Analysis of data from a trial of more than 1,300 infants has found that increased application of moisturizers at three months of age was associated with a higher likelihood of developing allergies in infancy.
The new study, published today (Thursday) in the Journal of Allergy and Clinical Immunology, found that this was still the case even when skin conditions such as eczema - which is linked with allergy development - were taken into account.
The research team, led by researchers at St George's, University of London and King's College London advise that moisturisers are still effective in easing the symptoms of skin conditions and that further work is required to understand why moisturiser use could lead to allergy development.
Previous research in a trial of 1,394 children had shown that moisturising infants is not effective in preventing the development of eczema. The results also observed a non-significant increase in food allergy in the moisturised group compared with the control group.
In this new study, the largest completed randomised control trial of the early introduction of allergenic foods, each additional moisturisation per week was associated with a 20% increase in the likelihood of developing food allergy (ORadj 1.20 (95% CI 1.13-1.27), p<0.0005).
Parents enrolled in the study were asked how often they moisturised their infant and what product they used. The most frequently used product to moisturise infants was olive oil.
It is not yet fully understood how moisturising may lead to food allergy development. Experiments in animals suggests that sensitisation to allergens can occur via exposure through the skin.
One theory the authors of the paper propose is that some moisturisers may have a damaging effect on the skin barrier, allowing allergens to make contact with the skin immune system more easily.
They also suggest that it could be that parents with allergens on their hands from cooking and eating may inadvertently be exposing their infant to greater contact with these allergens when applying the moisturiser.
This study does not say that parents should stop moisturising their children. The results have raised concerns that there may be something in the act of moisturising that could raise the risk of food allergy development, but we need further work to establish why this might be the case."
Dr Michael Perkin, Study First Author and Pediatric Allergist, St George's, University of London
"In the meantime, we recommend that parents wash their hands before moisturising their babies as a precautionary measure. Of course, if children have skin conditions, such as eczema, treatment guidance from their GP, allergist or dermatologist should still be followed."
Professor Carsten Flohr, dermatologist from St John's Institute of Dermatology at King's College London and Guy's & St Thomas NHS Foundation Trust and senior author of the paper said: "Further research is now required to understand the exact mechanisms behind why more regularly moisturised infants appear to be at a higher risk of developing food allergies and strategies to prevent this from happening then also need to be developed."
Perkin, M. R. et al. (2021) Association of frequent moisturizer use in early infancy with the development of food allergy. Journal of Allergy and Clinical Immunology. doi.org/10.1016/j.jaci.2020.10.044.