Update (2/27/15): Because of the concern among parents who have children with peanut allergies, the Kids with Food Allergies Foundation has issued the following statement. Please take a read. New Peanut Allergy Study Does Not Say Parents Are to Blame
Every now and again, a study comes along that changes things, and I truly believe that the Learning Early about Peanut Allergy (LEAP) study by Du Toit, et al.1 will usher in an era of solid evidence-based guidance in terms of infant dietary recommendations and a much needed "benchmark" for designing future studies addressing allergy prevention. This study is only the first step for re-writing the guidelines that have yet to make it into medical practice. Contrary to headlines, actions to “feed your infant peanuts” should not be changed overnight without working with a healthcare provider first.
Every now and again, a study comes along that changes things, and I truly believe that the Learning Early about Peanut Allergy (LEAP) study by Du Toit, et al.1 will usher in an era of solid evidence-based guidance in terms of infant dietary recommendations and a much needed "benchmark" for designing future studies addressing allergy prevention. This study is only the first step for re-writing the guidelines that have yet to make it into medical practice. Contrary to headlines, actions to “feed your infant peanuts” should not be changed overnight without working with a healthcare provider first.
Before I get into why I feel this study truly changes
things, I want to convey my initial emotions surrounding this study because I
know that I am not alone. Even though I am scientist, I am also a mom to two
young boys. One has multiple life-threatening food allergies and the other is
at high risk of developing life-threatening food allergies. My oldest guy with
allergies, “JR,” who is a first grader this year, is the inspiration behind
this blog. You could say that because of JR’s many life-threatening food
allergies, fear has been my constant companion, both for JR who could violently
react to traces of allergen and his younger brother, “Luke,” who is at risk for
developing life-threatening food allergies himself.
As a parent, I want nothing more than to do everything in my
power to prevent food allergies for Luke. The fact is, the current advice has
always been a “best guess” with very little hard data backing it up or
scientific understanding of how our immune system learns to tolerate harmless
foods in the first place. Within the last month, Luke gleefully blew out the
three birthday candles lighting his dinosaur cake. To me, those three candles
represent more than just a third birthday. To me, they symbolize a tinge of
regret in light of new evidence from the LEAP study. In spite of a few food
allergy scares while introducing solid foods, Luke currently tolerates all
foods he has tried. Conspicuously
missing from his palate are peanuts and tree nuts. Based on “best guess”
medical advice from our allergist, we decided to wait until three years old to
introduce peanuts and tree nuts. We did everything “right,” and yet…
For the “emotional” part of me, the results of this study
feel like a double whammy of fear and regret. Rationally, I know we’re – and by
we’re, I mean parents, caregivers,
clinicians, scientists, etc. - just doing our best, following the best advice/evidence,
hopefully preventing fears from manifesting into reality. There’s fear and
regret that perhaps I haven’t done enough to prevent a second child from developing
allergies. Then there’s fear of even
having those allergenic substances in the house for an already-allergic child
who could react with just a tiny trace of peanut or tree nut. Could I live with
the regret of causing a life-threatening reaction because I failed to
adequately clean up after a messy toddler in the name of prevention in my own home?! Damned if I do, and
damned if I don’t, I guess.
Beyond emotion.
As human beings, we tend to interpret information with our
"hearts" first and let "reason" come later. And many people
never even get beyond that initial "heart” interpretation. I acknowledge it’s ok to have these feelings
(and I hope that other allergy parents/caregivers out there do, too!), but I
hope to illuminate those dark places where fear and regret lurk. This study was
aimed at preventing peanut allergy in infants at high risk of developing food
allergies. If you are already dealing with a food allergy, this study does
not apply to your situation. Even though this new research can’t help my
family or maybe even your family, I am overjoyed that we have the beginning of
how to prevent allergies for other children! Refrain from reading any and all
article commentary from non-experts to avoid the “I told you so” and “stupid,
fearful parents for not feeding your kid our nation’s best, right-to-eat it
anywhere, delicious, nutritious snack.” These comments are examples of ignorant
people wrongfully interpreting scientific findings through a way too
generalized media filter to support what they already “believe” to be
true. Science is not about what we
“believe” to be true, but what we “know” to be true. And what we “know” to be
true for an entire population of human infants is not determined by this one
study. Far from it.
What makes this study
so special?
Prospective, randomized controlled trial. Say what?! In
terms of study designs, this type provides possible causal relationships.
The researchers recruited a large, VERY defined population before the study
began, and then they randomly assigned the participants to either the “avoid
peanut” group or the “consume peanut” group. You can imagine it to be like
putting 600 little pieces of paper with names into a hat, shaking all the
pieces of paper, and then the first 300 chosen are assigned to the “avoid
peanut group” and the remaining 300 individuals go to the “consume peanut”
group.
Even though the study participants were highly defined
upfront, it is possible that when you look across all participants included in
the study, there may be other “factors” that could influence or “confound” the
results. By doing this randomization process upfront, "treating" to an
exact and defined protocol, and following those individuals over time, the hope
is that these other potentially "confounding factors” will not be factors.
Rather, a prospective, randomized trial aims to evenly distribute or shake out
potentially confounding variables (i.e., sex, age, etc) between avoidance group
and peanut consumption group so they are testing what they want to test – does introducing
peanuts early or avoiding peanuts prevent peanut allergies from developing.
Nothing more. Nothing less. This has
NOTHING to do with reversing an already established food allergy. And the
beauty of this study design is that they can ask all of their study
participants for potential confounding information to later confirm that those
potential “confounding” variables did in fact shake out evenly between the
groups during the randomization process! How awesome is that?!
Many of the studies in the past rely on a different, less
robust study design – observational and retrospective (looking back on what has
already happened, i.e., peanut allergy vs. no peanut allergy correlated to when
peanuts are typically introduced into the diet across a large population). This
involves recruiting individuals who were “out in the wild” already consuming or
avoiding peanut in who knows what kinds of quantities for one reason or
another. While meaningful information may be gleaned, confounding variables are
difficult to control. Observational and retrospective studies are a great
starting point and often provide evidence to pursue those answers more
definitively with a much better (much more expensive, I might add),
prospective, randomized controlled trial. In fact, it was this same research
group a few years back who did a study of this type showing that the prevalence
of peanut allergy was much lower in Jewish children from Israel, where peanuts
are introduced very early in infancy, compared to Jewish children in the United
Kingdom, where peanut products, at the time, were not recommended for infants
before a year old.2
What this does NOT
mean
Because the study participants were a VERY defined
population – they were between 4-11 months at the start of the study, and they
were at risk of developing a peanut allergy (severe eczema, established egg
allergy, or both severe egg allergy and eczema), we cannot safely extrapolate
the findings beyond either the study population or the specific study parameters. The
accompanying editorial published in the New England Journal of Medicine by
Gruchalla and Sampson put it best:
"Given the results of this prospective, randomized
trial, which clearly indicates that the early
introduction of peanut dramatically decreases the
risk of development of peanut allergy (approximately
70 to 80%), should the guidelines be
changed? Should we recommend introducing
peanuts to all infants before they reach 11
months of age? Unfortunately, the answer is not
that simple, and many questions remain unanswered:
Do infants need to ingest 2 g of peanut
protein (approximately eight peanuts) three times
a week on a regular basis for 5 years, or will it
suffice to consume lesser amounts on a more
intermittent basis for a shorter period of time?
If regular peanut consumption is discontinued
for a prolonged period, will tolerance persist?
Can the findings of the LEAP study be applied to
other foods, such as milk, eggs, and tree nuts?"3
While many questions do remain, the same editorial goes on to say:
"…we believe that because the results of this trial are
so compelling, and the problem of the increasing
prevalence of peanut allergy so alarming, new
guidelines should be forthcoming very soon."3
They go on with suggestions for health care providers to follow for
introduction of peanuts while we patiently wait for those new guidelines.
Where to go from here
In the words
of pediatric allergist Dr. Dave Stukus, “This study may be called LEAP, but
it’s still only one step.” This study provides a “benchmark” for many future
studies. Being a basic scientist myself, I want nothing more than to take this
information and understand how and why. What features of early immune
system development impart tolerance when foods are introduced early? What changes
happen to the immune system after you cross that critical period or window of
opportunity? Along those same lines, how does prevention by early introduction differ
from a child or adult who clearly tolerated a food for some time period, but went
on to develop allergies much later on? We need to understand at a very
fundamental level how we define immune tolerance at a cellular level, what establishes it, how it is maintained, and how
it is lost.
Population studies such as the beautifully executed LEAP
study give us guidance, but my hope is that by honing in on the how’s and why’s, we will move toward tailoring prevention and treatment strategies
to the individual.
PS - Wish us luck as we trudge forward with introducing peanuts and tree nuts to Luke!
References
2. Du Toit G, Katz Y, Sasieni P, et al. Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy. J Allergy Clin Immunol. 2008;122(5):984-991. doi:10.1016/j.jaci.2008.08.039.
3. Gruchalla RS, Sampson HA. Preventing Peanut Allergy through Early Consumption - Ready for Prime Time? N Engl J Med. 2015;372(9):875-877. doi:10.1056/NEJMe1500186.
Wahoo! Bravo the crowds cheer. Excellent piece outlining this important LEAP study from the patient side and as a researcher. You brought up some very good points about us processing via our hearts first.
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ReplyDeleteI really love your write-ups guys continue the good work. a controlled, prospective, randomized trial. What's that? This kind of study design suggests potential causal relationships. Before the study began, the researchers recruited a large, very well-defined population. After that, they randomly assigned the participants to either the group that "avoids peanuts" or the group that "consumes peanuts."
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