Scientific evidence is necessary for the development of effective and enforceable regulations and government policy. To use scientific information appropriately, a systematic approach is needed for review and evaluation of the evidence. Federal agencies in the United States have developed useful approaches for such a review and evaluation to develop nutrition labeling, including health claims, and for updating of the Dietary Guidelines for Americans. The WHO is using a systematic evaluation process to update its recommendations on diet and health. The results of such reviews also highlight research needs to address relevant gaps in our knowledge.