Immunity encompasses all mechanisms and responses used by the body to defend itself against foreign substances, microorganisms, toxins, and incompatible living cells. Every aspect of immunity and host defense is dependent upon a proper supply and balance of nutrients. On the other hand, excessive intake of some nutrients may result in diminished immune responses. Phytochemicals (carotenoids, phenolics, and other secondary metabolites) in fruits and vegetables elicit immune-enhancing cellular responses that inhibit infection, inflammation and tumor formation. Bioactive food components such as probiotic organisms, animal-source peptides and fish oils, have immunomodulatory functions. This symposium will discuss aspects of diet and nutrition that influence immune function, covering recent scientific findings and the effects of traditional Asian foods on the immune system.