Functional foods are increasing in popularity owing to their ability to confer health and physiological benefits. Nevertheless, the notion that functional foods improve health when providing nutrients at levels above and beyond existing recommended intakes is inconsistent with the definition of requirement. This disparity highlights the need for an alternative definition of nutrient requirement. The present objective is to examine distinctions between optimization of health, as defined by what we currently deem as required intakes, versus adding physiological benefit using bioactive agents found in functional foods. Presently, requirement is defined as the lowest amount of intake of a nutrient that will maintain a defined level of nourishment for a specific indicator of adequacy. In contrast, functional foods are described as ingredients that are not necessary for body function, yet provide added physiological benefit that confer better overall health. Plant sterols are one example of such an ingredient. Plant sterols lower plasma cholesterol concentrations, and may thus be considered essential nutrients in physiological situations where circulating cholesterol concentrations are high. Similarly, intakes of omega-3 fats beyond existing requirement may confer additional health benefits such as hypolipidemic and anti-diabetic effects. These examples underscore the inconsistencies between what is defined as a nutrient requirement versus what is identified as a health benefit of a functional food. Such discrepancies emphasize the need for a more all-encompassing definition of a nutrient requirement; that is, one that moves beyond the prevention of overt deficiency to encompass improved health and disease risk reduction.