Until the middle of the last century, selenium was considered to be toxic, but recently it turned out to be a micronutrient with important physiological effects, whose lack impedes the functioning of several enzymes, while in the case of a prolonged deficiency, disease processes can also occur in the body. Hungary belongs to the selenium-deficient regions in Europe; therefore, our aim was to contribute to the improvement of selenium supply of the population through increasing the selenium content of milk and dairy products. A daily supplementation of 1-6 mg organic selenium to the feed of dairy cows increases the selenium content of milk from the value of 18 μg/kg to 94 μg/kg in 8 weeks, decreasing again to the initial value in 6 weeks after stopping the supplementation.
After producing various products from the control milk (18 μg/kg selenium content) and the selenium-enriched milk (53 μg/kg) obtained from dairy cattle fed on a feed supplemented with 2 mg selenium/day, we concluded that the selenium content of selenium-enriched milk compared to the products produced from the control milk increased from the value of 18.6 to 58.5 μg/kg in the case of yogurt, from 66.0 to 138.1 μg/kg in the case of telemea, from 80.8 to 163.7 μg/kg in the case of orda (urdă) and from 88.6 to 200.0 μg/kg in the case of semi-hard cheese obtained by mixed-coagulation. The selenium content of whey also increased significantly (from 8.8-9.7 μg/kg to 20.1-25.8 μg/kg), which could also be used as a food for people or feed for animals. According to our calculations, the selenium requirements of the developing organism could be satisfied by the consumption of 2-3 dl selenium-enriched milk until the age of 8 and with 4-6 dl selenium-enriched milk until the age of 20.