by Nancy Weyrauch Mehlert, MS

Understanding allergies can be difficult because they are complex! You may want to believe it is simple, such as, “if I eat x, it causes y”. Or if you are exposed to pollen or dust, it makes your nose run. Allergies are, unfortunately, not this simple. In fact, inhalant/airborne allergies can be difficult to distinguish from food allergies and often are related. One of the reasons allergies are so complex is due to cross-reactivity. Cross-reactivity occurs when molecular structures are so similar that the immune system is unable to make a distinction between them. For example, poison ivy, oak, and sumac are closely related molecular proteins to pork and black pepper. As a result, evidence of respiratory allergy may indicate an increased risk of food sensitivities and visa versa.

One type of cross-reactivity is when a food produces a reaction only in the presence of an inhalant allergen, such as pollen. Called concomitant foods, these foods cause a reaction only during the season when a specific inhalant, such as mold or pollen, are high, but not at other times of the year. Or another interesting example is for grill masters out there using oak, pecan, or mesquite woods for grilling/smoking who are experiencing cross reactivity to foods concomitant with these woods. Here is a short list of proven common concomitant foods:

Poison ivy, oak, and sumac ……………….pork and black pepper

Ragweed …………………………………………. egg, milk, mint, melon, cucumber, banana, sunflower, echinacea

Iva ciliate…………………………………………..wheat

Sage…………………………………….…………….potato, tomato, chewing tobacco

Pigweed…………………………………………… pork, black pepper

Grass………………………………………………… beans, peas, soybean, cottonseed oil

Cedar………………………………………………….beef, baker’s and brewer’s yeast, malt

Elm……………………………………………………..milk, mint

Cottonwood…………………………………….…lettuce

Oak……………………………………………………egg, apple

Pecan………………………………………………..corn, banana

Mesquite………………………………………….. cane sugar, orange

Dust………………………………………………….. cheese, mushrooms, truffles

Birch…………………………………………………..apple, carrot, celery, pear, tomato, cherry, tree nuts

Another type of cross-reactivity occurs when two foods are combined. These are called synergistic foods where a reaction may not occur when each food is eaten separately, but, when combined at the same meal, these foods cause symptoms. It might explain why a hamburger on a bun, or chicken/apple breakfast sausage with eggs are causing your symptoms. Here is a list of proven synergistic foods:

Corn………………………………………………………………banana

Beef……………………………………………………………….baker’s yeast, brewer’s yeast

Cane Sugar……………………………………………………..orange

Milk………………………………………………………………..mint

Egg………………………………………………………………….apple

Pork………………………………………………………………..black pepper

A third type of cross-reactivity can occur with those who have latex allergy. They may discover a cross-reactivity with banana, avocado, chestnut, kiwi, apple, carrot, celery, papaya, potato, tomato, or melons. Often times people are allergic to latex and don’t know it because they can tolerate exposure to latex quite well but react more severely to the foods that cross react with it.

Understanding cross-reactivity may help you better understand your inhalant or food testing results. If you have had testing, but can’t seem to sort out all of your allergies, getting tested with both skin prick and the specific IgE/IgA food testing via blood may provide much greater insight, and offer tailored treatment and relief. It is also important to explore the possibility of cross-reactivity in gluten-sensitive patients who are not experiencing improvements after eliminating gluten. Ask your provider if the skin screen test for inhalant/environmental allergens, or the IgE/IgA food sensitivity test are right for you.

https://www.usbiotek.com/blog/cross-reactivity-more-than-foods

Popescu F. D. (2015). Cross-reactivity between aeroallergens and food allergens. World journal of methodology, 5(2), 31–50. https://doi.org/10.5662/wjm.v5.i2.31

https://atouchoftherapy.com/prevent-allergies-concomitant-foods/