Answers from Dr. Greene

QUESTION:

Allergies run in my family. I'm pregnant with my first child (it's going to be a boy!) Is there anything I can do to prevent his developing allergies?

DR. ALAN GREENE:

Preventing asthma and allergies may be possible, according to a study in the June 2003 issue of Thorax. Children at high risk for asthma and allergies were recruited in 1990 to be part of this study. Half of them went about life as normal, and the other half had a low-allergy diet as infants - starting with breast milk (with moms on a low-allergy diet) or Nutramigen formula (not milk or soy-based). This group of families also undertook significant measures to avoid exposure to house dust during infancy. Both groups were followed for years, and those in the normal group were 4 to 5 times more likely to develop asthma, allergies, or eczema. The authors conclude that avoiding allergens during infancy is what made the difference. I wonder, though.

Allergies happen when the body is tricked into thinking that harmless particles are dangerous invaders. The immune system tries to get rid of these allergens by sneezing, flushing them out with tears or mucus, or dislodging them with nose rubbing. It tries to prevent them from getting into the lungs by constricting the airways. These are all normal responses to toxins and viruses. They are allergies if the trigger is not really a problem.

To me it makes sense that the infants' avoidance of those foods that commonly trigger allergies would result in fewer allergies. The immature gut allows intact proteins to slip into the body and trigger an immune response. Babies are built to start life with only one food, and then to have only a limited variety for a number of months. I believe that the hypoallergenic diet helped the children in the study.

Avoiding inhaled allergens, though, may have the opposite effect. Other studies have shown that babies who are exposed to dogs and cats before the first birthday, for example, are far less likely to develop allergies later. It seems to me that the nose is designed to detect changes - that is why you often no longer notice even very strong odors if you are around them long enough -- and that a baby's nose learns what is normal to have around them in the air during the first year or so. It then begins to consider some later arrivals as dangerous invaders - the body develops an allergic response to them. Perhaps the allergy prevention would have been even stronger without the mattress covers (if the mattresses they used were not off-gassing irritating chemicals)!

Once allergies are present, avoiding the allergens - whether they are pollens, pets, dust, foods, or anything else - is a powerful way to reduce the allergies. Avoiding one item you are allergic to can even reduce your allergies to something else (some people are only allergic to certain foods during the pollen season, for instance). But for babies who have not yet developed allergies, too clean may make matters worse.

There may have been other differences between the two groups in the study. One half certainly worked harder and paid more attention to allergy issues. We still have a lot to learn. What's exciting about this breakthrough study is that it demonstrates that preventing allergies, asthma, and eczema is truly possible. Now we just have to learn how best to do it.

Alan Greene, M.D. earned a Bachelor's degree from Princeton University and graduated from medical school at University of California at San Francisco. Upon completion of his pediatric residency program at Children's Hospital Medical Center of Northern California in 1993, he served as Chief Resident. During his Chief year, Dr. Greene passed the pediatric boards in the top 5 percent of the nation.

Dr. Greene entered primary care pediatrics in January 1993. He is on the Clinical Faculty at Stanford University School of Medicine where he sees patients and teaches Residents. He is also the Founder & CEO of DrGreene.com. Dr. Greene was also named Intel's Internet Health Hero for children's health. He is an author, medical expert, and a media personality.

Dr. Greene is the author of Raising Baby Green (Wiley Books, 2007), From First Kicks to First Steps (McGraw-Hill, 2004), and The Parent's Complete Guide to Ear Infections (Avon Books, 1997). He is also a co-author of the A.D.A.M. Illustrated Family Health Guide (A.D.A.M., Inc., 2004). Dr. Greene has appeared in numerous publications including the Wall Street Journal, Parenting, Parent, Child, American Baby, Baby Talk, Working Mother, Better Home's & Gardens, and Reader's Digest. He also appears frequently on television and radio shows as a medical expert.

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