(P27-009-24) Preliminary Results for the NIH Protocol of 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, biomarkers, and CLEAN-MED diet adherence.

Methods: Sample size will include 60 healthy adults in a two-month (short-term) randomized cross-over cohort who will consume one month of an intervention CLEAN-MED diet provided by the NIH and one month of their pre-study habitual Western diet. A separate 12-month (long-term) cohort of 50 volunteers will be educated to prepare their own CLEAN-MED foods. Volunteers for both cohorts must have a low baseline Mediterranean diet (MedDiet) score assessed using a survey adapted from the Prevención con Dieta Mediterránea (PREDIMED)-17 and consume high amounts of ultra-processed foods (UPFs) using the NOVA system. Once enrolled, volunteers must submit food logs and photos a minimum of three days per week. Nutritional analysis is conducted using Nutrition Data System for Research (NDSR) software. Fecal and fasting blood samples are collected weekly (short-term) or monthly (long-term).

Results: We present preliminary results from September 2022 to present. For the short-term cohort, 22 volunteers have completed some portion of the study. The average baseline MedDiet score is 4 out of 17, with 56% calories from UPFs, while the planned provided CLEAN-MED diet has a MedDiet score of 15 and 0% calories from UPFs. For the long-term cohort, of which 11 volunteers have been enrolled at least 2 months, the average baseline MedDiet score has been 5, with 56% calories from UPFs. By month 2, the average MedDiet score typically increased to 11, while UPF intake decreased to 11% of total calories. Changes in fecal short-chain fatty acid levels were observed in both cohorts.

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

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