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 The results were released at Friday's annual meeting of American
Academy of Allergy, Asthma and Immunology in Los Angeles one year
after the researchers demonstrated for the first time that eating
peanuts in infancy cut the risk of peanut allergies by 80 percent.
"The purpose of the new study was to see whether protection would
last with prolonged avoidance," Dr. Gideon Lack of King's College
London, who led both studies, told Reuters Health by phone. "We
wanted to make sure these children wouldn't rebound and develop a
peanut allergy" if the peanut therapy stopped.
"A 12-month period of peanut avoidance was not associated with an
increase in the prevalence of peanut allergy," the researchers said.
"Longer term effects are not known."
Up to 3 percent of children in developed countries have a peanut
allergy. It can be life-threatening in nearly 1 percent of children.
The initial study, known as LEAP, involved children who were
considered to be at high risk for peanut allergy because they had an
egg allergy and/or severe eczema. Half the children avoided peanuts
until they were 5 years old; in this group, 17.3 percent developed a
peanut allergy. Among the remaining children, who were exposed to
peanuts three or more times a week, the rate was 3.6 percent.
In the new follow-up study, known as LEAP-On, the 550 participants
were asked to refrain from eating peanut products for 12 months.
At age 6, 18.6 percent in the peanut avoidance group had a peanut
allergy, compared with 4.8 percent who had been given peanut
products but then stopped eating them. That amounted to 3 new cases
of peanut allergy in each group.
Among the children who remained peanut-free between their 5th and
6th birthdays, 21.5 percent who had always been kept away from
peanuts were found to be allergic to them, compared with 2.4 percent
of those who ate peanuts during those first five years.
The increase for children with previous peanut exposure was not
considered statistically significant, which suggests that children
don't have to keep eating peanuts to avoid developing a reaction,
said Lack.
In a companion study, known as EAT, the Lack team tried to use the
same technique to desensitize 1,303 breast-fed infants to six foods
with potential to spark an allergic reaction -- peanuts, cooked egg,
wheat, sesame, whitefish and cow's milk.
For example, the babies were supposed to be given 3 rounded
teaspoons of smooth peanut butter, two portions of cow's milk yogurt
and one small egg per week.
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At ages 1 and 3, there was no difference in sensitivity levels
between those who were or weren't exposed to the foods.
Yet when the researchers looked at only the children for whom the
study rules had been strictly followed, the sensitivity rate was 2.4
percent with early introduction of the foods versus 7.3 percent when
the foods were avoided.
And when they looked at egg and peanuts separately, and only among
infants whose diets were strictly controlled, it appeared that
exposure might have had a benefit. The rate of peanut allergy was 0
percent among those exposed to peanut and 2.5 percent for those in
the control group who were not. Egg allergy rates were 1.4 percent
with exposure and 5.5 percent without.
Rates for sensitivity to fish, sesame, milk and wheat did not differ
between the groups, but the researchers said the rates may have been
too low to show an effect.
Because only 43 percent of the children in the test group ate all
the required food, the early-feeding approach might be ineffective
in real life, Dr. Gary Wong of Prince of Wales Hospital in Hong Kong
said in an editorial.
Lack said that after last year's study revealed that exposing
high-risk children to peanut reduced the odds of an allergy
developing, there was still skepticism in the medical community over
the question of whether it's wise to expose all children.
The EAT study has helped to answer that question "because it looks
at all comers who were exclusively breast fed," whether they were
high risk or not, he said.
Both studies were released online in The New England Journal of
Medicine.
SOURCE: http://bit.ly/1YbYkjR and http://bit.ly/1Tfd3ep The New
England Journal of Medicine, online March 4, 2016.
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