet, so we do not know if the mothers of the infants in the exclusively breastfed group had cow’s milk protein in their diet or not. If cow’s milk protein was in their diet, we do not know how often it was consumed.
There is also variability in the amount and composition of allergens in maternal breastmilk. Furthermore, the study characterized the severity of AD, and patients with more severe AD had higher rates of food allergy. Since the parents were able to choose how they fed their child, there may have been bias in the choice that affected the results as well.
Finally, there were high rates of protocol deviations (about 50%) in the exclusively breastfed group.
In my experience with early peanut and egg introduction, intermittent exposure is usually found when IgE-mediated symptoms develop after successful early introduction. Therefore, I do think intermittent exposure of highly allergenic foods is probably worse than no exposure, although this is anecdotal.
It is important when directing families toward early introduction of highly allergenic foods to encourage families to keep these foods in their diet regularly. We do not have data on the best regimen for this, but likely two or three servings per week at least would work.
With respect to cow’s milk allergy, study results have been conflicting. More studies are needed.
To best answer the question regarding which strategy will be best at preventing cow’s milk allergy, we need a prospective, multicenter study looking at a variety of populations from different areas of the world.
These studies should include data on maternal diet and allergen exposure in the home. In addition, better characterization of the amount of exposure to formula and frequency as well as the reasons for these exposures would also be useful. It additionally would be useful to better characterize reasons for choosing a given feeding type and the severity of AD in the infant.
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