Just Say No to Nuts During Pregnancy

Daily consumption while expecting ups odds of asthmatic offspring, study suggests

TUESDAY, July 15, 2008 (HealthDay News) -- If you've got a strong family history of food allergies or allergic asthma, you might want to think twice before munching a handful of nuts when you're pregnant.

That's because recent research has found that regular consumption of nut products during pregnancy raises the odds of having a child with asthma symptoms by nearly 50 percent.

The study, published in the July 15 issue of the American Journal of Respiratory and Critical Care Medicine found "consistent positive associations between maternal nut product consumption, such as peanut butter, during pregnancy and wheeze, dyspnea (shortness of breath), steroid use, doctor-diagnosed asthma and persistent wheeze in children from 1 to 8 years of age," said study author Saskia Willers, a doctoral candidate at Utrecht University in the Netherlands.

As many as 4 percent of American children have food allergies, according to the American Academy of Allergy, Asthma & Immunology. Slightly more than 1 percent of people in the United States -- or about 3 million -- are allergic to peanuts or tree nuts.

Most allergies develop as a result of repeated "sensitization" to an allergen in susceptible individuals, and each time the body is exposed to the allergen, the reactions tend to increase. It's already recommended that children under 3 not be given nuts or nut products, because their immune systems are still developing and may be more susceptible to allergens, explained Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital and Medical Center in Detroit.

"If you say avoid nuts in children, and for nursing mothers because peanut protein can be transferred through milk, do we need to take it a step further and limit nuts during pregnancy?" said Appleyard.

To try to answer that question, Willers and her colleagues reviewed information gathered from interviews of more than 4,000 pregnant women -- 1,327 with a history of allergy or asthma and 2,819 with no such history. The women were asked about their diets, and their children were followed from birth to 8 years of age to assess whether or not diet impacted the risk of developing asthma.

They found no association between maternal consumption of vegetables, fish, eggs, milk or milk products and the development of asthma, according to the study. The researchers also found no association between rare or regular consumption of nuts and the development of asthma symptoms.

However, daily consumption of nut products increased the odds that a child would have wheezing by 42 percent, shortness of breath by 58 percent and steroid use to ease asthma symptoms by 62 percent, compared to children born to mothers who rarely consumed nuts. Overall, the odds of developing asthma symptoms for a child whose mother ate nuts daily were 47 percent higher, according to the study.

But, Willers said, it's too soon to recommend a complete nut ban during pregnancy. "The associations we found are pretty strong, only we are the first to find these effects, so they need to be confirmed by other studies before recommending the avoidance of peanuts and nuts during pregnancy," she said.

Appleyard agreed. "This subject definitely needs further investigation. And, if you can pass on the antibodies that cause nut allergy from mother to fetus, why not other allergies as well?" she asked.

However, she did suggest that women with a strong family history of food allergy may want to limit the amount of nut products they consume during pregnancy.

More information

To learn more about peanut allergy, visit the Food Allergy and Anaphylaxis Network.

SOURCES: Saskia Willers, M.Sc., doctoral candidate, Utrecht University, the Netherlands; Jennifer Appleyard, M.D., chief, allergy and immunology, St. John Hospital and Medical Center, Detroit; July 15, 2008, American Journal of Respiratory and Critical Care Medicine
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