There is an increasing focus on diet as a tool to maintain human health and prevent disease. Milk and milk products of ruminants are important source of fat and saturated fatty acids, which are not considered to be very favourable to human health, but are valuable sources of nutrients including bioactive fatty acids (FA), vitamins, and minerals, which can promote positive health effects. The nutritional characteristics of milk and dairy products are related to their composition, which depends on the source species, and varies due to numerous factors, among which the animal diet is the most important. An improvement in milk FA composition and other micronutrients can be reached through an animal feeding strategy. Natural pasture-based farming systems increase microconstituents that are beneficial to human health (CLA, PUFAs, n-3 FAs, antioxidants, vitamins A and E, and Se) and volatile compounds (flavour, and terpenes) in milk and cheese. There are still uncertainties about the health benefits of various milk FAs and other compounds; deep and extensive long-term clinical studies with humans are needed. The contamination of milk and dairy products by heavy metals or dioxins has dramatic negative consequences for human and livestock health and necessitates very urgent consideration and intervention.