Allergens and Hypersensitivity
An allergen is defined as a substance that can produce a hypersensitive allergic reaction in the body but may in itself not necessarily be intrinsically harmful. Examples include pollen and dust.
A food allergen occurs when an ingested food triggers production of antibodies against that food. This causes the release of histamines leading to swelling, inflammation and other symptoms. Common foods that act as allergens include wheat, dairy, eggs, soy, shellfish, nuts and seeds, corn and tomatoes.
A hypersensitivity reaction occurs within two hours of ingesting an allergenic food. Antigens in the food bind to IgE antibodies which trigger the release of chemical mediators including histamines and leukotrienes. Depending on the location of release of these chemical mediators a variety of allergic symptoms can occur including sinus congestion, skin rashes, joint pain, gastrointestinal disturbances and cognitive disorders.
Hypersensitivity is generally defined as an abnormal and exaggerated response by the immune system to an antigen (in this case a food allergen.
Food Intolerance in Children
Food intolerance in children is often related to excessive consumption of a limited number of foods on a daily basis. It may be advisable to abstain from potentially highly allergenic foods for several weeks or longer and then to implement a rotation diet in which each food or food group is consumed every four days or less often.
This type of diet reduces the likelihood of triggering an allergic response and is not likely to allow the development of new allergies. A rotation diet will also generally improve the child’s nutritional intake which can improve immune function and health in general.
Common Signs of Food Intolerance in Children:
Puffy face and eyes
Dark circles under eyes (allergic shiners)
Horizontal creases in the lower eyelid
Dry, scaly cheeks and lips
Base of ears may be red and cracked
Eyelashes wet with ends sticking together
Horizontal crease near end of nose; child may frequently wipe nose with back of the arm
Abnormal bowel movements; diarrhea, constipation
Tests to Detect Food Intolerance
Cytotoxic Food Allergy Test
The patients white blood cells are exposed to potential allergens and cellular changes are evaluated and graded as slight, moderate or severe.
False positives and negatives are common and there is often no relationship between identified foods and the patient’s symptoms. However this test may be useful to detect allergenic foods that did not show up with food elimination challenges.
RAST (Radio allergosorbent test)
This test measures the presence of IgE antibodies against specific foods and a positive result is completely reliable. However symptoms may not necessarily correspond with ingestion of identified foods.
A false result is not necessarily accurate because antibodies other than IgE may be involved in a food intolerance reaction and these will not be detected.
The Pulse Test
In individuals with food intolerance the pulse rate may increase dramatically after ingestion of the problem foods. The pulse rate should generally not vary greater than 16 beats a minute and a rapid rise after a meal suggests a reaction to one or more of the foods in that meal.
The accuracy of this test is questionable as not all food allergy/intolerances will produce an increased pulse rate. Other factors may disrupt the pulse rate such as physical exertion, stress, anxiety, illness and chemical sensitivity.
The pulse test may be an adjunctive tool in the diagnosis of food allergy in combination with other methods.
Urinary Ascorbic Acid Concentration
Food allergy and intolerance reactions dpelet vitamin C levels in the blood and in white blood cells which is then detectable in the urine. A drop in the urinary ascorbic acid level after a meal may indicate the presence of an allergenic food in the meal. However a food allergy may not be the sole cause of such a result.
Also known as ‘muscle testing’, applied kinesiology is performed initially to evaluated muscle strength. A food is then placed under the patient’s tongue and the test is performed again.
A weaker response indicates an adverse reaction to the food. A stronger response can indicate that the food is beneficial.