Allergens in nuts

Nuts are foods of vegetable origin, which are characterized by not containing juices, they are consumed in dried form. They come from plants that have no botanical relationship with each other. This group includes, in addition to nuts, seeds of different families and peanuts.

The number of allergies produced by nuts depends on the nutritional habits of each region. For example, in Spain, nut and almond allergy is more frequent, while in the United States, peanut allergy is more frequent due to the frequent use of peanut butter.

In Spain the most consumed nuts are:

• Nuts in shell.

Examples: hazelnuts, walnuts, almonds, cashews, pistachios, chestnuts and acorns, Seeds.

Examples: pumpkin, poppy, sesame, pine nuts, sunflower and flax. Peanuts (belonging to the legume family).

They can also be included in some mixtures (mix) of nuts and dried fruits:

• Dried fruits.

Examples: prunes, raisins and blueberries. Fried legumes and cereals.

Examples: chickpeas and corn. Characteristics of nut allergies:

• Allergic reactions to nuts usually occur immediately, only in some cases, it may take up to two hours after ingesting the food.
• Symptoms may vary, from very mild hives, reddening of the skin, swelling of the lips, eyelids, asthma, digestive symptoms, to anaphylactic symptoms.
• Nut allergens are thermostable, so they maintain their allergenicity after being subjected to different cooking methods.

Nut allergy affects approximately 1% of the population. They can appear at any age, generally after the age of three years.

In children, nut allergy is likely to disappear, but not as often as with egg and milk allergy. The later the onset, the greater the probability of permanence.

There is an association between sensitization to fresh fruits, such as peaches and apricots, and nuts. The nuts that most frequently cause allergic reactions are generally the most commonly consumed, such as walnuts, hazelnuts and peanuts. In Europe, hazelnut is the nut that causes the most allergic problems.

Patients allergic to more than one nut can often be found, without being able to establish which groups of nut allergies are most commonly associated. Some studies suggest associations in the following cases:

• There is cross-reactivity between walnut, hazelnut and almond.

• Several common allergenic proteins have been described in hazelnut and sesame seeds causing cross-reactivity.

• Associations have been described between cashew and pistachio, both from the same family, and there would also be cross-reactivity, as they contain some allergen in common.

• There are associations between nuts and certain pollens, such as that between hazelnut and birch pollen.

• The association between chestnuts, bananas, avocados and latex is frequent, since all of them have allergens identified as class 1 chitinases.

Treatment and recommendations for nut allergy sufferers. Avoid direct ingestion of nuts, as well as foods that include them among their ingredients.

Those allergic to nuts may consume nuts to which they are not sensitive, as long as they have the shell, since peeled nuts may have been contaminated during the manufacturing process.

Carefully check the labels of processed products, especially breakfast cereals, cookies, breads, chocolate spreads, among others. In case of doubts about the name of any ingredient, you should avoid consuming it until you clarify the meaning.

You should avoid consuming products with labels whose description is not very precise, such as:

• "may contain traces of nuts".

Avoid consuming oils obtained from nuts to which you are allergic.