About six percent of children under three suffers from a food allergy, and close to 2% are allergic to peanuts. And as the proportion of affected youngsters continues to grow, researchers and worried parents have been trying to pinpoint the source of the burgeoning numbers. How soon does sensitization to foods start? Could it begin as early as during pregnancy, with the foods that an unborn child is exposed to in utero?
According to a new study led by Dr. Scott Sicherer at Mount Sinai School of Medicine, that’s a strong possibility. Sicherer found that among 503 infants who showed signs of milk and egg allergies aged three to 15 months, those whose mothers ate peanuts more than twice a week while they were pregnant had higher levels of antibodies to peanuts than those whose mothers ate peanuts less often. The group focused on babies who react to milk and eggs because they are more likely to develop reactions to peanuts as well. Sicherer points out that higher levels of the antibody do not necessarily mean that the babies will definitely become allergic to peanuts, but that it’s a strong sign that they might be at greater risk of developing the food allergy. (More on Time.com: 5 Pregnancy Taboos Explained (or Debunked))
The results are only the latest in a confusing and conflicting set of studies that still leaves open the important question of whether a pregnant mother should watch her diet to lower the risk that her child will develop a food allergy. “Parents ask, did they eat too much peanuts and give their child a peanut allergy, or did they not eat enough peanuts and should have eaten more, to expose their child,” says Sicherer. “No mother should be on a guilt trip over this.”
Even the American Academy of Pediatrics has been flipping back and forth over their advice to mothers-to-be. Between 1998-2000, the pediatric experts advised women with a family history of food allergies to avoid highly allergenic foods such as peanuts during pregnancy in order to reduce the chances that their unborn child would become sensitive to the food. At the time, there was evidence that in utero exposure might be contributing to a heightened response by the still-developing fetal immune system to peanut proteins that could lead to an allergic reaction after birth. But in 2008, after some small studies in England found that such a policy did not seem to affect the rate of peanut allergies among newborns, the Academy rescinded that recommendation, instead alerting women that the scientific data wasn’t strong enough for them to change their diet in any way to avoid potential food allergies. (More on Time.com: Video: Filming Embryos Improves Chances of Pregnancy)
“The next question parents might ask is, ‘Are these results enough to change the recommendation that mothers should not worry about eating peanuts during pregnancy?’ And the answer is no,” says Sicherer. His group will continue to study the babies to determine how many actually go on to develop allergies to peanuts, in order to learn more about how such abnormal immune responses to food are triggered; some studies suggest that newborns are exposed to increasingly cleaner environments that lead their bodies to react more violently to any “different” proteins, including those from food, under the mistaken impression that these agents are dangerous and toxic. That’s why the team at Mount Sinai and elsewhere are investigating whether early exposure to such potential food allergens can tolerate babies to them and prevent an allergic reaction. There’s evidence that this might work, since a group at Duke has reported success in gradually exposing peanut-allergic youngsters to increasing amounts of peanuts as way to treat their allergies. “I don’t think we have enough evidence to tell families to do anything different than what they are already doing,” he says, “but the study shows that maybe we should consider in utero exposure as a potential risk factor and study it more going forward.”
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