These latest findings back current advice that only those women who are allergic to nuts should avoid eating them while pregnant or breastfeeding. Previously, several governments, including those in the UK and the United States, have advised all pregnant and breastfeeding women to avoid nuts. The earlier advice was based on the theory that early exposure might sensitise the developing foetus or very young baby to peanut or tree nut proteins, leading to later allergic responses.
However, public health bodies now say there is insufficient evidence to suggest that eating peanuts or tree nuts during pregnancy or while breastfeeding could lead to allergies.
Contrary to earlier thinking, this latest study supports the theory that early allergen exposure could in fact increase tolerance and reduce the risk of childhood food allergy.
"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 the study’s senior author Michael Young of Boston Children's Division of Allergy and Immunology. “Assuming she isn't allergic to peanuts, there's no reason for a woman to avoid peanuts during pregnancy."
Rising allergy rates
According to Allergy UK, peanut allergy is becoming increasingly common, with recent studies showing the rate of peanut allergy has doubled over a five year period both in Europe and in the United States. The prevalence of tree nut allergy has also risen. However, the reason for this remains unknown.
"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," Young said. "It was clear that a new approach was needed, opening the door for new research."
To clarify the role of maternal peanut and tree nut consumption in later allergy risk, Young and his team examined data from more than 8,000 children in the Growing Up Today Study (GUTS) and identified 140 cases of peanut or tree nut allergy.
They then examined maternal nut consumption during the peri-pregnancy period.
The researchers found that the rate of nut allergy was significantly lower among children in the study whose mothers ate peanuts during and after pregnancy – although they stressed that the data did not prove a cause-and-effect relationship.
The study adds to previous research, which has also found a link between maternal nut consumption and lower risk of childhood allergy.
This latest study is available online here.