Mediterranean-like Unprocessed (CLEAN-MED) Diet Intervention Study of the Gut Microbiome of Healthy Adults

NCT05411120 | Completed

• 2 other identifiers: 10000871000871-CC
• Study Type: interventional
• Target: 160
• Locations: 1 country
• Sites: 1

Brief Summary

Background: Trillions of tiny organisms-including bacteria, fungi, and viruses-live inside our intestines. These microorganisms break down nutrients in our food, aid our immunity, and help keep us healthy. The population balances among these organisms can vary in different people due to factors including genetics, lifestyle, and diet. More studies are needed to understand how dietary habits affect our intestinal microorganisms. Objective: To see how switching from a traditional Western diet (low in fiber, high in saturated fat) to a Mediterranean-like unprocessed foods diet (CLEAN-MED) changes the environment in the intestine. The CLEAN-MED diet includes lots of vegetables, fruits, and whole grains with little sugar or red meat. Eligibility: Healthy adults aged 18 to 60 Design: Participants will be divided into 2 groups. All will start with a trial week. Participants will log all the food they eat and answer questions about their diet throughout the entire study. Participants in the short-term group will eat a Western diet for 4 weeks and a CLEAN-MED diet for 4 weeks. Food will be provided for the CLEAN-MED diet. Participants will visit the clinic each week and complete surveys. They will log everything they eat. They will provide blood, urine, and stool samples. Participants in the long-term group will eat the CLEAN-MED diet for up to 12 months. They will visit the clinic each month and complete surveys. They will log everything they eat. They will provide blood, urine, and stool samples. Some foods will be provided for the first 2 weeks. Participants may choose to have a scan of their body composition every few months.

Conditions

Diet Therapy

Keywords

Immune System; Gastrointestinal Tract

Outcome Measures

Primary Outcomes (1)

• The primary objective is to assess changes in gut microbiome associated with a Mediterranean-like and unprocessed food diet compared to a habitual Western diet in healthy adults.

  -Dietary intake via Dietary History Questionnaire (DHQ) III -PREDIMED MedDiet Score -Landry MedDiet Score -The CLEAN-MED NOVA score -Healthy Eating Index (HEI)-2015 -Weight change -Gut microbiome as measured by 16S rRNA analysis of frequent stool collections -Shotgun sequencing will include fungal and viral sequences -Microbial functional pathway analyses

  9 weeks (Short Term) 12 months (long Term)

Secondary Outcomes (2)

• Measure biomarkers in various bodily specimens (stool, blood, etc.) using the pertinent biochemical assays.

  24 months

• Identify associations between Mediterranean-like unprocessed food diet adherence with perceived quality of life.

  24 months

Study Arms (5)

Long-term a Intervention: CLEAN-MED

EXPERIMENTAL

Study arm will consume a Mediterranean like diet, while tracking their food intake for 12 months

Other: CLEAN-MED

Short-term, Western Diet, high MedDiet score a Intervention: C

EXPERIMENTAL

Study arm will consume a Mediterranean like diet, while tracking their food intake for 9 weeks, With high MEdDIet score.

Other: Western Diet

Short-term, Western Diet, high MedDiet score a Intervention: W

EXPERIMENTAL

Study arm will consume a Mediterranean like diet, while tracking their food intake for 9 weeks, With high MEdDIet score.

Other: CLEAN-MED

Short-term, Western Diet, low MedDiet score a Intervention: CL

EXPERIMENTAL

Study arm will consume a western diet eating as they normally would for 9 weeks. With low MEdDIet score.

Other: Western Diet

Short-term, Western Diet, low MedDiet score a Intervention: We

EXPERIMENTAL

Study arm will consume a Mediterranean like diet, while tracking their food intake for 9 weeks. With low MEdDIet score.

Other: CLEAN-MED

Interventions

CLEAN-MED OTHER

Mediterranean like diet is a high consumption of vegetables, oil and moderate consumption of protein, with no processed foods.

Long-term a Intervention: CLEAN-MED; Short-term, Western Diet, high MedDiet score a Intervention: W; Short-term, Western Diet, low MedDiet score a Intervention: We

Western Diet OTHER

Western Diet is by high intakes of pre-packaged foods, refined grains, red meat, processed meat, high-sugar drinks, candy and sweets, fried foods, conventionally-raised animal products, butter and other high-fat dairy products, and low intakes of fruits, vegetables, whole grains.

Short-term, Western Diet, high MedDiet score a Intervention: C; Short-term, Western Diet, low MedDiet score a Intervention: CL

Eligibility Criteria

• Age: 18 Years - 60 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• In order to be eligible to participate in this study, an individual must meet all of the following criteria:
• Ability of subject to understand and the willingness to sign a written informed consent document
• Age 18-60, at the time of consent
• Willingness to adhere to the dietary regimen and report any major stressors that occur during the study (i.e. changing jobs, moving, death of a close relative/friend, etc.)
• Willingness to provide blood and stool specimens as specified
• BMI \>=18 and \<= 35 kg/m\^2
• Access to necessary resources for participating in a technology-based intervention: computer, smartphone, internet access, etc.
• Has the ability/transportation methods to attend on-site visits
• For 50 of the 60 participants in short-term cohort and for 40 of the 50 participants in the long-term cohort: Currently following a Western diet with PREDIMED-17 MedDiet score \<= 7 for \>= 1 months and a CLEAN-MED NOVA score of \>= 35% kcal in NOVA 4 category with \>= 14 items/week in NOVA 4
• For 10 of the 60 participants in short-term cohort and for 10 of the 50 participants in the long-term cohort: Currently following a Western diet with PREDIMED-17 MedDiet score \<= 10 for \>= 1 months and a CLEAN-MED NOVA score of \>= 20% kcal in NOVA 4 category with \>= 7 items/week in NOVA 4
• CLEAN-MED Logging Score of \>= 43 after initial trial week to continue in the study for the randomization step
• For long-term cohort only: Have resources and capability to consume freshly-cooked (i.e. not pre-packaged or frozen) meals

You may not qualify if:

• An individual who meets any of the following criteria will be excluded from participation in this study, at the discretion of the PI:
• Current use of medications or dietary supplements for weight or appetite control, whether prescribed or not, including laxatives (within the last 4 weeks)
• Currently eating a vegan, vegetarian, keto or other restrictive diet plan, or food allergies that would affect eating the study diet, at the discretion of the PI
• Active cardiovascular disease (in past year with myocardial infarction, coronary stent or bypass surgery)
• Diabetes (type 1 and 2) or history of gestational diabetes or on hypoglycemic medications or any other indication
• Kidney disease (eGFR less than 50 mL/min per 1.73 m\^2)
• Liver disease (liver transaminase higher than 3 times the normal range for the laboratory)
• Symptomatic gallstones
• History of active cancer in the past 3 years except for squamous or basal cell carcinomas of the skin that have been medically managed by local excision
• Has a diagnosed autoimmune condition (i.e. HIV, lupus, etc.) or other immunosuppressive or immunodeficient state, at the discretion of the PI
• Musculoskeletal disorders precluding regular physical activity
• Consumption of the following drugs: proton pump inhibitors, antidiabetic drugs, cholesterol lowering drugs, SGLT-2 inhibitors, GLP-1 receptor agonist, insulin, Amylin analog, Alpha-glucosidase inhibitor, Dopamine agonist, Bile acid sequestrant, corticosteroids, methotrexate or immunosuppressive cytotoxic agents
• Some types of abdominal surgery, including bariatric surgery, or severe intestinal problems (by discretion of study physician), including:
• Inflammatory bowel disease (IBD) including ulcerative colitis (mild-moderate-severe), Crohn s disease (mild-moderate-severe), or indeterminate colitis;
• Irritable bowel syndrome (IBS) (moderate-severe);

Sponsors & Collaborators

• National Institutes of Health Clinical Center (CC): lead

Study Sites (1)

National Institutes of Health Clinical Center

Bethesda, Maryland, 20892, United States

Location

Related Links

• NIH Clinical Center Detailed Web Page

MeSH Terms

Interventions

Diet, Western

Intervention Hierarchy (Ancestors)

Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena

Study Officials

• David B Sacks, M.D.

  National Institutes of Health Clinical Center (CC)

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: NIH
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 4, 2022
• First Posted: June 9, 2022
• Study Start: August 26, 2022
• Primary Completion: February 4, 2026
• Study Completion: February 5, 2026
• Last Updated: March 6, 2026

Record last verified: 2026-03-04

Locations

US (1)