The skin may hold the answer as to why some children develop peanut allergies before they’ve even eaten a single peanut, suggests new research.
Dr. Helen Brough is the lead author of a groundbreaking British study that reveals how exposure to peanut residue in household dust can increase the risk that children with eczema or other skin conditions will go on to develop peanut allergy.
Allergic Living has an exclusive interview with Dr. Brough but first, some background on the study:
- Researchers vacuumed sofas in the homes of 577 U.K. babies in their first year of life.
- Detectable peanut protein was found in more than 1/3 of the dust samples.
- Years later, at ages 8 and 11, the children in this same study group were tested for peanut allergy, as well as mutations of the FLG skin gene (such mutated genes are strongly associated with eczema).
- Of those who had become peanut-allergic, 1 in 5 had the mutated FLG gene.
- In homes with 3 times as much peanut in the dust, a child with the mutated gene was 3 times more likely to develop peanut allergy.
“Previously it was thought that children developed a predisposition to becoming peanut allergic by exposure to peanut from maternal peanut consumption during pregnancy or breastfeeding,” explains Dr. Brough, an honorary senior lecturer at King’s College London. “This study suggests that there may be an alternative route by which children might develop become peanut allergic – and that is through exposure to peanut through the skin.”
In the following interview with Associate Editor Ishani Nath, pediatric allergist Dr. Helen Brough discusses her groundbreaking study and what it could mean for our understanding of how peanut allergies develop.
Allergic Living: What is it about the skin and its immune system that is leading to allergy?
Dr. Helen Brough: In children with porous skin (due to FLG mutations) allergens are thought to penetrate the skin and predispose the body towards an allergic response. There is evidence that disruption of the skin – through constant scratching, irritation or inflammation – leads to an allergic immune response in the skin. Peanut could therefore penetrate disrupted skin when the immune system is predisposed towards allergy, and lead to a peanut-allergic response.
Infants in the study who did not have the mutated FLG gene were safe from the effects of peanut proteins in household dust.
AL: How does peanut protein get into household dust?
DB: Peanut can be measured on hands and in saliva at least three hours after eating a peanut-containing meal. Thus, peanut can be transferred into the environment by hands or saliva, for example onto bedding while asleep, for some time after eating peanuts.
AL: If you don’t eat peanuts in your home, will there still be peanut protein in your household dust?
DB: In our study, peanut protein was found in the dust of the infant’s bed and play area in about 10 percent of homes where there was no or minimal household peanut consumption. This may have been due to other friends and family visiting the home who did eat peanut.
AL: Can regular cleaning methods effectively remove peanut proteins from the home?
DB: Although peanut levels in the environment were not removed completely after routine cleaning, a significant reduction was achieved. Peanut levels in dust were reduced 1,000-fold from sofa covers and 40-fold from pillows using a single machine wash at 60º C with laundry soap.
Peanut protein levels on table surfaces were also reduced by cleaning with detergent. On granite tables, cleaning with detergent completely removed detectable peanut but, on wood tables, cleaning did not completely remove peanut. Thus, the type of table surface also affects the efficiency of removing peanut from the environment.
AL: What should parents of infants with atopic eczema (or otherwise damaged skin) do to help avoid the development of peanut allergy?
DB: We would recommend good treatment of eczema, using enough moisturizer to protect the skin barrier (500 grams of moisturizer per week).
The results from this study are not conclusive as they only show an association between high levels of peanut in the homes and an increase in peanut allergy in later life. In order to show that high environmental peanut levels lead to peanut allergy, a study would be required where environmental peanut levels were reduced in one group of children with eczema versus continuing as before in another group. Thus, no recommendation can be made to parents at this time.
The Learning Early About Peanut (LEAP) study is assessing whether early peanut consumption (from four to 11 months) may protect the child against developing peanut allergy. These results will be available in 2015. [Editor’s note: see our LEAP study article from February, 2015.]
Next: What does this mean for the future of peanut allergy prevention?