Health Library

Nutrition News and Views July / August 2002 FOOD ALLERGIES AND INTOLERANCES – PART I by Judith A. DeCaya, C.N.C., L.N.C.

Food allergies are becoming an increasingly common chronic disease in many Western and westernized countries. True food allergies affect 5% to 8% of children and 1 % to 3% of adults. Food allergy and hypersensitivity are synonymous when referring to an abnormal or exaggerated immunologic response to specific food constituents resulting in symptoms or disease. An estimated seven million Americans suffer from food allergies.

In contrast, food intolerance is considered an abnormal physiological – not immunologic response to a food or food additive and may include idiosyncratic, metabolic (e.g. digestive), pharmacological (e.g., chemicals in food), or toxic mechanisms. Up to a third of the population claims to react in some way to foods.

FOOD ALLERGIES

Food allergies occur when the immune system abnormally overreacts to specific food components, usually proteins. Although more than 200 food ingredients are known to trigger allergic reactions, the vast majority (an estimated 90%) are caused by the “big eight”: peanuts (a legume), nuts (like walnuts, almonds, etc.), milk, eggs, fish, shellfish, soybeans, and wheat. Avoiding contact with the offending food is the only way to avoid uncomfortable or, in some cases, life-threatening reactions.

Children are often thought to “outgrow” their allergies by adolescence, but allergies may take different forms, become delayed reactions, or create more vague or disguised symptoms. Some allergies—especially to peanuts, nuts, and seafood—do not go away, and anyone can develop new allergies at any time.

Reactions include:

• hives
• dermatitis
• eczema
• itching
• edema
• abdominal pain
• diarrhea
• nausea
• vomiting
• flushing
• swelling of the throat
• watery eyes
• swelling or itching of the lips, mouth, throat, or face
• throat clearing
• nasal congestion
• post-nasal discharge
• sneezing
• asthma
• pneumonia
• middle-ear inflammation
• heart rhythm irregularities
• low blood pressure

Medications may be used to treat symptoms. Antihistamines, decongestants, or steroids, for example, ease some symptoms for some people but may cause unwelcome side effects. Drugs do not cure the underlying problem, and allergy shots are not always dependable, proving effective only about half the time.

For most sufferers, allergic reactions are temporary discomforts. However, some people (an estimated 30,000 each year in the U.S.) experience anaphylactic shock—a serious reaction involving the respiratory tract, gastrointestinal tract, skin, and cardiovascular system. Throats can swell enough to cut off breathing, or blood pressure can drop dangerously low. Other symptoms include abdominal issues, collapse, and cyanosis. Epinephrine is considered the lifesaving drug, yet about 150 people a year die despite emergency interventions. Early administration of epinephrine “may not always be life-saving.”

Categories of Food Allergies

• Immediate Reactions: Symptoms begin to develop within minutes to an hour or so after ingestion of the offending food.
• Delayed Reactions: Symptoms appear 24 hours or longer after ingestion.

With the exception of celiac disease (an abnormal intestinal immune response to gluten-containing grains—wheat, rye, barley, triticale, spelt, kamut), the role of delayed hypersensitivity reactions to foods “remains poorly defined.”

• Occult (Hidden) Allergies: Pathology (damage) is evident but without obvious symptoms.
• Thermal Allergies: Symptoms occur after ingestion of a specific food followed by exposure to cold, heat, or light.

Terms Related to Food Allergies

• Cyclic Allergy: Worsens with repeated exposure; total avoidance for a few months to a few years reinstates tolerance. Resensitization can be prevented by limiting exposure when the food is reintroduced into the diet.
• Fixed (Permanent) Allergy: Reexposure to a food provokes symptoms even after it has been totally avoided for two years. Consuming the food will always cause a reaction.

Other factors that may affect the incidence and severity of food reactions include altitude, emotional stress, hormonal imbalances, infections or inflammations, metabolic diseases, seasons, and nutritional imbalances. Heredity and race can also play a role.

DOWNLOAD THE ARTICLE BELOW TO READ MORE.