House CallDec/Jan 2009 Issue

Allergy and Food Sensitivity Q&A

Pediatric allergist Harvey L. Leo, M.D., answers questions about allergies and food sensitivities.

Q. Is it possible to be allergic to Christmas trees?

A. Yes. Sensitive people notice they develop allergic symptoms, such as itchy eyes, runny nose and sneezing, when a Christmas tree is set up in their home. Some people can develop respiratory infections and even pneumonia.

People can be sensitive to the sap of spruce, pine and fir, but the trees themselves are only partially to blame. The bigger culprits of Christmas tree allergy are the pollens, molds and dust the trees harbor on their needles and branches.

Allergy and Food Sensitivity

Artificial trees can be a little easier on the allergies but, like real trees, their needles can hold dust and mold from year-long storage in damp basements or dusty attics. Old boxes of Christmas ornaments and decorations also contribute to the problem.

It may help to thoroughly hose down your real Christmas tree and let it fully dry in the sun and air before you bring it into the house.

Q. Is vitamin D somehow related to allergies?

A. Most people know that vitamin D is critical to healthy bones and the prevention of rickets. Now new research suggests that vitamin D may play a larger role in immune system function and development than previously recognized. Recent studies indicate that certain immune cells can be influenced away from allergic or autoimmune tendencies with increased doses of vitamin D. 

On an average day, our skin can produce from 10,000 to 20,000 IU of vitamin D with about 30 minutes of sun exposure. But Americans have been getting decreasing amounts of sunlight exposure over the past two to three generations (50 to 100 years). The reasons for this are varied, including the greater use of efficient sunscreens to protect against skin cancer, more indoor activities (television, computers), and improved home environments, like central air conditioning, that lure people inside during the sunniest time of year.

A theory is that our lower vitamin D levels may be partially contributing to the increase in many types of immune-mediated diseases, such as allergies, asthma, multiple sclerosis, type-1 diabetes and lupus. This is in conjunction with the hygiene hypothesis, the theory that our highly sanitized environment may under-stimulate the immune systems of newborns so that they over-react to newly introduced foods.

Does this mean that people should avoid sunscreen, that they should start taking mega-doses of Vitamin D or that they should expose their kids to a dirtier environment? Certainly not! These studies and theories address macro-trends is societal disease rates. They do not reflect individual risks or address individual behaviors.

Q. Our little girl, who has eczema and multiple food allergies, wants a puppy for Christmas. Is this a good idea?

Allergy and Food Sensitivity

A. Giving a dog or cat to an allergic child can be problematic. Allergy testing can offer some guidance about whether this is a good idea for your family, but testing is an unreliable predictor of whether or not your child will develop a sensitivity to her new pet. It isn’t unusual for a child to show negative results from skin testing or RAST testing yet still develop full-blown allergic symptoms after the pet is introduced into the household.

Some research suggests that exposing young children to dogs or cats may prevent development of asthma-like symptoms later in life but the chances of this are better for kids who have no family history of allergic disease.

With highly allergic kids, I advise parents to be cautious and think twice before purchasing a pet. There’s a good possibility your child will develop a sensitivity and the pet will have to be removed from your home.

Q. We’re flying across the country to visit family. How do we travel safely with our anaphylactic, milk-allergic, 8-year-old child?

A. Flying with a food-allergic child can be challenging. Many airlines now have “peanut-free” flights, for example, but safety can’t be guaranteed. There is always a risk of contact contamination because airplanes are turned over quickly and not cleaned thoroughly between flights.

Here’s what I advise: (1) Work closely with your child's pediatric allergist as you prepare for the trip. (2) Contact the airline well in advance to alert them that you are traveling with a high-risk child and to enlist their cooperation.(3) Carry a note from your child’s doctor describing the type of reaction/sensitivity and justifying the medications you carry. (4) Bring all medications in a carry-on bag with easy access. Make certain meds are up to date and that there’s sufficient supply for your trip. (5) Check your seats for residual wrappers and food before settling in. (6) Seat your child farthest from the aisle, away from other passengers. (7) Cover your child’s seat with a clean towel from home to prevent contact contamination. (8) Bring plenty of safe food and snacks in case flights
are delayed.

Harvey L. Leo, M.D., is a pediatric allergist with Allergy and Immunology Associates of Ann Arbor and an assistant research scientist with the Center for Managing Chronic Disease at the University of Michigan. LW

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