[Importance of nutrition for immune defense. The role of milk and its natural components].

The immune system is a complex and integrated system whose main function is to protect the body from external aggression by microorganisms, allergens, or toxic agents. Different studies show that maintaining optimal amounts of different nutrients in the body is essential to ensure the synthesis of different factors related to the immune system. Most interesting nutrients and bioactive compounds include: vitamins A, B6, B12, C, D, E, folic acid (B9) and biotin (B7); minerals such as zinc, iron, selenium, magnesium and copper; proteins (lactoferrin) and bioactive peptides; omega-3 fatty acids; and other nutrients and bioactive compounds such as fiber, polyphenols, carotenoids, probiotics, etc. Following a varied and balanced diet, including the servings recommended by food guides for each food group, is essential to achieve nutrient requirements. Food groups to which special attention should be paid are: fruits and vegetables (because of their high content in micronutrients and antioxidant compounds), fatty fish (because it contains omega-3 fatty acids), and dairy products (because this group contains a large number of nutrients). In particular, milk-especially enriched milk-contains many of the nutrients mentioned above. Moreover, their daily consumption, within a balanced diet, can help significantly cover their nutrient reference values. Finally, it is important to consider kind of milks as a good dietary alternative to increase the intake of some important nutrients for the proper functioning of the immune system, most especially some of them such as vitamin D, since a large percentage of the population have nutritional deficiencies.