Peanut allergy is a serious and life-long allergy affecting both children and adults. It is essential that individuals with peanut allergy avoid even the slightest exposure to peanuts to prevent life threatening reactions. The most common manifestation of peanut allergy is with acute hives (or urticaria) following exposure. However, some patients may rapidly develop severe angioedema, swelling of the face, bronchospasm and anaphylaxis following exposure. They are an uncommon cause of exercise induced anaphylaxis. Some individuals are so sensitive that they will develop symptoms if they kiss someone who has eaten peanuts or eat out of a food utensil which has been in contact with peanuts.
Peanuts are among the most allergenic foods. The peanut allergen (Ara h 1,2) are glycoproteins with a molecular mass of 63 kilodaltons. It is present in raw and roasted peanuts since it is heat stable. It may contaminate peanut oils. The proteins in peanuts can also be allergens, e.g. arachin, conarachin, peanut agglutinin and peanut phospholipase.
Source of peanut allergens
Peanuts are widely used in Western and Oriental cooking. Foods which often contain peanuts or peanuts products include the following:
- Baking goods
- Chinese dishes
- Egg rolls
- Ice creams
- Health bars
- Health bread
- Indonesian dishes
- Mixed nuts
- Peanut oil
- “Natural” flavouring
- Peanut butter
- Spaghetti sauces
- Thai dishes
- Vegetable fats and oils
NB: ALWAYS CHECK THE LABEL OR ASK THE CHEF IF EATING ANY OF THESE FOODS.
Nutritive value of peanuts
Peanuts provide niacin, magnesium, Vitamin C, manganese and chromium in significant amounts and smaller amounts of potassium, Vitamin B6, folic acid, phosphorus, copper and biotin. A peanut restricted diet will not negatively affect a growing child’s diet since many other foods provide these same nutrients.
What about allergy to other nuts?
Peanuts are not nuts; they are legumes. Most peanut sensitive individuals are not allergic to tree nuts such as pecans, walnuts or almonds. However, some patients have multiple allergies and may also be sensitive to tree nuts such as brazil nuts, cashews, hazelnuts, macadamia nuts, pine nuts and pistachios.
How is peanut allergy diagnosed?
A history of an allergic reaction occurring within an hour of exposure to peanuts suggests peanut allergy. This should be confirmed by the CAP RAST test performed at a laboratory on a small blood sample. The CAP RAST test is reliable, being both extremely sensitive and specific. We generally do not perform skin prick testing if a strong history of peanut sensitivity is given since it may trigger a severe reaction.
How is peanut allergy treated?
- Avoid any possible direct exposure to peanuts.
- Compile a list of possibly contaminated foods which should also be carefully avoided.
- It is important to carefully study labels of all packaged, processed foods, cereals and health foods.
- Take particular care when eating out particularly at oriental restaurants or at children’s parties.
- Caregivers in crèches, schoolteachers, family members, friends and their parents should be informed about the allergy and what to do in an emergency.
- Wear a Medic Alert badge.
- Always carry an injectable adrenaline syringe (e.g. Epipen or Anaguard) and be familiar with its use.
- NEVER TAKE A CHANCE WITH UNKNOWN FOODS.
Can peanut allergy be prevented?
There is now good evidence that early introduction of peanuts, as early as 4 months of age may prevent peanut allergy in predisposed children. This can be discussed with your allergy specialist.
Can you outgrow peanut allergy?
Generally, patients with peanut allergy do not outgrow their allergy. There are some exceptions, and this has to be confirmed by blood testing and food challenges.