NCT04543877

WHNRC (Western Human Nutrition Research Center) Fiber Intervention Study

• Status: Completed
• Phase: EARLY_Phase 1
• Study type: Interventional
• Enrollment: 60 (actual)
• Sponsor: USDA, Western Human Nutrition Research Center · Federal
• Sex: All
• Age: 18 Years – 59 Years
• Healthy volunteers: Accepted

Summary

The purpose of this study is to determine if adding dietary fiber, such as inulin, to a diet that does not have enough fiber would raise the levels of potentially beneficial bacteria, such as Bifidobacterium, in the gut. There is evidence to suggest that these microbes can affect gut health and immune response, including to vaccines. The investigators will examine how inulin in the diet (compared to the maltodextrin control) (1) causes changes in the composition and function of the gut microbes, (2) reduces gut inflammation and gut leakiness caused by the vaccine, (3) increases immune response to vaccination, and (4) changes the expression of important adhesion molecules on the surface of white blood cells. Intestinal and whole-body responses will be measured in all participants.

Detailed description

Inulin, a dietary fiber supplement, is known to increase gut levels of potentially beneficial bacteria, including Bifidobacterium that are indigenous to gut microbiomes. Our underlying hypothesis is that the commensal microbiome, including Bifidobacterium, in the proximal colon or distal ileum affects the environment of draining lymph nodes and can thus modulate immune responses, including to vaccines. In the current study, participants will consume 12 grams/day inulin or maltodextrin (control) for 3 weeks before the administration of the Ty21a typhoid fever vaccine, 1 week during the vaccine, and 1 week after the vaccine. Vaccine response will be measured by counting T cells and immunoglobulin G (IgG) or immunoglobulin A (IgA)-secreting plasma cells specific for Ty21a. Gut permeability will be measured at baseline, and before and after the vaccine administration. Systemic inflammation and immune activation will be measured by analyzing blood for markers of inflammation.

Conditions

• Inflammation
• Vaccine
• Intestinal Permeability
• Typhoid Fever

Interventions

Type	Name	Description
DIETARY_SUPPLEMENT	Inulin	Consume 12 grams/day of inulin for 5 weeks (Day 9 - 43).
DIETARY_SUPPLEMENT	Maltodextrin	Consume 12 grams/day of maltodextrin for 5 weeks (Day 9 - 43).
BIOLOGICAL	Ty21a Typhoid Fever Vaccine	All participants will receive the vaccine. One capsule is swallowed on alternate days, e.g. days 30, 32, 34, and 36 for a total of 4 capsules.

Timeline

• Start date: 2022-09-27
• Primary completion: 2025-06-11
• Completion: 2025-06-11
• First posted: 2020-09-10
• Last updated: 2025-12-17

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study