New developments require fundamental shifts in anti-allergy policies.
Prevention of peanut allergies is a controversial issue, leaving society uncertain whether children should eat or avoid peanuts. Recent scientific studies show that peanut consumption at a young age protects against peanut allergy in children with eczema and/or an egg allergy (high-risk children). What is the effect of these studies on major health organizations that provide anti- allergy guidelines?
Peanut allergy: A huge problem
Swollen eyes, abdominal cramps and shortness of breath: people with a peanut allergy can suffer from these and other symptoms within twenty minutes after peanut consumption. If multiple symptoms occur simultaneously at different sites in the body, one suffers from anaphylaxis. The allergic patient should be brought to the hospital immediately to prevent serious hazards or even death. Of all food allergies, peanut allergy is the most common cause of anaphylaxis and therefore the most lethal. In all people that become allergic to peanuts, the allergy persists in 75% of all cases, emphasizing the severity of the problem. Severity aside, it is also a growing problem. Over the past ten years, the prevalence has doubled to 1-3% of the infants born in Western societies. Until recently, Western major health organizations advised parents to avoid feeding peanuts to young children. However, the ever-increasing amount of peanut allergies and the lack of supporting evidence is convincing some of them to withdraw this advice. Recent studies contained large-scale questionnaires and a randomized controlled trial to direct major changes to anti-allergy guidelines.
First important development: The clinically validated questionnaires
In 2008, UK and Israeli scientists distributed over ten thousand clinically validated questionnaires to Jewish children and Jewish mothers with young children, both in Israel and the United Kingdom. These questionnaires revealed that the prevalence of peanut allergy in Jewish children in Israel was more than ten times lower compared to Jewish children in the UK (0,17% vs. 1,85%, respectively). Possible explanations like ancestry, socioeconomic class and breast feeding were similar in both Jewish populations. However, peanut feeding was about four times higher by Jewish mothers in Israel, raising the question of whether early peanut intake causes protection against peanut allergies in children.
Second important development: The LEAP-trial
In February this year, UK investigators reported whether the early introduction of peanuts offers protection against peanut allergy in young children with severe eczema and/or egg allergy, further referred to as the high-risk children. George De Toit and colleagues conducted a prospective randomized controlled trial (RCT), the so-called Learning Early About Peanut Allergy (LEAP) trial, selecting 640 high-risk infants with a median age of eight months. The children started the investigation with a skin-prick test (SPT), exposing whether infants are already sensitive to peanut protein. If infants developed wheals (redness and itching of the skin) larger than four mm, they were excluded from the trial due to safety concerns. The remaining participants were randomly assigned to consume six grams of peanut protein in the form of peanut butter per week or to avoid peanut butter until the age of five. Almost 600 children were adherent to the given regimen until the age of two and were therefore included in the so-called per protocol analysis at the age of five. During the challenge, the participants consumed five grams of peanut protein in a single dose and the researchers analyzed who developed an allergic reaction. Blood serum antibody-levels were measured to support the clinical findings. At the age of five, 17,3% had an allergic response to peanut butter in the avoidance group. In contrast, 0,3% of the peanut consuming children developed a peanut allergy, causing a reduction of more than 98%. Higher blood levels of peanut-specific IgG4-antibodies in the consumption groups were found. This is a logical discovery, because these molecules are known to suppress allergies.
Together, these two large-scale studies show that early peanut consumption in high-risk children is not only associated with less peanut allergies, but is likely to be a cause of this positive result. The subsequent LEAP-On trial is underway and will show whether the peanut-consuming participants remain protected from peanut allergy if they avoid eating peanuts for one year. Furthermore, the effective LEAP-trial opens the door for similar studies with other food allergies, such as allergies against tree nuts, sesame and eggs. Other studies should carefully test whether peanut protein protects very allergic infants (wheal size of more than 4mm) from peanut allergies.
The LEAP-study quickly convinced important anti-allergy organizations* throughout the world to reach a consensus on new guidelines regarding prevention of peanut allergy, informing health care providers about the best treatment of high-risk infants. Guidelines tell that when these infants reach between the age of four and six months, when children start eating solid foods, they should undergo peanut skin testing and/or peanut butter ingestion under the supervision of a clinician. If the wheal size of the infant is smaller than four mm, the child should start a peanut-containing diet (for instance, six g peanut protein/ week). Recommended peanut-containing food products are smooth peanut butter, peanut soup and yogurts with pieces of peanut, since whole peanuts are too big. These guidelines will probably improve public health tremendously. Since food allergies cost twenty five billion a year in the United States alone, these guidelines could also enormously reduce health care costs worldwide.
The consensus is between the following organizations: American Academy of Allergy, Asthma & Immunology; American Academy of Pediatrics; American College of Allergy, Asthma & Immunology; Australasian Society of Clinical Immunology and Allergy; Canadian Society of Allergy and Clinical Immunology; European Academy of Allergy and Clinical Immunology; Israel Association of Allergy and Clinical Immunology; Japanese Society for Allergology; Society for Pediatric Dermatology; and World Allergy Organization.
Future guidelines should also advise that low-risk children start eating peanuts regularly from the age of four months for three reasons, despite the lack of comprehensive evidence. First of all, regular peanut consumption is associated with less peanut allergies. Secondly, peanut-consuming high-risk children develop approximately 98% less peanut allergies than peanut-avoiding littermates. Despite the lower susceptibility of low-risk children, these figures imply that low-risk children also profit from early peanut consumption. Thirdly, gaining scientific evidence on the effect of early peanut consumption in low-risk children is much costlier and difficult than the LEAP-trial, because thousands of children are necessary for significant results.
These landmark studies are causing a huge shift in anti-allergy policies, from advising peanut avoidance by infants to emphasizing the importance of regular peanut consumption by (high-risk) infants. If the implementation of the new policies is successful, the prevalence of peanut allergies in Western countries will hopefully stop rising within five years.
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