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Understanding Allergen Cross-Reactivity and Food Sensitivities: How to Manage Them Using Labs and Functional Medicine Treatments

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Understanding Allergen Cross-Reactivity and Food Sensitivities: How to Manage Them Using Labs and Functional Medicine Treatments

The world of food reactions can often be confusing to some. Are food sensitivities the same as allergies? If not, what is the difference, and how does it affect your health? When you throw allergen cross-reactivity into this food reaction mix, it can make it even more complicated. The symptoms of food reactions can vary in severity and length from person to person, making these reactions more challenging to understand. However, proper testing utilizing functional medicine labs can help decipher these differences so effective management strategies can be implemented that are individualized to your specific reactions, allergies, or sensitivities.


What Are Food Sensitivities?

Although food sensitivities are not life-threatening, they do create an inflammatory response from the body's immune response toward a specific food that can cause chronic health problems. A food sensitivity will typically have a delayed response in which the reaction involves the specific immunoglobulins G (IgG). Evidence shows that an IgG food reaction occurs when a particular food is consumed, and the body creates an IgG antibody to attack that food leading to an inflammatory response and symptoms.

Are Food Sensitivities The Same As Food Allergies?

To help you decipher through some of the confusion around food sensitivities and food allergies, let's first state that these food reactions are not the same. These food reactions are often mistaken for each other. However, these reactions are mediated by different immune responses from your body. Food allergies have an IgE antibody reaction, whereas food sensitivities have an IgG antibody reaction. The IgE response can typically occur immediately or within hours, and IgG is generally more delayed. IgE responses can create life-threatening anaphylactic reactions; IgG responses are milder but can lead to chronic conditions.

What is Allergen Cross-Reactivity?

Cross-reactivity is when the immune system recognizes an allergen like pollen and similar proteins found in food and initiates an allergic response to it. This cross-reactivity can also occur between various foods. Foods are categorized into food families based on their taxonomic relationships and their ability to trigger cross-reactive antibody responses. Cross-reactivity occurs when you react to a food that is the same food family. Some common cross-reactive allergens include:

Pollen-Food Allergy Syndrome (PFAS)

PFAS, commonly referred to as oral allergy syndrome, arises from cross-reactivity between allergens present in pollen and certain raw fruits, vegetables, or tree nuts. Those affected by PFAS can often consume the same fruits and vegetables when they are cooked, as the heating process alters the proteins, making them unrecognizable to the immune system.

Latex-Fruit Syndrome

Latex-Fruit Syndrome, or latex-food allergy syndrome, affects up to 50% of people with a latex allergy. This condition arises due to the similarity between proteins in certain foods and those found in rubber tree sap used to make latex. Common trigger foods include avocado, banana, bell pepper, chestnut, fig, kiwi, peach, and tomato.

Wheat-Multiple Food Allergies

People with wheat allergies often exhibit cross-reactive allergies to other cereals, such as barley and rye, and occasionally to oats. This cross-reactivity is likely due to the taxonomic relationship among these grains since wheat, barley, rye, and oats all belong to the same family.

Mold Cross Reactions

Cross-reactivity can occur with mold as certain foods contain mold, such as cheeses, peanuts, melons, sake, vinegar, kombucha, alcohol, soured breads, fermented foods, cider, root beer, pickled and smoked meats, dried fruits, canned tomatoes, and canned juices. This cross-reactivity may occur because the mold has contaminated the food or because the deliberate use of specialized mold involves fermenting certain foods, like kombucha, sake, and soured foods.

Tree Nut Cross-Reactivity

Peanut and tree nut allergies can be potentially life-threatening and often persist throughout a person's life. While a peanut allergy is more prevalent, many individuals will develop sensitivity to both peanuts and tree nuts. Despite peanuts being legumes, approximately 20 to 30 percent of people with peanut allergies also experience allergic reactions to one or more types of tree nuts. Among tree nuts, walnut, pecan, and hazelnut form a highly cross-reactive group, while hazelnut, cashew, Brazil nut, pistachio, and almond constitute a moderately cross-reactive group.

Allergen Cross-Reactivity and Food Sensitivity Signs & Symptoms

Allergen Cross-Reactivity Signs and Symptoms are associated with the IgE allergy response. The common symptoms include:

  • Skin itching
  • Hives
  • Swelling of the skin
  • Nausea
  • Vomiting
  • Diarrhea
  • Breathing difficulty (wheezing, repeated throat clearing, cough, and throat tightness)

Anaphylaxis can occur with IgE allergies, and these symptoms include:

  • Rapid and progressive onset
  • Involvement of multiple organ systems from the above list
  • Dizziness or loss of consciousness (due to a drop in blood pressure)
  • Other serious, potentially life-threatening complications

Symptoms of food sensitivities can vary and range from person to person. The common symptoms include:

  • Abdominal distention and cramping
  • Irregular bowel movements
  • Skin issues
  • Headaches
  • Fatigue
  • Joint pain
  • Hair loss
  • Hives

Allergen Cross-Reactivity and Food Sensitivity Possible Causes

There are some differences in the causes for the allergen cross-reactivity versus food sensitivities. Cross-reactivity is caused by an IgE reaction to a similar protein to another IgE allergy response. The immune system recognizes similarities between proteins in different substances, like pollen and fruits or vegetables. When an individual encounters either of these proteins, their immune system may respond in a similar manner, even if they are not truly allergic to the specific protein. This cross-reactivity can lead to allergic symptoms in some instances.

In the case of food sensitivities, evidence suggests that the food reactions are caused by increases in intestinal permeability, also known as leaky gut. This permeability allows food particles to get into the body's circulation and trigger increased production of a food-specific antibody response, specifically an IgG response. It's the IgG response to foods that can cause symptoms in people.

Functional Medicine Labs to Test for Root Cause of Allergen Cross-Reactivity and Food Sensitivities

The following functional medicine labs will help you and your practitioner decipher your specific reactions so adequate treatment approaches can be utilized:

P88 Dietary Antigen Test

This food sensitivity and allergy test assesses for IgE, IgG, IgG4, and C3d reactions. The selection of the 88 foods on the test aims to cover a wide range of commonly consumed foods, providing valuable insights to providers. Additionally, the diversity of foods in the panel enables the detection of some items that may not be included explicitly. Cross-reactivity between different food groups is also considered, allowing clinicians to consider foods beyond the panel's specific scope and create appropriate dietary changes for their patients. This lab also provides a guide for practitioners that contains a table with the most common cross-reactivities.

Array 4

This gluten-associated cross-reactive foods and food sensitivity profile investigates sensitivity to dietary proteins and foods that cross-react with gluten, the protein found in wheat. By identifying other foods a patient might be intolerant to, this test helps determine potential eliminations required in their diet.

IgE Environmental Allergy Test

The environmental allergy panel assesses IgE antibodies to 88 different antigens, such as pollens and molds. This test can help practitioners identify the underlying cause of allergies and its possible cross-reactions. If you are reacting to foods such as cheese and peanuts or fruits, but those are not showing up on an IgE or IgG test. This environmental panel is a great lab test option to see if you may be cross-reacting.

Advanced Intestinal Barrier Profile

While clinicians frequently rely on food sensitivity testing or stool analysis to indirectly evaluate gut health, the IBA profile provides direct leaky gut markers. It measures Zonulin, DAO, and LPS, which are the three markers associated with gut permeability. Since food reactions are shown to be caused by increasing intestinal permeability, this test can get directly at the root cause to help address food sensitivities and improve them.


Functional Medicine Treatment for Allergen Cross-Reactivity and Food Sensitivity

One of the best strategies for treating allergen cross-reactivity and food sensitivities is through functional medicine approaches such as personalized nutrition and supplements to help reduce those reactions. Here are the functional medicine approaches often used by practitioners to address these concerns:


The standard approach for addressing known food allergies is to avoid the allergen that is creating the symptoms. If you do not know your specific food allergies, testing utilizing the functional medicine labs mentioned in this article can help guide you. The elimination diet can also be helpful. An elimination diet is a protocol that removes specific foods and chemicals to identify sensitivities. It is used in functional medicine to pinpoint food reactions that are difficult to detect through history and diet records alone due to various symptoms and delayed reactions. During the diet, suspected foods are eliminated for 3-4 weeks, followed by a gradual reintroduction under professional guidance. Foods that still cause symptoms are avoided for an extended period before considering reintroduction.

Supplements & Herbs

Functional medicine practitioners commonly use the following supplements and herbs to address food sensitivities and cross-reactivity:


Quercetin has various beneficial properties, including antioxidative, anti-inflammatory, anti-carcinogenic, anti-microbial, and immunomodulating effects. Quercetin has shown the potential to improve allergic diseases at 50 mg twice daily for eight weeks.

Vitamin C

Vitamin C is a major antioxidant and has been shown to have antihistamine and anti-inflammatory effects that can help with allergies. The Recommended Dietary Allowance (RDA) for Vitamin C varies depending on age. The RDA is 15mg for one-year-olds, while for male adults aged 19 and above, it increases to 90mg.


Omega-3s are essential fats that play a crucial role in human health due to their lipid-mediating and anti-inflammatory properties. This supplement may also play a role in preventing allergic type conditions in infants if the mom was taking it as a supplement. The general dosing recommendation is 1000 mg daily and for 4,000 mg (with ~ 1,100-1,600 mg EPA/ 920-2,250 mg DHA) per day from 20-25 weeks gestation until delivery to pregnant women with optional continuation for 3-4 months during breastfeeding.


Probiotics can help with maintaining a healthy microbiome which can help with gut health and permeability. Probiotics should be taken regularly for those with food reactions and intestinal permeability.


Another approach to healing intestinal permeability and gut health so you can improve your food reaction response is through a supplement called L-glutamine. This supplement is an amino acid that fuels the small intestine cells. Functional medicine practitioners often use this supplement to help support their patient's intestinal healing.

Complementary and Integrative Medicine

The following are complementary and integrative medicine approaches to manage cross-reactivity and food sensitivities effectively:


Acupuncture has been shown to be a great complementary therapy for alleviating allergy symptoms. Studies have determined its effectiveness in improving conditions like allergic rhinitis, which can be associated with secondary pollen food allergies. This therapy can help reduce nasal irritation and may also treat hives effectively. Acupuncture can be a powerful tool to help improve allergy-related symptoms and overall quality of life.

Tips for Coping with Food Sensitivities in Daily Life

Coping with food reactions can present some challenges in daily life. However, specific strategies can be utilized to help to guide you. One such strategy is navigating social situations and dining out. In this situation, you will want to inform the staff about your food reactions, ask for allergen-free options, or proactively choose restaurants that offer those options. Creating an allergen-free environment at home will also be important. In this scenario, one of the best things to do is to read all labels and their specific ingredients to avoid any hidden sources of reactive foods. While incorporating these dietary changes, it's also essential to have a support system to ensure your success. Educating your family, friends, or colleagues can set expectations and provide the support you need.



Although allergies, cross-reactivities, and food sensitivities can be challenging to navigate. With proper understanding and guidance, these food reactions can be easier to follow and manage.  If you are dealing with any symptoms from foods or other allergies, using functional medicine approaches such as testing can point you to your specific reactions so you can properly manage and treat those reactions. Once you receive the completed tests, functional medicine practitioners can use those results to personalize treatments using nutritional plans, supplements, or other integrative approaches to help you on your healing journey.

The information provided is not intended to be a substitute for professional medical advice. Always consult with your doctor or other qualified healthcare provider before taking any dietary supplement or making any changes to your diet or exercise routine.
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