Food Allergy Versus Food Intolerance

Reactions to foods are increasingly common it seems, with a large portion of the population experiencing some reactivity or sensitivity. There are several distinct types of food reactions, so I’m going to outline food allergy versus food intolerance to help distinguish. Often in Western medical circles, only a true food allergy is recognized, whereas many reactions may not fall into that category and ignoring other sensitivities can lead to ongoing symptoms that could be avoided.

Food Allergy

The definition of true food allergy is a type 1 immune reaction that occurs after eating certain foods. The prevalence of food allergies has been sharply rising, and is estimated to affect 7% of young children and 3% of adults.

The most common food allergies are:

• Milk (casein and whey)
• Eggs
• Wheat (gluten)
• Soy
• Peanuts
• Tree nuts
• Shellfish

There are 4 main types of Immune Mediated Hypersensitivity Reactions (food allergies), which vary slightly with symptoms and timing of symptoms.

Type 1: IgE Food Allergy

This is an immediate reaction and will occur in less than 2 hours post exposure to the allergen. This is an antigen: antibody reaction, where the person must have been exposed in the past to have created an antigen against this allergen. Once the antigen is made, following exposures will cause production of antibodies. The antibody created in this reaction is an IgE, which will bind to certain immune cells and cause the release of chemical mediators, like histamine. This may lead to a variety of allergic symptoms, dependent upon the location of the immune cells that IgE binds to.

Possible reactions include responses in the gastrointestinal tract, airways, and blood vessels.

• GI tract: diarrhea, vomiting.
• Airways: wheezing, coughing, phlegm, swelling and mucous secretion in nasal passages.
• Blood vessels: increased fluid leaks into tissues, causing swelling.
• Typical manifestations include systemic anaphylaxis and localized anaphylaxis, such as hay fever, asthma hives, food allergies and eczema.

Hereditary Considerations:

Atopy refers to a hereditary trait which leads to production of excessive levels of IgE antibodies, which we just discussed in the Type 1 hypersensitivity reactions. Common manifestations of atopy include allergic rhinitis, allergic asthma, and atopic dermatitis.

IgE Mediated Disorders:

• Pollen- Food Allergy (Oral Allergy)
• Immediate contact hypersensitivity confined to the mouth/throat.
• This syndrome is often associated with ingestion of various fresh/uncooked fruits and vegetables.
• Symptoms include rapid onset of itching and swelling of the lips, tongue, palate, and throat
• Generally rapid resolution of symptoms
• In up to 50% of patients with ragweed-induced allergic rhinitis, ingestion of melons and bananas will provoke oral symptoms. In some pollen-allergic patients, ingestion of raw potatoes, carrots, celery, apples, hazelnuts, and kiwi will provoke a reaction.
• GI Allergy
• Within 2 hours of consuming food, may experience nausea, vomiting, abdominal pain, and/or diarrhea.
• Infants may have a sub-clinical reaction, consisting or only a poor appetite and periodic abdominal pain.

Types 2,3,4: non-IgE Food Sensitivity

These are non- IgE mediated food sensitivities but still can be of great concern. These are what we refer to as food intolerances – they may not trigger the immediate IgE reactions, but they still cause immune activation, and symptoms. These tend to have a more delayed picture than the classic Type 1 hypersensitivity does. The onset of symptoms can be hours to days after food ingestion. Symptoms may include feeding difficulties in an infant, vomiting/GERD, persistent diarrhea, failure to thrive, and rectal bleeding. They may contribute to chronic inflammation in the intestines, as well as eczema.

Food Intolerance Manifestations:

• Gastro-intestinal complaints- stomach ache, IBS, IBD
• Skin complaints: itching, eczema, hives, acne
• Joint and muscle complaints: ranging from atypical to rheumatoid arthritis
• Headache and migraine
• Chronic fatigue
• Asthma, chronic rhinitis or sinusitis
• Pre-menstrual syndrome
• Hypoglycemia
• Depression, anxiety
• Sleeping disorders

Other Causes of Food intolerances

There can also be other reasons that one might not tolerate a certain food, outside of immune reactions. These might include:-

• Enzyme deficiencies (such as lactose)
• Reactions to chemicals in foods (MSG, food additives and chemicals)
• Reactions to sulfur compounds e.g. onions and garlic
• Digestive diseases
• Metabolic issues including fat and carbohydrate malabsorption

Testing For Food Intolerances

A common-sense approach to food reactions must be taken – meaning, if you don’t do well with a certain food, then don’t eat it, even if Western medicine does not define it as a true allergen. For testing purposes, there are 3 main options –

1.Food Allergy Testing
1.Testing for serum IgE, looking for true food allergies.

2.Food Sensitivity testing
1.Testing for food-protein specific serum IgG antibodies potential indicator of delayed food allergies or food sensitivities (response appearing 1-3 days post ingestion of food). This can often be done via a finger stick.
2.Testing Salivary IgA: indicates a new or active immune reaction.

3.Elimination Diet
1.The Elimination Diet is the gold standard as far as clinically discovering the source of a food intolerance or allergy. Although testing can give a framework, removing and re-introducing foods into your diet every few days can help to pin point the causative factors. This can be a long/ drawn out process, but can be helpful for identifying reactions that don’t seem to be clearly identified by testing.

By far my favorite test is the IgG food sensitivity test, and I find it very helpful for guiding people’s optimal nutrition plan tailoring it to their individual sensitivities.

I think the moral of the story here is that there are many different types of sensitivities and reactivities that can occur with different foods, so if an allergist, pediatrician or general practitioner does food allergy testing (via skin prick testing or bloodwork), and doesn’t find any positive foods, do not necessarily give up there. Find a naturopath who can help you dig deeper and find the hidden/delayed intolerances.