Food Sensitivity Testing

Introduction

The top results of a Google search for “Food Sensitivity Testing” include a number of companies selling at-home kits that promise to tell report back on the foods to which someone is sensitive. These kits may range anywhere from $50 on sale to more than a few hundred dollars. Below these results are a few articles that try to answer, ‘which test is the best?’, and ‘is food sensitivity testing actually a scam?’. It can be confusing and overwhelming to sort through.

One reason for the massive amount of often times confusing information on food sensitivities and food allergies is because food sensitivities and allergies are actually on the rise. Unfortunately, this creates a market ripe for companies to come in and take advantage of people who want answers and are willing to pay for them.

Two Elephants in the Room

Why are food sensitivities and food allergies on the rise? This is a very difficult question to answer and there are many more contributors than just one. Some of the contributors likely include that diets have changed, food sources have changed, exposure to microbiome has changed, people's immune systems may be different than they were hundreds of years ago, the world is more polluted, antibiotics tend to be overused, key micronutrient deficiencies don't help, people are more aware of their symptoms, and diagnosing illness is becoming better and easier. This is not an exhaustive list, there very well could be many other contributing factors to the increase in both food allergies and food sensitivities.

Are food allergies and food sensitivities the same thing? No, they most definitely are not.

The symptoms between food allergies and food sensitivities may appear to be similar. An allergy however is an immune system response whereas a food sensitivity is not. So, what does that mean?

When someone has an allergy to a food, their body views that food as a threat or a foreign invader. As a result, the body mounts a counterattack by releasing an antibody known as immunoglobulin E (IgE) which travels to cells telling them to release chemicals which are what triggers an allergic reaction. Unlike a food sensitivity, a food allergy can produce a serious or life-threatening reaction if only a microscopic amount of the food is eaten, touches the skin, or is inhaled. Symptoms of a food allergy can present on the skin as hives or a rash, as difficulty swallowing, swelling of the lips, tongue, or throat, wheezing or trouble breathing, and ultimately anaphylaxis. Symptoms can show up almost immediately after exposure to the food, or be delayed.

There are 9 foods that account for the majority of food allergies. These include eggs, fish, shellfish, milk, peanuts, soy, tree nuts, wheat, and sesame. Food allergies can develop at any time, even in adulthood, therefore it’s important to know the difference between an allergy and an intolerance. If someone gets diagnosed with a food allergy, they may need to carry an epi-pen as a preventative and life-saving measure.

Food sensitivities on the other hand are not an immune system response but rather take place within the digestive system in response to an inability to digest, or break down, a food. These can be the result of a lack of or imbalance of digestive enzymes in the body, an imbalance of the gut microbiome, low stomach acid, or a compromised structure of the gut as may occur in gastritis or leaky gut. Symptoms of a food sensitivity, or intolerance, are usually not life-threatening even though they may feel incredibly uncomfortable. They can include pain in the abdomen, gas, bloating, reflux, changes in bowels, headaches or migraines, and nausea. Symptoms may take a few hours to a few days to develop after eating the food.

How are they diagnosed? 

I ALWAYS recommend for patients who show up with unwanted gastrointestinal symptoms to visit their medical doctor, if they haven’t already, for additional testing and care. A doctor will perform an in-depth health history, a physical exam, and they will listen to the symptoms that present when eating a certain food or foods. The doctor may determine that additional testing, such as food allergy testing, is required. These tests may include:

• Skin prick test: where the skin is pricked with a tiny amount of a potential allergen to see the response.

• Blood testing: to measure antibody’s present for a specific food being tested.

• Oral food challenge: a medical doctor administered test where a small amount of a potential allergen is introduced to identify what might be contributing to symptoms as well as the severity.

• An allergist may also prescribe an elimination diet, where the suspected food is eliminated for a certain period of time and symptoms are recorded to see if they improve. The doctor may want to reintroduce the food under their medical supervision for further testing.

All of the above testing must be done under doctor supervision and when interpreted by a board-certified allergist are reliable tests to identify or rule out food allergies. If the body doesn’t produce an allergic response to a particular test, the doctor may diagnose a food sensitivity.

One thing I also recommend for patients to do is to begin a food diary. Record what you ate, with specific amounts, and how you felt after you ate. Write down the time that you ate and the time that you experienced symptoms. And be specific with the types of food, where you ate it, how it was prepared, etc. This can be really helpful for your doctor to use in helping you identify food allergies and sensitivities.

Food sensitivity testing

It is highly likely that any food allergy testing will be covered by insurance, as long as a doctor can justify a reason why the testing needs to be conducted. The challenge is that food allergy testing can be time consuming, and often times people want results quickly. Sometimes food allergy testing will require multiple different tests to confirm whether symptoms are a true allergy or rather a sensitivity. On the other hand, the over the counter food sensitivity tests are likely to not be covered by insurance.

Back to the Google search. Because sensitivities/intolerances and allergies are on the rise, many people are turning to the third-party companies to identify to what foods they are sensitive. But are the tests worth it?

The short answer is no. The long answer is because there is no good evidence that the tests actually work, they are not sensitive or specific enough to identify food sensitivities, and the tests themselves have not been validated or subject to quality or blinded trials. While the companies that market them will likely say on their website that their tests have been studied, most of the trials were too small and lacked the proper control groups to be considered a quality, valid study. For the companies, it is good marketing however for consumers it can be misleading.

There are downsides to doing these tests as well. The results may cause consumers to cut foods out of their diet to which they may not actually be sensitive, which may lead to a gap in macro or micronutrients and ultimately problematic deficiencies. This can actually worsen gastrointestinal symptoms.

Symptoms may also not be due to food sensitivities. Low stomach acid, for example, may appear as abdominal pain, gas, bloating, diarrhea, reflux, and undigested food in the stool. These symptoms may make someone think they're sensitive or intolerant to a food when in reality it's low stomach acid caused by a micronutrient deficiency.

Lastly, these tests can also create an unnecessary level of fear, stress, and anxiety, which all can exacerbate unwanted GI symptoms.

Bottom line

If you think you have a food sensitivity, call your doctor and a registered dietitian and work with them to determine whether your symptoms are related to a food sensitivity, food allergy, GI issue, or excess stress in your life. Wait until the companies offering food sensitivity tests spend their own money to validate their tests via high quality clinical studies, and make it worth your while to purchase what they offer.

References

American Academy of Allergy Asthma & Immunology. (n.d.). Food Allergy Testing and Diagnosis. Retrieved from https://acaai.org/allergies/testing-diagnosis/food-allergy-testing-and-diagnosis/

American Academy of Allergy Asthma & Immunology. (2020, September 28). Food Intolerance Versus Food Allergy. Retrieved from https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/food-intolerance

Callahan, A. (2022, September 13). Is Food Sensitivity Testing a Scam? The New York Times. Retrieved from https://www.nytimes.com/2022/09/13/well/eat/food-sensitivity-test.html

Cleveland Clinic. (2022, April 23). Food Allergy vs. Intolerance: What’s the Difference? Retrieved from https://health.clevelandclinic.org/allergy-or-intolerance-how-to-tell-the-difference/

National Institute of Health, National Institute of Allergy and Infectious Diseases. (2023, May 23). Causes and Prevention of Food Allergy. Retrieved from https://www.niaid.nih.gov/diseases-conditions/food-allergy-causes-prevention

National Institute of Health, National Library of Medicine, Medline Plus. (2023, February 28). Food Allergy Testing. Retrieved from https://medlineplus.gov/lab-tests/food-allergy-testing/

Santos, A. (2019, September 13). Why the world is becoming more allergic to food. BBC News. Retrieved from https://www.bbc.com/news/health-46302780

U.S. Food and Drug Administration. (2023, January 1). Food Allergies. Retrieved from https://www.fda.gov/food/food-labeling-nutrition/food-allergies