What You Need To Know About Food Allergies

It is estimated that more than 50 million Americans have a food allergy of some kind. Food allergies are estimated to affect six percent of children and four percent of adults, according to the Centers for Disease Control and Prevention.

While most common in babies and children, food allergies can appear at any age.

Here is an interview that Dr. Alyson Smith, a pediatrician and allergist at SBH Health System, did recently on SBH Bronx Health Talk.

Q. Dr. Smith, food allergies are more common with children. Does that mean that many children outgrow their allergies over time?

A. The majority of kids will outgrow their food allergies. The most common ones among small children are things like milk, egg, wheat, and soy. Generally they will outgrow those as they get older. Yet, many may develop allergies to things like peanuts, tree nuts and shellfish as they get older and, unfortunately, most will not outgrow those allergies.

Q. Now a food allergy is different than a food intolerance, right?

A. Yes. A lot of people will think they have a food allergy when they are more likely lactose intolerant, where maybe they get diarrhea or distention when they drink milk. They think of that as a food allergy, but when we’re talking about true food allergies we’re talking about an abnormal immune response to a food.

Q. Can a food allergy become progressively worse over time?

A. Absolutely. Sometimes a patient could have a really mild reaction, maybe a little itching with some food or a little bit of a rash and then the next time they could develop anaphylaxis and that’s where it’s scary because you don’t know what the next reaction is going to be.

Q. What exactly is anaphylaxis?

A. There’s different criteria for anaphylaxis, but the most common one that I like to use is that at least two systems are involved. So if you have, let’s say skin involvement, where you have hives or swelling, and then you have respiratory involvement, let’s say a dry cough or wheezing or shortness of breath, that would be anaphylaxis. We’re also looking at systems like the GI system so if a patient is having abdominal pain, vomiting, diarrhea that would be another system.

Q. Anaphylaxis is where you use the EpiPen, right?

A. Yes. So we recommend that anyone who has a food allergy carry an EpiPen anywhere they might be exposed to food. So they should have them in schools, at home, at work. It’s a really easy thing to use. People are very scared to use EpiPens, but it’s life-saving and it’s just a needle that the person presses into their leg, like an auto-injector, and then after it’s used that patient must go to the emergency room.

Q. Do you have children using it too?

A. Yes, so there’s different dosages for EpiPen. We have EpiPens for kids because it’s weight based and we have EpiPens for adults.

Q. I’m guessing you don’t test for a food allergy until there’s an episode right?

A. Yes. The problem with skin and blood testing for allergies is that there is a high false positive rate so we only recommend testing for foods if there’s a concern that a food might be causing a reaction. The gold standard for testing is a food challenge, so if someone is eating something right now and they’re fine eating it, then they’re not allergic to it. We do testing specifically for foods that we are concerned about.

Q. What does the testing entail?

A. So there’s different ways to do testing. The ones we do commonly in the office are skin testing and it’s similar to the testing we do for other allergies like pollen. It’s very easy. We just press something onto the top of the skin. It leaves a little drop of liquid and a very small amount is injected into the skin. Then you wait 15 minutes and if you get a little itchy bump or hive that tells us that the patient is sensitized to it. Again, it doesn’t tell us if the patient is necessarily going to have a reaction, but it will tell us if they have allergic antibodies in their body. The blood testing is very similar. We’re looking for specific reactions from their body in the blood.

Q. So you can diagnose a specific food allergy relatively quickly right from the time the patient comes in?

A. Exactly. So as long as they’re not on allergy medicine, there’s no reason why they can’t have skin testing done. We can tell in about 15 minutes if they have allergic antibodies in their body to that food.

Q. Are food allergies genetic?

A. You know it’s multifactorial. You know definitely if someone has a genetic predisposition to become an allergic person. Let’s say one’s family has asthma and eczema and other allergies; then that person is at a higher risk of developing a food allergy. But just because mom has a shellfish allergy doesn’t mean that she passes that shellfish allergy on to her child.

Q. Are food allergies seasonal? Or are they constant throughout the course of the year?

A. They’re constant. That brings up “oral allergy syndrome,” which I think is a really interesting phenomenon. That’s where a patient has certain pollen allergies, such as spring tree allergy. When the person bites into certain fruits or vegetables, particularly with things that come from trees, they might have a localized reaction in their mouth. This is actually really common and sometimes you might notice it more during the season. The most common thing we’ll see is people with a birch tree allergy, which is a spring allergy. When they bite into pitted fruits, particularly apples or things like peaches, pears or cherries, they might feel some itching in their mouth, maybe a little funniness in their throat. It feels like a true food allergy, but it’s actually oral allergy syndrome. It’s because your body, when you bite into the fruit, thinks you’re biting into the pollen. It’s generally not dangerous and you don’t need an EpiPen. And if you cook the food just a little bit the reaction goes away.

Q. There was an old movie I once saw about a woman who had an allergy to shellfish and I guess she decided she was going to go for broke and so ate like a 4-pound lobster and ended up with hives all over her body. Does the quantity of food you eat play a role in the reaction?

A. You know it really depends on the person. For some people if they eat a very small amount or it’s cooked in a certain way they’re okay and they only have a reaction if they eat a ton of it. But another person might react to a very small amount. That’s the concerning part because we really don’t know how much it’s going to take for someone to have a really bad reaction and we don’t know when that person might have anaphylaxis so that’s why it’s really recommended to avoid the food if you’re allergic to it.

Q. How do you know it’s not the seasoning or the way the food is prepared?Can that have an effect as well?

A. People are always asking about artificial colors and preservatives. It’s actually pretty uncommon to react to those. It’s not that it doesn’t happen. So when I take a history of a patient, when they’re telling me about the food, I do think about the most common things. So if the food contains shellfish, fish, nuts, peanuts or seeds, it’s most likely going to be an allergic reaction to those foods. But if they’re reacting to a bunch of different foods and the one common ingredient is a certain type of seasoning, then it most likely is the seasoning.

Q. I know one person in particular who has a terrible allergy to eggplant and she can literally walk onto a floor where someone ordered an eggplant pizza down the hall and it will affect her to the point that she has to go to the emergency room.

A. Yeah, you know, it’s interesting because a lot of people will say that if they’re just around the food or they smell it they get a reaction. There have been studies that show that a person shouldn’t get a reaction just from smelling the food. The issue is if it’s cooked or aerosolized, so if someone is in a restaurant where they’re frying or let’s say boiling shellfish and it’s getting into the air, there are small amounts of particles that one could inhale and that could cause either asthma or maybe some itching. You know a lot of times we think there may be some anxiety or stress involved. So if someone is allergic to peanuts and sees someone eating a peanut butter and jelly sandwich across the room and they start get feeling really itchy, that’s probably a little bit more anxiety.

Q. if you’re allergic to one food is it likely you’re going to be allergic down the road to other foods as well? Is there any connection to that?

A. You know if someone has a risk of a food allergy they’re at a higher risk of developing other food allergies than someone who’s not allergic. There are times when if someone reacts to one food in a certain group, let’s say shrimp, they could react to other shellfish or if they’re allergic to one nut they could react to other types of nuts.

Q. Again I think we may have touched on this briefly before, but if you have an adult who’s 45, 50, 55, 60 without any history of food allergies, they can still get a food allergy, right?

A. Yeah, unfortunately, it’s just like seasonal allergies. One could be fine for years and then something happens with their immune system and they develop that allergy. What’s really interesting around the Bronx is I see a lot of shrimp allergy. When I first started here, I couldn’t quite figure out why everyone was developing a shrimp allergy versus other types of food allergies. And when I did a little more research – and we actually did a little research study here – we found out that what one is allergic to in shrimp is the same thing they are allergic to in cockroaches and dust mites, and we all know in the Bronx we have a lot of cockroaches and dust mites and the thought is that people are becoming sensitized to the cockroach and dust mite. Over time when they continue to eat shrimp, their body sees the shrimp as foreign, as if they’re ingesting cockroaches or dust mites, so I think things like that can really start to trigger food allergy symptoms in older adults.

Q. That’s interesting. So environment can impact on your allergies over that period of time?

A. Yes, definitely.

Q. Do you recommend that people who have allergies wear bracelets or something that may indicate that they have a particular allergy?

A. Yes, there are bracelets or other things people can wear in case they develop a serious reaction and won’t be able to verbalize what they’re allergic to. The most important thing is that once one knows what they’re allergic to, whenever they go to a restaurant or anywhere where they’re going to have prepared foods, they instruct the waiter and the chef so there isn’t any accidental contamination.