What is a nut allergy?

Food allergies involve our bodies being flooded by the substance histamine (plus other inflammatory chemicals) in response to proteins we have eaten. Nut proteins are a common cause of allergy and can occur at any age but appear to be increasingly common among infants and young children up to the age of 3. Once a child has a nut allergy it is unlikely that they will grow out of it. Children may be encountering nuts from an earlier age in cakes and biscuits and via breast milk , and this could be causing “sensitisation”. Why take nut allergies seriously?

Symptoms are often fairly mild and include tingling of the mouth and lips, facial swelling, nausea and tightness of the throat. However, in some cases, even a tiny amount of nut can trigger severe swelling of airways and obstruct breathing, with a sudden drop in blood pressure, followed by collapse and unconsciousness.

When are nuts safe?

No child under 5 should be given whole nuts because of the risk of choking. This point aside, if a close member of your family has any allergy or asthma, or gets hay fever (collectively known as atopy), foods containing nuts should be avoided until your child is 3, as this may have a protective effect. Once he or she reaches 3, nuts can be introduced in a controlled way and the child observed for reactions. Introduce them via peanut butter, ground up in stews and casseroles, or in satay sauces. Children who don't have atopic family members on the mother or father's side can have nuts from weaning.

Which foods should be avoided?

Peanuts are legumes - the same family as beans and lentils - rather than “tree nuts”, so you can be allergic to peanuts but not to almonds, for instance. Or you could be allergic to all of them. Currently about one child in 70 aged under 3 in the UK is affected to some degree by peanut allergy. Foods most likely to contain hidden nut products include cakes, biscuits, pastries, ice-cream, satay sauce, curries, salad dressings, breakfast cereals, Chinese, Indian, Thai, Indonesian and vegetarian dishes. Food manufacturers must declare the presence of any kind of nut but packets may not carry a “warning”. If you are unsure, avoid them.

What about pregnant and breast-feeding women?

Again, if you have any allergies in the family, asthma or hay fever, it is probably best to avoid these foods. However, if that's not the case, it's fine to incorporate nuts into your diet.

Why eat nuts at all?

They give us protein as well as some B vitamins needed for energy release, and minerals such as iron and zinc for energy and immunity. They also supply “good” fats, with research suggesting that regular nut eaters have a lower risk of heart disease.

Amanda Ursell is the Times nutritionist

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