A carotenoid and a terpenoid in therapeutically-effective amounts is disclosed such that, upon ingestion in one preparation, or in two separated preparations, simultaneous or sequentially, and upon metabolism, the activity of natural killer (NK) cells is elevated. Specifically, the composition comprises lycopene and resveratrol in the range of 1:10 to 10:1 by molar； more preferably 1:1 to 3:1 by molar, and most preferably at 3:1. Alternatively, the preferred ratio may be expressed as 1:4 to 25:1 by weight； more preferably 2½:1 to 7½:1 by weight, and most preferably at 7½:1. The composition may be formulated for oral intake as a pharmaceutical, dietary supplement or food product and provided in therapeutically effective amounts to a mammal, preferably in a dosage of about 3.5 mg per day per 20 g of a mammalian body mass in a ratio of 2½:1 by weight, which can be translated to about 400 mg to 1000 mg per day for a typical human in need of elevating NK cell activity. Preferably, the therapeutically-effective aspect of the composition includes its metabolically-producing agents, prodrugs, metabolites or intermediate compounds useful in triggering NK cells into cytotoxic or cytolytic response.
