Consumers are aware of foods containing microcomponents that may have positive effects on health maintenance and disease prevention. In ruminant milk, meat, and milk products; these functional food components include eicosapentaenoic acid (20:5n3), docosahexaenoic acid (22:6n3), 9c11t-conjugated linoleic acid, and vaccenic acid (11t-18:1). Modifying ruminal microbial metabolism of fatty acid in rumen through animal diet formulation is an effective way to enhance these functional fatty acids in ruminant-derived food products. However, it requires an understanding of the interrelationship between supply of lipid through the diet and rumen fermentation. Lipids in ruminant diets undergo extensive hydrolysis and biohydrogenation in the rumen. Apparent transfer efficiency of eicosapentaenoic acid and docosahexaenoic acid from feed to milk is very low (1.9 to 3.3%), which is, to a large extent, related to their extensive biohydrogenation in the rumen. Therefore, feeding a rumen-protected supplement containing eicosapentaenoic acid and docosahexaenoic acid, can be used to bypass the rumen. Ruminant-derived foods also contain different types of conjugated linoleic acid isomers, which are intermediates of rumen biohydrogenation of linoleic acid (9c12c-18:2). The predominant isomer of conjugated linoleic acid is 9c11t, which has numerous health benefits in animal models. The concentration of conjugated linoleic acid in ruminant-derived food products can be significantly enhanced through animal diet modification. We conclude that most current functional food products from ruminants have potential for their health-supporting properties, and for this market to succeed, an evidence-based approach should be developed in humans.