Studies show that allergy rates are increasing throughout the world. In the U.S. alone, between 1997 and 2011, the Centers for Disease Control and Prevention measured a 50 percent rise in the number of children with food allergies. Parents are naturally left wondering why this is happening, and whether allergies are preventable.
A recent review article highlighted key risk factors for allergies, plus strategies for possible prevention. The authors nicknamed their risk factors “the 5 Ds,” which are summarized below:
Studies show that the risk of allergies increases for infants who have a delayed introduction to solids, particularly potential allergens such as peanuts and eggs. In fact, experts now recommend that all infants, especially those at high-risk of allergies, be introduced to supplemental foods between 4 and 6 months of age.
Research is also looking into whether the quality of food plays a role in whether an infant develops allergies. Studies have shown that infants who eat more fresh fruit, vegetables and meals prepared at home are less likely to develop allergies. It’s unclear why. There could be a protective benefit in nutrient levels, differences in fiber intake or some other mechanism.
Finally, evidence supports exclusive breast feeding for the first four to six months of a child’s life. Breast milk contains several beneficial factors that help with maturation of an infant’s immune system, although a specific link to allergy prevention remains unclear.
The "allergic march" describes the well-known relationship between atopic dermatitis (AD), including eczema, and future development of other types of allergies, including those to food. In fact, research shows that infants with eczema are not only five times more likely to have food allergies, but that those with more severe AD are much more likely to develop food allergies within their first year.
The "dual hypothesis theory" explains that a broken skin barrier, possibly due to dry skin or a rash such as eczema, predisposes children to allergens “leaking” into their immune system and triggering allergic pathways, while oral exposure to these same allergens can prevent allergies. Some researchers suggest that parents avoid using soaps that dry out their children’s skin, and use non-allergenic moisturizers.
Dribble (and Dirt)
A few years ago, I blogged about “Why Dirt is Good for Kids.” I cited the “hygiene hypothesis,” which theorizes that in a world of increasing exposure to antibiotics, sanitizing gels and disinfectants, our immune systems overreact when exposed to harmless microbes, leading to allergies and autoimmune diseases.
Other studies have shown that growing up in a household with more siblings decreases the risk of allergic diseases. Similarly, research has shown that when parents clean a pacifier by sucking on it themselves, an infant’s risk of allergy may be reduced. The protective benefits of these practices are thought to be from the increased and shared exposure to microbes.
Research has shown that children who spend time around farm animals and dogs have a lower risk of developing allergic diseases such as asthma and eczema. The theory here is that through exposure to these animals and their microbes, including parasites, children receive a protective benefit against allergies.
Researchers have found that infants who are deficient in Vitamin D are three times more likely to have an egg allergy and 11 times more likely to have a peanut allergy. Children with Vitamin D deficiency are also more likely to have multiple food allergies. Vitamin D is known to affect immune function, but the precise explanation for the deficiency and its correlation to food allergies remains unclear.
In summary, the last few decades have seen an increasing rate of allergic diseases in children. This has compelled research into how changing various aspects of a child’s environment may decrease the risk of developing allergies. The “5 Ds” provide a guide for parents trying to prevent allergies in their kids.
If you have concerns about your child and allergies, our pediatric gastroenterologists and allergists will work with you to reduce potential risks. Call 206-215-6005 to make an appointment.