Food allergy is caused when the body's immune system, responsible to keep us clean from infections, mistakenly thinks a protein in food (or part of it) is harmful. An immune response is triggered which starts a fight against this food protein. This includes the release of toxins to kill bacteria, but the same toxins end up damaging us instead (that's why we itch). Food allergy is distinct from food intolerance and one must not confuse them. 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 only 1-2% of the adults population. However, up to 10% of children may be allergic to one food or another (see Symptoms, next). On the other hand more than 50% of people are food intolerant (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)
Nose, Throat and Lung Reactions:
- Runny Nose
- Watery and/or Itchy eyes
- 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.
|Food Intolerance & Food Allergy Comparison|
|Cause||not enough enzymes to breakdown the sugars consumed in foods||immune system thinks certain proteins in foods are of those of harmful bacteria|
|Age||starts later in childhood but most common in adults, may be temporarily present in the form of colic in babies.||starts usually from early infancy and more common in children who overgrow it, triggered in later adult life in some who never had it in childhood.|
affects the digestive system only, mainly:
usually immediate and affecting more that one part of the body-
digestion: nausea, vomiting, stomach cramps and diarrhoea
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. See more details about Coeliac Disease and Non Coeliac Gluten Intolerance and the enzymes (Glutenzyme) available to help live a normal life. 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.
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. Hence, as explained in Better Nutrition Journal and several medical papers enzyme therapy can help eliminate or minimise symptoms. Read Enzymes to the Rescue. Commercially available enzymes that break down proteins are available on the market and two very good products are available in the 'products' section here. Both Polyzyme Forte and BioEnzyme have enzymes to break down proteins, but if your allergy is for milk Prolactazyme Forte does a brilliant job in most cases.
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, foods are slowly reintroduced one at a time to identify the offending substance. This should only be done under the supervision of a dietician, as children can end up in a state of malnutrition on a prolonged restriction diet.
- 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.
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).
This group of foods includes soya beans and peanuts. Peanuts are one of most allergenic foods and frequently cause 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.