Pregnant women should feel free to eat nuts without worrying about the risk to their child.
A new study suggests that pregnant women who eat peanuts or tree nuts are less likely than others to have a child with a nut allergy.
The more nuts women ate during their pregnancies, the less likely their child was to be allergic, according to the study, in today's JAMA Pediatrics.
Parents and doctors have been increasingly concerned over nut allergies in recent years, as the number of allergic kids has grown. The prevalence of a peanut or tree nut allergy more than tripled from 1997 to 2010, when it reached 1.4% of kids. Tree nuts include walnuts, almonds, pistachios, cashews, pecans, hazelnuts, macadamias and Brazil nuts.
The study included nearly 11,000 mothers and children, who were followed from birth through adolescence.
About one in 13 children today has a food allergy, according to an accompanying editorial by Ruchi Gupta of the Northwestern Feinberg School of Medicine in Chicago. Allergies can be serious: About 40% of allergic children have had a severe or life-threatening reaction.
Yet Gupta writes that women have a right to feel confused, as allergy guidelines have "flip-flopped" over the years.
In 2000, the American Academy of Pediatrics advised pregnant women to avoid peanuts and tree nuts while pregnant or nursing, to avoid exposing infants, and to keep kids away from nuts until age 3. The pediatric academy reversed this advice in 2008, telling women there was no need to avoid nuts during pregnancy or early childhood.
Gupta notes that some studies have found that avoiding nuts during pregnancy actually increases the child's risk of nut allergy.
And pregnant women already get a lot of advice on avoiding or limiting certain foods and beverages, including alcohol, caffeine, even deli meats and soft cheeses, which can carry Listeria, a bacteria that can cause stillbirth.
When it comes to nuts, though, Gupta writes that women who aren't allergic should feel free to include them in their diets, because they're both high in protein and folic acid, a vitamin that can help prevent neural tube defects such as spina bifida.
Carla Davis, a doctor in Texas Children's Hospital's allergy, asthma and immunology Department, says the study doesn't definitively prove that eating peanuts while pregnant prevents peanut allergy.
Given conflicting research results, Davis says there still isn't a clear answer whether "eating nuts before, during or after pregnancy would be beneficial for the child in the prevention of food allergy."
Davis notes that "this study does not eliminate the possibility that increased fruits and vegetables or earlier introduction of nuts may play a role in protection against nut allergy, too."