Adopting Plant-rich Dietary Patterns and Reducing Red and Processed Meat Intake: Examining How Diverse U.S. Food and Health Systems Actors May Support Sustainable Diet Transitions for American Adults

Expert bodies recommend that populations adopt plant-rich dietary patterns and consume less red and processed meats (RPM) as a high-impact climate action. This PhD dissertation describes three studies that examined how diverse food and health systems actors may encourage sustainable diet transitions for Americans to support human and planetary health. Study one examined U.S. adults' perceptions, beliefs, and behaviors toward plant-rich dietary patterns. The International Food Information Council's Food and Health Surveys (2012–2022) were analyzed using crosstabulation and chi-square analyses. Consumers' recent RPM intake trends were mixed. Despite interest in sustainable products and principles, few U.S. adults followed plant-rich dietary patterns or purchasing practices. Leadership and coordinated action are needed to incentivize Americans to adopt plant-rich dietary behaviors. Study two conducted a systematic scoping review of media campaigns that promoted plant-rich dietary patterns and traditional and novel plant-based proteins, and that encouraged or discouraged RPM products to Americans (1917-2023). Of 84 media campaigns identified, corporate marketing (58.6%) campaigns were most prevalent compared to public information (13.8%), corporate sustainability (12.6%), countermarketing (5.7%), social marketing (4.6%), and public policy (4.6%). Civil society campaigns promoted plant-rich dietary patterns, but only one campaign was evaluated. U.S. government, academia, businesses, and civil society should commit adequate resources and evaluate media campaigns to support a sustainable diet transition for Americans that prioritizes traditional and novel plant-based proteins. Study three explored U.S. Food is Medicine (FIM) experts' views on how plant-rich dietary patterns and other sustainable diet practices could be incorporated into FIM interventions. Twenty semi-structured interviews were conducted among U.S. food and health systems actors and analyzed using inductive and deductive thematic analysis. Results indicated that many FIM actions support human and planetary health, but the co-benefits are not often discussed. The FIM movement is a unique opportunity to promote food and health systems changes that support human and planetary health, but key challenges require coordinated action across sectors. The three studies in this PhD dissertation collectively addressed knowledge gaps, used novel conceptual frameworks, and offered recommendations to inform U.S. food and nutrition policies, programs, and research to encourage sustainable diet transitions for American adults.