Adherence to the Mediterranean diet in pregnant women from the NELA cohort (Nutrition in Early Life and Asthma)lnfluence on the microbiota of infants and the early onset of possible asthma precursor symptoms

Zusammenfassung

Asthma is the most common chronic disease in children, causing great morbidity. At least one in three infants has three or more episodes of asthma-like respiratory symptoms during the first year of life. Although many infants suffer from early wheezing that disappears by the age of 6 or 7, the prevalence of asthma is 10% among school-age children and adolescents in Spain. In humans, lung development takes place during the 2nd and 3rd trimesters of pregnancy and continues until at least the age of 7 years. During the early stages of growth and development in the womb, the lungs can be vulnerable to any aggression from the environment, which can cause permanent changes throughout the course of a person's life. Therefore, it seems reasonable to think that the interaction of the foetus with the environment in the womb and after delivery with the environment in the open air during the first moths of life, could be crucial in the development of the lungs and the programming towards those respiratory conditions. Pregnant women can influence the intrauterine environment through diet and a pattern of poor adherence to the Mediterranean diet by the mother during pregnancy has been associated with asthma in offspring in school years. On the other hand, the use of antibiotics in pregnancy, caesarean delivery or the type of breastfeeding seems to be risk factors for the development of asthma in the offspring and it is hypothesized that this effect is mediated by the interruption of a correct colonization of the newborn microbiota. Therefore, the main objectives of this doctoral thesis are: i) to characterize the adherence to the Mediterranean diet of mothers belonging to the NELA cohort and to study whether low adherence to this dietary pattern is associated with the early appearance of asthma precursor symptoms in the offspring at 3 months of age. ii) characterize the intestinal microbiota of infants and their fatty acid profile at 3 months of age and determine the influence of prenatal and neonatal factors (microbiota and short-chain fatty acids) on the early appearance of asthma precursor symptoms of infants 3 months of age. In Chapter 1, the characterization of adherence to the Mediterranean diet and a healthy diet pattern by mothers belonging to the NELA cohort was carried out and the possible sociodemographic and lifestyle factors that influence the degree of adherence were studied. to said dietary pattern. Pregnant women who are younger, have fewer previous deliveries, have a low level of education and practice unhealthy lifestyles are more likely to have low adherence to the Mediterranean diet and a healthy dietary pattern. The association between the degree of adherence to the Mediterranean diet of pregnant women and the early appearance of asthma precursor symptoms in infants at 3 months of age was also determined, without observing an association between a low degree of adherence to the Mediterranean diet. and an increased risk of asthma precursor symptoms in the offspring. These results raised the need to deepen the study of the diet of pregnant women and their relationship with the symptoms indicated above, focusing on groups of specific foods or nutrients that make up the diet, observing that a higher consumption of pastries and sweets in pregnant women it is associated with an increased risk of offspring developing asthma precursor symptoms at an early age. However, a high consumption of coffee, tea and infusions during pregnancy, due to its antioxidant nature, is associated with a lower risk of early onset of these symptoms. In Chapter 2, a pilot case-control study studied the prenatal, perinatal, and postnatal factors that may influence the infant's intestinal microbiota and its metabolites, as well as their association with the early onset of asthma precursor symptoms at 3 months of age. qPCR was performed for the characterization of certain bacterial species and groups and quantification of the short-chain fatty acids present in the faeces of infants at 3 months of age by gas chromatography. There are differences in the intestinal microbiota of infants between the control group and the case group, as well as in the molar proportions of the main majority short-chain fatty acids. Another conclusion was that higher counts of Akkermansia muciniphila and B. breve, and lower counts of Bacteroides-Prevotella, Clostridium cluster IVa and cluster XIVa, and B. longum, were associated with a higher probability of developing asthma precursor symptoms at 3 months of age. In relation to short-chain fatty acids and their possible association with the early onset of asthma precursor symptoms in infants, a lower concentration of butyric acid in the stool at 3 months of age was associated with a higher probability of the appearance of these symptoms.