Eat peanuts during pregnancy to prevent allergies
© 2014 Roy Benaroch, MD
It wasn’t that long ago that the usual advice to prevent food allergies was to avoid or delay certain foods. Now, the pendulum has fully swung over to the other side. As more and more evidence accumulates, it’s becoming clear that the way to prevent allergy is by exposures, not avoidance. Immune systems need to see allergens early to develop tolerance.
I’ve recently written about studies that show that at least some cases of peanut allergy can be overcome by gradual, graded consumption of peanuts. We also know that some food allergies are less likely to occur if babies eat things like grains and eggs beginning at around four to six months of age (this is likely true for other allergens, like peanut and fish, though the evidence isn’t as strong.) Now a new study shows that exposures from before birth can help a developing baby’s immune system learn to tolerate food proteins.
Researchers in Boston prospectively followed 8200 children, born from 1990 to 1994. Among the group, 140 became allergic to peanut or tree nuts (about 2%, which may strike you as low—but that’s the rate of allergy when strict criteria and independent assessments are used rather than parental reports alone.) They then compared the maternal diets during pregnancy between children who became allergic, versus those that did not. Among moms who themselves were not allergic to peanut, eating more peanuts and tree nuts more frequently during pregnancy was associated with a dramatically decreased risk of later allergy in their offspring. The reduced risk was probably in the range of 25-75%. Not bad for an intervention that’s cheap and safe.
Of course, moms who are themselves peanut allergic should not consume peanuts. In the study, nut-allergic moms who ate nuts were not more or less likely to have nut-allergic children than nut-allergic moms who avoided nuts.
The immune system is complicated, and the development of food and other allergies depends both genetic and environmental factors. But it’s clear that we can’t just run away from foods in the hopes that we won’t become allergic. Moms who are not allergic to food should enjoy a rich, varied diet throughout pregnancy, including peanuts and tree nuts. Nursing moms should eat what they’d like. Starting at four to six months, little babies should start complementary foods, including basically anything they’d like off of their parent’s plate, mushed up and tasty. Want to avoid food allergies? Eat.