Food Allergy


Food allergy is caused when the body's immune system wrongly responds to food substances often manifested by itching, runny nose, skin rash, or diarrhoea. In extreme cases shortness of breath and even anaphylaxis, a life threatening reaction may occur.

The immune system (IS) is responsible to protect us from foreign bodies called antigens, such as harmful bacteria, yeast and viruses. Just like us bacteria, yeast and viruses have proteins and an allergy is triggered when the IS responds to proteins in food mistakenly thinking they are proteins belonging to a harmful antigen. The first response of the IS is by literally dispersing poison (histamine) to kill the antigen (bacteria). White cells that produce this poison travel to the layer under the skin and disperse more poison. However, there is no bacteria to be killed and instead this poison starts damaging our own cells and we start itching like hell! This is were anti-histamine comes handy because it neutralises the histamine.

Food allergy is distinct from food intolerance and one must not confuse one with the other. Any protein or product that triggers an allergy is called an allergen.

Some 20% of people believe they are allergic to one food or another, but the truth is that food allergy affects far less of the adults population. However, up to 10% of children may be allergic to one food or another. People often mistaken their reactions to an allergy when in fact their symptoms are of food intolerance which affects 50% of the world population (a table to help you distinguish between food allergy and food intolerance is provided below)!


Symptoms of allergies vary from person to person and the amount of food needed to trigger a reaction also varies. They also depend on the severity of the allergy, and can appear in as little as a few minutes or may take up to an hour. Symptoms affect the skin, gastrointestinal tract, and in severe cases, the respiratory tract and blood circulation.

List of symptoms that may occur during a food reaction episode:


  • Hives - red, itchy bumps on skin
  • Oedema - swelling of the skin, sometimes of the eyes and lips
  • Eczema - a dry and bumpy rash

Stomach and Intestinal Reactions:

  • Abdominal pain and bloating
  • Diarrhoea (usually very runny)
  • Vomiting
  • Gas/wind
  • Cramps

Nose, Throat and Lung Reactions:

  • Runny Nose
  • Sneezing
  • Watery and/or Itchy eyes
  • Coughing
  • Wheezing
  • Shortness of Breath

Food Intolerance vs. Food Allergy:

The table below shows the differences between food intolerance and food allergy. Some symptoms may be common for both.

Coeliac Disease - the exception to the rule!

In Coeliac disease (gluten intolerance) the immune system is triggered by a protein called gluten, found in wheat, barley and rye-containing foods causing a food allergy. This ends up damaging the wall of the small intestine that produces the enzymes (lactase) responsible for the break down of lactose, the sugar found in milk. Symptoms of lactose (food) intolerance follow as well. So Coeliac disease is known to have symptoms of both food allergy and food intolerance. See more details about Coeliac Disease and Non Coeliac Gluten Intolerance. Read More  »»

Managing food allergy

The mainstay of treatment for food allergy is avoidance of the foods that have been identified as allergens. For people who are extremely sensitive, this may involve the total avoidance of any exposure with the allergen, including touching or inhaling the problematic food as well as touching any surfaces that may have come into contact with it.

Enzyme Therapy:

As explained above food allergy is triggered by proteins and the immune system mistakenly thinks they are harmful proteins. Proteins are broken down by enzymes when digested, and lack of proper breakdown may be the cause for the proteins to become allergens. Better Nutrition Journal and several other medical papers discuss how enzyme therapy may  help eliminate or minimise symptoms. Read Enzymes to the Rescue. Commercially available enzymes that break down proteins are available on the market.

Diagnosing food allergy

Food allergy can be diagnosed by means of skin-prick tests to various foods or by a RAST (radioallergosorbent test) on a blood sample.

If no food can be identified, but an allergic reaction is strongly suspected, an elimination diet lasting two to four weeks should be instituted. This involves eating only a limited number of foods that are unlikely to cause allergies, such as lamb, rice, pears and sweet potato.

Once the allergic symptoms settle, food is slowly reintroduced one at a time to identify the offending substance. When this involves children it is highly recommended to be done under the supervision of a dietician, as they can end up in a state of malnutrition on a prolonged restriction diet.

Allergenic Foods

  • Cow's Milk: Two out of a hundred infants under one year old suffer from cow's milk allergy, making it the most common food allergy of childhood. In general children lose this sensitivity as they grow up with nine out of ten losing it by the age of three; it is unusual for adults to suffer from this allergy.
  • Eggs: Allergy to eggs is usually observed in young children rather than adults, and like cow's milk allergy, fades with time. Occasionally children suffer from a severe form of allergy which is not outgrown.
  • Fish and shellfish: Allergies to shellfish are unusual in children, mostly being experienced by adults. Reactions to fish are found in children and adults. The incidence of seafood allergy is higher in those countries with a high consumption of fish and shellfish.
  • Fruits: In general allergic reactions to fruits and vegetables are mild, and are often limited to the mouth, and are called the oral-allergy syndrome (OAS).
  • Legumes: This group of foods includes soya beans and peanuts. Peanuts are one of most allergenic foods and frequently causes very severe reactions, including anaphylaxis. Allergy to peanuts is established in childhood and usually maintained throughout life.
  • Tree nuts: This group includes true tree nuts, such as Brazil nuts, hazelnuts, walnut and pecan. Whilst not as intensively studied as peanuts, indications are that tree nuts can cause symptoms as severe which can occasionally be fatal.
  • Cereals: Suffered by children and adults alike, wheat allergy appears to be particularly associated with exercise-induced anaphylaxis. The more of a cereal (wheat, rye, barley, oats, maize or rice) we eat the more likely we are to suffer an allergy. Thus rice allergy is found more frequently in populations eating ethnic diets.

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