Micronutrients are essential for maintaining a good human health, and although they are needed in only trace amounts, deficiencies reportedly affect 3 billion people worldwide. One of such micronutrients is selenium (Se). This element is a cofactor of many enzymes (e.g. glutathione peroxidase or thioredoxin reductase) and it is important for the protection against oxidative stress demonstrating the highest activity as a free radical scavenger and anti-cancer agent, T-cell immunity, and its role regulating the thyroid hormone metabolism. Currently, inadequate dietary Se intake affects up to 1 in 7 people globally with the associated risk of developing many chronic degenerative diseases. Animals, including humans, are not able to easily transform inorganic species of Se into organic forms and, in fact, due to its toxicity, the human body can tolerate only very low levels of inorganic Se. However, plants are able to transform the inorganic species of Se to seleno-amino acids, which are the forms of selenium desired for animal diets. The selenium present in our diet comes indirectly from the reservoir in soils. Thus, regions with low Se level in soils would provide Se deficient diets. In order to overcome this problem, the elaboration of functional foods starting from Se-enriched edible plants has been proposed as a solution to overcome low levels of Se in the diet of animals and humans. This research action is aimed to produce Se-enriched dairy products and cheese as functional food through Se-biofortified alfalfa hay for feeding milking cows. To achieve the transferability of the methodology to different regions, Se will be applied directly to the plant (foliar application), instead to the soil, overcoming issues related with the unpredicted bioavailability of Se in soils with different physicochemical characteristics. Hence, this methodology will ensure an appropriate level of Se into the diet regardless the particularities of the agricultural soil.