One tiny peanut can unleash an immunological storm that leaves a person on the verge of death. The immune system makes a mistake, it takes a non-harmful element as harmful – a nut, a drop of cow’s milk or a piece of egg, for example – and upon ingesting it, it triggers a disproportionate response that ranges from a mere hives to a anaphylaxis (a widespread and life-threatening reaction). This is how food allergies work, a phenomenon on the rise throughout the world that has the scientific community on edge. According to the World Health Organization, around 10% of the global population suffers from food allergies: it is estimated that it affects one in 10 adults and one in 12 children. Any food can generate this abnormal revolt of the immune system, but eggs, cow’s milk, nuts, fish and fruits are the most problematic foods.
To address this explosion of cases, allergists have looked back to the first times, to the first contact with these potentially allergenic foods in childhood. Traditionally, the global recommendation of scientists was to delay the introduction of some products, the most allergenic, in early childhood with the idea of waiting until the child’s immune system was more mature to correctly discern what things were harmful and what were not. However, for a decade, experts have turned the helm in the opposite direction and advocate, with increasing emphasis, that the sooner some of the most allergenic foods are introduced, the better. For example, peanuts, in a texture adapted to the age of children (in the form of peanut butter, for example) to avoid choking or swallowing problems.
“Previous recommendations to delay the introduction of allergenic foods were based on the biological assumption that avoiding exposure of the infant’s immune system to proteins in foods would prevent the development of allergic responses. However, these recommendations were not based on clinical or scientific evidence and did not take into account the principle that the development of tolerance to a food is an active immunological process that requires early exposure to the food through the gastrointestinal tract,” defends Gideon. Lack, professor of Pediatric Allergology at King’s College London. Precisely, this researcher is co-author of a study published last Tuesday in the journal New England Journal of Medicine Evidence where they found that giving peanuts regularly during the first five years of life reduces the risk of allergies to these foods in adolescence by 71%.
In the scientific community there is increasing consensus in favor of the early introduction of foods to avoid allergies, but there is still a heated debate on several points and the evidence is limited in some foods. The Spanish Association of Pediatrics (AEP) recommends maintaining exclusive breastfeeding until six months of age and, from then on, “gradually add the rest of the foods.” Regarding those potentially allergenic, the AEP points out: “There is no evidence that delaying their introduction beyond six months prevents the development of allergy. On the contrary, there are studies that suggest that the early introduction of these foods in small quantities can reduce the subsequent appearance of allergies.” Rosaura Leis, pediatric gastroenterologist and coordinator of the Nutrition and Breastfeeding Committee, defends a progressive introduction of foods from six months of age, but with breastfeeding as a priority until one year of age.
Pediatric allergists, for their part, are more flexible in the start times of introducing new foods and advocate starting even before six months of age: “The sooner, the better. “Better to desensitize than to prohibit,” summarizes pediatrician and allergist María Mesa del Castillo, vice president of the Spanish Society of Clinical Immunology, Allergology and Pediatric Asthma, which also belongs to the AEP.
Lack’s latest research is the culmination of several studies that analyzed the impact of early exposure to peanuts over time. “It is a continuation of the Leap study that showed that regular consumption of peanuts during the first five years of life reduced the development of allergies.” [a este alimento] by almost 90%. However, we did not know what would happen to these children if they stopped eating this food regularly and whether they would remain protected against peanut allergy in adolescence,” explains the scientist by email. To answer this, they advised study participants whether or not to eat peanuts freely for the next seven years and observed whether, at the age of 13, those who had been introduced to peanuts early were still protected. “We discovered that the tolerance acquired in early childhood was a long-term immunological tolerance and that these children remain safe and protected regardless of whether they ate peanuts or not,” he summarizes.
A window of opportunity
This finding is a boost to the current thesis of pediatric allergists, who defend that in the first months of life there is a window of opportunity where the immune system is more moldable. Specifically, between four and six months of age. “There is an immunological window period that can deviate towards allergy or food tolerance. This study supports the paradigm shift of early introduction of foods, not only to induce tolerance in childhood, but also for life,” says Montserrat Álvaro, pediatrician and allergist at the Sant Joan de Déu Children’s Hospital, who has not participated. on the research.
The specialist clarifies, however, that it will be necessary to see if these results with peanuts, which are a legume, can be extrapolated to all nuts. Experts maintain that there is solid evidence of the benefits of bringing forward the introduction of peanuts and eggs, but there is a gap in knowledge in other foods. “As we know that delaying the introduction of peanuts and eggs is harmful and there is no good biological reason why the immune system would respond to different foods in different ways, there are good clinical and ethical reasons to recommend earlier introduction of all foods. allergens,” says Lack.
The food that generates the most controversy, if anything, is cow’s milk, admits the British professor: “This is partly because we do not have enough evidence about the early introduction of cow’s milk and also because there are different types of cow’s milk allergy with different underlying mechanisms and it is not clear whether the early introduction strategy would apply to all of these different types of cow’s milk allergy.” Tomás Chivato, who is vice president of Science at the European Academy of Allergy and Clinical Immunology (EAACI) and has not participated in Lack’s study, assumes that early introduction of foods is “a new approach,” but promising. “The debate is about preventing or treating. These studies are going to shed light and continue as a guide, because there is no consensus,” he weighs.
The debate, however, remains open because there are many variables and nuances to take into account to give precise and incontestable recommendations. To begin with, when to start introducing food will also be determined by the child and whether she is able to eat solids, coordinating chewing and swallowing to avoid the risk of suffocation. Various textures can also be used (whole, crushed, crushed, in creams…) to adapt the food to its capabilities.
But, also, apart from when it starts, how food is ingested is key to the potential development of allergies: preparation and cooking. Chivato gives an example: “Natural tomato causes allergies, but fried tomato or ketchup does not. How we eat food influences it.” Regarding this, Álvaro has completed a study on the prevention of egg allergies with baked food, for example, in a sponge cake: “Putting the egg in a carbohydrate matrix and cooking it makes the protein less allergenic. , but that induces tolerance,” he explains. In fact, pediatric allergology experts recommend pre-cooking boiled or baked eggs, never raw eggs.
Another fundamental variable is to analyze the child’s baseline risk. That is, if children suffer from severe atopic dermatitis or if they have a family history of parents and siblings with atopy (allergies, dermatitis or asthma). In these cases, the probability of developing allergies is greater. “In terms of preventing allergies, in general it can be said that the sooner the better, especially in babies with eczema (atopic dermatitis), who have a much higher risk of developing food allergies and develop them much earlier in the first year of life.”, reflects Lack.
Shock with exclusive breastfeeding
The proposal to advance the introduction of certain foods, however, collides head-on with one of the sacred cows of child nutrition: breastfeeding, with extensive benefits for mother and baby and recommended by the WHO exclusively up to six months. Mesa del Castillo, who practices at the University Hospital of Móstoles, says, for example, that when faced with a baby at high risk, she recommends the early introduction of everything, even before six months, as a supplement to breastfeeding: “From on day two, cow’s milk; at four months, boiled egg, not raw; and four to six, crushed nuts in cereals.” Leis, on the other hand, warns: “Although it has recently been published that the incorporation of small amounts of cow’s milk (five milliliters) in the first months could promote tolerance, there is not enough evidence and, furthermore, the indisputable benefits of breastfeeding maternal health for the child’s health in the short, medium and long term, make the scientific recommendation to promote exclusive breastfeeding up to six months of life.
Lack calls for “reconsidering” the WHO guidelines: “While prolonged breastfeeding is very beneficial for many aspects of child health and development until at least one year of age, the requirement to exclusively breastfeed until six months deprives babies from acquiring early oral tolerance and will cause more food allergies,” he says. The scientist maintains that the early introduction of peanuts – around 2% of children in North America, the United Kingdom, Western Europe and Australia are allergic to this food – will prevent more than 100,000 new cases of allergy to this food each year in everyone.
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