Effects of Sourdough Fermentation Duration and Acid Development on Postprandial Blood Glucose in Prediabetic Adults

Effects of Natural Sourdough Fermentation Duration and Acid Development on Postprandial Blood Glucose in Prediabetic Adults

The primary intervention for management of prediabetes is lifestyle changes. Eating healthier and increasing physical activity was found to slow the progression of prediabetes into diabetes, reduce the risk of other diseases like cardiovascular disease and hypertension, and have a lasting impact even after the intervention is discontinued. Studies found that increasing the intake of fiber, pre- and probiotics, and fermented foods have been linked to improved glycemic biomarkers. The goal of this crossover randomized trial is to assess the relationship between lengthened fermentation time of sourdough bread, e.g., an increased amount of lactic acid and acetic acid in the bread product, and postprandial glycemic response in healthy adults with prediabetes.

Study Overview

• Status: Completed
• Conditions: Insulin Resistance
• Intervention / Treatment: Other: sourdough bread 24; Other: yeast bread; Other: sourdough bread 48; Other: sourdough bread 72

Detailed Description

Sourdough bread has been proven to have higher fiber content and contains beneficial microorganisms from the fermentation process and has been linked to reduced risk of various diseases like diabetes, cardiovascular disease, and dyslipidemia. The fermentation of sourdough bread products converts starch and sugar in the dough into resistant starches and other slower digesting compounds. Sourdough bread products also have a lower glycemic index value, meaning they do not cause the blood sugar to rise as quickly, thus slowing the release of insulin in the body, leading to reduced risk of insulin resistance. However, very few studies exist studying the effects of naturally fermented sourdough products in individuals with prediabetes. It is worth exploring if increasing the fermentation time of naturally fermented sourdough bread increases the effects on relevant biomarkers relating to postprandial glycemia and insulinemia in prediabetic adults.

This study examined the acute effect of varying lengths of sourdough fermentation times on postprandial blood glucose levels over a 4-week period in adults with prediabetes (as evidenced by fasting glucose ≥100 or diagnosis by physician), but not taking diabetic medications. For each trial, the sourdough bread was ingested after an overnight fasting period in order to evaluate the effects of the bread when incorporated into the diet in place of breads made with baker's yeast. The goal of this crossover randomized trial was to assess the relationship between lengthened fermentation time, meaning an increased amount of lactic acid and acetic acid in the bread product, and glycemic and insulinemic response.

• Study Type: Interventional
• Enrollment (Actual): 5
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Arizona
    • Phoenix, Arizona, United States, 85004
      • 850 PBC

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• prediabetes; not on metformin; no known food allergies or sensitivities; not supplementing pre/post biotics

Exclusion Criteria:

• following diet that restricts carbohydrates; medication use affecting blood glucose; acute illness; smoker; pregnant; lactating; GI tract surgery; not willing to follow protocol

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: sourdough bread 24; 24 hours fermentation	Other: sourdough bread 24; fermentation time=24 hours
Active Comparator: Control bread; 12 hours fermentation	Other: yeast bread; no fermentation
Experimental: sourdough bread 48; 48 hours fermentation	Other: sourdough bread 48; fermentation time=48 hours
Experimental: sourdough bread 72; 72 hours fermentation	Other: sourdough bread 72; fermentation time=72 hours

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
blood glucose	blood glucose will be measured using a glucometer and capillary blood from finger prick	conducted at fasting and 30, 60, 90, and 120 minutes post-meal

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
bread palatability	bread palatability will be measured by Likert scale	conducted at 120 minutes post-meal
hunger rating	Hunger rating will be determined using Likert scale. Anchors: not hungry at all and as hungry as I have ever felt. A higher score indicates greater hunger.	conducted at 120 minutes post-meal

Collaborators and Investigators

• Sponsor: Arizona State University

Study record dates

Study Major Dates

• Study Start (Actual): April 4, 2025
• Primary Completion (Actual): August 15, 2025
• Study Completion (Actual): December 15, 2025

Study Registration Dates

• First Submitted: April 6, 2025
• First Submitted That Met QC Criteria: April 6, 2025
• First Posted (Actual): April 13, 2025

Study Record Updates

• Last Update Posted (Actual): January 23, 2026
• Last Update Submitted That Met QC Criteria: January 22, 2026
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: pre-diabetes; fermentation; sourdough bread; post-prandial glycemia
• Additional Relevant MeSH Terms: Metabolic Diseases; Glucose Metabolism Disorders; Hyperinsulinism; Hyperglycemia; Nutritional and Metabolic Diseases; Insulin Resistance; Glucose Intolerance
• Other Study ID Numbers: STUDY00021470

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: We do not plan to publish in ICMJE journals

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No