Peanut allergy could plummet by 77% if peanut products were added to all babies' diets at four to six months of age.
Peanut allergy has seen a three-fold increase in recent decades. It now affects around one in 50 children in the UK.
Previous research led by Professor Gideon Lack from King's shows that eating peanut products from an early age during infancy can reduce the risk of allergy and help reverse this trend.
A new study published in the Journal of Allergy and Clinical Immunology Now, identifies a clear 'window of opportunity' between four and six months of age depending on the child's health.
The new analysis was led by Professor Graham Roberts from the National Institute for Health and Care Research (NIHR) Southampton Biomedical Research Centre and University of Southampton, and Professor Gideon Lack at King's, with expertise from the Immune Tolerance Network (ITN) and National Institute of Allergy and Infectious Diseases (NIAID) in the USA.
Most peanut allergies have already developed by the time a child turns one year of age.
It is more common in children with severe eczema and egg allergy. Children of non-white ethnicity are also more likely to be affected.
The new study, with contributions from Professor George du Toit and Mary Feeney from King's, used data drawn from the Enquiring About Tolerance (EAT) and Learning Early About Peanut Allergy (LEAP) randomised-controlled trials - both studies led by Professor Lack at King's and Guy's and St Thomas' NHS Foundation Trust - plus the Peanut Allergy Sensitization observational study. These include children who are at high and others who are at low risk of developing peanut allergy.
The modelled approach showed it was best to introduce peanut products to babies at four to six months of age. For babies with eczema, four months is recommended.
This should be in the form of smooth peanut butter or other peanut snacks suitable for babies – not whole or broken peanuts. The baby should also be developmentally ready to start solids.
Researchers advise mothers to breastfeed at least the first six months of their child's life as well as introducing peanuts to their diet from four to six months.
Overall, the data found that introducing peanut products into all babies' diets by six months could reduce peanut allergy across the population by up to 77%.
Waiting to introduce the peanut products until 12 months of age would lead to only a 33% reduction.
Professor Graham Roberts, from the National Institute for Health and Care Research (NIHR) Southampton Biomedical Research Centre and University of Southampton said: "Over several decades, the deliberate avoidance of peanut has understandably led to parental fear of early introduction.
"This latest evidence shows that applying simple, low-cost, safe interventions to the whole population could be an effective preventive public health strategy that would deliver vast benefits for future generations."
The benefits of introducing peanut products into babies' diets decreases as they get older. This reflects the experience in Israel, a culture in which peanut products are commonly introduced early into the infant diet and peanut allergy is rare.– Professor Gideon Lack, from King's and Guy's and St Thomas' NHS Foundation Trust
He added: "There is a narrow window of opportunity to prevent an allergy from developing. Introducing peanut products at four to six months of age could substantially reduce the number of children developing peanut allergy."
The research also showed that the greatest benefit can be achieved if the whole population is targeted. This is because most allergies occur in the many babies without any known risk factors.
The findings provide evidence for recommendations in recent North American and European allergy guidelines. These recommendations suggest the early introduction of peanut products for all infants, based on an extrapolation of previously published data from the LEAP and EAT studies conducted at King's.
Research into the prevention of peanut allergy in children has been driven by years of investment by the NIHR, ITN, NIAID, and partners around the globe.
The LEAP study was led by Professor Gideon Lack and Professor George Du Toit from King's College London and the NIHR Guy's and St Thomas' Biomedical Research Centre (BRC). The trial examined the early introduction of peanut products and enrolled 640 babies considered at high risk of developing peanut allergy from the Evelina London Children's Hospital.
It was supported by grants from the US National Institute of Allergy and Infectious Diseases of the National Institutes of Health and by Food Allergy Research and Education, the Medical Research Council (MRC) and Asthma UK Centre. The UK Food Standards Agency (FSA) provided additional support.
The EAT Study investigated the early introduction of six allergenic foods: milk, peanut, sesame, fish, egg and wheat. It was supported by the NIHR through the Guy's and St Thomas' BRC and an NIHR Clinician Scientist Award with grants from the FSA and MRC.
