Efficacy of a multi-level intervention designed to promote adherence to WCRF/AICR dietary guidelines for cancer prevention

Organizations such as the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) recommend that adults eat a diet rich in whole grains, vegetables, and fruit; limit consumption of “fast foods” and other processed foods high in fat, starches, or sugars; and limit consumption of red and processed meat and sugar sweetened beverages (SSBs). The degree of adherence to these dietary guidelines predicts cancer incidence and cancer-related mortality. Primary prevention programs that facilitate sustained adherence to these dietary recommendations are sorely needed. The proposed study will evaluate the efficacy of a preventive intervention informed by the profound influence the food environment has on eating behavior. Our team pilot tested the planned approach and intervention delivery with a factorial design, yielding data on feasibility, acceptability, and effect sizes that informed the optimization of the experimental intervention components. In the proposed study, index participants (n = 236) will be randomized to either receive nutrition education (i.e., control group) or the experimental intervention, which is referred to as “Eatwell.” Both conditions will provide an equal number of group sessions held remotely over a period of 18 months. The curriculum in both conditions will be mindful of social determinants of health. In the Eatwell condition, grocery shopping will be the primary intervention target, with the goal of maximizing availability of healthy foods and limiting availability of unhealthy foods in the home environment. The intervention also will encourage participants to increase the proportion of meals prepared at home to take advantage of the optimal defaults present there, and teach strategies to manage temptation when eating away from home. Eatwell coaches will provide a foundation of nutrition education, teach self-regulation skills, and use innovative methods to enhance motivation for change (e.g., using a digital platform to monitor and provide feedback on grocery purchases). Eatwell will employ a multi-level approach, such that each index participant (i.e., the participant who initiates enrollment) will invite an adult household member to engage in select aspects of the intervention, to increase support for change in the home food environment. We expect that focusing on the home food environment will heighten the intervention impact, improving dietary quality and decreasing cancer risk for all members of the home. Assessments will be completed at months 0, 6, and 18. Dietary intake will be measured with food recalls, yielding a cancer prevention dietary adherence score as the primary outcome. Intake of fruit and vegetables and fiber; ultra-processed foods; red meat and processed meat; and SSBs will be examined as secondary outcomes. The biological impact of the intervention on inflammation will be measured with interleukin-6 and C-reactive protein. Changes in dietary quality among household members will be evaluated. Mediators and moderators of intervention effects will be tested. The findings will be relevant not only to the field of cancer prevention, but to the prevention of other diseases for which dietary quality is important.