When Priya*, now 11, was a 3-month-old baby in the US, she developed eczema on her face. Worried, her mother took care not to introduce any potential allergens into Priya’s diet during her first couple of years, a standard response promoted by the American Academy of Allergy, Asthma and Immunology at the time. But when she was 2, Priya came into contact with peanuts for the first time at a restaurant. She didn’t eat any, but only playing with the shells caused her eyes to swell.

A few weeks later, after eating cashews and developing a full-body rash, Priya was officially diagnosed with a nut allergy, with particular sensitivity to peanuts. It left her mother feeling confused – hadn’t she done everything right? But new evidence is suggesting that everything doctors and parents thought they knew about allergies, particularly peanut allergy, is wrong.

Peanut allergy spreading around the world

Peanut allergy affects only a small number of children (3 to 5 % of children in developed countries such as the US, UK and Australia), but the severity of its consequences means it’s treated with a lot of caution.

“Genuine peanut allergy is rare but can be fatal,” says Dr. Kiran Kinger, a Bangalore-based consultant pediatrician who has worked with children in both developed and developing countries.

As a result, whole communities can change at the crack of a nut; many schools in the US are now peanut-free thanks to lobbying on behalf of a small number of children.

But now, that number is growing and it’s growing worldwide. In recent years, there has been a huge increase in food allergies, especially to peanuts. Studies have found that peanut allergy in Western countries doubled in the 10 years before 2014 and is a growing problem in Asian and African countries, where it has, to date, been uncommon.

Dr. Mahesh PA, professor and head of pulmonary medicine at JSS Medical College in Mysore, recently completed a survey of food allergies in the Mysore and Bangalore regions as part of Europrevall, a European Commission project to examine the prevalence, cost and basis of food allergies worldwide. He blames the adoption of Western diets and practices for the rise in food allergy in India.

“Unlike in the Western world, actual food allergy for any food, including peanut, is very low in India,” Dr. Mahesh says. “I strongly believe the Indian diet is responsible for the low prevalence of food allergy.”

Dr. Mahesh says Indian clinicians are seeing a clear upward trend in food allergies and severity, but is careful to note that whether an actual increase in incidence or just greater awareness among patients is responsible for this increase in cases is not yet clear.

Dr. Kinger agrees that diet plays a big role in allergy development, starting in the womb.

“The developing nations have much lesser incidence of peanut allergy, because of more widely available, affordable and acceptable peanut use in the diet,” he says. “Hence, the pregnant mother who is used to eating peanuts gives a ‘sensitisation’ experience to the unborn fetus who is then used to the flavor and food containing peanut. These children do not react as severely as unsensitised children do.”

A new theory around what causes peanut allergy

What Dr. Kinger describes is now influencing a paradigm shift in how doctors thinking about and treating peanut allergy and how parents are advised in the early years of childhood to prevent peanut allergy. Until now, guidelines recommended avoiding potentially allergenic foods until 12 to 36 months of age for babies with allergy risk factors (that is, babies with asthma, hay fever, eczema or dermatitis, or a family member with food allergies). Specifically, these former guidelines prohibited non-human milk in the first year of an infant’s life, eggs and nuts until age 2, and fish until age 3. Families like Priya’s followed these recommendations only to find their children develop food allergies anyway.

But spate of new studies are reversing this dogma. The hypothesis that delayed introduction of allergenic foods is not just unhelpful, but could actually increase the likelihood of developing food allergies is rooted in a 2008 study that compared the risk of developing a peanut allergy between Jewish infants in the UK, where peanut consumption is avoided in the first year of life, and Jewish infants in Israel, where peanut-based foods are introduced in the diet around 7 months of age. Researchers found that the UK infants were 10 times more likely to develop a peanut allergy, suggesting early introduction may be preventative.

This idea was confirmed early last year, when the results of a separate study found that earlier introduction of the peanut, rather than later, to high-risk children’s diets reduced the development of food allergies by as much as 80%.

Now, peanut allergy recommendations have been turned upside down. Experts from the American Academy of Allergy, Asthma and Immunology, American Academy of Pediatrics, Australasian Society of Clinical Immunology and Allergy (ASCIA), World Allergy Organization and more are calling for earlier introduction of the peanut for high-risk infants. Formal revision of guidelines is expected to follow this year [Ed. note: It now has.]; in the meantime, the group recommends peanuts be introduced around 6 months of age for high-risk infants and kept a regular part of their diet in order to maintain tolerance. They also advise pregnant and nursing mothers not to eliminate peanuts from their diet, unless they are themselves allergic, in which case eating small amounts could help prevent their infants from developing peanut allergy too.

Dr. Kinger has a simpler take.

“Give the children what the family is used to,” he says.

To introduce new foods into a baby’s diet, the American Academy of Allergy, Asthma and Immunology recommends:

• Introducing a new food every 3 to 5 days in an age-appropriate manner (to avoid choking)
• Starting with grains, yellow and orange vegetables, and fruit
• Introducing one of the potentially allergenic foods, if well-tolerated, in small amounts
• Introducing highly allergenic foods at home, rather than at restaurants
• Increasing the quantity of new food over several days