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Food Allergies


 

Often, patients come in telling us what foods they are allergic to on the basis of allergy testing done years before. It's quite possible that they are not allergic to those foods at all. Allergy testing is very accurate when we test for dust mites, mold, and pollen. But it's less accurate when we test for foods. Years ago, many allergists, even those board certified by the American Board of Allergy and Immunology, would tell patients to avoid foods on the basis of skin test results alone. The most reliable way to confirm a food allergy is with a food challenge. This test involves giving a capsule to a patient that contains either the food that they suspect or a placebo. To ensure the objectivity and validity, the patient (and often the doctor) doesn't know which capsule they receive.

Reactions can range from immediate itching or swelling of the lips and/or tongue, to hives, coughing, and wheezing. These usually happen within a few minutes after eating the food, sometimes up to an hour. But some true food allergies cause stomach cramping and diarrhea hours later. Unfortunately, there are no safe and effective forms of allergy shots or allergy drops for food allergy at this time. Food allergies can be life-threatening, especially if one is allergic to peanuts, shellfish, or tree nuts. Besides avoiding these foods, the doctor should prescribe an injector device with epinephrine (adrenaline) to be available at all times. Make sure that the one you buy has at least 12 months left until it expires. You often get the freshest at 24-hour pharmacies. Still, if anaphylaxis occurs and all you have is an expired device, good research shows that it's still worthwhile using it.

A careful distinction must be made between "food allergy" and "food intolerance." Many people have lactose intolerance, which causes gastrointestinal symptoms upon eating milk products. Other examples of food intolerance include headaches from drinking wine or a runny nose from eating spicy foods.


 

Flu Vaccine and Egg Allergy

Influenza vaccine (injectable and nasal) is grown on chick embryos. For decades, the thinking was that those allergic to eggs could have allergic reactions to the vaccine. But when you withhold the vaccine, thousands of egg-allergic patients come down with the flu. Yes, we have medicines to treat the flu like Tamiflu, but 1) we have begun seeing flu strains resistant to Tamiflu, and 2) Tamiflu is not a panacea (instead of feeling like you were run over by a truck for five days, you feel that way for four days).

Several years ago, state-of-the-art advice from a board-certified allergist was to get allergy skin tested with the flu vaccine. If the skin test was negative, we would give you a test dose with 10 percent of the flu vaccine. If you were OK 30 minutes later, we would give you a second shot with the other 90 percent of the dose and then observe you for 30 minutes.

That allergy test is no longer necessary. Bottom line – it is almost always safe for those allergic to eggs to get the flu vaccine, even for people who have the most severe reactions to eggs (e.g., anaphylaxis). A 2011 study included 27 young children (under 3 years old) who had anaphylaxis from eggs; none of them had serious reactions to the vaccine. In another 2011 study, 64 egg-allergic children received the vaccine. One got hives, and two had a single hive; none of them had wheezing, shortness of breath, tight throat or more serious reactions. A higher percentage of the control group (kids without egg allergy) got hives after their flu shot.

If you are egg allergic, it is recommended you get your flu shot in a doctor's office; if you have a severe egg allergy, or had a serious reaction after getting a flu shot, it is recommended you get the flu shot in an allergist's office. Remember, there is definitely a risk to not getting immunized – influenza-related illness in the U.S. averages 200,000 hospitalizations per year and 10,000 deaths per year.

Note: Information contained in this article should not be considered a substitute for consultation with a board-certified allergist to address individual medical needs.


 

Will My Child Become Allergic to Peanuts?

Laura is one of our patients and is planning her first pregnancy. She has allergies and mild eczema, and her husband has severe peanut allergy. What are the chances that their baby will have peanut allergy?

Very good question, and the answers are different now than they were in 1998.

In 1998, the United Kingdom's Committee on Toxicity recommended that mothers of at-risk infants avoid eating peanuts during pregnancy and breast-feeding, and that peanut products be withheld from such infants in early life. In 2000, the American Academy of Pediatrics suggested that nursing mothers of at-risk infants eliminate peanuts from their diet and that introduction of peanut be delayed until 3 years of age.

But from 1990 until 2005, the number of children with food allergies went way up. The percentage of American and British children with peanut allergy doubled. An interesting study done in Israel and in the UK looked at groups of Jewish children. Some of them lived in Israel, and the others lived in UK. Genetically and socio-economically they were very similar. The children in England were ten times more likely to develop peanut allergies than the children in Israel. In Israel, they do not delay introduction of solid foods. Babies are often fed peanuts at 4 months of age.

Since that time, some studies confirm their results, but other studies suggest that avoiding the foods protects against the kids getting food allergies. Maybe it was the peanuts themselves—In the USA and UK, most peanuts are dry roasted, but in Israel, most peanuts that infants consume are boiled.

Bottom Line: the answer to Laura's question is "We don't know". That doesn't sound very intelligent, but that is where the science currently is. Perhaps instead we should say, "The precise mechanisms have not yet fully been elucidated". It still means we don't know, but it sounds smarter.

Here is the official advice from the expert panel published in December, 2010:

Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel:

The introduction of solid foods should not be delayed beyond 4 to 6 months of age. Potentially allergenic foods may be introduced at this time as well.

  • Rationale: Insufficient evidence exists for delaying introduction of solid foods, including potentially allergenic foods, beyond 4 to 6 months of age, even in infants at risk of developing allergic disease.
  • Balance of benefits and harms: Restricting exposure to food antigens during infancy has been hypothesized as a means of preventing development of food allergy. However, restricting developmentally appropriate solid food variety beyond age 6 months can lead to inadequate nutrient intake, growth deficits, and feeding problems.
  • Quality of evidence: Low
  • Contribution of expert opinion: Significant

 

Clearly more data are needed. The LEAP study was designed to answer this question. Learn Early about Peanut Allergy (LEAP) started in 2008 and results will start becoming available in 2013. Stay tuned.

Note: Information contained in this article should not be considered a substitute for consultation with a board-certified allergist to address individual medical needs.


 

Food Allergy Treatment - An Unmet Need

For the most part, treatment of allergies and asthma is much easier, and much more effective, than when my father was in my shoes as a 48-year-old allergist. The year was 1972. We didn't have Seldane, much less Claritin or Allegra, the non-sedating antihistamines. We didn't have Advair, much less Pulmicort or Asmanex, the state-of-the-art asthma maintenance inhalers. Triple therapy for asthma was Theo-Dur, albuterol tablets, and an Alupent inhaler.

We also didn't have any help for patients with severe food allergies except: avoid eating that food, and here's a prescription for injectable epinephrine in case some pieces of allergic food slip into your meals. Guess what? That's still the treatment guidelines for severe food allergies. I don't mean eating chocolate gives you a headache. I mean eating peanuts gives you a tight throat and drops your blood pressure to zero. What's worse, the number of people with true food allergies is getting bigger every month. We clearly have an unmet need in the treatment of food allergy.

But we're close. Every year, those of us in the field hear about how research protocols for food allergy treatment have been successful. Basically, the treatments are like allergy shots, but the immunotherapy is taken under the tongue rather than an injection. Much of the funding for these important studies comes from The Food Allergy & Anaphylaxis Network. That's one of the reasons why my wife and I are big supporters of FAAN.

I invite you to check out their website, and to participate in the Houston Food Allergy Walk this year. Details are available at Walk for Food Allergy. Several of us from The Allergy Clinic will be there at our booth since our clinic is the original platinum sponsor for this walk. So, let's hope for great weather, and we'll see you there.

Note: Information contained in this article should not be considered a substitute for consultation with a board-certified allergist to address individual medical needs.


 

Food Allergy Treatment - Working to Make It Easier

Part of the reason I love practicing allergy is that we have so many successful ways to handle the problems that come up. Those allergic to dust mites find successful relief with avoidance of dust, treatment of symptoms with pills, or prevention of symptoms with nose sprays. Airborne allergy can even be changed with allergy shots, which are designed to make you less allergic. Things are not so easy with food allergies. The only effective treatment is avoiding what you're allergic to.

If a severe reaction occurs, we try to prepare our patients ahead of time to carry injectable epinephrine, either an EpiPen or Twinject. There are no effective allergy shots that can fix a food allergy. Try being allergic to peanuts and scheduling an evening flight on Southwest Airlines. Or enjoying a meal at a nice restaurant if you experience anaphylaxis when eating pecans, almonds, or shellfish. Luckily, a tremendous asset exists for those with food allergies: The Food Allergy & Anaphylaxis Network.

The difficulties in living with food allergies are made easier by their practical tips. Check out the Downloads section of the website for School Guidelines for Managing Food Allergy, or How to Read a Food Label.

Each year the Food Allergy Walk comes to Houston. The Allergy Clinic is a platinum sponsor of the Walk and invites all of our patients (as well as the whole community) to participate. Sign up at Walk for Food Allergy.

Unfortunately, the incidence of severe food allergy keeps increasing. We are trying to raise awareness about what it's like to live with food allergies and support NIH funding so that, one day, treatment of food allergy will be no more difficult than treatment of dust mite allergy.

Note: Information contained in this article should not be considered a substitute for consultation with a board-certified allergist to address individual medical needs.

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