(P20-010-23) NIH Protocol for the Mediterranean-like Unprocessed (CLEAN-MED) Diet Intervention Study of the Gut Microbiome of Healthy Adults

Objectives: The primary objective of this study is to measure changes within the gut microbiome in healthy adults who transition from a Western diet to a Mediterranean-like unprocessed food (CLEAN-MED) diet. Additional objectives include identifying associations between the gut microbiome and psychosocial variables, biomarkers, and CLEAN-MED diet adherence, given strict data submission requirements.

Methods: We aim to recruit 110 healthy individuals following detailed review of their routine habitual diet. Sample size will include 60 volunteers in a two-month randomized cross-over cohort who will consume an intervention diet of CLEAN-MED foods provided by NIH or their pre-study habitual Western diet. A separate 12-month cohort of 50 volunteers are educated to prepare their own CLEAN-MED foods. The ability of volunteers to adhere to the study requirements is assessed during a 7-day trial week. During this time, volunteers must submit food logs, food photos, and a 6-question well-being survey each day. In order to qualify for the study, volunteers must have a low baseline Mediterranean diet score assessed using a survey adapted from the Prevención con Dieta Mediterránea (PREDIMED)-17, consume high amounts of ultra-processed foods using the NOVA system, and adhere to our study logging requirements.

Results: Out of 25 volunteers who consented to date, 17 completed the full trial week. Of those, 10 began the study, 3 are on-hold due to travel commitments, and 4 have withdrawn. Preliminary results show the average baseline Mediterranean diet score is 4 out of 17, while approximately 59% of total calories were from ultra-processed foods. The average study adherence score, as defined for this specific study, is 56 out of a total possible 63 points for the initial trial week.

Conclusions: This study will add valuable data to the field because there are few studies that examine the combination of Mediterranean diet and unprocessed foods, and even fewer with detailed gut microbiome data. Importantly, adherence to the prescribed diet can greatly affect the outcome and interpretation of the data, thus detailed adherence measurements are a critical element of this ongoing study.

Funding Sources: Protocol #CC-000871 is supported by the NIH Clinical Center Intramural Research program.