Peanut and Other Food Allergies -- Scott Sicherer, MD -- 07/24/03
By Scott Sicherer
Peanut allergies continue to make the news, and other food allergies, from wheat to dairy, seem to be on the rise. Are they? What's the latest info on prevention and treatment? And how does an allergy differ from an intolerance? We welcomed food allergy expert Scott Sicherer, MD, to WebMD Live.
The opinions expressed herein are the guest's alone and have not been reviewed by a WebMD physician. If you have questions about your health, you should consult your personal physician. This event is meant for informational purposes only.
Moderator: How prevalent are peanut allergies? And how serious are they?
Sicherer: Well, we estimate that approximately one in 150 people has a peanut allergy, and the severity of a peanut allergy can range from quite mild to very severe and potentially deadly.
Moderator: What would a reaction entail?
Sicherer: Reactions can range from mild symptoms, such as an itchy mouth to other symptoms, for example, reactions of the skin with hives and swelling; breathing problems, such as throat tightness, and wheezing; gut problems, such as stomach pain and vomiting. The most severe symptoms can affect circulation with heart failure, passing out; this is where reactions can progress to death.
Member question: How do peanut allergies develop?
Sicherer: Individuals may be at risk for allergy, in general, based upon, for example, a family history of allergy, things like asthma, eczema and hay fever. In allergy, when the immune system, the part of our body that is supposed to help us fight infections, directs itself against harmless proteins, such as those in peanut, and when this happens we may develop a peanut allergy or other food allergy.
Moderator: There has been some exciting news lately for people with peanut allergies.
Sicherer: One of the hopes for treating food allergy is that we could say more to our patients than just avoid the food and have medications ready to treat reactions. There are several angles of research under way to try to get to this point. One of the most recent exciting findings was the use of a medication called anti-IgE. This treatment binds up the protein that our bodies make in an allergic reaction, which is called IgE antibody. In the study that we did, persons over age 12 with peanut allergy were treated with this medication at various doses, and what we saw was that on average at the highest dose they went from having a reaction at about half a peanut to tolerating on average about nine. This treatment is not really peanut specific and we hope it would be similarly protective for other foods. However, this was just a first study and we need to do more to learn exactly what protection and how to dose this medication.
Moderator: It doesn't prevent an allergic reaction, but increases the level of tolerance for those with allergies?
Sicherer: The primary use of this medication would be to provide a safety net for someone with food allergy. In other words, they would still avoid the food, but if an accident occurred, they would perhaps have milder or no symptoms. There are also a number of research efforts to create vaccines like allergy shots that would more definitively stop the allergic response to various foods.
Member question: Is my 6-year-old son eligible to receive the vaccine?
Sicherer: Currently there is no vaccine available for food allergy, it is just being researched in animal models of food allergy, not in people. For the anti IgE discussed earlier, we need to do more studies in younger individuals for more foods and for different dosing regimens.
Member question: In your opinion, how long will it be before these treatments are available to the general public?
Sicherer: It's hard to predict when these would be available. But we certainly are making efforts to move things as quickly as possible.
Member question: If my son has a Level 5 peanut allergy, does that mean he could have a terrible reaction if he's in the same room with someone eating a peanut butter sandwich?
Sicherer: The blood tests for food allergy are measuring the IgE antibody I mentioned earlier. The more of this antibody to peanut, for example, that an individual makes, the more likely it is that they would have a reaction if they eat peanuts.
However, the level does not correlate well at all with severity of reaction. For example, two persons with the same level may have very different reactions compared to each other and may also have different types or severities of reactions at different times. It is generally considered to be unusual for someone to have a significant reaction from casual exposure to peanut butter such as smelling it, and we did a study recently that confirmed this notion. It seems that peanut butter is less likely to put off peanut protein into the air than might happen, for example, when powdering peanut snacks are opened on an airplane. However, even a tiny amount of peanut butter, if ingested, could cause a severe reaction for a person with peanut allergy, and therefore care in school settings, for example, is very important.
Member question: My son accidentally consumed peanuts hidden in food and experienced allergic reaction three times in the past. His reaction has developed from mild to severe. Why?
Sicherer: There is an impression that each time a person is exposed to the food to which they are allergic that the reaction may get worse. This is actually a myth. In general, on average, reactions tend to be similar from time to time. The problem is that severity is unpredictable and someone who has experienced only mild reactions may at some point have a severe one. That is why it is always important to be careful for avoidance and have emergency medications, such as epinephrine available.
Member question: Is one likely to outgrow the type of allergy that causes anaphylaxis?
Sicherer: Let's take peanut allergy as an example. The dogma has been that no one outgrows a peanut allergy. However, recent studies have shown that about one in five young children outgrow their peanut allergy by age 4 or 6. In several of the studies about the phenomenon, even children with severe reactions sometimes outgrew peanut allergy. In these studies, children who outgrew their allergy tended to have few additional food allergies and at the age of 4 or 6, had relatively low IgE antibody to peanut on blood tests, and relatively small allergy skin tests, and these seemed to be the best predictors for those who have outgrown their allergy.
Member question: Can't Epipens be dangerous in to use?
Sicherer: Epinephrine is the primary treatment for severe allergic reactions from foods or other causes; for example, bee stings. This medication should be given promptly because delayed administration has been associated with poor outcomes, including death. This medication is quite safe and was the same medication used to treat asthma before aerosols were available. The primary side effect is that the heart races, which is not dangerous for people who do not have heart disease; but actually, even if you had heart troubles, this would be the right medication to use to prevent a bad outcome from an allergic reaction.
So the answer for anyone and everyone who's having a severe reaction is to use this medication. After it's used, it is essential to go to an emergency room, e.g., call 911, for further treatments. Sometimes reactions recur, and I suggest staying in the emergency room for at least four hours to be certain the reaction has subsided.
Member question: How accurate is the labeling of foods in the U.S. and Canada? Many things have the warning "may contain," which severely limits choices.
Sicherer: Unfortunately we have to depend upon the manufacturers in regard to labeling.
At this time such labeling is voluntary. The FDA is currently investigating various practices to try to improve labeling. I tell my patients that they have to avoid the foods when the package indicates that it may contain what they are allergic to. What becomes tricky and is an important educational point for people with food allergies is that ingredient labels pose numerous challenges, including one, that ingredients may change, even within the same product; two, that ambiguous terms, such as "spices" or "natural flavor" may be used and one would have to ask the company what this means, and; three, scientific terms are sometimes used, such as casein or whey for milk protein. Hopefully, new laws will improve the situation. It's very important to read the label each time.
Member question: When my son was diagnosed with peanut allergy I was told to avoid all legumes, even though he had eaten green beans and peas and never had a problem with them. Why is this?
Sicherer: It turns out that peanut, which is a legume, is really much more allergenic than other beans, and therefore studies have shown only one in 20 persons with a peanut allergy react if they eat other beans. However, if one performs allergy tests to a group of beans, they are likely to be positive in an individual who has peanut allergy, even though they can usually eat these other beans. Therefore, I usually do not have persons who are tolerating other beans stop eating them; however, if they are not eating them, I need to consider the possibility, 5%, that they may have a problem. In your son's case, you will need to discuss this again with your doctor because there may be other circumstances for him.
There appear to be several beans that are a bit more problematic than others, and these include lentil, garbanzo, and lupine. Again, all of this needs to be individualized with your doctor.
Member question: Is it true that children are more likely to develop peanut allergies if their mothers eat peanuts while pregnant or nursing?
Sicherer: My answer to this question is that we do not have enough studies to put anyone on a guilt trip. Studies have not definitively shown that alteration of the diet during pregnancy impacts future allergy to peanut, although it has been recommended that in families with a high risk of having a child with food allergy that peanut be avoided in the third trimester. The definition for an at-risk child would be one where both parents or a parent and other sibling have allergies. However, this recommendation from the American Academy of Pediatrics mentions that this dietary avoidance should be considered and that it is not a definitive recommendation for breastfeeding, it has also been recommended to avoid peanut but some studies show no effect and others show a possible effect for this recommendation. Lastly, in allergic prone children, it has been recommended not to introduce peanut until after age 3. I must emphasize that these recommendations are just that, recommendations, and definitive studies do not exist.
Member question: Ever since my son was diagnosed with peanut allergy we haven't had any peanut products in our home. I never ate it when I was pregnant with his younger sister and she has never been exposed. Should I have her tested to see if she is allergic? And at what age?
Sicherer: In a study on the genetics of peanut allergy, we found that there is a 7% risk for peanut allergy in a sibling of a peanut allergic child. Certainly with that risk I would suggest testing before introducing peanut. You will have to discuss with your doctor at what point to undertake testing. For example, perhaps waiting to the age where you might give peanut or near school entry. It turns out that 80% of the time that individuals have a reaction to peanut it has been on what they consider their first known exposure. So for your daughter who has not been exposed, it is still possible for their allergy to occur.
Member question: I recently read something in the newspaper about using liquid charcoal to treat a peanut allergy reaction. Should I buy liquid charcoal?
Sicherer: The study that you're referring to took what is called activated charcoal, mixed it with peanut butter in a test tube and tested the mixture for the ability of this substance to absorb out the peanut. Activated charcoal is a treatment used for poisonings to remove toxins from the gut. This study showed that peanut could also be neutralized. However, this was a study done in a test tube, and we do not know how well it might work in the setting of a true peanut ingestion in an allergic individual. Therefore, for right now, I still suggest standard treatments outside of the hospital setting. Activated charcoal is also very difficult to give, particularly to young children -- it tastes terrible. And it could potentially neutralize oral antihistamines that may be helpful for an allergic reaction. Overall, using this treatment is something you need to discuss with your doctor, but I would be cautious.
Moderator: Let's look at other food allergies -- what are some of the most common food allergies besides peanuts?
Sicherer: Well, peanut has dominated this discussion for several clear reasons. However, there are many other foods that can cause allergy. In children, milk, egg, wheat, soy, peanut, tree nuts, and seafood are all common allergens and the group accounts for 90% of food allergies in children. Fortunately, most children outgrow their allergy to milk, egg, wheat and soy. In adults, the most common significant food allergies are to peanut, tree nut, and seafood (fish and shell fish). However, any food can potentially cause an allergic reaction, and the most common cause of mild allergic reactions, such as an itchy mouth, are raw forms of fruits and vegetables.
Member question: I am allergic to most fruits and vegetables. Is there anything I can do so that I won't get sick eating them?
Sicherer: Individuals who experience an itchy mouth from a variety of fruits and vegetables in the raw form usually have what is called oral allergy syndrome or pollen-food allergy syndrome. This happens because initial allergy to pollens, such as birch and ragweed occur. And the proteins are in these pollens are very similar to those in a variety of fruits and vegetables. Luckily, most people with this type of allergy have mild symptoms and tolerate the cooked form of the foods. Unfortunately, a minority may have more severe reactions sometimes even to the cooked forms, and these issues need to be discussed with your doctor. Most physicians recommend avoiding the foods that cause a reaction in the mouth, but the cooked forms are usually tolerated.
Member question: I am allergic to ragweed and when I eat raw apples my mouth breaks out and my ears itch. Could this turn into a severe reaction like the peanut allergy?
Sicherer: Usually allergy to birch pollen is associated with mouth and ear itching to rock fruits, such as apple, peach, and plum. Usually this is a mild reaction but one or two percent experience a more severe one. Some people with this type of allergy believe that they are allergic to fertilizers because if they peel the apple they have fewer symptoms. Actually, the proteins are concentrated near the peel, and that is the explanation for this phenomenon. Again, the majority of allergists recommend not eating the fruits causing this problem and usually not every fruit within the family (e.g., plum, pear) causes the problem. Again, cooking the fruit or eating the canned versions should bypass the problem.
Member question: I have recently found that whenever I eat cashews or almonds I break out in hives. I have two questions. One, why has my body suddenly become allergic to them when I never used to be? Two, how come I can't eat those nuts but can eat peanuts?
Sicherer: An allergy can happen at any age and unfortunately, we do not know why. When an individual is allergic to one type of tree nut, they may often experience reactions to other tree nuts. Tree nuts include walnut, cashew, Brazil nut, macadamia, pecan, pistachio, and others. However, peanut is a legume, a bean, and is generally unrelated to these tree nuts.
Epidemiologically, because these are all allergenic foods, there is a higher rate of having both tree nut and peanut allergy. However, it is quite possible to be allergic to one and not the other.
Member question: I am allergic to fish, but can eat canned tuna! Can you explain more about fish allergies?
Sicherer: Similar to the tree nut story, it is possible to be allergic to one type of fish and no others. However, most individuals with a fish allergy react to numerous types of fish.
Canned tuna is a special case. In the canning process, many of the allergenic proteins are destroyed and so many fish allergic individuals tolerate canned tuna. However, like everything in medicine, there are exceptions, and some individuals even react to tuna.
Interestingly, for those of you allergic to things like milk, read your tuna fish cans carefully. Sometimes you will see that casein has been added and this is a milk protein. That could be problematic for those with milk allergy.
Moderator: Dr. Sicherer, we are almost out of time. Before we wrap up for today, do you have any final comments for us?
Sicherer: Food allergy causes a variety of problems, not just immediate reactions, but if you suspect a food allergy you must discuss it with your doctor. An allergist is best qualified to diagnose and treat food allergy. These are serious disorders, and anyone who suspects they have a food allergy should get a definitive diagnosis, be educated about avoidance of the food, and learn how and when to use lifesaving medications, like epinephrine. More information is available of the web site of the Food Allergy and Anaphylaxis Network and that's www.foodallergy.org, and the web site of the American Academy of Allergy, Asthma and Immunology and that's www.aaaai.org.
Moderator: Thanks to Scott Sicherer, MD, for sharing his expertise with us today. For more information, please visit our message boards: Allergies: Support Group and Pediatrics: Steven Parker, MD.
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