Can your diet during pregnancy and breastfeeding protect your baby from food allergies?
You'd probably do just about anything when you're pregnant to keep your baby from developing food allergies. Avoid shrimp? Check. Stay away from eggs? No problem. Skip soy? Consider it done. Unfortunately, the advice on how to prevent food allergies keeps changing. So where does that leave you if someone offers you a peanut butter cookie?
It's an important question. For the 6 percent of babies and toddlers with true food allergies, eating certain foods triggers an immune system overreaction that can cause anything from chronic itching and eczema to sudden difficulty breathing and even life-threatening anaphylactic shock.
The problem is growing—the incidence of food allergies in children increased 18 percent from 1997 to 2007. Scientists aren't sure why, but theories include greater awareness among parents and doctors, lower immunity because of less exposure to bacteria and lack of exposure to common allergens early in life. However, keep in mind that a true allergy is different from a more common food intolerance (also known as sensitivity) in that the latter typically triggers less serious problems, such as gas, bloating or diarrhea.
In the past, conventional wisdom held that avoiding highly allergenic foods during pregnancy and breastfeeding and withholding them from a child during his early years could reduce his risk for food allergies. (These foods are wheat, soy, cow's milk, fish, shellfish, peanuts, tree nuts and eggs.) But recent evidence has turned that advice upside down. Now it seems there may be no reason to say no to allergenic foods, particularly wheat, eggs and fish; in fact, avoiding them may actually increase your baby's risk of developing food allergies.
Confused? That's not surprising. So are immunology researchers. Studies delving into these questions are in the works, but you're pregnant now— what should you do? Here are the current recommendations based on the latest research.
When you're pregnant It's OK to eat highly allergenic foods unless you are allergic to them. There is no proof that staying away from them lowers allergy risks in babies. In fact, cutting them from your diet may cause more harm than good, as most allergenic foods provide crucial nutrients for you and your baby. For example, omega-3 fatty acids in fish and shellfish promote fetal brain development, and the folate in peanuts helps prevent neural-tube defects, such as spina bifida.
When you're breastfeeding Again, avoiding allergenic foods while breastfeeding has not been shown to provide any benefit to your baby. However, researchers do believe that breastfeeding itself may help ward off food allergies. "Exclusive breastfeeding—no formula—for four months or longer is the best thing," says Frank R. Greer, M.D., professor of pediatrics at the University of Wisconsin and co-author of an American Academy of Pediatrics clinical report on food allergies. If your breastfed baby reacts to something you eat, avoid it. As for the opposite tactic—going out of your way to eat allergenic foods during pregnancy or breastfeeding— there's no evidence that doing so offers any protection against allergies either, Greer says.
When you introduce solids According to the American Academy of Pediatrics, offering your baby allergenic foods is OK starting at four to six months; just be sure to watch for any allergic reaction (symptoms include hives, itchy eyes or mouth, vomiting, pale skin, fainting, difficulty breathing and swelling of the eyes, tongue or lips). Not only does withholding these foods offer no protection, but a 2008 study found a tenfold greater chance of peanut allergies in children who did not eat foods containing peanuts during infancy and early childhood compared with those who did. "Introducing allergenic foods to your infant after four months while he's still being breastfed may also protect against the development of food allergy," Greer says.
All in the family A baby is more likely to develop allergies of any kind (including food allergies, hay fever, asthma or eczema) if either parent has them, says Ananth Thyagarajan, M.D., attending physician at the Virginia Adult and Pediatric Allergy and Asthma Practice in Richmond. But if this is the case, there's no evidence that avoiding allergenic foods (other than those you're allergic to yourself) while you're pregnant or nursing will help your baby.
Feeding your baby nothing but breast milk for his first four to six months, then continuing to breastfeed after you introduce solids, appears to be the only way to improve your baby's odds of dodging food allergies if they run in the family. "If you must wean your baby off the breast before four months, a partially hydrolyzed formula is likely beneficial compared to a standard cow's milk formula," says pediatric allergy expert Frank R. Greer, M.D. Find out what your pediatrician recommends.