Updated 15 June 2017

Nuts in pregnancy lowers baby's allergy risk

In a study of 62 000 Danish mothers, the children of those who ate peanuts and tree nuts while pregnant were less likely to develop asthma or allergies.


In a study of 62 000 Danish mothers, the children of those who ate peanuts and tree nuts while pregnant were less likely to develop asthma or allergies.

The results support the recent withdrawal of recommendations that pregnant women should avoid nuts because they might raise a child's risk for allergies to the nuts themselves and for other hypersensitivities like asthma, according to the US and Danish researchers.

"There's some mixed data out there and this current study is showing that maybe there might be a benefit to your child in having less asthma later on if you continue to just eat the way you're still eating and not avoid (nuts)," said Dr Todd Mahr, a pediatric allergist at Gundersen Lutheran Medical Center in La Crosse, Wisconsin, who was not involved in the study.

Nuts and pregnancy

In 2008, the American Academy of Pediatrics rescinded its recommendation that women should avoid eating peanuts while pregnant to prevent a possible food allergy, and the UK's health agency did the same in 2010.

There is little research implicating peanuts, specifically, eaten by a pregnant mother and her child's risk for peanut allergy - much less a wider range of sensitivities. Yet the fear continues to lead many expectant mothers to steer clear of nuts.

How the study was done

Dr Ekaterina Maslova, a researcher at the Center for Fetal Programming at Statens Serum Institut in Copenhagen, wanted to take a more extensive look at nut exposure and the possible health outcomes in kids.

Dr Maslova's team, who published their results online June 29 in The Journal of Allergy and Clinical Immunology, collected survey responses from more than 61 908 Danish women who gave birth between 1996 and 2002, and analysed their kids' medical records at the ages of 18 months and seven years.

The mothers had provided information about how often they ate peanuts and tree nuts during pregnancy. At age 18 months, 15% of kids whose moms ate peanuts more than once a week had asthma, compared to more than 17% of kids whose moms never ate peanuts. When other asthma risk factors were taken into account, the researchers concluded that kids whose mothers ate peanuts regularly were 21% less likely to develop asthma.

At seven years old, this same group of kids was 34% less likely to have a diagnosis of asthma than kids whose moms had abstained from peanuts. Similarly, mothers who ate tree nuts more than once a week had 18-month-olds who were 25% less likely to have asthma and wheeze than the moms who avoided the nuts, although this difference appeared to fade as the kids reached seven years old.

Vitamin E and antioxidants still in question

Peanuts appeared to have no effect on whether kids developed nasal allergies, and the children of moms who frequently ate tree nuts were 20% less likely to have allergies. Dr Maslova said the findings are further reassurance that pregnant women don't need to avoid peanuts and tree nuts, although the study doesn't prove that nuts are actually protective against asthma and allergies. She said the fatty acids, vitamin E or antioxidants in nuts might be playing a role. "We're looking at food intake, so we can't say this is the one nutrient that's driving this association," she said.

Dr Mahr, who chairs the section on allergy and immunology at the American Academy of Pediatrics, noted that interviewing people about what they eat can introduce some accuracy issues, but the findings are still interesting."A take home from this would be if there's no food allergy in your family, but there's an asthma history in your family, maybe you might not want to avoid peanuts specifically," Dr Mahr said.

(Reuters Health, Kerry Grens, July 2012)

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Dr Morris is the Principal Allergist at the Cape Town and Johannesburg Allergy Clinics with postgraduate diplomas in Allergology, Dermatology, Paediatrics and Family Medicine dealing with both adult and childhood allergies.

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