Fresh vs Store-Bought Produce for Gut Microbiome

(GFF Trial)

Overseen By Gwynne Mhuireach, PhD

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of Oregon

Must not be taking: Antibiotics, Corticosteroids, Cytokines, others

Disqualifiers: BMI, Age, Pregnancy, Immunosuppression, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 1

20 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial examines how eating fresh garden produce versus store-bought fruits and vegetables might alter gut microbes. The study includes two groups: one begins with supermarket produce and then switches to garden-fresh, while the other does the reverse. It is ideal for individuals with regular bowel movements and a stable diet without significant changes in the past month. The aim is to determine which type of produce might benefit gut health more. As an unphased trial, this study provides a unique opportunity to contribute to groundbreaking research on gut health and dietary impacts.

Do I need to stop my current medications for the trial?

The trial does not specify if you need to stop your current medications, but you cannot participate if you've used certain drugs like antibiotics, corticosteroids, or large doses of probiotics in the last 6 months.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research shows that both garden-fresh and supermarket produce are generally safe to eat. For garden-fresh foods, studies suggest a small risk of contamination, but most germs found on them are harmless. Thus, eating garden-fresh fruits and vegetables is usually safe.

Supermarket produce often undergoes more washing and sanitization than garden-fresh produce, reducing the risk of harmful bacteria. However, instances have occurred where supermarket produce was linked to foodborne illnesses. Despite these concerns, the overall risk remains low, especially if produce is washed properly at home.

In summary, most people can safely eat both types of produce. Washing fruits and vegetables before eating them is always a good idea to reduce any potential risks. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores how different types of produce might impact the gut microbiome. Unlike traditional approaches that focus on probiotics or dietary supplements, this trial looks at the effects of eating fresh garden produce versus store-bought produce. The unique focus here is on understanding whether the freshness and source of the produce can lead to a healthier gut, offering a natural and accessible way to potentially improve gut health. By comparing these two produce sources, researchers hope to uncover new insights into optimizing diet for better digestive health.

What evidence suggests that this trial's treatments could be effective for the gut microbiome?

This trial will compare the effects of garden-fresh foods and supermarket produce on the gut microbiome. Studies have shown that fruits and vegetables from a garden and those from a store host different types of tiny organisms. Garden-fresh foods often contain a wider variety of these organisms because they undergo less washing and sanitization than store-bought produce. These tiny organisms can inhabit the gut and may enhance gut health by increasing microbial diversity. A more diverse gut is linked to better digestion and overall health. Research suggests that organisms from garden-fresh foods may benefit the gut more than those from store-bought foods. Participants in this trial will experience both interventions to assess their impact on gut health. ^{2 6 7 8 9}

Who Is on the Research Team?

Gwynne Mhuireach, PhD

Principal Investigator

University of Oregon

Are You a Good Fit for This Trial?

This trial is open to adults aged 18-45 with a BMI between 18 and 35, not pregnant or lactating, without a history of cancer (except certain skin cancers), stable bowel movements, no heavy alcohol use, controlled GI disorders, stable diet, no major immune issues or recent heavy drug use for infections.

Inclusion Criteria

Not applicable.

Exclusion Criteria

Body mass index (BMI) greater than or equal to 35 or less than or equal to 18

I am currently pregnant or breastfeeding.

I have had skin cancer treated by surgery but no other cancers.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Intervention

Participants undergo the Supermarket Produce and Garden-fresh Produce interventions in two periods

3 weeks

Baseline, 1 week, 3 weeks

Follow-up

Participants are monitored for changes in fecal bacterial abundance, diversity, and composition

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Garden-fresh Foods
• Supermarket Produce

Trial Overview The study compares the types of microbes on garden-fresh produce versus supermarket produce and their effects on human gut microbiomes. It aims to understand how these different food sources can influence gut health.

How Is the Trial Designed?

Group I: Supermarket First Experimental Treatment 2 Interventions

Participants assigned to this study arm undergo the Supermarket Produce intervention during the first period and the Garden-fresh Produce intervention during the second period.

Group II: Garden First Experimental Treatment 2 Interventions

Participants assigned to this study arm undergo the Garden-fresh Produce intervention during the first period and the Supermarket Produce intervention during the second period.

Who Is Running the Clinical Trial?

University of Oregon

Lead Sponsor

Trials

91

Recruited

46,700+

Citations

1. portal.nifa.usda.gov portal.nifa.usda.gov/web/crisprojectpages/1029759-nifa-microbiomes-of-garden-fresh-vs-store-bought-produce-and-variation-in-their-effects-on-the-human-gut-microbiome.html

NIFA: Microbiomes of garden-fresh vs store-bought produce ... Edible plants host abundant microorganisms, many of which can survive transit through the mammalian gut and may even be metabolically active.

2. buildhealth.uoregon.edu buildhealth.uoregon.edu/2025/02/28/garden-fresh-foods-the-gut-microbiome/

Garden-Fresh Foods & the Gut Microbiome Previous studies have demonstrated that time spent gardening increases the diversity of the microbiome on individuals' hands, however little is ...

3. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10519362/

The edible plant microbiome: evidence for the occurrence ... This study revealed evidence that fruit and vegetable-derived microbes could be found in the human gut and contribute to gut microbiome diversity.

4. gffstudy.com gffstudy.com/about/

About the GFF Study To better understand differences between the microbial communities of garden-fresh and store-bought fruits and vegetables, as well as their potential to ...

5. frontiersin.org frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1623710/full

Impact of fresh and fermented vegetable consumption on ... This study evaluated the effects of fermented vegetables (FVs) intake including fermented carrots, kohlrabi, and kimchi on human health parameters

6. nal.usda.gov nal.usda.gov/research-tools/food-safety-research-projects/nifa-microbiomes-garden-fresh-vs-store-bought-produce-and-variation-their-effects-human-gut

NIFA: Microbiomes of garden-fresh vs store-bought produce ... The goal of this Seed Grant, therefore, is to generate preliminary data needed to support a full-scale proposal to examine fruit and vegetable microbiomes ...

7. fda.gov fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-guide-minimize-microbial-food-safety-hazards-fresh-fruits-and-vegetables

Guide to Minimize Microbial Hazards for Fresh Fruits and ... This guidance is intended for all fresh-cut produce firms, both domestic and foreign, to enhance the safety of fresh-cut produce by minimizing the microbial ...

8. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10494634/

Microbiological quality assessment of fresh produce This study aimed at assessing the microbiological quality of fresh produce grown onsite or supplied to South African schools that are part of the national ...

9. sciencedirect.com sciencedirect.com/science/article/abs/pii/S0924224424004618

Impact of fruit consumption on gut microbiota Low fruit intake increases systemic inflammation due to reduced microbial diversity. Researchers are investigating how fruit consumption affects gut microbiota, ...