Researchers estimate that 32 million Americans have food allergies, including 5.6 million children, according to Food Allergy Research and Education.
This translates to one in 13 children. About 40% of children with food allergies are also allergic to more than one food.
The prevalence of food allergy in children increased by 50% between 1997 and 2011, according to the CDC. Specifically, between 1998 and 2008, the prevalence of peanut or tree nut allergy appears to have more than tripled in U.S. children.
While most food allergies arise in childhood, at least 15% of patients with food allergies are first diagnosed in adulthood. More than one in four adults with food allergies indicate all their food allergies developed during adulthood, and nearly half of adults with food allergy report having developed at least one food allergy during adulthood.
The forces behind the rising number of statistics is yet to be identified, reported Leapsmag. However, the leading suspects are elements of our modern lifestyle that are known to throw the immune system out of whack.
Weaker Immune Systems
In the late 1980s, British epidemiologist David P. Strachan, MD, found that children in larger households had fewer instances of hay fever, or allergy caused by pollen. He suggested the reason could be their immune systems were strengthened by exposure to their sibling’s germs.
Since then, other researchers discerned more evidence for Dr. Strachan’s “hygiene hypothesis:” higher rates of allergy in cities versus rural areas, in industrialized countries versus developing ones, in lab animals raised under sterile conditions versus those exposed to germs.
Experts theorize that fending off a variety of pathogens helps train the immune system to better distinguish and to respond to threats in a more subtle way. In an era of increasing urbanization, shrinking family sizes, and more sheltered lifestyles, this type of conditioning may be harder to come by.
“When we were kids, we played in the dirt,” observed Cathryn R. Nagler, PhD, a professor and food allergy researcher at the University of Chicago. “Today, children tend to be on their screens, inside sealed buildings.”
Vitamin D Deficiency
Other factors could be to blame for the allergy epidemic as well, such as more time spent indoors. More time indoors means less exposure to sunlight, which can lead to a vitamin D deficiency-a nutrient crucial to immune system regulation.
Links have been made between variations in sunlight exposure, latitude, birth season, and vitamin D status with food allergy risk, according to “Cellular and Molecular Mechanisms of Vitamin D in Food Allergy” published in Journal of Cellular and Molecular Medicine by a group of researchers from Australia.
The article indicates that populations of the U.S. and Australia in regions furthest from the equator have an increased risk of overall allergy-food allergy and food allergy markers-compared to those closest to the equator. After controlling for population and region characteristics, one study reported prescriptions for epinephrine autoinjectors were higher in the northernmost states of the U.S., particularly those in the New England region when compared to southern regions.
In another study, infants with low vitamin D were 11 times more likely to have a peanut allergy, almost four times more likely to have an egg allergy, and more than 10 times more likely to have multiple food allergies when compared to infants with adequate vitamin D concentrations.
Altered Microbiomes
The allergy surge also correlates with several trends that may be altering the human microbiome. In 2014, a team led by Dr. Nagler published a study showing that clostridia, a common class of gut bacteria, protects against these allergies.
Researchers fed peanut allergens to germ-free mice (born and raised in sterile conditions to have no resident microorganisms) and to mice treated with antibiotics as newborns (which significantly reduces gut bacteria). Both groups of mice displayed a strong immunological response. This sensitization to food allergens could be reversed by reintroducing a mix of clostridia bacteria back into the mice.
“In simple terms, what we found is that these bacteria prevent food allergens from gaining access to the blood in an intact form that elicits an allergic reaction,” said Dr. Nagler. A growing body of evidence suggests that our eating habits are throwing our gut microbiota off-balance, in part by depriving helpful species of the dietary fiber they feed on.
In addition, increasing exposure to antibiotics and antimicrobial compounds could be harming beneficial bugs. Such depletions could affect children from birth. Because babies are seeded with their mothers’ microbiota as they pass through the birth canal, they may be inheriting a less diverse microbiome than did previous generations.
Is There a Solution?
There is no cure for food allergies. Food allergies are best managed by avoiding the problem food(s) and learning to recognize and treat reactions to symptoms.
Contrary to some belief, delaying introduction of allergenic foods does not provide protection against food allergy. In fact, feeding peanut foods early to infants has been found to dramatically reduce their risk of developing peanut allergy.
Food allergy therapies are under study in clinical trials, but none has been approved yet for general use.
However, in January, FDA approved the first drug for treatment of peanut allergy for children. Aimmune Therapeutics, Inc.’s Palforzia was approved to mitigate allergic reactions, including anaphylaxis, that may occur with accidental exposure to peanuts.
Treatment with Palforzia may be initiated in children ages 4 through 17 with a confirmed diagnosis of peanut allergy and may be continued in individuals 4 years of age and older.
“Peanut allergy affects approximately 1 million children in the U.S. and only one out of five of these children will outgrow their allergy. Because there is no cure, allergic individuals must strictly avoid exposure to prevent severe and potentially life-threatening reactions,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research. “Even with strict avoidance, inadvertent exposures can and do occur. When used in conjunction with peanut avoidance, Palforzia provides an FDA-approved treatment option to help reduce the risk of these allergic reactions in children with peanut allergy.”
