High-Fiber Diet for Flu Vaccine Response

Overseen By Jennifer Wargo, MD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: M.D. Anderson Cancer Center

Must not be taking: Antibiotics, Fiber supplements

Disqualifiers: Diabetes, Inflammatory bowel disease, others

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

Compensation: Varies

Number of Visits: Unknown

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores how different diets might boost the body's response to the flu vaccine by improving gut microbes, such as bacteria. Participants will follow either a high-fiber diet (HFD) or a Prebiotic Food-Enriched Diet (PreFED) to determine if these can enhance the immune system. The trial seeks MD Anderson employees planning to get their flu shot there, who have no major dietary restrictions and are willing to follow the study's diet plan and procedures. As an unphased trial, this study offers a unique opportunity to contribute to groundbreaking research on diet and immune health.

Will I have to stop taking my current medications?

The trial information does not specify if you need to stop taking your current medications. However, if you are taking antibiotics or fiber/prebiotic/probiotic supplements, you must stop at least 30 days before starting the study.

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

Previous studies have shown that diets high in fiber help the immune system respond better to the flu vaccine by improving gut health. This indicates that a high-fiber diet benefits health and is safe for most people.

Research shows that prebiotic foods, which nourish beneficial gut bacteria, can also enhance the immune response to the flu vaccine in adults. This suggests that a diet rich in prebiotic foods is generally well-tolerated and does not cause serious side effects.

Both types of diets aim to improve gut health and support the immune system. Current evidence reports no major negative effects, so these diets are considered safe for consumption. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about these treatments because they explore how dietary changes might enhance the body's response to flu vaccines. Unlike standard flu prevention measures, which typically involve vaccines and antiviral medications, both the High-Fiber Diet (HFD) and the Prebiotic Food-Enriched Diet (PreFED) focus on boosting the immune system through nutrition. The unique feature here is the use of high-fiber and prebiotic-enriched foods, which are believed to improve gut health and, in turn, enhance immune function. This approach is distinctive because it suggests a non-pharmaceutical way to potentially increase vaccine effectiveness by leveraging the gut-immune system connection.

What evidence suggests that this trial's dietary interventions could enhance the immune response to the flu vaccine?

Research shows that a high-fiber diet can improve the body's response to the flu vaccine. Studies with mice have found that more dietary fiber makes the vaccine more effective. Fiber supports beneficial gut bacteria, boosting the immune system's response to the flu shot. In this trial, participants in the High-Fiber Diet (HFD) intervention will consume only the study-provided meals and snacks.

Similarly, consuming foods rich in prebiotics, which nourish these beneficial bacteria, might also enhance vaccine effectiveness. A meta-analysis, which combines results from several studies, found that prebiotic foods can enhance the immune response to the flu vaccine in adults. Participants in the Prebiotic Food-Enriched Diet (PreFED) intervention will integrate study snacks and meal components into their usual diet. Both diets aim to improve gut health, potentially leading to a stronger defense against the flu. ^{1 2 3 6 7}

Who Is on the Research Team?

Jennifer Wargo, MD

Principal Investigator

M.D. Anderson Cancer Center

Are You a Good Fit for This Trial?

This trial is for English-speaking MD Anderson employees aged 18 or older with a BMI of 18.5-40, who plan to get the flu vaccine there and can provide blood and stool samples. Participants must not have major dietary restrictions, diabetes needing treatment, inflammatory bowel disease, history of significant gut surgery, recent antibiotic use or be pregnant.

Inclusion Criteria

Willing to adhere to the provided dietary interventions

English-speaking

Has easy access to a scale at home, work, or in their community

Exclusion Criteria

Major dietary restrictions (including vegetarian or vegan diets) or food allergies

I have had major surgery on my digestive system, not counting surgery to remove my appendix or gallbladder.

I have health conditions that prevent me from following the study's diet.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Dietary Intervention

Participants follow either a high-fiber diet or a prebiotic food-enriched diet prior to influenza vaccination

4-6 weeks

Vaccination

Participants receive the seasonal influenza vaccine

1 day

Follow-up

Participants are monitored for immune response and changes in gut microbiome after vaccination

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• High-Fiber Diet (HFD)
• Prebiotic Food-Enriched Diet (PreFED)

Trial Overview The study tests if a High-Fiber Diet (HFD) or Prebiotic Food-Enriched Diet (PreFED) can boost gut microbes and improve immune response to the flu vaccine. Participants will follow assigned diets, complete questionnaires/logs, and submit specimens.

How Is the Trial Designed?

Group I: Prebiotic Food-Enriched Diet (PreFED) Intervention Experimental Treatment 1 Intervention

Participants are expected to incorporate study snacks and meal components provided into your usual diet.

Group II: High-Fiber Diet (HFD) Intervention Experimental Treatment 1 Intervention

Participants are expected to eat only the study meals and snacks provided

Who Is Running the Clinical Trial?

M.D. Anderson Cancer Center

Lead Sponsor

Trials

3,107

Recruited

1,813,000+

Published Research Related to This Trial

Dietary fiber intake may enhance immune responses to influenza vaccination, particularly in first-time vaccinees, suggesting that gut health could influence vaccine efficacy.

In animal studies, increased dietary fiber led to improved vaccine responses through the production of short-chain fatty acids, indicating a potential mechanism for how diet affects vaccine effectiveness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Potential Association Between Dietary Fibre and Humoral Response to the Seasonal Influenza Vaccine. Cait, A., Mooney, A., Poyntz, H., et al.[2022]

In a study involving 29 participants, adding 10 g of extrinsic wheat fiber to solid food significantly increased fecal bulk, indicating a beneficial effect on digestive health.

However, when the same amount of fiber was consumed in the form of drinks, it did not lead to a significant change in fecal bulk, suggesting that the form of fiber intake matters for its effectiveness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of Extrinsic Wheat Fiber Supplementation on Fecal Weight; A Randomized Controlled Trial. Brandl, B., Lee, YM., Dunkel, A., et al.[2020]

A study by Trompette et al. demonstrated that dietary fiber and short-chain fatty acids can improve the immune response to influenza A virus by enhancing the function of CD8+ T cells.

These dietary components also promote the differentiation of alternatively activated macrophages, which may help reduce inflammation and tissue damage during viral infections.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A Little Fiber Goes a Long Way. Castillo, PAC., Hand, TW.[2019]

A high-fiber diet increased survival rates in influenza-infected mice by enhancing the production of specific immune cells, which helped reduce harmful inflammation in the airways.

Diet-derived short-chain fatty acids (SCFAs) improved the function of CD8+ T cells, promoting effective immune responses while preventing excessive tissue damage during the infection.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Dietary Fiber Confers Protection against Flu by Shaping Ly6c- Patrolling Monocyte Hematopoiesis and CD8+ T Cell Metabolism. Trompette, A., Gollwitzer, ES., Pattaroni, C., et al.[2019]

Dietary fiber has been recognized for its positive health effects since the 1970s, and certain types of fiber, known as prebiotics, can enhance the activity of beneficial gut bacteria.

Studying the metabolites produced from the fermentation of dietary fiber in the colon may provide clearer insights into how fiber contributes to health benefits, potentially helping to close the gap between recommended and actual fiber intake among consumers.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prebiotics, Fermentable Dietary Fiber, and Health Claims. Delcour, JA., Aman, P., Courtin, CM., et al.[2018]

In a study of 24 elderly in-patients over 14 weeks, a formula containing prebiotics and fermented milk products significantly increased Bifidobacterium counts and maintained higher antibody titers against the A/H1N1 influenza strain compared to a standard formula.

While the prebiotic formula did not affect antibody responses to A/H3N2 and resulted in lower titers against B, the overall findings suggest that improving intestinal microbiota with prebiotics may enhance the duration of immune response to certain vaccines.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of a Formula Containing Two Types of Prebiotics, Bifidogenic Growth Stimulator and Galacto-oligosaccharide, and Fermented Milk Products on Intestinal Microbiota and Antibody Response to Influenza Vaccine in Elderly Patients: A Randomized Controlled Trial. Nagafuchi, S., Yamaji, T., Kawashima, A., et al.[2022]

In a study involving 38 participants over 7 weeks, resistant maltodextrin was well tolerated and led to a slight increase in beneficial Bifidobacterium populations, suggesting potential prebiotic effects.

Supplementation with resistant maltodextrin shifted the production of short-chain fatty acids (SCFA) towards butyrate, which is beneficial for colon health, indicating favorable fermentation characteristics in the gut.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A novel resistant maltodextrin alters gastrointestinal tolerance factors, fecal characteristics, and fecal microbiota in healthy adult humans. Fastinger, ND., Karr-Lilienthal, LK., Spears, JK., et al.[2019]

Polylactose, a novel prebiotic fiber, was found to be highly fermentable and significantly increased the abundance of beneficial Bifidobacterium in the gut microbiota of rats on a high-fat diet, indicating its potential to improve gut health.

Rats fed polylactose showed a 29% reduction in epididymal fat pad weight and lower liver lipids compared to those on a high-fat diet without polylactose, suggesting it may help reduce obesity-related health risks.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Polylactose Exhibits Prebiotic Activity and Reduces Adiposity and Nonalcoholic Fatty Liver Disease in Rats Fed a High-Fat Diet. Abernathy, BE., Schoenfuss, TC., Bailey, AS., et al.[2023]

In a study involving enterally fed elderly individuals, prebiotics in the diet led to an increase in beneficial gut bacteria, such as Bifidobacterium and Bacteroides, compared to a control group without prebiotics over a 10-week period.

The group receiving prebiotics maintained higher antibody titers against influenza vaccine strains (H1N1, H3N2) compared to the control group, suggesting that prebiotics may enhance the immunological response to vaccination in the elderly.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Enhanced vaccination effect against influenza by prebiotics in elderly patients receiving enteral nutrition. Akatsu, H., Nagafuchi, S., Kurihara, R., et al.[2022]

A high-fiber diet (HFD) for about 4 months in men with type 1 diabetes significantly reduced whole-body protein turnover, decreasing both protein degradation and synthesis by approximately 20% and 25%, respectively.

Despite these changes in protein metabolism, the HFD did not negatively impact insulin sensitivity, glucose disposal, or overall metabolic control, indicating that a high-fiber diet can be safely integrated into the management of type 1 diabetes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A High-Fiber Diet Decreases Postabsorptive Protein Turnover but Does Not Alter Insulin Sensitivity in Men with Type 1 Diabetes Mellitus. Bruttomesso, D., Tessari, P.[2023]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC8635806/

Potential Association Between Dietary Fibre and Humoral ... In support of these observations, dietary fibre consumption significantly enhanced humoral influenza vaccine responses in mice, where the effect ...

2. mdanderson.org mdanderson.org/patients-family/diagnosis-treatment/clinical-trials/clinical-trials-index/clinical-trials-detail.ID2022-0450.html

Impact of High Dietary Fiber on Microbiome and Vaccine ... To learn if diet can enhance the microbes (such as bacteria and viruses) found in your gut and improve the body's immune response to the influenza (flu) vaccine ...

3. cancer.gov cancer.gov/research/participate/clinical-trials-search/v?id=NCI-2022-07926

Impact of High-Fiber Diet Compared to Prebiotic Food ... Diets high in fiber may enhance the microbes found in the gut and improve the body's immune response to the influenza (flu) vaccine. Eligibility Criteria ...

4. medicalnewstoday.com medicalnewstoday.com/articles/diet-metabolic-health-flu-vaccine-effectiveness

Flu vaccine: How diet and metabolic health determine ... A recent mouse study examined how healthy dietary interventions prior to vaccination could influence metabolic health and increase flu vaccine effectiveness.

5. tandfonline.com tandfonline.com/doi/full/10.1080/1040841X.2025.2480230

Diet, microbiome, and probiotics establish a crucial link in ... This article aims to comprehensively review how diet and probiotics can modulate gut microbiome composition, which is linked to vaccine efficacy.

6. frontiersin.org frontiersin.org/journals/immunology/articles/10.3389/fimmu.2025.1618921/epub

Immunomodulatory effects of gut microbiota on vaccine ... Additionally, an observational study examined the impact of dietary fiber (DF) intake on the humoral immune response to the TIV, finding a ...

7. immunopaedia.org.za immunopaedia.org.za/breaking-news/2018-articles/reduced-flu-severity-due-to-high-fibre-diet/

Reduced Flu severity due to high fibre diet This study clearly demonstrates that dietary fibre and SCFAs reduce influenza-associated disease severity by promoting differentiation of AAMs and enhancing CD8 ...