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Effect of Monosodium Glutamate on Microbiome-Derived Imidazole Propionate Production in Healthy Volunteers

NCT07700368 · Status: NOT_YET_RECRUITING · Phase: NA · Type: INTERVENTIONAL · Enrollment: 18

Last updated 2026-07-14

No results posted yet for this study

Summary

The goal of this clinical trial is to learn whether dietary monosodium glutamate (MSG), a common food flavor enhancer, increases the blood level of a gut-microbiome-derived compound called imidazole propionate (ImP) in healthy adult volunteers. ImP is a compound made by gut bacteria from the amino acid histidine, and higher blood levels have been linked to problems with blood-sugar control. The main questions this trial aims to answer are:

Does taking MSG together with L-histidine increase blood ImP levels compared with taking a salt (sodium chloride) placebo together with L-histidine? How do blood ImP levels change over time in response to MSG and L-histidine taken together?

Researchers will compare a 7-day period of L-histidine plus MSG against a 7-day period of L-histidine plus sodium chloride (a salt placebo with matching sodium content) to see whether MSG changes blood ImP levels. Each participant completes both periods in random order and serves as their own comparison.

Participants will:

Take L-histidine capsules twice daily (morning and evening with meals) during two separate 7-day periods.

Dissolve either MSG powder or salt powder in water and drink it twice daily during each period, with the two periods separated by a 7-day break (washout).

Give a fasting blood sample at the start of the study and on day 7 of each period.

Optionally provide a stool sample at the end of each period. Complete a daily treatment diary and a follow-up phone call after the final sample.

Conditions

  • Healthy Adult

Interventions

DIETARY_SUPPLEMENT

L-histidine

USP-grade L-histidine, 4 g/day, taken as capsules divided into 2 g in the morning and 2 g in the evening with meals, during each 7-day treatment period. Administered in both treatment periods for all participants.

DIETARY_SUPPLEMENT

Monosodium glutamate (MSG)

Food-grade monosodium glutamate, 3 g/day, provided as identical-appearing single-dose powder sachets divided into 1.5 g in the morning and 1.5 g in the evening, each dissolved in approximately 240 mL

DIETARY_SUPPLEMENT

Sodium chloride (NaCl)

USP-grade sodium chloride, 940 mg/day, provided as identical-appearing single-dose powder sachets divided into 470 mg in the morning and 470 mg in the evening, each dissolved in approximately 240 mL of water and taken with meals during the placebo treatment period. The sodium content is matched to that of the 3 g/day MSG dose to isolate the effect of glutamate.

Sponsors & Collaborators

Study Design

Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Model
CROSSOVER

Eligibility

Min Age
18 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2026-07-15
Primary Completion
2027-12-31
Completion
2027-12-31

Countries

  • United States

Study Locations

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Entities

Companies

Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT07700368 on ClinicalTrials.gov