Blueberries for Gut, Brain, and Cardiometabolic Health in Prediabetes

Not Applicable

Recruiting

• Conditions: Prediabetes (Insulin Resistance, Impaired Glucose Tolerance); Female; Adult; Endothelial Function (reactive Hyperemia); Arterial Stiffness; Cognition; Oxidative Stress; Gut Microbiota; Overweight; Inflammation

• Registration Number: NCT06735651
• Lead Sponsor: Georgia State University

Brief Summary

The goal of this clinical trial is to determine the effectiveness of using a freeze-dried wild blueberry powder on cardiometabolic health, cognitive function, and gut microbiota composition in adult women with prediabetes.

Detailed Description

In the U.S., 35.3 million adults have type 2 diabetes mellitus (T2DM) and 96 million have prediabetes. Eight out of 10 people with T2DM die from cardiovascular disease. People with T2DM also have a 50% higher risk of developing dementia compared to healthy counterparts. Further, studies show that gut microbes play a major role in the development of T2DM. Prevention and treatment of T2DM focus on lifestyle changes including dietary modifications such as increased consumption of deep-colored fruits like berries. Blueberries are rich in fiber and phytochemicals and have several health benefits. We and others have shown that blueberry intake improves heart health in healthy men, hypertensive postmenopausal women, and men and women with metabolic syndrome. Yet, a comprehensive study in women with prediabetes that measures changes in cognitive performance and the underlying heart and gut health has not been conducted to date. Thus, the overall objective of this study is to investigate and bring forth evidence that blueberries improve gut, cardiometabolic, and cognitive function in women with prediabetes.

Therefore, this pilot six-week randomized, placebo-controlled parallel-arm clinical trial aims to investigate whether daily consumption of 22 g of freeze-dried blueberry powder improves gut, cardiometabolic, and cognitive function in women with prediabetes. Investigators hypothesize that daily consumption of blueberries will improve cardiometabolic parameters, gut dysbiosis, and cognitive impairments in our study population. To test these hypotheses, the following specific aims are proposed. To investigate whether daily consumption of 22 g of freeze-dried blueberry powder:

* Reduces levels of fasting blood glucose (FBG), insulin, and HOMA-IR (homeostatic model assessment of insulin resistance) and improves lipid profile in women with prediabetes.

* Reduces blood pressure and improves endothelial function in women with prediabetes.

* Improves cognitive function (verbal memory and executive functions \[inhibition, working memory, cognitive flexibility\]) in women with prediabetes.

* Favorably modulates gut microbiota composition in women with prediabetes.

* Improves serum markers of oxidative stress and inflammation in women with prediabetes.

Additionally, whether changes in the gut microbiota are associated with changes in cardiometabolic and cognitive function outcomes and whether changes in cardiometabolic outcomes are associated with changes in cognitive function parameters will be explored.

Study Timeline

• Study Start: 2024-09-20
• Study First Submitted: 2024-11-05
• Study First Submitted QC: 2024-12-11
• Study First Posted: 2024-12-16
• Status Verified: 2025-03
• Last Update Submitted: 2025-03-18
• Last Update Posted: 2025-03-19
• Primary Completion: 2025-05-01
• Study Completion: 2025-06-01

Recruitment & Eligibility

• Status: RECRUITING
• Sex: Female
• Target Recruitment: 30

Inclusion Criteria

• Women aged 45-65 years old
• Prediabetes (fasting blood glucose 100-125 mg/dL and/or HbA1c percentage between 5.7-6.4)
• Body Mass Index between 25-30 kg/m^2

Exclusion Criteria

• Allergies to berries
• Use of insulin, antidiabetic, antibiotics, and anti-inflammatory drugs
• Active cancer, gastrointestinal, renal, thyroid, stage 1 & 2 hypertension and other cardiovascular diseases, neurological diseases, or severe head injury
• Smoking
• Consumes greater than 2 alcoholic beverages per day
• Consumes antioxidant, probiotic, and prebiotic supplements
• Pregnant or Lactating
• Actively participating in a weight loss program
• Currently taking berry supplements or recently participated in another study taking berry supplements

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Blood Glucose	Baseline and 6 weeks	Measurement of fasting blood glucose
Ambulatory Blood Pressure	Baseline and 6 weeks	Assessment of whole-day ambulatory blood pressure during daytime and nighttime periods.

Secondary Outcome Measures

Name	Time	Method
Fasting Insulin	Baseline and 6 weeks
Homeostasis model assessment-insulin resistance (HOMA-R)	Baseline and 6 weeks	Calculated as fasting insulin (mU/mL) x fasting glucose (mg/dL)/405
Blood Lipid Profile	Baseline and 6 weeks	Measurement of blood lipid profile
Associative Memory	Baseline and 6 months	Measured using NIH Toolbox Face Name Associative Memory Exam and Face Name Associative Memory Exam Delay tests
Gut Microbiota Composition	Baseline and 6 weeks	Analysis of stool sample for determination of absolute levels of bacteria and relative species composition
Global Cognitive Ability	Screening	Measured using NIH Toolbox Picture Vocabulary test and Oral Reading Recognition
Performance Validity	Baseline and 6 weeks	Assessed using Rey 15
Verbal Memory & Recognition	Baseline and 6 weeks	Measured using Rey Auditory Verbal Learning Test with appropriate alternate forms
Working Memory	Baseline and 6 weeks	Measured using Digit Span and NIH Toolbox List Sorting
Processing Speed	Baseline and 6 weeks	Measured using NIH Toolbox Pattern Comparison and Oral Symbol Digit tests
Cognitive Inhibition	Baseline and 6 weeks	Measured using Delis-Kaplan Executive Function System Color Word Interference, and NIH Toolbox Flanker Inhibitory Control and Attention
Cognitive Flexibility	Baseline and 6 weeks	Assessed using Delis-Kaplan Executive Function System Trails and Verbal Fluency Switching
Attention	Baseline and 6 weeks	Assessed using Wechsler Adult Intelligence Scale - IV and Rey Auditory Verbal Learning Test Trial 1.
Problem-Solving	Baseline and 6 weeks	Assessed using NIH Toolbox Visual Reasoning Test

Trial Locations

Locations (1)

Georgia State University; 🇺🇸 Atlanta, Georgia, United States