Current evidence suggests that increased intake of plant foods may reduce the risk of certain types of cancer; this has been attributed in part to their many phytochemicals. 1,2 To determine their beneficial effects on health, the effects of specific plant foods or food components have been studied in isolation. However, foods are not consumed in isolation but in combination with other foods. An effect of a specific component in a food may not necessarily be equivalent to the effect of the specific food because a component may act either synergistically or antagonistically with other components of the same food. It is therefore important to understand whether food components act in a complementary or adverse manner. Similarly it is of interest to determine whether different foods with the same or complementary mechanisms of action will interact in such a way that the results are more beneficial to health than the intake of the single food alone.