Dietary Oxysterols and β-Cell Function Among African Americans

April 14, 2026 updated by: Jennifer Rooke, MD, MPH, Morehouse School of Medicine

African Americans (AAs) have a higher risk of developing type 2 diabetes than the general population. AAs are also more likely to eat foods that contain cholesterol oxides/oxysterols.

Dietary oxysterols can harm the cells that produce insulin and decrease insulin production.

This pilot study seeks to determine if removing dietary oxysterols with a plant-based diet will improve insulin production and decrease the risk of type 2 diabetes among AAs.

Study Overview

Detailed Description

African Americans (AAs) have almost twice the incidence and prevalence of Type 2 diabetes (T2D) compared to the general population. T2D occurs when pancreatic β-cell dysfunction prevents secretion of sufficient insulin to overcome insulin resistance. While the causes of β-cell dysfunction are not fully understood, the role of cytotoxic oxidative stress is well documented. Serum oxysterols are biomarkers of oxidative stress. Oxysterols form endogenously or exogenously when cholesterol in food is exposed to light, heat, and processing. Dietary oxysterols are cytotoxic, they are absorbed and carried in the blood by lipoprotein carriers or circulate freely in serum. 7-Ketocholesterol (7-KC), the most common oxysterol in food and serum is a biomarker of cholesterol oxidation. High serum levels of 7-KC are associated with an increased risk of T2D. AAs who consume Southern dietary pattern foods such as fried and processed meats have a higher consumption of dietary oxysterols than the general population. Our central hypothesis is that the higher consumption of dietary oxysterols among AAs contributes to β-cell dysfunction and higher rates of T2D. The aim of this pilot study is to determine the effect of lowering dietary oxysterols on serum 7-KC and β-cell function among AAs with prediabetes and early T2D (HbA1c 5.7% - 7.0%). The expected outcome is that decreased exposure to dietary oxysterols will decrease serum oxysterols and β-cells oxidative stress which will improve β-cell function and glycemic control. The knowledge gained from this study may lead to improved T2D prevention and treatment strategies that may decrease the burden of T2D in all communities and eliminate the racial disparity among AAs.

Study Type

Interventional

Enrollment (Actual)

12

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Georgia
      • Atlanta, Georgia, United States, 30310
        • Morehouse School of Medicine

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria: Participants must be:

  1. HbA1c: 5.7% - 7.0%: This HbA1c range reflects mild to moderate β-cell dysfunction.
  2. Self-identified AA: This group has higher rates of T2D than the general population.
  3. Adults over18 years old: This age group is at higher risk of T2D.
  4. Ability to read, understand and communicate effectively in English: All information about the study and instructions for the study protocol will be in English.
  5. Committed to eating the allocated study diet for 12 weeks: This is important to ensure that the study protocol is followed, and the data collected from participants is meaningful/valid.
  6. On stable medication dosages for the three months prior to recruitment: This is to avoid bias or confounding with new medications or dosages changes.
  7. Able to safely store a week's supply of prepared meals: Participants will receive packages of prepared food that has to stored and last them for the following week.
  8. Mentally competent and able to follow the study protocol and provide informed consent
  9. Currently eating the Standard American diet: The baseline diet of the participants will be assessed and correlated their baseline serum 7-KC levels and HOMA2 Index of β-cell function.

Exclusion Criteria: Participants cannot:

  1. Be pregnant or lactating: Fetuses and breast-feeding infants are a protected vulnerable group. The risk of involving them in research must outweigh the benefits, Hormonal levels and other factors in pregnant and lactating woman may confound study results.
  2. Be taking statin medications or any other cholesterol lowering drugs or supplements: These medications may artificially lower serum cholesterol and oxysterol levels.
  3. Be currently on a vegan, vegetarian, or any type of plant-based diet for the 3 months prior to recruitment: Participants currently on these diets may not see significant changes on the dietary interventions of the study protocol.
  4. Be a current smoker: Smoking is a risk factor for oxidative stress - this could be an effect modifier or a confounding faction for this study.
  5. Be on medications or supplements to lower blood glucose or treat diabetes: This will be an effect modifier or confounding factor. We will not know the effect of the dietary intervention if the participants are also on medications for diabetes.
  6. Be status post blood transfusion in the previous 3 months: This will interfere with the test for HbA1c levels. This is one of our primary outcomes:
  7. Have a hemoglobin or any other blood disorder: This will interfere with the test for HBA1c which measures glycation of hemoglobin in red blood cells.:
  8. Be taking biotin supplements: This interferes with the test for fasting C-Peptide.
  9. Be on dialysis or have any stage of renal failure: Dialysis patients need special diets and more intense monitoring than is planned for the participants in this study.
  10. Have food allergies: Participants will be screened for food allergies. This is to prevent food sensitivities or adverse reactions to the prepared meals in the study.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Group B - Plant Based ADA diet with no oxysterols (PB-ADAØ).
Participants in this group will be given prepared meals based on ADA guidelines but with no dietary cholesterol oxides/oxysterols - Plant-based ADA diet
This group will be given prepared plant-based meals that exclude all cholesterol oxides/oxysterols, adhere to the ADA guidelines, and meet specified daily calorie levels based on age and sex. Macronutrient levels for the diet will fall within the Acceptable Macronutrient Distribution Range for fat (20-35%), protein (10-35%), and carbohydrate (45-65%). The goal is weight maintenance, but weight loss may occur. A 1-5% weight loss will be acceptable and not deemed a potential confounder. Participants will be screened for food allergies and intolerances prior to receiving their research diets. All meals will include culturally familiar foods to enhance adherence. The dietary intervention will be conducted over an 8-week period. Meals will be packaged labeled and distributed to participants once per week. Participants will consume their meals at home.
Other Names:
  • Cholesterol Oxide-free plant-based diet
Active Comparator: Group A - Standard ADA dietary guidelines (SADA)
Participants in this group will be given prepared meals based on standard ADA dietary guidelines for 8 weeks.
This group will be given prepared meals that adhere to the ADA guidelines and meet specified daily calorie levels based on age and sex. Macronutrient levels for the diet will fall within the Acceptable Macronutrient Distribution Range for fat (20-35%), protein (10-35%), and carbohydrate (45-65%). The goal is weight maintenance, but weight loss may occur. A 1-5% weight loss will be acceptable and not deemed a potential confounder. Participants will be screened for food allergies and intolerances prior to receiving their research diets. All meals will include culturally familiar foods to enhance adherence. The dietary intervention will be conducted over an 8-week period. Meals will be packaged labeled and distributed to participants once per week. Participants will consume their meals at home.
Other Names:
  • ADA Diet

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The Homeostasis Model Assessment of β-cell function (HOMA-B) Index
Time Frame: 8 Weeks
The HOMA-B index will be calculated using the HOMA2 Calculator with fasting C-peptide and fasting blood glucose levels. This study will compare the effect of the standard American Diabetes Association (ADA) diet that contains oxysterols and a plant-based ADA diet that does not contain oxysterols on the HOMA-B index of African Americans (AAs) with prediabetes and early diabetes.
8 Weeks
Glycated Hemoglobin (HbA1c)
Time Frame: 8 weeks C-peptide levels are elevated in renal failure It is produced in equim C
HbA1c is a measure of glycemic control. This study will compare the effect of the standard ADA diet that contains oxysterols and a plant-based ADA diet without oxysterols on the HbA1c of AAs with HbA1c levels between 5.7% and 7.0%.
8 weeks C-peptide levels are elevated in renal failure It is produced in equim C
Serum 7-Ketocholesterol (7-KC)
Time Frame: 8 weeks
7-KC is one of the most abundant oxysterols in food and serum. This study will compare the effect of a standard ADA diet with oxysterols and a plant-based ADA diet without oxysterols on serum 7-KC levels. 7-KC will be measured by tandem liquid chromatography /mass spectrometry at the Emory Lipidomics lab.
8 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) Index
Time Frame: 8 Weeks
This index will be calculated using the HOMA2 Calculator with fasting insulin and fasting blood glucose levels. The impact of the 2 different study diets on the HOMA-IR will be determined.
8 Weeks
Fasting Insulin
Time Frame: 8 weeks
Insulin is a hormone produced by beta cells in the pancreas, it regulates serum glucose levels. The impact of the 2 different study diets on fasting insulin will be determined.
8 weeks
Fasting C-Peptide
Time Frame: 8 weeks
C-peptide is a short chain of amino acids that is released as a byproduct of insulin production. It is produced in equimolar amounts as endogenous insulin but excreted at a more constant rate over a longer time. It is a sensitive, clinically validated assessment of of β-cell function. This study will measure the effect of the 2 study diets on fasting C-peptide.
8 weeks
Fasting Blood Glucose
Time Frame: 8 weeks
Glucose is the main sugar found in blood. Elevated fasting blood glucose is a sign of diabetes. This study will measure the effects of the 2 study diets on fasting blood glucose.
8 weeks
Total cholesterol (TC)
Time Frame: 8 weeks
TC is a measure of the total amount of cholesterol in blood. This study will determine the effect of the 2 study diets on serum TC levels.
8 weeks
High Density Lipoproteins (HDL)
Time Frame: 8 weeks
HDL is the lipoprotein carrier that carries cholesterol from the cell to the liver to be excreted. This study will measure the effect of the 2 study diets on serum HDL levels.
8 weeks
Low Density Lipoproteins (LDL)
Time Frame: 8 weeks
LDL is the liproprotein carrier that carries cholesterol from the liver to the cells of the body. This study will measure the effect of the 2 study diets on serum LDL levels.
8 weeks
Oxided Low Density Lipoproteins (Ox-LDL)
Time Frame: 8 weeks
Ox-LDL form when LDLs carry cholesterol oxides/oxysterols. Ox-LDLs are cytotoxic and better indicators of cardiovascular risk than native LDL levels. This study will measure the effect of the 2 study diets on serum LDL levels.
8 weeks
Aspartate Amino Transferase (AST)
Time Frame: 8 weeks
AST is an enzyme that is released from the liver when it is injured. It is an indicator of liver function. This study will measure the effect of the 2 study diets on AST levels.
8 weeks
Alanine Amino Transferase (ALT)
Time Frame: 8 weeks
ALT is an enzyme that is released from the liver when it is injured. It is an indicator of liver function. This study will measure the effect of the 2 study diets on ALT levels.
8 weeks
Glomerular Filtration Rate (GFR)
Time Frame: 8 weeks
GFR is an index of kidney function. This study will measure the effect of the 2 study diets on GFR. In addition, it is important to measure kidney function in this study because C-peptide levels are elevated in renal failure
8 weeks
Blood Urea Nitrogen (BUN)
Time Frame: 8 weeks
BUN is a breakdown product of protein that is cleared from the blood by the kidneys. It is an indicator of kidney function. This study will measure the effect of the 2 study diets on BUN.
8 weeks
Creatinine
Time Frame: 8 weeks
Creatinine is a by-product of normal muscle breakdown that is cleared from the blood by the kidneys. It is an indicator of kidney function. This study will measure the effect of the 2 study diets on serum creatinine levels.
8 weeks
White Blood Cell (WBC) Count
Time Frame: 8 weeks
The WBC count is a measure of the number of WBCs the body. WBCs are immune cells and markers of inflammation. This study will measure the effect of the 2 study diets on WBC counts.
8 weeks
Hemoglobin (Hb)
Time Frame: 8 weeks
Hb is a protein in red blood cells that carries oxygen from the lungs to the body. This study will measure the effect of the 2 study diets on Hb levels. In addition, it is important to know Hb levels because Hb abnormalities affect HbA1c levels.
8 weeks
Platelet Count
Time Frame: 8 weeks
The platelet count is the number of platelets in blood. Platelets are involved in clotting, which is dysfunctional in diabetes. This study will measure the effect of the 2 study diets on platelet counts.
8 weeks
Calcium
Time Frame: 8 weeks
This is measure of serum calcium levels. A plant-based diet may cause low calcium levels. This study will measure the effect of the 2 study diets on serum calcium levels.
8 weeks
Vitamin B12
Time Frame: 8 weeks
This is a measure of vitamin B-12 levels. People on plant-based diets may have lower vitamin B12 levels. This study will measure the effect of the 2 study diets on vitWBC amin B12 levels.
8 weeks
Blood pressure (BP)
Time Frame: 8 weeks
BP is the pressure of circulating blood against the walls of blood vessels. It is an indicator of cardiovascular health. It will be measured at baseline, 6-weeks and post intervention. This study will measure the effect of the 2 study diets on BP.
8 weeks
Body composition using the Dual X-ray Absorptiometry (DEXA) Body Composition scan
Time Frame: 8 weeks
The DEXA scan provides an analysis of body fat, muscle mass and bone density. This study will measure the effect of the 2 study diets on body composition.
8 weeks
Body Mass Index (BMI)
Time Frame: 8 weeks
BMI is defined as the body weight divided by the square of the body height. This is expressed in units of kg/m². It will be used to classify study particpants according to body mass into underweight, normal, overweight or obese groups. This study will measure the effect of the 2 study diets on BMI.
8 weeks
Waist circumference (WC)
Time Frame: 8 weeks
WC is the measurement taken around the abdomen at the level of the umbilicus (belly button). This measures abdominal obesity which may be a better indicator of health risk than BMI. This study will measure the effect of the 2 study diets on WC.
8 weeks
World Health Organization (WHO-5) Index of Well Being
Time Frame: 8 weeks
The WHO-5 Well-Being Index is a short self-reported measure of current mental wellbeing. This study will measure the effect of the 2 study diets on this indicator of well being.
8 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Collaborators

Investigators

  • Principal Investigator: Jennifer Rooke, MD, MPH, Morehouse School of Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

July 1, 2021

Primary Completion (Actual)

December 31, 2023

Study Completion (Actual)

December 31, 2023

Study Registration Dates

First Submitted

September 24, 2021

First Submitted That Met QC Criteria

October 8, 2021

First Posted (Actual)

October 11, 2021

Study Record Updates

Last Update Posted (Actual)

April 17, 2026

Last Update Submitted That Met QC Criteria

April 14, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

No individual participant data will be shared.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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