You’ve probably already seen headlines about a study showing that feeding children small amounts of peanut products in the first 5 years of life can prevent the development of peanut allergy. The study was conducted in the U.K., led by Gideon Lack of King’s College London, and was published this week in the New England Journal of Medicine (free full text available here).1
Why is this study important?
Food allergies are on the rise in Western countries, and peanut allergy is one of the scariest. In the U.S., more than 2% of children and their families are now living with a peanut allergy, representing a 5-fold increase in prevalence since 1997.2,3 And this allergy isn’t just an inconvenience; it’s now the biggest cause of anaphylaxis and death related to food allergy in the U.S.4 This is a huge concern to parents wondering when and how to introduce peanuts to their kids, but the advice on this matter has been really confusing over the last 15 years.
In 2000, the AAP recommended delaying the introduction of peanut and other commonly allergenic foods (i.e., wheat, eggs, fish, cow’s milk) until at least the first birthday and until age 3 for kids thought to be high-risk for allergy.5 While this advice may have seemed reasonable, it was never based on good evidence – just a best guess based on knowledge at the time.
Meanwhile, the incidence of food allergies continued to climb, and epidemiological evidence emerged that avoiding allergens might backfire. In 2008, the AAP issued new guidelines stating that there was no evidence that delaying introduction of solid foods, including common allergens, beyond 4 to 6 months of age would protect children from developing allergies.6 This document was intentionally vague, because at the time, there weren’t any studies to give more specific guidance on when to introduce what, in what amounts, etc. And this flip-flop in advice, which was also mirrored in many other countries, has left a lot of parents confused.
Gideon Lack and colleagues published a study in 2008 that found that the incidence of peanut allergy among Jewish children in the U.K. was 10-fold higher compared with those growing up in Israel.7 Comparing the mean age of introduction of peanut protein between the two countries, they found that babies in Israel were commonly introduced to peanut in their first year, while babies in the U.K. were not. This led them to their hypothesis that early exposure to peanut might help prevent the development of peanut allergy, and that’s what the current study tested.
How was this study conducted?
The researchers recruited babies between the ages of 4 and 11 months that were high risk for developing peanut allergy because they had severe eczema, egg allergy, or both. Before entering the study, the babies were tested using a skin-prick test to see if they were already sensitive to peanut. If so, they were excluded from the study. Those who showed no sensitivity (530 babies) or only mild sensitivity (98 babies) were included in the study and randomized to two groups. In the “avoidance” group, parents were instructed not to feed their children peanut at all. In the “consumption” group, parents were asked to give their children 6 grams of peanut protein per week, spread across at least 3 meals. Both treatments were continued through age 5, when all of the children were tested for peanut allergy.
What does 6 grams of peanut protein look like? It’s the amount in about 25 peanuts, or 3-4 tablespoons of peanut butter. In this study, parents in the consumption group were encouraged to feed a snack called Bamba, made of puffed corn and flavored with peanut butter. (Think Cheetos but with peanut butter instead of neon cheese powder.) Bamba was chosen because it was reported to be one of the main peanut sources for Israeli babies in the previously mentioned study. Kids who weren’t into Bamba were given smooth peanut butter instead.
What were the results of the study?
The study found a striking reduction in peanut allergy in the kids that ate peanut during the first 5 years of life. Among the kids without peanut sensitivity at the start of the study, 13.7% of those that avoided peanut had peanut allergy, whereas just 1.9% of those who had consumed peanut were allergic by age 5. That’s an 86% reduction in peanut allergy, and yes, that’s a HUGE result.
Among the kids that had a mild reaction to the baseline skin prick test, peanut allergy was more common, but again, the prevalence was reduced by peanut consumption early in life (10.6% in the consumption group vs. 35.3% in the avoidance group). Thus, the researchers concluded that exposing kids to small amounts of peanut protein early in life could both prevent peanut allergy and even treat those already mildly sensitized. Remember that all of the kids in this study were already high-risk for developing peanut allergy due to having eczema and/or an egg allergy. Normally, about 15-20% of this group would end up with a peanut allergy
We don’t yet know what will happen beyond 5 years of age, but the researchers are conducting a follow-up study in which the same children have been asked to completely avoid peanut for a year to see if this impacts their development of peanut allergy.
What does this mean for parents feeding children?
We should always be cautious about changing practices based on the results of just one study. However, this is is a really strong study showing dramatic results. Although we’ve known for a while that avoiding peanuts early in life doesn’t help, this is the first study to test peanut exposure in high-risk kids, and it showed that this can actually prevent allergy. I think it is a game changer.
Still, there is a lot we don’t know. We don’t know if there is an optimal window for introducing peanut or how much is really needed, and we don’t know if early peanut exposure could help infants that have already developed a real peanut allergy. We need more studies to help clarify these questions, but at least we’re asking the right questions now.
In a Scientific American interview (well worth reading in its entirety), the lead researcher for this study, Gideon Lack, gave his advice to parents wondering what to do about peanuts (Note that in the U.K., the term “weaning” means the introduction of solid foods, not stopping breast or bottle-feeding.):
“Among low-risk kids that account for 80 to 90 percent of population—those that don’t have eczema in the first six months to year of life and don’t have any evidence of food allergies—I would recommend that these children eat peanut protein or peanut in various forms, depending on the culture. Low-risk children should start eating peanut butter as soon as weaning is established. You don’t want peanuts to be the first food because if the kid is gagging or choking, it could represent allergic manifestation but it may also just indicate the child hasn’t developed the coordination to eat solid foods.
Higher-risk kids, those with any manifestation of eczema or food allergy, should see an appropriate health care provider, which could be an allergist or a pediatrician, and have skin prick testing done for peanut as soon as these high-risk symptoms develop. If the child tests negative, the child should be encouraged to eat peanut at home. If the skin test is a small positive, like it was for some of the kids in our study, then the children should have their first exposure or consumption of peanut under medical supervision; and if they tolerate it they should be encouraged to continue to have peanut regularly in their diet for at least the first three years of life. Based on the evidence we have, one could arguably say the first five years of life.”
I think this advice makes good sense. If you’re worried that your baby might be high-risk for peanut allergy, definitely talk to your child’s pediatrician to make a personalized plan for introduction. Keep in mind that you should always pay close attention whenever your baby tries a new food for the first time so that you can be alert to a reaction. Also take care to ensure you’re introducing peanut in a form that your child can handle, like smooth peanut butter or peanut sauces, avoiding whole peanuts until you’re confident that your child can chew them without choking. (Anyone want to place bets on how long it will be until we see a Bamba-like product marketed towards babies and young kids in the U.S.? I’m not aware of one currently.)
The big question in my mind is whether or not this same strategy of early exposure will apply to other common allergens. We already have some evidence for this. For example, one study found that children first exposed to wheat between 4 and 6 months (vs. after 6 months) had a 4-fold decreased risk of wheat allergy.8 Another found that children who first had cooked egg at 4 to 6 months had the lowest incidence of egg allergy, whereas those starting egg at 10-12 months had a 6-fold increased risk.9 Interestingly, this protective effect only worked with cooked egg (boiled, scrambled, fried, or poached), not with egg in baked goods. (Maybe baking denatures the egg protein more?) However, these were observational studies – not randomized – and confounding factors could have influenced allergy risk and early feeding practices. We need more randomized studies like the current peanut one to know if the early exposure strategy will work for other allergens and to figure out optimal timing and amounts of exposure.
The peanut study adds to a growing body of evidence that there may be a kind of sweet spot for introducing food proteins, including those that can trigger allergy – not too early and not too late. Studies show that introducing foods before 4 months can increase the risk of allergy, but waiting too long might also be problematic. Introducing babies to these foods at the right time seems to give their developing immune systems a chance to learn to tolerate the protein rather than attacking it.
As parents, it can be frustrating to see the “official” advice on introducing allergens flip-flop so dramatically in just 15 years. I’m sure there are parents out there who diligently followed the AAP’s advice from 2000, avoiding giving their children peanut, maybe even avoiding it themselves during pregnancy and breastfeeding, whose kids ended up with peanut allergies. Now we know how wrong that advice was, and that’s just maddening. But this is an area where the science has rapidly advanced in the last couple of decades, and the AAP and other health organizations have just been giving the best advice they can based on what we know. Finally, I think we are headed towards true evidence-based recommendations in this area. As a parent who will be introducing peanut to my baby in a few months, I think that’s something to celebrate.
What advice were you given about introducing peanuts to your baby? Will this study change the way you do it with a new baby?
- Du Toit, G. et al. Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy. N. Engl. J. Med. 0, null (2015).
- Sicherer, S. H., Muñoz-Furlong, A., Godbold, J. H. & Sampson, H. A. US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-year follow-up. J. Allergy Clin. Immunol. 125, 1322–1326 (2010).
- Bunyavanich, S. et al. Peanut allergy prevalence among school-age children in a US cohort not selected for any disease. J. Allergy Clin. Immunol. 134, 753–755 (2014).
- Sampson, H. A. Peanut Allergy. N. Engl. J. Med. 346, 1294–1299 (2002).
- Nutrition, C. on. Hypoallergenic Infant Formulas. Pediatrics 106, 346–349 (2000).
- Greer, F. R., Sicherer, S. H. & Burks, A. W. Effects of Early Nutritional Interventions on the Development of Atopic Disease in Infants and Children: The Role of Maternal Dietary Restriction, Breastfeeding, Timing of Introduction of Complementary Foods, and Hydrolyzed Formulas. Pediatrics 121, 183–191 (2008).
- Du Toit, G. et al. Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy. J. Allergy Clin. Immunol. 122, 984–991 (2008).
- Poole, J. A. et al. Timing of Initial Exposure to Cereal Grains and the Risk of Wheat Allergy. Pediatrics 117, 2175–2182 (2006).
- Koplin, J. J. et al. Can early introduction of egg prevent egg allergy in infants? A population-based study. J. Allergy Clin. Immunol. 126, 807–813 (2010).