Food Allergies

About Food Allergies

When you study and investigate allergies you can not fail to discover a disparity of opinion with regard to food allergies. For example, is a food-related reaction a true allergy or is it some other type of negative reaction to a specific food substance? The confusion seems to stem from the variety of terms used with which to describe minor differences in various types of allergic reactions. Some basic terminology should be defined here so we are able to distinguish between a true allergic reaction and some of the other types of adverse reactions to food.

Getting the Terminology Straight

This is the body's abnormal response to the ingestion of a particular food. However, rather than immune system being involved, the reaction involves the body’s metabolism. For example, those suffering a lactose intolerance are grouped in this category, as their reaction is caused by a deficiency in an enzyme which facilitates the digestion of lactose. Other common types of intolerances include glucose intolerance and fructose intolerance.

Adverse reaction

An adverse reaction to food is not a true allergy, but rather a negative response to a particular food. The reaction may resemble a food allergy but is usually milder and does not include the immunoglobulin IgE, an antibody involved in immune system reactions.

Food Allergy

Also called hypersensitivity to a particular food, this is a true allergic reaction to a food and does involve the antibody, immunoglobulin IgE. During a food allergy reaction, IgE antibodies interact with allergens and then histamine is released, along with various other chemicals, from body tissues. When histamine and other chemicals are released within the body, allergy symptoms emerge. A true food-related allergy reaction, therefore, involves three components that would need to be present: first, there needs to be contact between the body and a food allergen, and this allergen will most likely involve a protein contained in food; next, the antibody immunoglobulin E needs to be involved in the reaction; Finally, after IgE interacts with a food allergen, histamine and other chemicals are released.

The Offending Foods

In children, the most common foods causing an allergic reaction include: milk, eggs, wheat, peanuts, soy, fish and shellfish. Allergies to milk and eggs, though, often are outgrown over time, although allergies to the other foods tend to persist throughout a person's lifetime.

In adults the most common allergic reactions to food include: milk, peanuts, eggs, tree nuts, fish, and soy. There are fewer allergic reactions to fruits, although they do occur. In most cases, it is the protein component of foods that initiate an allergic reaction. Experts believe the reason for this is that protein is more difficult to digest than other components of food.

The Symptoms

Eczema (or atopic dermatitis) is another allergic reaction involving the skin. The skin becomes red, itchy, and scaly. Eczema is usually a chronic condition and is very common with people suffering from allergies. Foods containing high levels of vitamin B and C have been found to be common causes of eczema.

Asthma can be triggered by a food allergies. Asthma causes a person’s airway to narrow making it difficult to breathe. Foods known to cause this allergic reaction include: milk, cheese, yeast, sugars, and food additives.

Aside from the reactions mentioned above, food allergies can cause gastrointestinal symptoms which include: vomiting, diarrhea, stomach cramping and pain, swelling of the stomach, and gas and rashes around the mouth and throat. Children commonly experience this last symptom although they are classified as “temporary reactions” and not true allergic reactions. Children will usually experience these symptoms in response to ingesting fruits, cow’s milk, egg whites, wheat, or peanuts.

Other symptoms which are a result of an allergic reaction to food include: obesity or weight gain, bad breath, canker sores, recurrent ear infections, arthritic pain, and fatigue. In addition, headaches can occur as a result of food related allergies involving sugar, eggs, wheat, MSG, wine, and chocolate.

Diagnosis

To properly diagnose a food allergy, a complete medical history should be taken by a physician. A complete physical examination should be performed as well as any required tests to ensure that there are no other underlying medical conditions that may be causing the adverse reactions.

Once the examination has been performed, it is important to identify the food allergen causing a patient's issues. Some experts recommend that an individual use a food diary to track all the foods they eat as well as noting any reactions that may be experienced and timelines of when they occured.

Elimination diets can be implemented to try and determine what foods are causing an allergic reaction. If keeping a diary, eliminate certain foods, such as dairy, and track which symptoms if any occur. If no symptoms have occurred or if there have been fewer symptoms after a few weeks, begin to introduce the food back into the diet and continue to record any symptoms that return.

Skin tests can be performed to identify allergic reactions although they are also known for their high percentage of false positives. Many patients tested will appear as though they have an allergy to the tested food when in fact, they do not. A skin test, on its own, should not be used to determine whether an individual suffers from a food sensitivity. Although more expensive, blood tests can also be used to determine if an individual has a food allergy, even though they may not be as accurate as skin testing. Certain situations warrent their use, however.

Another test is the food challenge. This involves an individual ingesting a suspected food allergen and then waiting for an allergic reaction to occur. Because the allergic reaction could be severe, however, this practice should be monitored by a medical professional, and this supervision may need to take place in a hospital so immediate medical care is possible.

Treatment