About-Face on Preventing Peanut Allergies

By: New England Journal of Medicine and The Wall Street Journal

About-Face on Preventing Peanut Allergies

Study finds introducing peanuts in many infants’ diets could help avoid the allergies later in childhood:

A diet that includes peanuts in the first year of life may greatly reduce the chance of developing peanut allergies in children at risk for getting them, according to a highly anticipated new study.

The findings appear to be the most definitive evidence yet to discount the medical community’s longtime recommendation that parents avoid giving peanut products to young children. That practice has failed to stem the growing rate of peanut allergies. Some doctors now suggest that not eating peanuts may actually have helped spur more allergies.

“We have had a whole ethos within the practice of pediatrics and pediatric allergy that the way to avoid any allergy was avoidance,” said Gideon Lack, a professor of pediatric allergy at King’s College London and senior author of the study, which was published online in the New England Journal of Medicine. “At least with respect to peanuts, avoidance may actually worsen the problem.”

Health experts caution parents not to suddenly start including peanuts in their babies’ diets. Some children are at increased risk for developing allergies and could react adversely if they were to begin eating peanut products. An allergy specialist can test for risk. The study only looked at children at risk for peanut allergies, and some experts said it isn’t clear if the findings apply to all children.

Gideon Lack, a professor of pediatric allergy at King’s College London and senior author of the new study. The findings appear to be the most definitive evidence yet to discount the medical community’s longtime recommendation that parents avoid giving peanut products to young children.

The growing prevalence of peanut allergies—which have more than quadrupled in the U.S. in the 13 years ended 2010—has puzzled and worried the medical community. More than 2% of children age 18 years and younger have a peanut allergy, according to a 2008 study. Peanut allergies are the leading cause of death related to food allergy in the U.S. and many day-care centers, schools and summer camps enforce no-peanut policies.

For years doctors advised parents of children at risk for food allergies to avoid peanuts until the child was 3 years old, based on guidelines outlined by the American Academy of Pediatrics in 2000. In 2008 the AAP revised its guidelines, citing insufficient evidence that delays prevented the development of food allergies. But the medical group didn’t say when and how highly allergenic foods should be introduced.

The new study, which was also presented at the annual meeting of the American Academy of Allergy Asthma and Immunology in Houston, found that 17.2% of the children who avoided peanuts until age 5 ended up with a peanut allergy compared with 3.2% of those who regularly ate peanuts, said George Du Toit, a consultant in pediatric allergy at King’s College London and a co-investigator of the study.

“That’s an 80% reduction in peanut allergy,” said Dr. Du Toit. “This is an extremely strong effect.”

The study followed 640 children from the United Kingdom at risk for developing peanut allergies for about five years. The children were enrolled in the trial between the ages of 4 months and 11 months. They were considered at risk for peanut allergy if they had severe eczema or egg allergies.

The children were divided into two groups based on the results of a skin-prick test to assess sensitivity to peanuts. About 85% of the participants had negative test results, meaning they showed no evidence of peanut allergy. The rest had a minor reaction to the test, indicating they were starting to develop an allergy to peanuts.

Children in each group were then randomly assigned to either completely avoid peanut products or to regularly consume them. Parents of the children eating peanuts were instructed to give them at least two grams (roughly eight peanuts) of peanut protein three times a week.

In the negative skin test group—those with no sign of a peanut allergy at the start of the study—13.7% of the children who avoided peanuts developed an allergy. That compared with just 1.9% of the children who consumed peanut protein.
In the group that had positive skin test results—suggesting the beginning of a peanut allergy—the difference was 35.3% versus 10.6%.

The study showed consuming peanuts appeared to keep the immune system from becoming sensitized to peanut protein, known as primary allergy prevention. It also appeared to block an allergic disease from developing after the immune system had been sensitized, known as secondary prevention.

The researchers are currently working on a follow-up study to see whether the children in the peanut-consumption group would remain allergy-free if they subsequently stopped eating peanuts for an extended period. The results of that study are expected later in 2015.

While researchers believe delayed introduction to certain foods may have played a role in the increased prevalence of food allergies, there are many other possible factors. Some experts believe that as westernized countries have become more hygienic, children aren’t exposed to the same level of germs, which can affect the development of the immune system.

Some experts say it is likely that early introduction of other highly allergenic foods—such as eggs, fish and dairy products—also could help prevent allergies, but more studies are needed.

“We wouldn’t presume there’s anything particularly unique about peanuts in this situation so the same philosophy would pertain to other common food allergens,” said Robert Wood, director of pediatric allergy and immunology at Johns Hopkins University School of Medicine, who didn’t participate in the peanut study.

Another continuing study by Dr. Lack is testing a variety of foods. The research includes more than 1,300 children randomly assigned to either exclusively be breast-fed for six months or to be breast-fed for three months and then start eating a diverse diet, including all of the highly allergenic foods. Preliminary data are expected later in 2015, Dr. Lack said.

Since the American Academy of Pediatrics revised its peanut guidelines in 2008, some doctors say their advice to parents has been vague.
“We weren’t suggesting avoidance but we weren’t advocating for early introduction either,” said Rebecca Gruchalla, a professor of internal medicine and pediatrics at the University of Texas Southwestern Medical Center in Dallas. “We weren’t really making firm statements one way or the other whereas now we will.”

Dr. Gruchalla and Hugh Sampson, director of the Jaffe Food Allergy Institute at Mount Sinai Hospital in New York, wrote an editorial in the NEJM to accompany the new research, saying they believe the “landmark” study warrants new guidelines for when to introduce peanuts into children’s diets.

Both doctors say they plan to give new advice to parents whose infants are at risk for developing a peanut allergy. These children should get a skin test to check for reactions between 4 months and 8 months of age, Drs. Sampson and Gruchalla say. If the test is negative the children should be started on a diet that includes peanut products. If it is positive, the children should do a peanut challenge with an allergy specialist to be sure they can tolerate peanuts before introducing it into the diet, they say.

The study could be a “practice changer,” but it remains to be seen if the findings also apply to babies who don’t appear to be at risk for a peanut allergy but go on to develop one anyway, said Donald Leung, head of pediatric allergy and immunology at National Jewish Health in Denver, who didn’t participate in the study. “This is a special group of people that they studied. We don’t know if it applies to all people who have a tendency to get peanut allergies,” he said.

Other experts say parents should generally feel free to introduce a variety of foods—including highly allergenic ones like peanuts—to children. Dr. Lack said babies with no eczema or family history of peanut allergies who have begun eating solid foods should be encouraged to have peanut products. “Even the low-risk [children] can develop peanut allergy,” he said.

The new research into when peanuts can be consumed “completely turns on its ear what we were told to do as parents,” said Janet Atwater, of Chadds Ford, Pa. Her 17-year-old son was diagnosed with a peanut allergy at 11 months and now always carries two EpiPens, used to inject a hormone in the event of anaphylaxis from accidentally ingesting peanuts.

Although the findings won’t help her son, “I’m thrilled for the next generation of kids,” said Ms. Atwater, who is on the board of Food Allergy Research & Education, a nonprofit advocacy group.

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