The 2005 Dietary Guidelines were unique because they offered quantitative recommendations for consumption of whole-grains. This case study examines the hypothesis that the changed recommendations were responsible for the recent increase in retail sales and consumption of whole-grain food products. We find that release of the Dietary Guidelines and related media attention did increase availability and sales of whole-grain foods. A large impact on consumption occurred through reformulation of existing products, induced by competition among food suppliers. This study reveals the key role product reformulation plays in inter-firm competition and in realization of dietary changes recommended by public policy.