Food allergies affect 32 million Americans, or almost 10% of the US population. In people with food allergies, proteins in a specific food are attacked by the immune system, causing symptoms that range from an itchy mouth to anaphylactic shock. While there is currently no cure for existing food allergies, scientists are working on ways to prevent them from developing in the first place.
Allergies to foods like milk, peanuts, eggs, sesame, cod, and wheat are frequently associated with eczema. Eczema is an immunological condition characterized by dry, itchy, inflamed patches of skin. During an eczema flare-up, skin cells separate and produce tiny openings. Substances from outside the body can leak through these tiny openings, activating the immune system and causing inflammation.
Overactive immune cells produce the symptoms for both food allergies and eczema. Therefore, scientists hypothesize that a method for reducing eczema could also prevent food allergies from developing.
Lotions and oils soothe inflamed skin and patch the tiny openings that form between skin cells. One scientist proposed that by blocking the openings in the skin this way, moisturizers might also reduce the intake of substances through the skin. They suggested this moisturizing treatment could both prevent further eczema and stop any immune response that produces a food allergy.
A previous study on eczema showed that infants given an intensive treatment of lotions and oils were less likely to develop food allergies than infants who did not receive the treatment. However, a different study showed the opposite effect: not only did rigorous moisturization fail to reduce eczema, it also failed to stop food allergies from developing. This second study suggested that moisturization might even have increased the likelihood of infants developing a food allergy.
Given these conflicting conclusions, a group of scientists from the UK and the Netherlands set out to test whether frequent moisturization could cause food allergies in infants. They collected data from more than 1100 three-month-old infants that they separated into two groups. One group displayed visible signs of eczema or had a family history of related diagnoses, like hay fever or asthma. The other group showed no visible signs of a skin condition and had no family history of eczema.
At each child’s three-month check-up, the scientists asked the parents or guardians to share how many times per week they moisturized their child. They also administered a skin prick allergy test for the six foods most frequently associated with eczema.
The scientists discovered that the children who were moisturized multiple times per day as infants were more likely to develop a food allergy by three years of age than the children who were moisturized only a few times per week. Of the 1,161 babies they followed, 74 developed a food allergy by age three. Under 5% of the babies that were moisturized less than once per day developed a food allergy. About 10% of the babies that were moisturized daily developed a food allergy. Over 30% of the babies that were moisturized multiple times per day developed a food allergy.
The team’s results suggested that being moisturized multiple times per day increased the child’s risk of developing a food allergy by 20%. These data were independent of whether or not the children had eczema, meaning more frequent moisturization was associated with a higher risk of developing a food allergy in all infants. The association between moisturization frequency and food allergies was also independent of any family history of eczema.
The scientists proposed two mechanisms to explain the link between moisturization and food allergies. The first was that moisturizers can break down the top layer of skin cells, termed the skin barrier. The skin barrier keeps environmental threats outside the body. If the skin barrier is damaged, external compounds like food proteins can get inside the body more easily, which could cause a food allergy to develop.
The second explanation they considered was that the act of moisturizing an infant could pass food proteins from the hands of the parent or guardian to the skin of the infant. Lotions and oils are designed to permeate the skin barrier. Therefore, food proteins from the parent or guardian’s hands could be carried by the moisturizer as it crosses the skin barrier, triggering the development of a food allergy.
The team suggested further research is needed to determine what causes the link between moisturization and food allergies in infants. The next step will be determining if specific moisturizers are more strongly linked with the development of food allergies. In the meantime, they recommended a thorough hand washing before applying moisturizer to an infant, to reduce the risk of transmitting food proteins and potential allergies to children.