|“I Can’t Eat That!” Introduction to Food Allergies in Corrections|
|By Jeffrey E. Keller MD|
In my previous incarnation as an emergency physician (before I discovered “The Way” of correctional medicine), I saw a lot of cases of acute allergic reactions. It is a very common emergency complaint; I have probably seen hundreds in my career. But when I began my jail medicine career, I was still unprepared for the sheer volume of food allergies claimed by inmates. Who knew so many inmates had so many food allergies?
Of course, most of them don’t. Most just don’t want to eat something on the jail menu. Inmates believe that if they claim an allergy to a food they dislike, you cannot serve it to them. They will claim allergies to tomatoes, onions, mayo, etc., when really, they just don’t like these foods. Tuna casserole doesn’t seem very popular, for some reason. However, some inmates truly are allergic to some foods and we can potentially harm them by ignoring their complaint. How do we correctional medical staff sort out the truly allergic from the “I don’t like it” crowd? It is an important question because we certainly don’t want anyone in our care to have a sudden anaphylactic reaction!
To answer this question, we need to understand the mechanism of food allergies, the overall incidence of food allergies as well as the incident of death, how to accurately diagnose a true food allergy and what steps to take once we find one. All of this is important to make accurate risk assessments.
The incidence and causes of food allergies vary markedly with age. For the most part, food allergies are a problem of childhood. In children, the most common food allergies are milk, eggs, wheat and nuts. However, most of these allergies abate with time. So a child who is allergic to eggs most likely will be able to eat eggs as an adult. One important exception to this rule is peanuts and tree nuts (like almonds, cashews, etc.). Those allergies tend to persist into adulthood. The most common adult food allergies are peanuts, tree nuts, shellfish and fish.
True food allergies come in two types. The first are called IgE Mediated Allergic reactions because the IgE antibody is essential to the reaction. The second type of allergic reactions does not involve IgE and so, of course, are called non-IgE mediated food allergies. The best example of this is celiac disease in which patients are allergic to gluten found in grains. Non-IgE mediated allergic reactions are typically indolent and chronic and may not be discovered for several years.
IgE is an antibody that is created by the body to react to a specific antigen substance. This substance can be ragweed pollen, of course, but it also can be food proteins. Later on, if the person eats the same food to which IgE was created, the protein locks onto the IgE which causes the release a bunch of inflammatory chemicals, such as histamine, cytokinens, prostaglandins and leukotrienes.
The most common symptom caused by these inflammatory chemicals is hives, the itchy splotchy rash we have all seen. The second most common symptom is angioedema, which is swelling of the face. Angioedema most commonly occurs around the eyes but also rarely can cause the tongue to swell. Third and less frequently, the allergic reaction can cause bronchospasm in the lungs, so the patient wheezes as if having an asthma attack. Finally, the patient can suffer anaphylaxis, which consists of acute vasodilation leading to hypotension, shock and possibly death.
All of these allergic symptoms occur within minutes of eating. Allergic hives occurring several hours after eating are probably NOT due to the food.
Of these four allergic symptoms, by far the most common are hives and angioedema. However, most of the time hives and andioedema are nuisances rather than life threatening emergencies. On the other hand, anaphylaxis is an acute medical emergency. Anaphylaxis is the allergic reaction we should fear the most and work to prevent.
The CDC estimates that approximately 100 deaths from food allergies occur in the US per year. Almost all of these deaths occurred in teenagers or young adults who knew that they were allergic to the food they ate. By far, the most common culprit foods are peanuts and tree nuts (85%) with shell fish coming in second. In contrast, 400 deaths due to allergic reactions to penicillin occur every year, most of those occur in people who have no idea that they are allergic.
Now let’ summarize some of the more important points presented so far.
However, there are other tests that also can help you sort out the confusing cases. The first is called a CapRAST test. This is a blood test that measures the levels of IgE to a certain specific allergen, say peanuts. We then draw blood for a CapRAST for peanuts. A positive result is peanut specific IgE of greater than 2.0 Ku/L. If the test comes back at, say, 0.35 Ku/L, then the patient is not allergic. The test is quite sensitive but not specific. That means that you can believe a negative result, but patients with positive results might still NOT be allergic. The main problem with a CapRast test is that it is expensive—around $45.00! However, that is probably less expensive than the cost in time and energy putting out a special diet.
A second test is the skin prick test. In this test, the patient’s skin is pricked with a small instrument and a drop of allergen extract is placed on the site. If a patient is truly allergic, she will form an itchy wheal at the site within 5-15 minutes. The advantage of this test is that it is cheap and easy to do and the results are immediate. The disadvantage is that you have to order and store the extracts and be trained in the procedure, usually by an allergist.
“Food Challenge” tests probably should not be done in a correctional setting. This is where you simply feed the food to the patient and wait to see what happens. If this is done in a double blinded fashion, it is the most accurate test of all. Sometimes, patients will have done their own food challenge without knowing it. For example, a patient might say he is allergic to eggs but admits to eating pasta and mayonnaise, both of which are made with eggs. He is likely not truly allergic.
Of course the easiest way to deal with the foods most likely to cause severe allergic reactions is not to serve them at all. Most jails do not serve shellfish to inmates (if your jail does, write me; I would like to know about it!) If your facility uses tree nuts in cookies, consider eliminating them from the menu. Then you won’t have to worry about it. That just leaves peanuts as the food served in most prisons and jails that has the greatest potential to cause allergic reactions.
Once you have discovered that a patient has a positive CapRAST test to peanuts, what should you do then? It may not be enough to simply order a peanut free diet. Since allergic reactions can be triggered by even a small amount of allergen contact, you should consider these other factors:
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