The study – published in the Journal of Allergy and Clinical Immunology this month – examined the relationship between maternal peanut intake during pregnancy and the development of allergy and allergic diseases children.
The links between maternal intake of nuts and risk of childhood allergy has been controversial area of research in recent years, with scientific findings offering mixed findings on whether maternal nut intake has any effect on childhood allergy incidence – and if so whether it increases or decreases risks.
For example until a few years ago, women were advised to avoid nuts due to fears that they could increase the risk of their child developing a peanut allergy. However, this advice with withdrawn in the UK in 2009 when the Food Standards Agency said there was ‘no clear evidence’ of any risk.
Led by Ekaterina Maslova from Statens Serum Institute, Denmark, the researchers followed more than 60,000 mothers and their children, from early pregnancy until the children were seven – finding that consumption of nuts during pregnancy reduced the incidence of allergies and lowered the chance of a child being classed as asthmatic at 18 months by about a quarter, and a third at seven years.
“We found that maternal peanut and tree nut intake one or more times per week during pregnancy decreases the risk of allergic disease in childhood,” said Maslova and her colleagues.
“These results do not support avoidance of nuts during pregnancy,” they stated.
Commenting on the research, the UK NHS Choices service noted that even though the study takes into account a multitude of possible factors that may influence the association between nut-eating during pregnancy and child asthma, “it is difficult to ensure that they have all been fully accounted for.”
However the service added: “The idea of exposing an individual to low levels of an allergen in order to decrease their sensitivity to it is not a new one, and in fact this sort of therapy (immunotherapy) is already used in the treatment of certain allergies. Therefore, it is plausible that consumption of nuts during pregnancy would expose the developing baby to the compounds that are in nuts and so may decrease the likelihood that they would develop allergy as a child.”
Maslova and her colleagues asked 61,908 women halfway through their pregnancy about their diet, including information on how often they ate nuts.
The team then checked the health of the women’s babies after they gave birth, specifically looking at whether the child had been diagnosed with asthma by the time they were 18 months, or had symptoms of wheeze. This was followed by a second assessment taken when the child was 7 years old.
The main finding of the investigation was that maternal consumption of peanuts or tree nuts (defined as consumption at least once a week) was associated with a 20-25% decreased risk of the child being diagnosed with asthma at 18 months.
Compared with never consumption, children of mothers who ate peanuts one or more times per week were also 34% less likely to have an asthma diagnosis recorded in the registry and were 17% less likely to have a prescription recorded for asthma medication at age seven.
They authors said it is plausible that consumption of nuts during pregnancy would expose the developing baby to the compounds that are in nuts and so may decrease the likelihood that they would develop an allergy.
Source: Journal of Allergy and Clinical Immunology
Volume 130, Issue 3, September 2012, Pages 724–732, doi: 10.1016/j.jaci.2012.05.014
“Peanut and tree nut consumption during pregnancy and allergic disease in children—should mothers decrease their intake? Longitudinal evidence from the Danish National Birth Cohort”
Authors: Ekaterina Maslova, Charlotta Granström, Susanne Hansen, Sesilje B. Petersen, et al