Breast milk is considered the gold standard for infant nutrition thanks to its ability to provide adequate nutrition and a high amount of protective factors for the baby's health. According to the guidelines of the World Health Organization (WHO), exclusive feeding with breast milk should be conducted until the end of 6 months of life and should be continued in the following months with the simultaneous introduction of complementary foods. Several evidence demonstrates that breast milk intake is associated with positive health outcomes, both during infancy and later in the life. Given the protective role of breast milk for the health of the child and the future adult, studying its content is of fundamental importance to have an integrated vision of the biological effects of its components on the child health, and of the factors that are able to modulate its composition. The "Building a Deeper Knowledge on Breast Milk Composition" (BuKoBc) project was designed to study the content of human milk in its entirety and at different times during the feeding and day, also in relation to environmental factors capable of modulating its composition. The results of this study may provide data on optimal reference ranges for nutrient intake in breastfed infants and may provide guidance for defining optimal nutrient intake for infants who cannot be breastfed. Furthermore, the in-depth study of the environmental factors capable of influencing the composition of breast milk will allow the development of nutritional intervention strategies for the breastfeeding mother in order to positively modulate the composition of her milk.

Inclusion Criteria:

• Italian women aged between 20 and 40 years who exclusively breastfeed children born at term from normal pregnancy
• Written informed consent

Exclusion Criteria:

• Non-Italian women;
• Age <20 and >40 years;
• Mothers of children born preterm;
• Non-exclusive breastfeeding;
• Mothers suffering from chronic diseases:
• malignancies;
• immunodeficiencies;
• chronic infections;
• autoimmune diseases;
• chronic inflammatory intestinal diseases;
• celiac disease;
• genetic-metabolic diseases;
• cystic fibrosis;
• chronic lung diseases;
• malformations of the cardiovascular/respiratory/gastrointestinal system;
• neuropsychiatric disorders;
• neurological diseases.

100 Italian women, aged 20-40 years, who breastfed children born at full term, observed at the specialist pediatric clinics of the "Federico II" University Hospital of Naples, of the "La Sapienza University of Rome", of the "La Statale University of Milan", the "University of Pisa" and the "University of Verona".