Professor Gideon Lack, of King's College London, said: "For decades, allergists have been recommending that young infants avoid consuming allergenic foods such as peanut to prevent food allergies.
"Our findings suggest that this advice was incorrect and may have contributed to the rise of peanut and other food allergies."
Peanut allergies, which have doubled over the past few decades and affect about one per cent of the population, can cause hives, abdominal pain and severe anaphylaxis, which can kill if left untreated.
Professor Lack added: "This is an important clinical development and contravenes previous guidelines.
"While these were withdrawn in 2008 in the UK and US, our study suggests that new guidelines may be needed to reduce the rate of peanut allergy in our children.
"The study also excluded infants showing early strong signs of having already developed peanut allergy; the safety and effectiveness of early peanut consumption in this group remains unknown and requires further study.
"Parents of infants and young children with eczema and, or egg allergy should consult with an allergist, paediatrician, or their general practitioner prior to feeding them peanut products."
The co-investigator of the study, Dr George Du Toit, a consultant in paediatric allergy at Guy's and St Thomas' NHS Foundation Trust and an honorary senior lecturer at King's College London, said: " [We] will continue to monitor those children who consumed peanut to see if they remain protected against allergy even if they stop consuming peanut for 12 months."
What to know about the research
Children at high risk of developing peanut allergies are far less likely to do so if they are given peanut-containing foods before they turn 1, finds a major study that is expected to quickly change dietary advice to many parents.
Some things to know:
Peanuts pose a serious problem
Peanut allergies are rising and affect more than 2 percent kids in the United States alone. They are the top cause of food allergy-related severe reactions and deaths.
Food allergies often are inherited, but also can develop during life, and age of exposure may matter. In recent years, doctors have wondered whether avoiding certain foods in infancy does harm or good.
The experiment
Researchers in England studied more than 600 children ages 4 months to 11 months old with possible signs of an allergy but no strong evidence of one on a skin test. They were assigned either to avoid peanuts until age 5, or to regularly eat them, usually as peanut butter or a peanut puff snack.
At age 5, peanut allergies had developed in 3 percent of peanut eaters versus 17 percent of abstainers.
Warnings to parents
Don't try this on your own. Babies in the study were tested to ensure they didn't already have a peanut allergy before they were fed peanut-based foods.
Also, whole peanuts pose a choking risk. Doctors recommend peanut butter or other peanut-containing foods instead.
What's next?
Food guidelines may change. The American Academy of Pediatrics used to recommend against giving children peanut-based foods before age 3 but dropped that advice in 2008 because there was no evidence it prevented allergies. Now, most parents introduce peanut-based foods when other solid foods are added unless a child is known to have a peanut allergy.
- AP, The Independent