Frequent moisturization may induce food allergies among infants

Young infants may develop food allergies due to frequent moisturization of the skin through transcutaneous sensitization, according to a population-based, randomized study.

“There are two possible explanations for our findings: moisturizers might be facilitating the passage of food allergens across the skin barrier, or moisturizers might be damaging the skin barrier and allowing the passage of the food allergen,” Michael R. Perkin, PhD, senior lecturer in pediatric allergy at Guy’s and St. Thomas’ NHS Foundation Trust, and colleagues wrote. “Moisturizers are known to facilitate the passage of substances across the skin.”

Perkin and colleagues evaluated data from the Enquiring About Tolerance, or EAT, study, which, between Nov. 2, 2009, and July 30, 2012, enrolled 1,303 healthy, exclusively breastfed 3-month-old infants born at term in England and Wales. Participating infants were randomly assigned to a standard introduction group (SIG) or early introduction group (EIG). Until 6 months of age, those in the SIG continued exclusive breastfeeding, whereas those in the EIG were breastfed and introduced to cow’s milk yogurt first, then peanuts, hard-boiled eggs, sesame and cod randomly, then wheat.

“The EAT cohort provides an opportunity to further assess the relationship between early moisturization and the development of food sensitization and food allergy,” Perkin and colleagues wrote. “In line with the dual allergen hypothesis, we postulated that frequent contact of a parent’s hands with their child’s skin during moisturizer application might be facilitating the transcutaneous exposure to food allergen, resulting in food allergy developing.”

Families completed a questionnaire on their history of atopic disorders. A section on skin problems and treatments included questions on the infant’s current moisturization frequency, moisturizer name and the infant’s age at initiation of moisturization.

Researchers assessed visible eczema at 3, 12 and 36 months of age; transepidermal water loss at 3 and 12 months of age; and reactions to foods introduced to the EIG, as well as to house dust mite, cat, dog, grass and tree pollen by skin prick test at 12 and 36 months of age. A positive skin prick test for any of the six foods or history of positive challenge before age 12 months elicited food challenge.

Among 1,161 infants evaluable for food allergy, 74 developed allergies, including 48 of 284 infants (16.9%) with visible eczema at enrollment and 26 of 877 (3%) without eczema at enrollment.

Food allergy development and moisturization frequency showed a statistically significant dose-response relationship, with each additional weekly moisturization application corresponding to 20% increased odds of food allergy (adjusted OR =1.2; 95% CI, 1.13-1.27). For those with eczema at enrollment, the aOR was 1.2 (95% CI, 1.11-1.31); for those without it, aOR was 1.18 (95% CI, 1.07-1.3).

Aeroallergen sensitization development and moisturization frequency had a similar relationship at 36 months of age.

The researchers wrote these results are limited by a lack of mechanistic data, so future studies may investigate “whether moisturizers facilitate food and aeroallergen uptake; whether moisturizers become contaminated by these allergens from the hands or the environment; and whether the effects are limited to certain types of moisturizer or to specific susceptible individuals,” Perkin and colleagues wrote.

“In the interim it would seem sensible that before moisturizers are applied, hands are washed thoroughly, and that careful consideration be given to the frequency of moisturizer application and the type of moisturizer used in infant skin care,” they added.