Tests carried out by Oxford University researchers found that eaten raw the nuts had little effect on the immune system.
They are now working on safe, dry-roasted peanuts to help prevent an allergy that affects one in 50 children.
‘We did a simple experiment and found that the mice fed the dry-roasted proteins got an immune response indicative of allergy,’ said researcher Quentin Sattentau.
‘Whereas the mice fed the raw peanut proteins didn’t or did to a much lesser extent.’
The result was the same whether the mice were fed peanut protein or had it rubbed into broken skin – both ways in which peanuts are thought to trigger allergies in humans.
Professor Sattentau added: ‘This is the first time, to our knowledge, that a potential trigger for peanut allergy has been directly shown.’
The finding helps explain why peanut allergy is much more common here than in the Far East, where the nuts are more commonly eaten raw, boiled or fried.
It is believed that the process of dry-roasting involves temperatures high enough to change the peanut’s chemistry in a way that confuses the immune system and leads to allergic reactions.
It will be some years before safer dry-roasted peanuts are on supermarket shelves and the complex nature of the immune system means that those who already have a peanut allergy are unlikely to be helped. While the majority of reactions are mild, nut allergy can trigger a life-threatening anaphylactic shock.
The Oxford team said it would be premature for people to avoid the nuts because of their research, published in the Journal of Allergy and Clinical Immunology.