Today I’d like to explore food allergies vs. intolerance vs. sensitivity. I think there is a lot of confusion around these terms and how, even if, they differ. The words are bandied about the news and Internet, along with fear-inducing warnings and questionable information. It seems more and more people have problems with certain foods, or claim they do, and it’s hard to know when the claims are serious. You may have been on an airplane where they announced “No peanuts today as there is a passenger with a peanut allergy on board.” Or maybe your child’s school sent a note prohibiting peanut-containing snacks or lunches. “Wow,” you may think, “is it really that dangerous?” For some people the answer is yes. So let’s outline the differences and similarities.

          An actual allergy to a food causes the body’s immune system to react, sometimes aggressively. The body views a protein in the food as an invader and attacks the invader with antibodies. You may be familiar with people taking an anti-histamine medicine when they have hives or itchy seasonal allergy symptoms – the histamine produced by the body in this fight against invaders causes those symptoms. However, a true food allergy can be much more serious, causing anaphylactic shock in some people. Other symptoms are less serious but can increase in severity if exposure continues. These could be skin reactions, like hives, swelling, and itching or digestive symptoms like vomiting, diarrhea, nausea, and stomach pain.

          A food intolerance does not involve the immune system. Intolerance most often means your body cannot break the food down properly in your digestive track. Milk intolerance is the most common, and is due to lack of the enzyme lactase needed to break down the lactose in the milk. Other causes of intolerance are certain food additives like sulfites or nitrites; extreme aversion to a certain food; and intolerance of naturally occurring substances like histamines. Generally the symptoms of food intolerance are gastrointestinal-related. Some blog articles point to skin disorders from intolerances but the medical sites did not list skin problems as related to food intolerance. Food intolerance will not cause anaphylactic shock.

          Food sensitivity is sometimes the term used for food intolerances, but where it is distinguished it refers more to the    discomfort some people may experience after eating spicy foods or acidic foods, or the faint mouth itchiness some people get after eating a banana but with no other symptoms. Food sensitivities also do not involve the immune system.

While allergies and intolerances share some symptoms, the main difference is the involvement of the immune system. Also, reactions from a food allergy generally begin immediately or within a short time of eating the food, where reaction from a food intolerance may not show up for hours or even a few days. An allergy causes a reaction from even a small amount of the food but intolerance usually flares up after eating a lot of the problem food. I am lactose intolerant but find I can have a small amount of cheese, for instance, without symptoms, especially if I indulge only on occasion. My experience highlights another difference – an allergy causes the reactions every time the offending food is eaten but a food intolerance often only flares up if the food is eaten often. Allergies can be life-threatening but intolerances are not.

Just as food allergies and intolerances can be outgrown or fade, we can also develop an allergy or intolerance as adults, even after eating the food for years without problems. This is very common for milk intolerance. Children with food allergies often outgrow them, especially milk, egg, and soy allergies, usually by age 6 or 10. It is less likely they will outgrow peanut, tree nut, or shellfish allergies.[1] The most common allergens, accounting for about 90% of food allergies, are: milk, eggs, fish, shellfish, peanuts, tree nuts, wheat, and soybeans. [Note that gluten is not listed here, even though it seems to be such a huge topic. You may think people with celiac disease(~ 1% of the US population) are allergic to gluten but it is not an allergy, rather it’s an autoimmune disease.  ‘Non-celiac gluten sensitivity’ is a fairly new disorder and one that is difficult to diagnose, as there is no test for it and removing gluten from the diet may also remove other causes of the symptoms.]

If you suspect you have an allergy to a food, you should avoid the food and seek testing to be sure. If it proves you are allergic you will need to continue to avoid the food, and other foods that may include it. If your symptoms are severe you should carry an epinephrine pen at all times.  If you suspect you have a food intolerance, the best way to be sure is to track what you’ve eaten when you experience the symptoms, and then try an elimination diet on the most likely culprits. This should tell you if you can eat a little on occasion or should just eliminate it for good. Remember to check on preparation when eating out – was the sauce made with shrimp stock and you are allergic to shrimp? I have a friend who is allergic to potatoes and has to be careful of fried foods, soups, breads, and sauces because they often have potato or potato starch, or were cooked alongside potatoes. Read labels, ask questions, and protect your health.

[1] http://blog.foodallergy.org/2013/09/13/who-is-likely-to-outgrow-a-food-allergy/

 

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