By Andrea Markowitz, Special to Tribune Newspapers
July 26, 2010
Food allergies affect nearly 4 percent of adults and 7 percent of children under 4 years old, and account for approximately 30,000 severe allergic reactions and 150 deaths per year in the United States, according to the National Institutes of Health.
What is a food allergy?
A food allergy is caused by the body having an abnormal reaction to eating certain foods. As in all types of allergies, the body's immune system mistakenly identifies a neutral substance as harmful, and produces antibodies (histamine and other chemicals) to attack it. These chemicals cause an allergic reaction.
What are the symptoms?
Symptoms of an allergic reaction to food range from mild to severe, and include coughing; tingling in the mouth; hives; itching; eczema; a swollen lips, face, tongue, throat or other part of the body; wheezing, nasal congestion or other breathing difficulties; nausea, vomiting, stomach pain and/or diarrhea; and a life-threatening reaction called anaphylaxis.
Symptoms of anaphylaxis, which can cause a coma or death, include constriction and tightening of the airways; a swollen throat or lump in your throat that makes it difficult to breathe; shock; a severe drop in blood pressure; a rapid pulse; dizziness; lightheadedness; and/or fainting, according to MayoClinic.com.
Who typically has food allergies?
The National Center for Chronic Disease Prevention and Health Promotion reports that a family history of allergies (any type) or asthma, a genetic predisposition to allergic disease, elevated allergen-specific serum immunoglobulin levels (IgE concentrations) and being younger than 3 years are the greatest risk factors for having food allergies.
While some children are born with allergies to certain foods, others develop food allergies over time, according to the NIH, which also points out that children are more likely than adults to outgrow milk, eggs or soy allergies. But they don't outgrow peanut allergies.
The NIH warns that people who have asthma carry a higher risk of having an anaphylactic reaction, and that most deaths in children from an anaphylactic reaction to a food occur in those who have asthma.
People who do not meet any of the food allergy risk criteria, in most instances, eat anything they like without worrying about having an adverse reaction to food. But some people who don't have food allergies may still exhibit allergy-like symptoms (such as stomach pains and nausea) when they eat certain foods. These people have what's called "food intolerance."
What is "food intolerance?"
Food intolerance is the inability to properly digest certain foods. MayoClinic.com lists the following conditions that can cause food intolerance:
•Absence of an enzyme that's needed to fully digest a food. An example is lactose intolerance, which can cause bloating, cramping, diarrhea and excess gas.
•Irritable bowel syndrome, which can cause cramping, constipation and diarrhea.
•Food poisoning, which is triggered by eating bacteria in spoiled food or other toxins, and causes severe digestive symptoms.
•Sensitivity to food additives such as sulfites, which are used to preserve dried fruit, canned goods and wine, and can trigger asthma attacks in sensitive people.
•Recurring stress or psychological factors.
•Celiac disease, a chronic digestive condition that's triggered by eating gluten, a protein found in grains, including wheat, barley or rye and the foods that contain these grains. Symptoms of celiac disease include diarrhea, abdominal pain and bloating.
Which foods cause the most food allergies?
The foods that most commonly effect people with food allergies are, according to NIH, fish; shellfish, such as shrimp, crayfish, lobster and crab; eggs; milk; peanuts; and tree nuts such as walnuts. Peanut and tree nut allergies are the leading causes of anaphylaxis.
Moreover, if you're allergic to certain foods you may also be allergic to similar foods — a phenomenon called cross-reactivity. For example, if you're allergic to shrimp you may also be allergic to other types of seafood.
Some people who exercise soon after they eat experience exercise-induced food allergies. MayoClinic.com explains that as exercise stimulates the body it can cause itchiness, lightheadedness, hives or anaphylaxis. An article authored by William B. Stratbucker, M.D., M.S., and Paul H. Sammut, MBBCh, FAAP, FCCP, (http://emedicine.medscape.com/article/886641-overview) lists the following food allergens, based on patient case reports, as having caused exercise-induced anaphylaxis: shrimp, oyster, celery, cheese sandwich, pizza, wheat gliadin (a protein in gluten), egg, peach, grape, pomegranate, chick pea, pear, poppy seed, soybean and snail.
People who have exercise-induced food allergies should wait a couple of hours after eating before exercising, and avoid trigger foods.
Finally, fruits, vegetables, nuts and spices that contain proteins that are similar to those found in allergens that cause hay fever can trigger allergy attacks in people who suffer from hay fever. Called "pollen-food allergy syndrome," this condition can cause throat swelling and anaphylaxis. Cooking these particular trigger foods may help prevent an allergic reaction to them.
How to prevent allergic reactions to food
The one and only way to fully prevent an allergic reaction to food is to avoid eating that food, and other foods in which it is an ingredient. People with nut allergies must be particularly careful to read the ingredients label of prepared foods, to make sure the food 1) does not contain nuts; and 2) was not manufactured in a facility that processes nuts.
•National Institutes of Health, nih.gov
• Mayo Clinic, mayoclinic.com
•The Food Allergy & Anaphylaxis Network, foodallergy.org
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