Adverse food reactions

Do I have an allergy or intolerance?

An adverse food reaction is, very simply put, any negative reaction an individual has to a food. The broad categories of adverse food reactions are broken down into:

- allergies (reactions that involve an immune system response)

- intolerances (a non-immune system response).

Within those categories, adverse food reactions are further broken down, but largely those details are information a healthcare provider needs to know, with the exception of a patient who already has a diagnosis. Details into these categories for healthcare professionals (HCPs) can be found in a food allergy articles series a colleague of mine and I published in Nutrition Today in the March/April Issue (An Overview) & November/ December Issue (IgE-mediated) and will be continuing into 2024. Patients should always be aware of the necessary details surrounding their diagnosis to best manage their allergy or intolerance.

Adverse food reactions are defined based on the body’s response mechanism.

A food allergy is an immune system response.

A food intolerance is not.

What is a food allergy?

There are 2 main categories of food allergy diagnosis identified by the immune system mechanisms involved: IgE-mediated or non-IgE-mediated (or a combination of both.)

“Classic” Food Allergy

A “classic” food allergy, also called an IgE-mediated food allergy, can occur with exposure to trace amounts of food and can result in signs and symptoms predominantly noted to include hives/rash, swelling, vomiting, difficulty breathing, and/or a drop in blood pressure that can lead to anaphylaxis. Anaphylaxis is a very serious reaction that can be fatal. It is imperative for anyone who suspects they may have this type of food allergy to seek a medical professional’s advice, such as that from a trusted primary care physician or allergist.

How are IgE-mediated food allergies diagnosed?

IgE-mediated food allergies are diagnosed based on clinical history, supporting bloodwork or skin prick tests, and if needed an oral food challenge. Sometimes physicians can diagnose without an oral food challenge, but that is determined on a case-by-case basis. Lab tests are supportive of a diagnosis however due to the potential for false positives a clinical response (visible reaction when exposed to the food allergen) is the primary factor in diagnosis.

Can I outgrow this allergy?

In some instances, this type of food allergy may be outgrown, and a healthcare professional (HCP) can help determine if this is possible. NEVER give your child, or consume yourself, an allergen if you are unsure what type of food allergy or intolerance you are experiencing until you have cleared it with a medical professional.

What is the treatment for this type of food allergy?

The management plan must be reviewed with your physician, but typically it requires 100% avoidance of the food. There are exceptions and this is another reason to speak with your HCP. Some allergens may be outgrown faster and some management plans may help prevent the development of new allergies. This may seem vague but food allergy care is very nuanced. There has been great success with new treatments for food allergy for those who do not fit the profile to “naturally develop tolerance”. The most utilized treatments are Oral Immunotherapy, or Sublingual Immunotherapy, which are now often covered by insurance.

Non-IgE-Mediated Food allergy

A second type of food allergy, called a non-IgE-mediated food allergy, generally has a less immediate reaction time and predominantly impacts the gastrointestinal (GI) tract. This often makes the term “allergy” confusing as it appears to mimic an intolerance, which is also largely a gastrointestinal response. (Remember, the GI tract begins in the mouth and ends with the colon.) The allergic reactions in this category are not immediately life-threatening, although the chronic reaction in some diagnoses may require a higher acuity of management or treatment.

How are Non-IgE-mediated food allergies diagnosed?

Food allergies in this category are diagnosed based on an elimination of the suspected food allergen, followed by a resolution of signs and symptoms, then a reintroduction challenge with the return of signs and symptoms. Food allergies in this category will not have supporting lab work, although blood or skin tests may be performed to either rule out an IgE-mediated food allergy or determine the baseline of sensitivity for future comparison.

Can I outgrow this type of food allergy?

This type of food allergy is often outgrown, and a HCP can help determine if this may be possible and provide management plans utilizing best practices in these diagnoses. Please follow up with your HCP to provide an accurate diagnosis. Self-diagnosis has the potential to do more harm than good and is not a recommended practice.

“I’m not certain what type of food allergy I have...”

If you suspect you have a food allergy please reach out to a qualified healthcare provider.

What are the top allergens in the U.S.?

The top 9 allergens in the U. S. Are cow’s milk, peanut, tree nuts, sesame, fin fish, shellfish, soy wheat, & hen’s egg; however, ANY food can be an allergen.

The most common food allergens in the U.S. are cow’s milk, peanut, tree nuts, sesame, fin fish, shellfish, soy, wheat, and hen’s egg; however, any food may be the cause of an allergic reaction. The U.S. Food & Drug Administration (FDA) has provided guidance for the food industry to protect consumers who have food allergies. All of the top allergens in the U.S. must be identified in plain language on food labels. You can read more about these regulations here.

What is a food intolerance?

A food intolerance is any response to a food that does not involve the immune system and is largely GI in nature.

A food intolerance is not an immune system response. The most common intolerance reactions involve the GI tract however there can be extraintestinal signs and symptoms, like flushing, headaches, or even swelling seen in some types of intolerance reactions. Reaction time can be immediate and acute or delayed and chronic, making it difficult to discern the culprit. In some instances, food can be tolerated in low amounts, confusing the issue even more.

How is a food intolerance diagnosed?

Food intolerances fall into a number of different categories (listed below) and while some types of intolerances have supporting diagnostic tests patient diagnosis begins with clinical history. It seems to go without saying that if an individual eats something that causes a poor reaction obviously that food or ingredient should be avoided. However, self-diagnosis is not advised in this category for complicated food intolerances or those who have a poor quality of life-related to intolerance. Qualified HCPs can help expand diet, improve quality of life, and prevent any secondary concerns that may arise from self-diagnosis.

Can I outgrow a food intolerance?

Often these food or chemical intolerances are for life, however, there are instances where they are transient and can resolve with the appropriate treatment. Working with a qualified dietitian, allergist, or gastroenterologist can help you determine the best course of action to manage or treat your intolerance.

Are there top food intolerances in the U.S.?

A food allergy is an immune system response, typically to a specific protein in a food. Food intolerances can be either:

- problem metabolizing a food (usually the problem with carbohydrate digestion or absorption),
- a pharmacological intolerance (caffeine histamine, tyramine, etc.),
- microbial toxins (e.g. scombroid poisoning from fish), or
- sensitivities with poorly defined mechanisms (sulfite, monosodium glutamate, etc.)

Key take away regarding adverse food reactions

The key takeaway regarding adverse food reactions is to seek the support of qualified healthcare professionals in diagnosis and management. Self-diagnosis has the potential to be harmful for a variety of reasons including lack of access to life-saving emergency medicine, utilizing best practice management plans, and improving quality of life. Ensuring optimal nutrition and development is especially important for pediatric populations.

A quick review of Adverse Food Reactions

Classic Food Allergy, Food Allergy, or Food Intolerance

Classic Food Allergy (IgE):

- Involves an immune system response (IgE-mediated)
- Reaction time: immediate (defined as within 2 hours)
- Signs & Symptoms: may include hives, rash, swelling, shortness of breath, nausea/ vomiting, etc.. and may lead to a very serious reaction called anaphylaxis.
- Diagnosis: based on clinical history, supporting blood or skin test, an oral food challenge. A physician diagnosis is required to be prescribed the life-saving medication epinephrine as well as a management plan utilizing best practices that are patient-specific.
- Management: avoidance of the food and all derivatives of the food, with some caveats in management plans regarding baked goods.
- The top allergens in the U.S. are cow’s milk, peanut, tree nuts, shellfish, finfish, wheat, hen’s egg, soy, and sesame. The allergic reaction is to one or more protein components of the food.
- Prognosis: there is the possibility to outgrow this allergy in some cases. There are also therapeutic treatments, such as OIT or SLIT currently showing effectiveness in developing tolerance/ desensitization or in some populations sustained unresponsiveness. There is no cure for IgE-mediated food allergy, but more treatment options are still being studied, and individuals should discuss the options for treatment utilizing a shared-decision making process between patient and physician.

Food Allergy (non-IgE):

- Involves an immune system response (non-IgE-mediated), often a pediatric disease.
- Reaction time: is a delayed, chronic reaction (will not lead to anaphylaxis)
- Signs & Symptoms: vary with diagnosis but are largely GI in nature (diarrhea, bloody stool, vomiting, etc.) and occasionally poor weight gain/failure to thrive.
- Diagnosis: clinical history; an elimination of the suspected allergen, confirmed with resolution of symptoms, and the return of symptoms following a re-introduction challenge
- Management: avoidance of the food; however, best practice includes a food re-introduction challenge date planned at the onset of the elimination period to determine if the patient has outgrown the allergy. IgE-allergy development prevention should be a consideration in the pediatric population.
- The top allergens for non-IgE allergy are cow’s milk, wheat, hen’s egg, soy, rice, and oats. The allergic reaction is to one or more protein components of the food.
- Prognosis: is often outgrown at varying points in childhood; however, some diagnoses and cases do persist into adulthood.

Food Intolerance:

- Does not involve an immune system response.
- Reaction Time: varies greatly, may be acute or chronic, immediate or delayed
- Signs & Symptoms: often GI in nature (gas, bloating, nausea, diarrhea) although may have extraintestinal symptoms as well (headache, flushing, swelling, etc.)
- Diagnosis: clinical history coupled with an elimination diet that supports resolution of symptoms. Medical diagnosis versus self-diagnosis
- Management: Avoidance of the food, drug, additive, etc. trigger. Many food intolerances are dose-dependent and case-specific, meaning, they are highly individualized regarding how much or which type of food is not tolerated. Working with a qualified healthcare professional can improve the management of food intolerances.
- The top intolerances: Most commonly intolerances involve a metabolic problem (inability to digest or absorb the food) with a carbohydrate although there are other types of intolerances to caffeine, histamine, microbial toxins, food additives, etc… Lactose intolerance (milk carbohydrate) is the most common food intolerance globally.
- Prognosis: This is highly specific as each intolerance needs to be identified by category, then whether the intolerance is the secondary or primary diagnosis. If intolerance is not the primary diagnosis in some instances the food may be tolerated once the primary diagnosis is resolved.

At Weston Nutrition & Wellness Eva Weston RDN, LD, NBC-HWC is a registered dietitian nutritionist and national board-certified- health and wellness coach (NBC-HWC).

Eva has additional certificates of training in Adult Weight Management from the Commission for Dietetic Registration (CDR) & in Pediatric Food Allergy from Food Allergy Research & Education (FARE).

WNW is here to help individuals living with a food allergy or intolerance.

Adverse food reactions: Do I have an allergy or intolerance? #002