A recent review published in the journal Nutrients explores the connection between changes in gut microbiota during the first 1000 days of a child’s life and the onset of food allergies (FAs). Allergic diseases, including asthma, eczema, and FAs, have become increasingly common, especially among children. These diseases are a result of abnormal immune system responses to allergens. In the United States, 1 in 13 children suffer from FAs, significantly impacting their daily lives.
The review highlights the importance of gut microbiota in influencing immune responses and development. Early exposure to microbes plays a beneficial role in immune system development. The “hygiene hypothesis” suggests that early infections protect against allergies, but the adoption of sanitized lifestyles disrupts this natural process. Factors such as breastfeeding promote the establishment of healthy gut microbiota in infants, but other factors like birth methods and the use of antibiotics can alter the composition of gut microbiota.
Studying the changes in gut microbiota during the early years of life can provide insights into the onset of allergies. However, more research is needed to identify specific interventions that can prevent allergies.
The review conducted a thorough analysis of literature from 2013 to 2023, focusing on original papers, clinical trials, meta-analyses, and English-language reviews. Various keywords were used to identify relevant studies, while case reports and letters were excluded.
Gut microbiota refers to all microorganisms residing in the human body, mainly bacteria but including viruses, fungi, and others. The gut microbiota, in particular, is characterized by its richness and diversity. Richness refers to the number of different bacterial species present, while diversity indicates the abundance of individual bacteria per species. There are two types of diversity – alpha diversity, which measures the complexity of a sample, and beta diversity, which describes the differences in bacterial composition between samples. Atopy, a predisposition to allergies, can influence gut diversity, and exposure to specific microbes can induce resilience against inflammation.
Epigenetic changes, which alter gene expression without changing DNA sequences, play a role in the development of allergies. Dietary habits can influence the composition of gut microbiota, affecting intestinal functions, gene expression, and immune responses. Microbiota-derived metabolites also play a role in influencing gene expression. Dietary factors such as certain proteins and lipids can impact gut health, while breastfeeding is associated with specific DNA methylation patterns in children. The review highlights the need for further research to understand the role of breastfeeding in these epigenetic changes and allergy prevention.
Nutrigenetics, which refers to the digestion and metabolism of dietary molecules influenced by individual genotypes, and nutritional epigenetics, which involves the regulation of gene expression by environmental and dietary factors, are also significant in understanding food allergies.
The first 1000 days of life, which include pregnancy, the newborn period, and the first two years of a child’s life, are crucial for establishing a healthy gut microbiome. Various factors during this period can influence the composition of gut microbiota, some beneficial and others increasing the risk of disease. Factors such as vaginal delivery, breastfeeding, rural living, exposure to pets, and a diet rich in fiber have been identified as protective against food allergies. The balance between specific bacterial families is essential for gut health, and deviations from this balance may indicate an immature microbiome. Short-chain fatty acids, particularly butyrate, have protective roles against autoimmune and inflammatory diseases.
The review also explores the impact of gut health during pregnancy on allergy risks. The maternal diet can shape the newborn’s gut microbiota, affecting the development of allergies. Nutrients like vitamin D and certain fatty acids play a crucial role. Diets rich in vegetables and yogurt during pregnancy promote gut health in offspring, while other foods may increase the risk of allergies. Living on farms has been shown to boost children’s immune system through the activation of regulatory T cells.
The mode of delivery, whether vaginal or C-section, significantly affects the composition of gut microbiota in newborns. The location of delivery, such as home versus hospital, can also impact the child’s health.
The review highlights the significant link between gut microbiota and the development of food allergies. Variations in bacterial abundance and richness in the early months of life can predict sensitization to specific foods in the future. Additionally, the use of antibiotics during early life, which alters gut composition, is linked to the development of allergies.
Contrary to previous beliefs, human milk is not sterile and contains a variety of microbes from the infant’s oral cavity and the mother’s gut. Breast milk plays a pivotal role in influencing the infant’s intestinal microbiota and can impact the potential development of food allergies.
Human milk oligosaccharides (HMOs) have gained attention for their beneficial roles in infant development. These compounds are not digested in the upper gut and serve as food for beneficial bacteria, potentially preventing allergies.
The introduction of solid foods to an infant’s diet increases microbial diversity in the gut. The timing of introducing solid foods can influence gut diversity and metabolism. Delaying the introduction of allergenic foods is not recommended, as early exposure might prevent food allergies. Different feeding practices, such as baby-led weaning, also influence gut microbiota and potential food sensitizations.
Before the onset of food allergies, dysbiosis, an imbalance in microbial communities, is observed. Dysbiosis compromises the gut barrier, amplifying allergic reactions. Food sensitization is the first indication of the development of food allergies.
In conclusion, the review highlights the significant role of gut microbiota changes during the first 1000 days of life in the onset of food allergies in children. Factors such as breastfeeding, vaginal delivery, rural living, and a fiber-rich diet have been associated with a reduced risk of food allergies. Understanding the impact of these factors and the role of gut microbiota can contribute to developing interventions for allergy prevention.
Sources:
– “The First 1000 Days of Life: How Changes in the Microbiota Can Influence Food Allergy Onset in Children,” published in Nutrients.
