The Bamber theory

This was been the finding of collaborative research by Gideon Lack, professor of paediatric allergy at King’s College London, and Israeli scientists. The vast difference in incidence rates left them scratching their heads, reports Professor Lack.

One theory, the so-called hygiene hypothesis, is that peanut allergies thrive among people who live in clean environments, because their immune systems are under-used in their fight against dirt and thus choose to reject peanuts. “Hygiene did not really stand up as a factor with Israel, as it is western in habits and clean,” he says.

“There also exists the possibility that increased exposure to sunlight, or a Mediterranean diet, protects.”

However, Professor Lack became interested in another “far more interesting possibility”.

As peanut allergies have become more widespread in recent years, health authorities in the UK, Canada, the US and other countries have concluded that the best prevention technique is withholding foods containing peanuts until the age of three. Hence the Department of Health advice — no peanut products until a child’s third birthday.

The rationale is that, when allergies do occur, the severe reaction that can follow the first peanut consumption is most difficult to deal with in very young children. Secondly, medical evidence and biological theory have traditionally suggested that exposure to peanut in the early years of life is a cause of people developing allergies.

However, some scientists suggest the opposite — that if exposed to peanuts at an early age, a child’s body can learn to tolerate the allergen — peanut protein.

It is fair to say that, when it comes to disputes, Israel is hardly known for settling them. But Professor Lack realised it may offer a solution to this one.

The country is unique in the fact that “people at a young age are exposed to lots of peanuts”, he says. This is because one of the first foods given to most children is the peanut-packed Bamba, chosen because it is softer than rusks but solid enough to give relief from teething, and it is enriched with vitamins.

Just under a year ago, he set up an 18-strong research team at London’s St Thomas’ Hospital to work out whether the Bamba culture accounts for low rates of peanut allergy in Israel and offers a model for the rest of the world.

Their project is called Leap (Learning Early About Peanut Allergy). It is run by Professor Lack and America’s Immune Tolerance Network. Funding is from The National Institute of Allergy and Infectious Diseases (NIAID) at America’s National Institutes of Health.

It uses a sample of 600 babies aged 11 months or under who already show signs of eczema, which means they are more likely to be allergic to peanuts. Half are being fed Bamba and other peanut snacks three times a week, half have no peanuts or peanut products at all.

“Our hypothesis is that early introduction of may account for the low incidence in Israel and could reduce the possibility of peanut allergy.”

Intriguingly, he says this need not undermine the strategy of complete avoidance. “It may be that protection from the allergy comes from either high-dose exposure or complete avoidance, but that anything between the two makes people susceptible.”

The results of the study will be known in five years, when all participants have reached school age. Data on the numbers of allergic children from each group will be audited and then submitted for publication to a peer-reviewed scientific journal.

Despite his enthusiasm for his theory, Professor Lack warns against people changing their children’s diets at the moment, saying: “This is a hypothesis, and people should not act on it at this stage.”