Will giving my baby peanut products increase or decrease his risk for a peanut allergy?

DEAR DOCTOR K:

My baby has an egg allergy. His doctor says this increases his risk of developing a peanut allergy. She recommends avoiding peanut products for now. But another doctor gave me the opposite advice. What should I do?

DEAR READER:

If your child has a food allergy, you may well agonize over the safety of his every meal and snack. And no wonder. Food allergies can cause severe — even deadly — allergic reactions. Peanut allergies can cause bad rashes, severe difficulty breathing, a dangerous drop in blood pressure and other dangerous results.

But a study recently published in The New England Journal of Medicine offers some hope for parents of infants who may be headed toward a peanut allergy. That hope is peanuts.

For the study, researchers recruited 640 infants aged 4 to 11 months. These infants all had an egg allergy or eczema. (Eczema is an allergic disorder that affects the skin.) Both eczema and an egg allergy make it more likely that a child will develop a peanut allergy.

So, the kids in the study all were at higher risk for developing a peanut allergy than most kids. Then, these kids were tested to see who already had developed a sensitivity to peanuts. This was done with a test in which a drop of peanut extract was placed under the surface of the skin. Redness or swelling in that spot indicated that the infant was sensitive to peanuts.

The children were divided into two groups: children whose skin tests showed that they were already sensitive to peanuts, and children who weren’t.

Within each of those groups, the children were further divided into two groups. The parents in one group were asked to make sure their children didn’t eat any peanuts, peanut butter or other peanut-based products until age 5. Parents in the other group were asked to give their children a peanut-based snack called Bamba or peanut butter three times a week until age 5.

The results were surprising and dramatic. Of children who were not already sensitive to peanuts, a peanut allergy developed in only 1.9 percent of children who ate peanut products, compared with 13.7 percent of those who didn’t eat peanuts.

Even more surprising, of the kids who were already sensitive to peanuts, a peanut allergy developed in only 10.6 percent of children who regularly ate peanut products, compared with 35.3 percent of those who didn’t regularly eat peanut products.

In other words, feeding peanuts to young children who are at high risk for developing a peanut allergy can actually protect them from developing that allergy later in life. Somehow, it makes a child’s immune system more “accepting” of peanuts and less likely to respond violently. A peanut diet does not offer perfect protection against a peanut allergy developing later in life, but it does reduce the risk.

What does this new research mean for parents? If your infant is allergy-prone, ask his or her pediatrician about adding peanuts to your child’s diet now, to prevent a peanut allergy down the line.