The study of functional foods appears to hold the promise of improved quality of life, particularly for older persons who fight chronic disease. Many laboratories are studying the mechanisms of action of individual bioactive food components; but, relatively few studies are concerned with the interaction of the many components found in a single food or with a comparison between effects of the putative major bioactive component and the whole food. This overview is an introduction to the papers that follow, which were given as a symposium at the 2004 Experimental Biology meetings and which address the interactive effects of bioactive food components, particularly those in soy, broccoli, berries, and tomatoes. However, conclusions to be drawn go further than these 4 foods. The studies act as examples, identifying needed areas of focus in the study of functional foods and specifically the need for research into functional foods to encompass 3 areas of study: strength in chemical analysis, mechanistic studies carried out in cell culture, and animal studies comparing effects of dietary exposure to purified components and whole foods. Together, data from these 3 areas can give the solid scientific basis needed, so that clinical studies can be properly planned and executed.