Allergy to peanuts and tree nuts is the leading cause of fatal
and near fatal reactions to foods.
Tree nuts encompass a group of foods that commonly include walnut, almond, hazelnut,
cashew, pistachio, and Brazil nuts. Like peanut allergy, patients allergic to tree
nuts usually do not outgrow or lose their sensitivity during their lifetime.
Tree nuts are being added to an increasing variety of foods such as barbecue sauces,
cereals, crackers, and frozen desserts. Ethnic foods, commercially prepared baked
goods, and candy can be cross contaminated with nuts as they are frequently being
used in some varieties of foods.
These foods indicate the presence of Tree Nuts:
- Brazil nut
- Hickory nut
- Macadamia nut
- Marzipan/almond paste
- Nut butters, nut oil, paste
- Pine nuts (pignolia, Pinion)
These "Nuts" are not included in Tree Nuts:
- Water chestnut
Prevalence of Tree Nut Allergy
At least 0.6% of the general population is found to be allergic to at least one
Age of onset
Most children develop their allergic reactions to tree nuts some time between 2-4
years of age.
In one study of peanut-allergic children, 19 of 32 challenge-positive children were
skin tested to tree nuts; 12 of 19 had a positive skin test to one or more nuts:
- Walnut 11
- Filbert 10
- Cashew 9
- Almond 6
- Pecan 6
- Pistachio 6
None of these children experienced a reaction on
to a nut.
Most physicians dealing with peanut allergy also ask that the patient avoid tree
nuts as well. The reason is that there a significant number of children who initially
had only peanut allergy and did not avoid tree nuts, and then went on to have an
allergic reaction to tree nut.
Cross-reactions between tree nuts
For convenience it is better for someone who is allergic to any tree nut to avoid
all of them in his or her diet. It is very difficult to determine which one of the
tree nuts is contained in any particular food. Because some food manufacturers frequently
use multiple tree nuts in their factories, the likelihood of contamination with
another tree nut is higher.
Results from lab studies indicate that the protein in all tree nuts that cause allergic
reactions is very similar. The proteins that primarily cause allergic reaction are
seed storage proteins that are concentrated in the nut of the tree. They mainly
exist to provide energy to the next life cycle of the plant. This important medical
finding indicates that the possibility of developing a reaction to more than one
nut is greater.
From a medical standpoint, there is no reason to avoid coconut, nutmeg, or water
chestnuts if you are allergic to any of the tree nuts. There is no evidence to suggest
that acorns should be avoided either (some recommend avoiding it).
Diagnosis of Tree Nut allergy
Skin Prick Test or CAP RAST
is very reliable.
Sesame (Sesamum Indicum) is becoming increasingly popular in Western diet. Those
small seeds that characterize hamburger rolls & other bread products are sesame.
The sweet nutty flavour of sesame seed increases when it is mildly toasted.
Sesame is also known as Benne, Gingelly, Til or Teel, Simsin and Anjonjoli on foreign
Sesame seeds are extremely potent allergens and can cause severe
allergic reactions (anaphylaxis) in susceptible individuals. Sesame is used extensively
in the food industry and the seeds present a danger because of their versatility.
They have been identified in non-sesame products, especially bread, due to cross-contamination.
Humous, Tahini, and Halvah are three very popular sesame products
which are sometimes added to other foods without any clear declaration. Other common
sources of sesame include:
- Bakery products
- Confection bars
- Processed Meats
- Stir Fries
Cross contamination from sesame seed products made on the same line as non-sesame
products is becoming more common.
The popular herbal drink, Aqua Libra, contains sesame.
Sesame oil is used unrefined in food products and as a result it
is hazardous to those allergic to sesame. The prize oil possesses unique properties.
It resists rancidity and is extremely popular with Chinese chefs.
Sesame oil is used in pharmaceutical products, such as plasters, liniments, ointments
and soaps. It is used in cosmetics, where it may be listed as sesamum indicum.
Eating out requires great caution as sesame is so widely used these
Under the current food labelling regulation, known as the 25% rule, small amounts
of sesame may be present in any foods without any clear declaration.
The generic 'vegetable oil' complies with the current regulation.
Awareness of sesame allergy is low. It is less common than peanuts, but allergic
reactions can be just as severe.
Use the same precautions for Peanut Anaphylaxis.
Credits for the Sesame Allergy section in this article
'Reproduced with permission from work done by Maggie Spirito Perkins, British Allergy