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A food allergy is a reaction of the body's immune system to otherwise harmless substances in certain foods. This is different from a food intolerance, which does not necessarily involve the immune system. Although 25% of people believe they are allergic to certain foods, only 4 - 8% of children and 2% of adults have diagnosed food allergies. While most food allergies are mild, in some cases they can cause anaphylactic shock, a serious, sometimes life-threatening reaction. Food allergies affect mostly young children, and about 90% of these allergies are caused by 8 foods: cow's milk, eggs, soy, peanuts, tree nuts, wheat, fish, and shellfish. With the exception of peanut allergy, the majority of children outgrow their food allergies.
Signs and Symptoms
Many people who think they have food allergies actually have food intolerances that may cause serious health issues themselves. Symptoms of a true food allergy usually involve the skin and intestines and typically begin just after eating and not longer than 2 hours following ingestion of the particular food. Common symptoms include:
When the symptoms listed above are extreme, they can be life threatening. Call a medical emergency response unit if you see the following signs of extreme allergic reaction (anaphylactic shock):
In most cases, allergies occur when an individual who has a genetic sensitivity to certain allergens is exposed to the substance. Foods frequently responsible for food allergies include:
Foods that may cause intolerance include:
Family history -- If both parents have food allergies, you have a 75% chance of having one yourself. If one parent has food allergies, you have a 30 - 40% chance. If neither parent has allergies, you have a 10 - 15% chance.
Excessive exposure to a particular food -- For example, in Japan where rice is a staple, rice is a common food allergen. In Scandinavia, the common allergen is codfish, and in India, chickpeas.
Your health care provider will take a comprehensive history to find out what symptoms you experience after eating and how soon after eating they occur. Your doctor will also want to know how often you have the reaction and what type of medical treatment you have received. Even if your symptoms seem clearly related to a specific food, your doctor may still want to do some tests to be sure that you have a true food allergy and to verify the food or foods responsible for your reaction.
The food causing the allergy can sometimes be identified by the following techniques:
Guidelines from reputable health agencies suggest some steps parents can take to reduce their child's chances of having food and other allergies, although there are no guarantees of success. If either or both parents have a personal or family history of allergy, for example, asthma, eczema, hay fever, perennial allergic rhinitis (allergy to animals, dust mites, or molds) the following is recommended:
Note: Not all studies agree on exclusive breastfeeding. The latest and largest study investigating the relationship between breastfeeding and allergies, particularly asthma, suggests that breastfeeding in the early months of life can prevent allergies until your child is 2 years old.
Since delaying foods allows the child's gastrointestinal tract to mature, the following strategies may be helpful:
The goals of treatment are to reduce symptoms and avoid future allergic reactions. Some allergiest prescribe desensitization therapies such as allergy shots. Once you are aware of the allergy, the best way to avoid a reaction is by not eating that food. Treatment at the time of a reaction varies according to the severity and type of symptoms. Mild symptoms may go away without treatment. Doctors generally recommend over-the-counter or prescription antihistamines to relieve mild itching, swelling, rash, runny nose, or headache. Soothing skin creams may provide some relief of rashes. Severe allergic reactions (anaphylactic shock) can come on suddenly and accelerate quickly; in this case, emergency treatment is needed. In some instances, survival may depend on an injection of epinephrine (adrenaline). Food allergy sufferers routinely learn to self administer epinephrine, which may save their life. Avoiding the offending food is the best way to prevent future allergic reactions.
Avoid offending foods. Read all package ingredients carefully (many foods are processed with peanuts, eggs, or milk products, such as whey). Call ahead when eating out. Take your own food with you on trips.
If you have a history of anaphylactic shock, you should keep a preloaded syringe of epinephrine with you. Your doctor will teach you and a close family member how to use it should the need arise. You should wear a medical bracelet or necklace indicating your particular food allergies.
Antihistamines are recommended for mild itching, swelling, rash, runny nose, or headache. They are available both by prescription and over the counter in many cold, sinus, and allergy remedies. These include diphenhydramine (Benadryl), cetirizine (Zyrtec), clemastine (Tavist), chlorpheniramine (Chlor Trimeton), desloratadine, fexofenadine (Allegra), hydroxyzine (Atarax), and loratadine (Claritin). Possible side effects include drowsiness, irritability, dry mouth, and heart palpitations.
Skin creams can help soothe rashes.
Epinephrine injection is used to prevent anaphylactic shock. If you have a food allergy that causes such a serious reaction, your doctor will have you carry an injectable epinepherine pen and teach you, and those with whom you spend a lot of time, how to use it in an emergency.
Nutrition and Dietary Supplements
Although you should avoid foods that provoke an allergic reaction, you do not need to restrict variety in your diet. Studies show that the vast majority of people are allergic to only one or two foods. However, you should be aware of the families of foods to which you are allergic. For example, if you are allergic to walnuts, you may also be allergic to pecans and almonds. An allergy to shrimp may also indicate an allergy to crab.
Following these nutritional tips may help reduce symptoms:
You may address nutritional deficiencies with the following supplements:
Herbs are generally available as standardized, dried extracts (pills, capsules, or tablets), teas, or tinctures or liquid extracts (alcohol extraction, unless otherwise noted). Mix liquid extracts with favorite beverage. Dose for teas is 1 - 2 heaping teaspoonfuls in a cup of water steeped for 10 - 15 minutes (roots need longer). People who have a blood disorder or who are taking blood-thinning medications should only take herbs under the supervision of a doctor since some herbs may have blood thinning effects.
The American Academy of Medical Acupuncture endorses the use of acupuncture for allergies such as food allergies. Acupuncture can help restore normal immune function.
Although very few studies have examined the effectiveness of specific homeopathic therapies, professional homeopaths may consider individualized remedies for the treatment of food allergy based on their knowledge and experience. Before prescribing a remedy, homeopaths take into account a person's constitutional type -- your physical, emotional, and intellectual makeup. An experienced homeopath assesses all of these factors when determining the most appropriate remedy for a particular individual.
Women who have a food allergy or a partner with a food allergy may be able to reduce the risk of allergy in their child by avoiding common allergenic foods during pregnancy and nursing.
Prognosis and Complications
Food allergies may cause symptoms ranging from mild abdominal discomfort to life-threatening anaphylaxis. Avoiding offending foods may be easy if the food is uncommon or easily identified. However, successful avoidance of offending foods requires strict reading of all ingredients in a package and detailed inquiries when eating away from home. Asthma may develop in about 5% of people who suffer from food allergy and current asthma may be triggered by foods among 6 - 8% of children and 2% of adults. Children may outgrow food allergies (particularly to milk or soy), but adults are unlikely to lose their allergies.
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Review Date: 1/12/2012
Reviewed By: A.D.A.M. Editorial Team: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Steven D. Ehrlich, NMD, Solutions Acupuncture, a private practice specializing in complementary and alternative medicine, Phoenix, AZ (12/14/2009).
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