Allergies to foods can cause swelling of the lips, throat, face and tongue; cause an upset stomach, vomiting, cramps, hives, eczema and even asthma. Some common food allergens are milk, soy, eggs, peanuts, wheat, fish and shellfish. Food allergies are most common in childhood, but can also occur in adults.
Pseudo-allergies are not related to the immune system, even though they may exhibit the same symptoms as "real" allergies.
Pseudo-allergies are provoked by foods containing histamine or causing histamine release during chemical reactions, such as in the digestive tract.
Canned tuna or mackerel, for example, might contain high levels of histamine, directly triggering symptoms exactly like those of an allergic reaction. Having such a reaction to histamine does not mean to say that you are allergic to tuna or mackerel.
Other food products may also trigger pseudo-allergies, such as certain food additives (colourings, preservatives, flavourings). These should be avoided. Amongst the 3000 or so commonly used food additives, the more frequent causes of hypersensitive reactions are:
- sulphites and derivatives: E 220-227
- nitrites: E 249-252
- benzoic acid and derivatives: E 210-219
- sorbic acid
- butyl-hydroxyanisole: E 321
- butyl-hydroxytoluene: E 321
- tartrazine: E 102
- yellow-orange S: E 110
- azorubine: E 122
- amaranth: E 123
- cochineal red: E 124
- erythrosine: E 127
- brilliant black BN: E 151
- glutamates: B 550-553
“True” food allergies
The term food allergy really applies only to an immunological reaction (IgE antibodies), resulting in allergic symptoms. These may be digestive (abdominal pain, vomiting, diarrhoea), respiratory (sneezing, blocked nose, congested bronchi), or cutaneous (itchy skin, swelling, rash). Reactions may be immediate or delayed.
Allergy to cow’s milk
Signs of intolerance appear within first few months of life (usually before the age of 6 months). Cow's milk contains certain highly allergenic proteins. Because they are rather resistant to heat, they can still be very allergenic even after cooking.
A baby who is allergic to cow's milk normally will outgrow the problem, very often between the ages of 2-4 years.
Treating allergy to cow's milk consists in replacing it with substitutes such as soya milk or a special hypo-allergenic formula. Unfortunately, children who are allergic to cow's milk often are also allergic to the substitutes. If this is the case, you should use protein hydrolysates (proteins that have been broken down), which are much less allergenic than whole proteins.
Some breast-fed children show signs of allergy after the first few feedings because mother's milk may contain small quantities of cow's milk allergens. This is a very rare occurrence. The general rule still stands: Breast is best!
In the majority of cases, signs of allergy appear only after the baby is weaned, often in the form of atopic eczema.
Allergy to egg white
Hypersensitivity to this food is often associated with an allergy to cow's milk but may also occur by itself.
Certain vaccines (e.g. measles, mumps), based on chicken embryos, can also provoke acute allergic reactions in people allergic to egg white.
Tip: Food allergies are not forever!
Intolerance to animal proteins decreases as a child grows, so as the child becomes older you may very cautiously try re-introducing foods which previously caused a reaction. B u t always consult your doctor first! Example: some children will tolerate egg yolk after the age of 1 year.
Allergy to fish
These allergens, found in their muscles, are often common to different species of fish. However, some people are only hypersensitive to a certain type of fish (e.g. cod).
Allergy to shell fish
Culprits: crustaceans (crabs, shrimps, prawns, etc.) and bivalve molluscs (oysters, mussels, cockles, etc.).
Here too these may be mono-allergies (due to just a sin-gle species) or crossed-allergies (e.g. due to both mussels and oysters).
Allergy to stamps!
Licking stamps to put them on letters can sometimes trigger an allergic reaction. This apparently bizarre allergy is due to the fact that the adhesive gum is made from fish bones!
Allergy to fruit, vegetables and nuts
The principal culprits are apples and pears, and stone fruits (cherries, apricots, peaches, etc.).
Amongst vegetables we could list spinach, tomatoes, parsley, celery, and chervil.
Handling and cutting up kiwi fruit can trigger generalised reactions in some sensitive people.
Some of the most severe reactions are to nuts: tree nuts such as walnuts, hazelnuts, almonds, and Brazil nuts, as well as groundnuts (peanuts).
Hypersensitivity to fruits and vegetables is nearly always related to an allergy to pollen. For example, 50% of people allergic to birch pollen are also allergic to apples. The allergens in fruit and vegetables are frequently, but not always, thermolabile, i.e. they are destroyed when cooked.
Remember that children become more tolerant to certain foods as they grow older (most food allergies disappear between 2-4 years of age). However, this very much depends on the food in question. Allergies to fish or to peanuts last much longer than allergies to cow's milk or eggs. We do not know why.