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General Nutrition and Diet Facts

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Food Allergy

 

Food Allergy

We often use the word 'food allergy' to describe the adverse physical reactions to foods.Food allergy is nothing but an abnormal response of the body's immune system to certain foods and ingredients.

An abnormal response occurs when the immune system overreacts to substances (usually proteins) that are harmless to most people and starts releasing antibodies called immunoglobulin E (IgE). These antibodies attached themselves to special cells called mast cells, which then release substances that cause a variety of allergic reactions.

Symptoms

Commonly they will affect the gastrointestinal tract, the skin and the respiratory system. The symptoms includes,
* nausea
* vomiting
* diarrhea
* skin rash
* breathing difficulty
* sneezing
* itchy, watery eyes

In some severe cases, anaphylactic shock may occur even if the allergic person has consumed only traces of the offending food. The signs of anaphylactic shock include itching and flushing of the skin, followed by severe vomiting, diarrhea, hypo tension and constricted respiratory passages.

Less sensitive people may be better able to tolerate small amounts of the allergens in the foods they eat. They also may tolerate the allergen if they are not under stress.

Susceptibility

Children are more susceptible, up to 7 percent may be affected, but their symptoms often subside as they get older. Some children who as infants had allergies to certain foods are able to eat them again by the age of 3.

The later in life food allergies appear, the less likely they will go away. People with allergies to plant foods may have cross-allergies. For example, if they are allergic to peanuts, they may also be allergic to other legumes, such as green peas, soybeans, and lentils.

Common Food Allergens

About 90 percent of all food allergies are caused by just a few culprits. The most common allergens include:
* cow's milk
* egg whites
* shellfish and fish
* legumes
* peanuts, walnuts, pecans, almonds and cashews
* wheat
* soybeans

A number of foods commonly believed to be allergenic,are not allergenic. Chocolate, strawberries, tomatoes, citrus fruits and corn are foods that often cause allergic reactions, but they are rarely the cause. Sugar is not an allergenic food, although it is often thought to be.

Diagnosing Food Allergies

Diagnosis usually begins with a physical examination by a physician . The qualified allergist will take a detailed medical history.

To help determine which foods affect you adversely, you might be asked to keep a diary of what you eat every day and record any symptoms you experience. You may also be asked to follow an elimination diet, in which all foods that are not very well tolerated are eliminated. These foods are then gradually re-introduced one by one to see if you develop a reaction to them. This process is called a food challenge.

Other diagnostic tools are skin and RAST tests. Whether foods flagged by a skin test actually cause problems can be confirmed by a food challenge. If the methods described so far do not reveal the source of your symptoms, the gold standard for evaluating allergies is the double-blind challenge test. In this test, the patient takes capsules of dried food suspected of causing reactions, along with capsules containing non-reactive substances; neither the doctor nor the patient knows which is being administered at any given time. If symptoms occur only with the food being tested, the patient is allergic to that food. Double-blind challenges are valuable because they can detect and rule out allergies or intolerances to many foods and other substances such as additives. They also eliminate non-food influences that can cause symptoms, including psychological factors.

Clinical ecologists, cytotoxic testing and sublingual testing are not recommended for reliably determining true food allergies.

How to Avoid

Once a food allergy has been diagnosed correctly, the only effective treatment is strict avoidance of the offending food. This can be tricky if you are allergic to something which is used as one of several ingredients in a dish and which cannot be easily detected by sight or smell. Here are some points by which you can avoid this,

In a Restaurant
* Identify your allergy.
* Ask how the dish was prepared.
* Never taste food before asking questions.

At the Supermarket
* Always read the labels on packaged foods.
* Become familiar with unfamiliar names used on labels; for example, sodium caseinate and casein are ingredients to avoid if you are allergic to milk protein.
* If you have questions about favorite foods, contact the manufacturers of the product.

The following chart lists the names for common food allergens.

   MILK    EGGS
   Lactalbumin    Albumin
   Caseinate    Vitellin
   Lacotglobulin    Ovovitellin
   Sodium caseinate    Ovomucin
   Curds    Ovomucoid
   Casein    Globulin
   Whey    Livetin


   WHEAT    CORN
   Gluten    Corn starch
   Cracked wheat    Corn sugar
   Graham flour    Corn flour
   Durum flour

The allergist may recommend a consultation with a registered dietitian to help you make food choices.

About Additives

More than 2,000 food additives are commonly used today, including:
* preservatives
* conditioners
* flavorings
* colorants
* sweeteners

The following chart lists food additives that may cause adverse reactions.

   ADDITIVE NAME    PURPOSE
   Aspartame    Sweetener
   Benzoates    Preservatives
   BHA, BHT    Antioxidants
   FD and C Dyes    Colorants
   MSG    Flavoring
   Nitrates/Nitrites    Preservatives
   Parabens    Preservatives
   Sulfites    Preservatives


Sulfites are among the most widely used additives in prepared foods, and they may also be the most likely culprits when it comes to reaction incidents. Sulfating agents are used to preserve foods and sanitize containers for fermented beverages. When checking food labels, keep in mind that some sulfites are also known as SO2; these include sulfur dioxide, sodium or potassium sulfite, bisulfite and metabisulfite.

Sulfites are commonly found in :

* Baked goods
* Teas
* Condiments
* Relishes
* Processed seafood products
* Jams and Jellies
* Dried fruit
* Fruit juices
* Canned vegetables
* Dehydrated vegetables
* Frozen vegetables
* Soup mixes
* Beer
* Wine
* Wine coolers

 


 
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