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The link between food allergies and genetics

Girl scratching an itchy neck
Article

read time: 4 min

Topics:

Health & Wellness, Nutrition

Lately, your gut has been feeling off-kilter. Could it be something you ate? Taking a home DNA allergy and food sensitivity test reveals you have multiple potential food allergies or sensitivities. Does this mean you should avoid the foods completely or risk an allergic reaction?

Let’s take a closer look into the science linking food allergies and genetics before you start to make radical changes to your diet. The genes you inherit are only 1 of many factors that go into a food allergy or food sensitivity diagnosis.

The power and influence of your DNA

Your DNA (deoxyribonucleic acid) plays a role in every part of you, including your health. Every living thing on earth starts with DNA. Like a blueprint, this fascinating molecule contains our genetic information and provides instructions on how to build our bodies. Genes, which are made up of DNA, influence your physical and biological characteristics. Even health conditions, such as allergies, can be coded into your genes like hair color, eye color, and blood type.

Discovering the connection between allergies and your genetic code

The Human Genome Project,1 an international study of DNA, mapped all the genes in our bodies. Researchers identified genetic markers, which helped link inherited diseases (including allergies) with the responsible gene.

The science is still evolving, but 1 study scanned the complete set of genes of thousands of people exposed to various allergens. It found that those with the SERPINB gene cluster (like a hot spot in our DNA) were at increased risk for a food allergy and the physical reaction, such as throat swelling, most often took place in the esophagus. The study even found that a particular location in the cluster was specifically linked to peanut allergies.2

What triggers an allergy gene to turn on?

So, while it’s possible for allergies to be inherited, that doesn’t mean the allergy will definitely emerge. There are several more factors that must line up perfectly for a true allergy to activate.

Inherit the gene

Let’s use shellfish as an example. First, your biological parents need to pass down a gene linked to a shellfish allergy. The genetic marker means you have a higher risk for the allergy. However, the gene is only activated when…
Illustration of DNA and genes

Proteins turn on the gene

Proteins must activate, or turn on, the gene. But that doesn’t always happen. Without a corresponding protein, the gene remains dormant and a lobster dinner shouldn’t cause you any harm. However, it’s possible that exposure to external factors like environment, stress, or medications may also trigger genes.
DNA gene illustration

Antibodies poised to fight

Even if the gene is activated, your body also needs to spike immunoglobulin E (IgE) antibody production when you consume shellfish. IgE antibodies are proteins your immune system makes to detect and fight off germs and infections. High amounts of IgE antibodies mean you are sensitized to the substance.
IgE Antibodies

Your body reacts to the invader

True allergies require the presence of IgE antibodies and an immune-related response. Symptoms of an immune response can range from an itchy rash to life-threatening anaphylaxis3, which includes difficulty breathing, feeling faint, and a rapid heartbeat. But not every reaction is connected to your immune system. Perhaps shellfish causes discomfort in your digestive system instead—that’s considered a food sensitivity, not an allergy.
Illustration of body reacting to allergens

Good news/bad news about allergies

Our bodies change throughout our lifespans. So, what’s true today may not be in a few years.

Good news: Children often grow out of specific food allergies, especially those to milk or eggs.

Bad news: As people age, we become susceptible to new allergies as well. Seafood allergies, like fish or shellfish, are a typical example.

Decode your food allergy through testing

Observing and testing is the only way to get an accurate, personalized allergy diagnosis. But what kind of test is best, especially considering your genetic factors?

DNA food allergy tests

These are often available to purchase online as at-home kits—but read the fine print. They test the likelihood of having the genetic marker, but they do not diagnose an allergy. If you take 1 of these tests and it shows a predisposition to an allergy, your next step should be to explore more comprehensive test options with your doctor. Insights from these home tests can be informative, but they are not the best tool to use for a diagnosis.

Lab-based food allergy tests

Any time you suspect a food allergy, you should talk to your doctor and get tested to clarify your allergy’s nuances and limitations. Many doctors suggest a combination of the following:

Antibody blood test
Measures IgE antibody levels to indicate a suspected allergy.

Skin prick test
Observes your body’s reaction when exposed to a food allergen.

Component testing
Identifies which individual proteins in a food spike your IgE antibody levels.

Oral food challenge
Observes the severity of your allergic reaction under medical supervision and limits how much of the food you can eat.

Fooling genetics to delay or treat allergies

If you have a genetic marker predisposing you to a food allergy, you may not be able to beat biology. But you can sometimes fool it or at least work around it. Discuss the following treatment options with your doctor:

Desensitization through exposure

Many parents work with a pediatrician or allergist to slowly introduce new foods to babies to gradually desensitize their bodies while their immune systems are still building up. This process is called oral immunotherapy.4

Change food at an elemental level

Cooking or baking foods to a high temperature can restructure some of its protein components. For example, many people with a milk allergy don’t react to baked milk, so they can eat cookies or casseroles where the milk ingredient has been baked.

Medications to prevent or delay a food allergy

If you find out you’re at risk for a food allergen, explore what treatments are available before you ever experience an allergic reaction. For example, medications are being studied to block the IgE antibodies that trigger peanut allergies.

Cope with it

If you discover that your allergic reaction is pretty tame and tolerable to you (think mild rash that lasts a few minutes), you may be OK to eat the food in limited quantities.

There are a few caveats: beware of eliminating a food allergen from your diet and reintroducing it later. If you’re predisposed to that allergy, it may shock your body and send an allergic reaction into overdrive.

There are a lot of variables surrounding food allergies and sensitivities, and they go beyond genetics. Environmental factors, like where you live, your diet, pollution, and allergen exposure, can also play a role. So, DNA test results can’t give you a quick answer on what foods to avoid.

References

The Human Genome Project.
Genome.gov. Accessed November 9, 2022. https://www.genome.gov/human-genome-project

Marenholz I, Grosche S, Kalb B, et al. Genome-wide association study identifies the SERPINB gene cluster as a susceptibility locus for food allergy. Nat Commun. 2017 Oct 20;8(1):1056. doi: 10.1038/s41467-017-01220-0

Anaphylaxis-NHS.
NHS. Accessed November 9, 2022. https://www.nhs.uk/conditions/anaphylaxis/

Oral immunotherapy for peanut allergy in young children.
National Institutes of Health. Published February 15, 2022. Accessed November 9, 2022. https://www.nih.gov/news-events/nih-research-matters/oral-immunotherapy-peanut-allergy-young-children#:~:text=This%20involves%20giving%20people%20increasing,peanut%20than%20waiting%20until%20later

Page Published: March 16, 2023

The Quest Editorial Team

Contributors:
Nicholas deVries
Quest Diagnostics, New Solution Product Director

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