Women need not fear that eating peanuts during pregnancy could cause their child to develop a peanut allergy, according to a recent study from Boston Children’s Hospital (BCH).

The study, which was published on 23 December 2013 in the online journal JAMA Pediatrics, found that peanut and tree nut allergy incidence was lower among children whose mothers ate them during pregnancy.

“Our study showed increased peanut consumption by pregnant mothers who weren’t nut allergic was associated with lower risk of peanut allergy in their offspring,” said Dr Michael Young, from BCH’s Division of Allergy and Immunology and the study’s senior author. “Assuming she isn’t allergic to peanuts, there’s no reason for a woman to avoid peanuts during pregnancy,” he said.

Previously, women had been advised to avoid highly allergenic foods such as peanuts and tree nuts during pregnancy and while nursing, and their children should avoid peanuts until three years of age. BCH researchers said the goal of these recommendations, despite a lack of supporting research, was to minimise early allergen exposure and sensitisation, thereby reducing the risk of developing childhood peanut allergy. The American Academy of Pediatrics (AAP) endorsed these recommendations in 2000. However, from 1997 to 2007, the number of peanut allergy cases in the US tripled, leading the medical community to re-examine its recommendations. Based on the lack of evidence supporting the dietary avoidance, the AAP rescinded the recommendation in 2008.

“No one can say for sure if the avoidance recommendation for peanuts was related to the rising number of peanut allergies seen in the late 1990s and early 2000s, but one thing is certain: it did not stop the increase,” Dr Young said. “It was clear that a new approach was needed, opening the door for new research,” he said.

Study method

To further define the relationship between maternal diet and the development of the food allergy in offspring, Dr Young and his team analysed large amounts of data provided by the Growing Up Today Study (GUTS). Examining the records of 8,205 children, the researchers positively identified 140 cases of peanut or tree nut allergies. They then examined the diets of each child’s mother — specifically peanut and tree nut consumption — during the peri-pregnancy period and compared them with the dietary habits of pregnant women whose children did not develop a peanut allergy.

The findings showed that the rate of peanut allergy was significantly lower among children in the study whose mothers ate peanuts during the peri-pregnancy period. Although this is a substantial findings, the researchers emphasised that the data demonstrate only an association between maternal diet and the risk of peanut allergy in children.

“The data are not strong enough to prove a cause-and-effect relationship,” Dr Young said. “Therefore, we can’t say for certainty that eating more peanuts during pregnancy will prevent peanut allergy in children. But we can say that peanut consumption during pregnancy doesn’t cause peanut allergy in children,” he said.

“By linking maternal peanut consumption to reduced allergy risk we are providing new data to support the hypothesis that early allergen exposure increases tolerance and reduces risk of food allergy,” Dr Young said.

Peanut allergy rates in Australia

In Australia, food allergies affect 10 per cent of infants, 4-8 per cent of children aged between 5 and 13 years, and roughly 2 per cent of people over 13.

Among children, peanuts are the most common food allergy (along with cow’s milk and egg), affecting an estimated 3 per cent of Australian children by the age of 12 months, according to Dr Raymond Mullins, Chair of the Australasian Society of Clinical Immunology and Allergy (ASCIA) Anaphylaxis Working Party, and nearly 80 per cent of those with peanut allergy did not grow out of the problem. Dr Mullins said this means that if the rate of peanut allergy was uniform across Australia, there could be approximately 9,000 new cases of peanut allergy each year.

The mainstay of treatment for peanut allergies is food avoidance and, for those considered a higher risk of having a potentially dangerous reaction, an adrenaline auto injector can also be provided. But treatments involving “switching off” allergies are currently being researched. Australian Food News reported in August 2013 that US research had identified the enzyme that is essential to the allergic reaction to peanuts.

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