American scientists published the results of pilot clinical trials on the use of fecal transplantation to treat peanut food allergy in the journal Science Translational Medicine.
It was noted that some participants in the trial showed a positive clinical effect. This response correlates with changes in T-lymphocyte populations, as well as an increase in bile acid metabolite concentration.
Similar biological changes were also recorded in experiments on mice that received fecal transplants from patients who had shown improvement in their condition.
A systematic review analyzing data from 2.8 million children across 40 countries identified the main elements linked to the onset of food allergies in early life. Published in the journal JAMA Pediatrics, the study suggests that this condition results from the interaction between genetic predisposition, changes in the skin barrier, early exposure to antibiotics, and environmental influences.
Food allergy manifests when the immune system responds inappropriately to certain proteins found in foods such as milk, egg, peanuts, nuts, or fish. Instead of considering these proteins harmless, the body perceives them as a threat, which can lead to symptoms ranging from mild to severe reactions, such as anaphylaxis. According to pediatric allergist Renata Rodrigues Cocco, the child's immune system is still developing, allowing it to identify food proteins as foreign, triggering the allergic reaction.
The researchers examined 190 studies and evaluated 342 potential factors. The main conclusion points to the relevance of atopic dermatitis (eczema) in the first year of life, late introduction of allergenic foods (such as egg and peanuts), antibiotic use in the first months, and family history of allergies. Although smaller correlations were noted with Cesarean delivery, male sex, and being the firstborn, these aspects had less impact.
Renata Cocco comments that today it is understood that food allergy does not have a single cause, and it is classified as a disease characteristic of contemporary life. She adds that factors such as alterations in the microbiome, diets rich in ultra-processed foods, pollution, and other environmental elements can increase mucosal permeability, causing the immune system to begin treating food proteins as dangerous.
One of the most significant findings of the review is the link between atopic dermatitis and the appearance of food allergies. Babies who presented with eczema in the first year of life showed three to four times higher risk of developing allergies. This is due to the protective role of the skin. The specialist explains that atopic dermatitis is seen as a warning sign, part of the so-called 'atopic march,' a sequence that can progress from eczema to food allergies and subsequently to rhinitis and asthma.
Another crucial point addressed by the study is the timing of food introduction. It was found that offering peanuts only after 12 months of age more than doubles the chance of the child developing a food allergy. This data corroborates recent pediatric guidelines, which discourage delaying potentially allergenic foods as a preventive measure.
Renata Cocco advises that exclusive breastfeeding should be maintained until six months, starting gradual food introduction from this period, including all food groups, such as egg, fish, and peanuts, according to child development and under pediatric guidance. The study also established a connection between antibiotic use, especially in the first month of life, and an elevated risk of food allergies. The most plausible hypothesis for this lies in the effect of these medications on the microbiome, the collection of microorganisms essential for the development and strengthening of the child's immune system.
Additionally, genetic predisposition is a relevant factor, as children whose parents or siblings are allergic have a higher probability of developing the condition. However, the doctor emphasizes that the genetic component is not the sole cause, but rather the combination of genetics and environmental factors that seems to favor the development of allergies.
The work also correlated food allergies with low birth weight, post-term birth, partial breastfeeding, maternal diet during pregnancy, and gestational stress. However, the specialist advises caution in interpreting these results, mentioning important methodological limitations related to stress and nutrition during pregnancy. She concludes by stating that there is already more solid evidence that restricting allergenic foods during pregnancy does not prevent the emergence of allergies in the child.
