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CompletedNCT03275662Updated Feb 24, 2023

Fermented and Fiber-rich Food (FeFiFo) Study

An interventional study of Dietary Fiber and Fermented Foods in Metabolic Syndrome, Microbiome and Immune Function, sponsored by Stanford University. Completed at 1 site in United States. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2023-02-24.

Sponsored by Stanford University · Not applicable, Interventional, and Prevention

From the registry’s dates

  • Registered 1 year after the study started (first participant enrolled Aug 2016, registered Sep 2017).
Phase
Not applicable
Study type
Interventional
Enrollment
37
Allocation
Randomized
Ages
18 Years and older
Sex
All
01

Study summary

The primary objective is to contrast the degree to which increased consumption of dietary fiber vs. fermented food can decrease inflammation, increase microbiota diversity and can impact microbiota production of short-chain fatty acids (SCFA), potential normalizers of metabolic and immune dysfunction, in obese and non-obese adults.

Read the detailed description

The gut microbiota is central to human health, and the modern, industrialized gut microbiota has been linked to numerous chronic diseases that are driven by inflammation. It is likely dietary changes in the last half-century consistent with adoption of the Western diet have had an adverse impact on the gut microbiota. A critically important next step in this field of research is to identify how different dietary interventions can potentially restore healthy features of the gut microbiota in alignment with the optimization of human health. Dietary interventions that target the microbiota and reduce inflammation may reverse or prevent chronic diseases including obesity, metabolic syndrome, and inflammatory bowel disease. This study is designed to elicit and contrast inflammatory markers in blood with the amount of increase in microbiota diversity and related metabolic output achievable by two dietary approaches commonly available to the general population. The results could contribute to dietary recommendations for reversing the chronic disease epidemics of Westernization.

02

Conditions studied

  • Metabolic Syndrome
  • Microbiome
  • Immune Function
  • Inflammation
03

In context

Metabolic Syndrome

2,116 studies on the registry are indexed under Metabolic Syndrome; 347 are open to participants now.

This study's enrollment of 37 is below the median of 60 across 1,572 interventional studies indexed under Metabolic Syndrome.

Browse Metabolic Syndrome studies →

Lead sponsor

Stanford University is the lead sponsor of 2,168 studies on the registry; 431 are open to participants now.

Of its 267 completed or terminated interventional studies of FDA-regulated products, 207 (78%) have results posted.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
Yes

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • 18 and older, both genders, all ethnic backgrounds
  • Healthy subjects willing and able to provide blood, as well as stool specimens
  • Able to provide signed and dated .

Exclusion criteria

Exclusion Criteria:

  • higher than 40.
  • Vital signs outside of acceptable range at Screening Visit, i.e., blood pressure greater than 160/100, oral temperature greater than 100 degrees F, pulse greater than 100.
  • Use of any of the following drugs within the last 6 months:

    1. systemic antibiotics, antifungals, antivirals or antiparasitics (intravenous, intramuscular, or oral);
    2. oral, intravenous, intramuscular, nasal or inhaled ;
    3. cytokines;
    4. methotrexate or cytotoxic agents;
    5. large doses of commercial probiotics consumed (greater than or equal to 10e8 cfu or organisms per day) - includes tablets, capsules, lozenges, chewing gum or powders in which probiotic is a primary component.
    6. consumption of > 20 g fiber/day and > 7 servings of fermented foods per week.
  • Acute disease at the time of enrollment (defer sampling until subject recovers). Acute disease is defined as the presence of a moderate or severe illness with or without fever.
  • Chronic, (unresolved, requiring on-going medical management or medication) pulmonary, cardiovascular, gastrointestinal, hepatic or renal functional abnormality, as determined by medical history or physical examination.
  • History of cancer except for squamous or basal cell carcinomas of the skin that have been medically managed by local excision.
  • Unstable dietary history as defined by major changes in diet during the previous month, where the subject has eliminated or significantly increased a major food group in the diet.
  • Recent history of chronic alcohol consumption defined as more than five 1.5-ounce servings of 80 proof distilled spirits, five 12-ounce servings of beer or five 5-ounce servings of wine per day.
  • Positive test for , or .
  • Any confirmed or suspected condition/state of immunosuppression or immunodeficiency ( primary or acquired) including HIV infection.
  • Major surgery of the GI tract, with the exception of cholecystectomy and appendectomy, in the past five years. Any major bowel resection at any time.
  • History of active uncontrolled gastrointestinal disorders or diseases including:

    1. inflammatory bowel disease (IBD) including ulcerative colitis (mild-moderate-severe), Crohn's disease (mild-moderate-severe), or indeterminate colitis;
    2. irritable bowel syndrome (IBS) (moderate-severe);
    3. persistent, infectious gastroenteritis, colitis or gastritis, persistent or chronic diarrhea of unknown etiology, Clostridium difficile infection (recurrent) or Helicobacter pylori infection (untreated);
    4. chronic constipation.

Female who is pregnant or lactating.

Terms in these criteria, in plain language(8)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

BMI (body mass index)

Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.

What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

Immunosuppression

A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.

Read whether the line is about a condition or about medicines, and which medicines and doses it means.

Clinically significant

Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.

HIV

The human immunodeficiency virus, which weakens the immune system.

Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.

Hepatitis B tests

Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.

Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.

Hepatitis C tests

Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.

After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.

05

Study design

Phase
Not applicable
Primary purpose
Prevention
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Single (Outcomes assessor)
Enrollment
37 participants (actual)

Study arms

  • Experimental
    Fiber Group

    Participants are asked to increase their usual dietary fiber intake by 20 grams/day.

    Behavioral: Dietary Fiber

  • Experimental
    Fermented Foods Group

    Participants are asked to consume 6 servings of fermented foods per day.

    Behavioral: Fermented Foods

Interventions

  • BehavioralDietary Fiber
  • BehavioralFermented Foods
06

What researchers measure

Primary outcomes

  1. Immune profile: Cytokine Response Score (CRS)

    Change from baseline in CRS at 10 weeks

    Time frame: Baseline and 10 weeks

Secondary outcomes

  1. Microbiota metabolites: short-chain fatty acids (SCFA)

    Change from baseline in short-chain fatty acids (SCFA) at 10 weeks.

    Time frame: Baseline and 10 weeks

  2. Microbiota composition

    Change from baseline in 16S rRNA enumeration at 10 weeks, determined using Illumina-based sequencing.

    Time frame: Baseline and 10 weeks

07

Study locations

1 site
  • Stanford University School of Medicine
    Stanford, California 94305, United States
08

References and documents

Publications

  • Wastyk HC, Fragiadakis GK, Perelman D, Dahan D, Merrill BD, Yu FB, Topf M, Gonzalez CG, Van Treuren W, Han S, Robinson JL, Elias JE, Sonnenburg ED, Gardner CD, Sonnenburg JL. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021 Aug 5;184(16):4137-4153.e14. doi: 10.1016/j.cell.2021.06.019. Epub 2021 Jul 12. PubMed 34256014 ↗

Individual participant data

Plan to share: No

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Feb 24, 2023, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT03275662
Responsible party
Justin L. Sonnenburg (Associate Professor of Microbiology and Immunology, Stanford University) — Principal investigator
First posted
Sep 7, 2017
Start date
Aug 29, 2016
Primary completion
Jun 2, 2017
Completion
Jun 2, 2017
Last update
Feb 24, 2023

Study contacts

Justin L Sonnenburg, PhD
principal investigator · Stanford University
Christopher D Gardner, PhD
principal investigator · Stanford University

Oversight

FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Feb 2023. You cannot join it, but the record below documents what was studied.

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