Low-Carbohydrate and Plant-Based Dietary Effects on Vascular Health

Short-term Effects of a Low-carbohydrate Diet and a Whole-food, Plant-based Diet on Newer Markers of Vascular Health

This is a randomized trial with a crossover design to investigate the short-term effects of two different dietary patterns on markers of vascular health. A low-carbohydrate diet and a whole-food, plant-based diet will be used. In addition to more traditional markers (cholesterol, blood pressure, inflammation), endothelial progenitor cells and trimethylamine N-oxide will be assessed.

Study Overview

• Status: Completed
• Conditions: Hypertension; Hyperlipidemias; Heart Disease, Ischemic
• Intervention / Treatment: Other: Whole-Food, Plant-Based Diet and Low-Carbohydrate Diet

Detailed Description

This study is an investigation of the short-term effects of two different diets on both conventional as well as newer markers of vascular health among subjects over the age of 50 who have a cardiovascular risk factor. The low-carbohydrate diet will be consistent with low-carbohydrate diet maintenance plans, with "net" carbs kept under 50g per day. The whole-food, plant-based diet will exclude animal foods, oils, and solid fats. Meals will be provided, and subjects will consume each diet for 2 weeks, with a 4-6 week washout period between dietary phases. Subjects will be randomized 1:1 to start with either the plant-based diet or the low-carbohydrate diet. Its primary aim is to assess the short-term effect of a whole-food, plant-based diet and a low-carbohydrate diet on levels of endothelial progenitor cells and trimethylamine N-oxide among this population. Secondarily, we will assess more conventional measures of vascular risk, including cholesterol, weight, blood pressure, insulin resistance, and inflammatory marker, as well as fullness and changes in nutritional intake.

• Study Type: Interventional
• Enrollment (Actual): 45
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • New York
    • Webster, New York, United States, 14580
      • UR Medicine Nutrition in Medicine Research Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age >50
• Diagnosis of any of the following cardiovascular risk factors: hypertension (Diagnosis present in chart or use of antihypertensive medications); hyperlipidemia/dyslipidemia (non-HDL cholesterol ≥ 130 within the past year or current use of antihyperlipidemic medication); prediabetes (HbA1c ≥ 5.7% and < 6.5% in the past year); diabetes (HbA1c ≥ 6.5% in the past year); obesity (body mass index ≥ 30).
• Willing and able to comply with the protocol for the duration of the study, including food provision, scheduled meetings and testing visits.
• Able to speak and read English fluently because counseling and education is only available in English.

Exclusion Criteria:

• Active malabsorption syndrome (celiac disease, history of gastric bypass within the past year, uncontrolled Crohn's disease, protein-losing enteropathy, etc…)
• Use of any of the following medications that require close monitoring and adjustment during major dietary change: insulin, sulfonylureas, or warfarin
• Chronic or acute kidney disease, with eGFR < 50 on two or more lab tests in the past 6 months
• Diagnosis of cirrhosis or liver failure
• Hyperkalemia (defined as potassium >5.4 on two or more lab tests in the past 6 months)
• Major surgery in the past 3 months
• Myocardial infarction in the past 6 months
• Current, active eating disorder as determined by chart review, investigator assessment, or subject history
• Food allergies or intolerances that would interfere with eating study food or require special accommodation as determined by subject history, investigator assessment, or chart review
• Consuming a current diet described by the subject as vegetarian, vegan, very low-carbohydrate, or ketogenic
• Illicit drug use (not including marijuana)
• High risk alcohol use, based on subject history (defined as greater than 7 drinks/week for women and greater than 14 drinks/week for men)

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Whole-Food, Plant-Based Start; This group starts with the whole-food, plant-based diet, then gets the low-carbohydrate diet after the washout period.	Other: Whole-Food, Plant-Based Diet and Low-Carbohydrate Diet; Participants will consume two weeks of each diet, with a 4-6 week washout period in between. Meals and snacks are provided for convenience to enhance adherence to each dietary pattern, but subjects can add or include their own home-prepared foods as long as they meet dietary guidelines. Each dietary intervention will include an education session via Zoom teleconference, and at least 2 individual contacts by phone to address questions and assess for adverse events.
Experimental: Low-Carbohydrate Start; This group starts with the low-carbohydrate diet, then gets the whole-food, plant-based diet after the washout period.	Other: Whole-Food, Plant-Based Diet and Low-Carbohydrate Diet; Participants will consume two weeks of each diet, with a 4-6 week washout period in between. Meals and snacks are provided for convenience to enhance adherence to each dietary pattern, but subjects can add or include their own home-prepared foods as long as they meet dietary guidelines. Each dietary intervention will include an education session via Zoom teleconference, and at least 2 individual contacts by phone to address questions and assess for adverse events.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Endothelial Progenitor Cells	2 weeks
trimethylamine N-oxide	2 weeks
HDL function	2 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cholesterol Panel	Total, LDL, HDL, non-HDL cholesterol, and triglycerides	2 weeks
Blood Pressure		2 Weeks
Resting Heart Rate		2 weeks
Weight		2 weeks
Insulin resistance	HOMA-IR	2 weeks
Insulin		2 weeks
Blood Glucose		2 weeks
Inflammatory Markers	hsCRP, TNF-a, IL-6	2 weeks
Satiety Assessment	Adapted SLIM (satiety labeled intensity magnitude)	2 weeks
Food "liking"	5 food liking factor scales adapted from 5-Factor Satiety Questionnaires	2 weeks
Change in nutritional intake	assessed by 3 day food records at baseline and in second week of dietary phase	2 weeks

Collaborators and Investigators

• Sponsor: University of Rochester
• Investigators: Principal Investigator: Thomas Campbell, MD, University of Rochester

Study record dates

Study Major Dates

• Study Start (Actual): December 20, 2022
• Primary Completion (Actual): April 23, 2024
• Study Completion (Actual): April 23, 2024

Study Registration Dates

• First Submitted: June 2, 2022
• First Submitted That Met QC Criteria: June 7, 2022
• First Posted (Actual): June 10, 2022

Study Record Updates

• Last Update Posted (Actual): July 16, 2024
• Last Update Submitted That Met QC Criteria: July 15, 2024
• Last Verified: July 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Metabolic Diseases; Lipid Metabolism Disorders; Dyslipidemias; Heart Diseases; Myocardial Ischemia; Hyperlipidemias
• Other Study ID Numbers: RSRB 0007277

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No