The Blame Game: What Causes Food Allergies?
Are food allergies genetic?
Have you ever described your child’s allergies to the family and been shocked when they respond with a, “Me too!”? It seemed the more we talked about food allergies; the more family members admitted they were plagued with similar issues. Aunt Mable carries an Epi-Pen for peanuts, Grandma grew out of a shellfish allergy, and Cousin Timmy can’t eat dairy.
Several scientific research teams have analyzed these correlations and reported interesting findings.
Food Intolerance Genes
First, lets talk about non-allergic food hypersensitivity. These are what we commonly refer to as an intolerance, such as a lactose or fructose intolerance. This reaction occurs due to enzymatic defects which cause the inability to properly digest a specific substrate. For example, humans must have beta-galactosidase (fancy enzyme word) to break down the sugar in cow’s milk. Luckily for scientists, determining the genetic causes for these types of reactions are simple because they are caused by a single gene mutation. This single mutation results in the inability to express the proper enzyme . Pretty straightforward!
Food Allergies Genes
This is where things get complicated. Unfortunately, researchers have found that IgE-mediated food allergies are not based on a single mutation (learn about IgE and non-IgE mediated disorders here). Instead, these disorders are associated with a complex of multiple genes which may contribute to excessive IgE production .
In both debilitating food situations, predisposition and family connections have been implicated. The strongest predisposition evidence is seen in twin studies. A whopping 64% of monozygotic twins have correlated peanut allergies while only 6.8% dizygotic twins both have the same aliment. This points to individuals being genetically predisposed to the food allergy. Additionally, studies show that the general population has a 0.5% likelihood of a peanut allergy while families with a history have an increased rate of 7% .
Genetic Predisposition + Environmental Factors = Food Allergy
It is probable that a large portion of the population is genetically predisposed to food allergies without ever showing symptoms. Many external influences can affect whether a person expresses these mutated genes in such a way that leads to reactions. Unfortunately, these factors are vast and not well understood. Diet, pollution, stress, exercise, sunlight, and so much more can play a role in this seemingly simply equation.
Much more research is needed to better understand how our genes and the environment lead to food allergies.
Once identified, targeted therapies could alleviate symptom severity.
Understanding how our bodies react to allergens could lead scientists to creating genetically modified plants which lack the common allergic portion (maybe a future post!) .
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Hourihane, J. O'B., T. P. Dean, and J. O. Warner. "Peanut allergy in relation to heredity, maternal diet, and other atopic diseases: results of a questionnaire survey, skin prick testing, and food challenges." Bmj 313.7056 (1996): 518-521.
Dodo, Hortense W., et al. "Alleviating peanut allergy using genetic engineering: the silencing of the immunodominant allergen Ara h 2 leads to its significant reduction and a decrease in peanut allergenicity." Plant biotechnology journal 6.2 (2008): 135-145.