The study, involving 628 babies prone to developing peanut allergy, found the risk of developing the allergy was cut by over 80 per cent.
Researchers focused on babies as young as four months who had already developed early warning signs of allergies such as eczema.
Tests were used to identify those who had not yet developed peanut allergy or had only a very mild response.
To reduce the risk of choking, half of the children were given peanut-based products rather than whole peanuts. The other half continued avoiding peanuts.
The results found that for every 100 children, 14 would normally go on to develop a nut allergy by the age of five. However this fell by 86% to just two out of every 100 children with early exposure.
Lead researcher Gideon Lack told the BBC that even children who were already becoming sensitive to peanuts benefited from the trial as their allergy rates fell from 35 to 11 per cent.
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"It was exciting to realise for the first time that in allergy, we can actually truly prevent the development of disease,” he said.
Before exposure to peanut products, Lack warns that high-risk children should be evaluated by a medical professional and receive skin-prick testing and dietary advice.