Dietary standards and future developments.

The field of nutrition is in the midst of a major and rapid transition. Just how far we have come can be illustrated by the judgement that it is possible, and indeed desirable, to define multiple criteria of adequacy, multiple levels of requirement, and hence a multitiered population assessment. Moreover, in the past few years, there has also been widespread acceptance of other important concepts: no single dietary standard meets every user's needs; the quality of a diet, as well as its quantity, needs to be considered; alternative dietary standards are required and available; and finally, patterns of dietary intakes must be considered. Finally, there are fresh approaches to the relation of dietary factors and free radicals that appear to be most promising. Indeed, the issues are still unresolved, but a new definition of what RDA might mean may well emerge, along with the other evolving alternative dietary standards. The addition of a new category of naturally occurring compounds to be taken prophylactically under certain circumstances of high risk from free radicals, emphasizes the magnitude of the progress that has already been achieved.