Children with cow’s milk allergies smaller, lighter than peers with nut allergies


A retrospective study reveals that children with cow’s milk allergies—and the restrictive diets they must follow—may negatively impact their growth and development in comparison to their peers with other food allergies.

Children who have cow’s milk allergies may struggle with long-term growth moreso than their peers with other food allergies, according to a recent study.

The study1 on the effect of milk allergies on overall childhood growth was published through a letter to the editor in the Journal of Allergy and Clinical Immunology. Food allergies are prevalent in childhood, but some food allergic children may be at risk for decreased growth measures. Previous research has suggested that food allergies and elimination diets can affect childhood growth and nutrition, and that milk or multiple food allergies are especially problematic in this way. Information on growth patterns has been lacking for children in these groups, making it difficult to determine the long-term effects of food allergies and diet restrictions may have.

Lead author Karen Robbins, MD, from the Division of Allergy and Immunology at Children’s National Health System in Washington, DC, says the goal of the research was to describe growth patterns of children with cow’s milk allergy longitudinally, as they develop from early childhood to adolescence.

“There has been research to look at growth in children with food allergy, but most of these studies only look at children at one point in time,” she says. “Decreased growth has been observed in the past, but previous work has not addressed whether these children achieve catch-up growth. Furthermore, all food allergies are not the same, and cow's milk allergy specifically may be a risk factor for growth and/or nutritional problems.”

The research team used a retrospective review of children enrolled at the Johns Hopkins Pediatric Allergy Clinic in Baltimore, Maryland, who had persistent food allergies and strict elimination diets. Children with other conditions beyond food allergies that may have negatively impacted their growth were excluded.

Nearly 200 children were included in the final study, with data from more than 1100 clinic visits reviewed. The children primarily had cow’s milk or peanut and tree nut allergies.

The research team found that, as in prior studies, children with cow’s milk allergies typically restricted other foods from their diet that are common allergens. These included eggs, peanuts, and tree nuts. However, the researchers found that children with cow’s milk allergies also had lower weights and heights than even their peers with peanut and tree nut allergies. The presence of other conditions like asthma and eczema or inhaled corticosteroid use had no significant effect on the findings. Additionally, decreases in weight and heights among children with persistent milk allergies became more pronounced as the children aged.

“Children with persistent cow's milk allergy—meaning, cow's milk allergy that does not resolve in early childhood—are at risk for decreased growth,” Robbins says. “It is important to follow their growth and nutrition closely, pay attention to other factors that could also impact growth, such as repeated courses of steroids in uncontrolled asthma or eating problems, and offer additional support if needed.”

The report outlines the long-term challenges of milk allergies and the impact food restrictions attributed to those allergies could have on growth as children age. Although the research team says a true control population was not possible in this study, there were children with cow’s milk allergies who only avoided nuts and not other foods, allowing for a wider comparison of strict versus non-strict diet restrictions on growth and development. The study also notes that throughout the study years, the team observed improved access and referral to dietary advice, improved information about food allergen ingredients in foods, and wider availability of allergen-free foods which may have impacted long-term growth and diet options.

Overall, the team’s research was limited because it was a retrospective study, but the study did conclude that children with cow’s milk allergies were lighter and smaller than their peers with nut allergies, and that growth problems increased as they aged if their allergy persisted.

“It is not entirely known what explains the growth differences in these children, but that is an important question to address next,” Robbins says. “Most children with cow's milk allergy had multiple food allergies, so cow's milk allergy may just be a marker for children with multiple food allergies. It is possible that the allergic condition impacts growth, since most of the children with cow's milk allergy had multiple food allergies or avoidances and many had asthma. There could also be some differences in nutritional intake and/or maladaptive eating patterns, or children with food allergies may watch their intake more carefully.”

If a child has unpleasant experiences such as allergic reactions with food, this could impact their diet and eating habits, she notes.

“Some children could have nutritional deficiencies, but that was not addressed in this study,” Robbins adds. “Furthermore, there may be factors that we do not know at this time. We did not conclude that size or growth may contribute to reaction to cow's milk or assess for this, because that was not an aim of the study.”

Robbins says the study found that these children can benefit from nutritional guidance, and it is important for primary care providers and allergists to monitor diet, nutrition, and growth closely. Referral to a registered dietician should be considered, as well, she says.

“Ideally, this research will highlight growth and diet as important topics to address for food allergic children, especially those with cow's milk allergy, multiple food allergies, and other medical conditions that could impact growth,” Robbins says. “I also hope that it allows for ongoing study of the impact of allergy on childhood growth and development.”


  1. Robbins K, Wood R, Keet C. Persistent cow’s milk allergy is associated with decreased childhood growth: a longitudinal study. Journal of Allergy and Clinical Immunology. 2020:145(2):713-716.e4. doi:10.1016/j.jaci.2019.10.028
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