Food Allergy vs. Food Intolerance, How Can We Tell the Difference?
Food intolerances are much more common than food allergies
and luckily, less severe! Unfortunately, food allergies seem to be
So, a patient comes to you with a burning sensation on the skin,
diarrhea, and a headache, and claims he has a food allergy. On
questioning, you discover that he usually has a small piece of
chocolate every day, but earlier that morning, he was really
hungry, so he went for the whole bar. This is not a food allergy.
This is food intolerance! Food allergies and intolerances can
have very similar presentations. Let’s look at some of the
A food allergy is an abnormal immune system response to the
protein constituent of certain foods. Symptoms occur very soon
after consuming the food, and can be very severe, leading to
anaphylactic shock and death. Whereas food intolerance is
a chemical reaction that some people have to certain foods,
it is dose dependant, thus a small amount of the food may be
tolerated, while a larger amount may cause symptoms, which
are not necessarily immediate, and can take several hours to
Symptoms of food intolerance can include:
• Nervousness, tremor
• Rapid breathing
• Headache, migraine
• Burning sensations on the skin
• Tightness across the face and chest
• Breathing problems - asthma-like symptoms
• Allergy-like reactions
Common foods causing food intolerance include:
• Eggs, particularly egg white
• Dairy products, including milk, cheese and yoghurt
• Strawberries, citrus fruits and tomatoes
• Wine, particularly red wine
• Food additives
• Flavour enhancers such as MSG (monosodium glutamate)
• Histamine and other amines in some foods.
A food allergy can be inherited, the person may be born with it,
in which case he may outgrow it or not, or he may develop it later
in life. The symptoms of food allergy can be life threatening.
Common symptoms include:
• Itching, burning and swelling around the mouth
• Runny nose
• Skin rash (eczema)
• Hives (urticaria – skin becomes red and raised)
• Diarrhea, abdominal cramps
• Breathing diffi culties, including wheezing and asthma
• Vomiting, nausea.
90% of all food allergies are caused by just 8 different foods
(referred to as the big 8). These are:
6. Tree nut
8. Crustacean shellfish
(Tree nuts include: Almond, Hickory nut, Beechnut, Lichee
nut, Brazil nut, Macadamia nut, Butternut, Nangai nut, Cashew,
Pecan, Chestnut Pinenut Coconut, Pistachio, Filbert, Sheanut,
Ginkonut Walnut, Hazelnut).
Identifi cation of the allergen:
When symptoms appear within a few minutes of eating the
particular food, it makes pinpointing the allergen an easy task.
However, if the cause is unknown, diagnostic tests may be
needed, such as:
• Keeping a food and symptoms diary to check for patterns
• Removing all suspect foods for two weeks, then reintroducing them one at a time to test for reactions (except in cases of anaphylaxis).
• Skin prick tests using food extracts
• Blood (RAST) tests. (IgE antibodies)
1. Exclusive breastfeeding during the fi rst four to six months
appears to protect against the development of allergies in
early childhood. Exposure to cigarette smoke and starting
solids early can increase the risk of developing allergies
in early childhood. If a baby is known to be allergic to a
particular food, a breastfeeding mother should avoid eating
Studies have shown that using soy milk formula does not prevent
the development of allergies in children.
Partially hydrolyzed formula – these are cow’s milk based and
have been processed to break down most of the proteins that
cause symptoms in infants who are allergic to cow’s milk. They
reduce the risk of developing eczema and cow’s milk allergy in
infancy and early childhood.
Most children outgrow allergies to milk, egg, soy, and wheat
by 10 years old, often by age 5. Peanuts, tree nuts, fi sh and/or
shellfi sh are generally lifelong allergies.
1. The easiest way to treat a food allergy or intolerance is to
eliminate it from the diet. Sometimes, the body can tolerate
the food if it is avoided for a time, then reintroduced in
small doses, particularly for food intolerances.
If avoidance is not possible, then:
2. Antihistamines are used for mild reactions
3. Epinephrine is used for severe reactions. The patient is taught to use an epi-pen which he carries with him, in case of emergency.
4. Food oral immunotherapy (OIT): Under close supervision, a person takes in small daily doses of a food allergen by mouth or under the tongue. The goal is to try to make the immune system tolerate the allergen so that the body won’t react as badly to it. This is called desensitization.