Effect of Amount and Type of Dietary Carbohydrates on Risk for Cardiovascular Heart Disease and Diabetes

This study has been completed.
Sponsor:
Collaborator:
Information provided by (Responsible Party):
Frank M. Sacks, Brigham and Women's Hospital
ClinicalTrials.gov Identifier:
NCT00608049
First received: January 23, 2008
Last updated: July 3, 2014
Last verified: July 2014
  Purpose

Cardiovascular disease (CVD) and diabetes are health conditions that are strongly influenced by a person's diet. Although the best diet to prevent CVD and diabetes is uncertain, reducing intake of saturated and transunsaturated fats is known to help lower cardiovascular risk. However, even diets low in these fats can vary widely in other energy providing nutrients, particularly carbohydrates. This study will determine the effects of a higher versus lower carbohydrate diet, each with a high or low glycemic index (GI) composition, on risk factors for CVD and diabetes.


Condition Intervention
Overweight
Cardiovascular Diseases
Behavioral: High carbohydrate and low glycemic index (GI) diet
Behavioral: Low carbohydrate and low GI diet
Behavioral: High carbohydrate and high GI diet
Behavioral: Low carbohydrate and high GI diet

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: Optimal Macronutrient Intake - Carbohydrate

Resource links provided by NLM:


Further study details as provided by Brigham and Women's Hospital:

Primary Outcome Measures:
  • Systolic blood pressure (SBP), Low Density Lipoproteins (LDL) cholesterol, High Density Lipoproteins (HDL) cholesterol, triglycerides, and insulin sensitivity [ Time Frame: Measured at Week 5 of each dieting period ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Diastolic blood pressure (DBP); apolipoproteins B, CIII, A-I, and Very Low Density Lipoproteins (VLDL); and LDL with apolipoprotein CIII [ Time Frame: Measured at Week 5 of each dieting period ] [ Designated as safety issue: No ]
  • Beta cell response, glucose effectiveness, and fructosamine; postprandial glucose, insulin, lipids, and hormone levels [ Time Frame: Measured at Week 5 of each dieting period ] [ Designated as safety issue: No ]
  • Overall CVD risk using risk equations [ Time Frame: Measured at Week 5 of each dieting period ] [ Designated as safety issue: No ]

Enrollment: 189
Study Start Date: February 2008
Study Completion Date: February 2011
Primary Completion Date: February 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 1
Participants will follow four diet plans, each for a period of 5 weeks, in the following order: high carbohydrate/high GI, high carbohydrate/low GI, low carbohydrate/high GI, and low carbohydrate/low GI
Behavioral: High carbohydrate and low glycemic index (GI) diet
The high carbohydrate and low GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: Low carbohydrate and low GI diet
The low carbohydrate and low GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: High carbohydrate and high GI diet
The high carbohydrate and high GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Behavioral: Low carbohydrate and high GI diet
The low carbohydrate and high GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Experimental: 2
Participants will follow four diet plans, each for a period of 5 weeks, in the following order: high carbohydrate/high GI, high carbohydrate/low GI, low carbohydrate/low GI, and low carbohydrate/high GI
Behavioral: High carbohydrate and low glycemic index (GI) diet
The high carbohydrate and low GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: Low carbohydrate and low GI diet
The low carbohydrate and low GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: High carbohydrate and high GI diet
The high carbohydrate and high GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Behavioral: Low carbohydrate and high GI diet
The low carbohydrate and high GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Experimental: 3
Participants will follow four diet plans, each for a period of 5 weeks, in the following order: high carbohydrate/low GI, high carbohydrate/high GI, low carbohydrate/high GI, and low carbohydrate/low GI
Behavioral: High carbohydrate and low glycemic index (GI) diet
The high carbohydrate and low GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: Low carbohydrate and low GI diet
The low carbohydrate and low GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: High carbohydrate and high GI diet
The high carbohydrate and high GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Behavioral: Low carbohydrate and high GI diet
The low carbohydrate and high GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Experimental: 4
Participants will follow four diet plans, each for a period of 5 weeks, in the following order: high carbohydrate/low GI, high carbohydrate/high GI, low carbohydrate/low GI, and low carbohydrate/high GI
Behavioral: High carbohydrate and low glycemic index (GI) diet
The high carbohydrate and low GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: Low carbohydrate and low GI diet
The low carbohydrate and low GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: High carbohydrate and high GI diet
The high carbohydrate and high GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Behavioral: Low carbohydrate and high GI diet
The low carbohydrate and high GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Experimental: 5
Participants will follow four diet plans, each for a period of 5 weeks, in the following order: low carbohydrate/high GI, low carbohydrate/low GI, high carbohydrate/high GI, and high carbohydrate/low GI
Behavioral: High carbohydrate and low glycemic index (GI) diet
The high carbohydrate and low GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: Low carbohydrate and low GI diet
The low carbohydrate and low GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: High carbohydrate and high GI diet
The high carbohydrate and high GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Behavioral: Low carbohydrate and high GI diet
The low carbohydrate and high GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Experimental: 6
Participants will follow four diet plans, each for a period of 5 weeks, in the following order: low carbohydrate/high GI, low carbohydrate/low GI, high carbohydrate/low GI, and high carbohydrate/high GI
Behavioral: High carbohydrate and low glycemic index (GI) diet
The high carbohydrate and low GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: Low carbohydrate and low GI diet
The low carbohydrate and low GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: High carbohydrate and high GI diet
The high carbohydrate and high GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Behavioral: Low carbohydrate and high GI diet
The low carbohydrate and high GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Experimental: 7
Participants will follow four diet plans, each for a period of 5 weeks, in the following order: low carbohydrate/low GI, low carbohydrate/high GI, high carbohydrate/high GI, and high carbohydrate/low GI
Behavioral: High carbohydrate and low glycemic index (GI) diet
The high carbohydrate and low GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: Low carbohydrate and low GI diet
The low carbohydrate and low GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: High carbohydrate and high GI diet
The high carbohydrate and high GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Behavioral: Low carbohydrate and high GI diet
The low carbohydrate and high GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Experimental: 8
Participants will follow four diet plans, each for a period of 5 weeks, in the following order: low carbohydrate/low GI, low carbohydrate/high GI, high carbohydrate/low GI, and high carbohydrate/high GI
Behavioral: High carbohydrate and low glycemic index (GI) diet
The high carbohydrate and low GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: Low carbohydrate and low GI diet
The low carbohydrate and low GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of less than 45 on the glucose scale.
Behavioral: High carbohydrate and high GI diet
The high carbohydrate and high GI diet will require 58% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.
Behavioral: Low carbohydrate and high GI diet
The low carbohydrate and high GI diet will require 40% of daily calories to be from carbohydrates and will be composed of meals with a GI of greater than 65 on the glucose scale.

Detailed Description:

A healthy diet can have a remarkable effect on a person's overall health. Research has consistently confirmed the association between diet and serious health problems, including heart disease, diabetes, high blood pressure, and gastrointestinal disorders. Most healthy diets aimed at disease prevention promote a low intake of fats, but the optimal diet to prevent CVD and related disorders is uncertain. Recent emphasis has turned to the influence of carbohydrate consumption on risk of CVD and diabetes. Carbohydrates comprise a wide range of foods, which are categorized by their absorption rate, also known as glycemic index (GI). There is much current debate over how the level and type of dietary carbohydrates affect cardiovascular health. This study will determine the effects of a higher versus lower carbohydrate diet, each with a high or low GI composition, on risk factors for CVD and diabetes.

Potential participants will attend three screening visits that will include questionnaires, clinical measurements, and blood and urine tests. Participants will then undergo an 8-day run-in phase to become familiar with the feeding patterns of four different diets: high carbohydrate with high GI, high carbohydrate with low GI, low carbohydrate with high GI, or low carbohydrate with low GI. During the run-in, participants will be provided all of their food, snacks, and calorie-containing beverages. Participants will also complete a daily food diary, symptoms questionnaire, medical and social history, and daily weigh-in. After meeting with a dietician to review progress, eligible participants will be randomly assigned to one of eight sequences of the four diet plans.

Participants will follow each of the four diet plans for 5 weeks, with a period of at least 2 weeks separating each plan. During each dieting period, participants will be provided all of their food and snacks and most beverages. All participants will be required to eat at least one on-site meal per day, 5 days per week. Participants will keep a daily food diary and will undergo weekly blood pressure measurements for the first 3 weeks of each dieting period. Assessments will occur in the fifth week of each of the four dieting periods and will include symptoms and satiety questionnaires, blood pressure measurements, and a blood draw. One month following the completion of the last dieting period, participants will receive nutritional counseling on the prevention of CVD.

  Eligibility

Ages Eligible for Study:   30 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • SBP of 120 to 159 mmHg and DBP less than 100 mmHg at study entry (mean over three screening visits) (note: participants with stage 2 hypertension [SBP greater than 160 mmHg or DBP greater than 100 mmHg] based on the mean over three screening visits will be excluded, as will participants with a mean SBP greater than 170 mmHg or DBP greater than 105 mmHg at any one visit)
  • Overweight or obese, as defined by a body mass index (BMI) greater than 25 kg/m2
  • Willing to eat at least one on-site meal per day, 5 days per week, and willing to eat study diets and nothing else during controlled feeding periods

Medication Exclusion Criteria:

  • Symptomatic ischemic heart disease (e.g., angina pectoris)
  • Regular use of medications that raise or lower BP during the 2 months prior to study entry
  • Use of a lipid lowering agent in the 3 weeks prior to study entry
  • Unstable dose of hormone replacement therapy, thyroid hormone replacement therapy, and psychotropic medications known to cause weight gain or affect the outcome variables (unstable is defined as a change in dose within 2 months of study entry)
  • Use of insulin, oral hypoglycemic agent, lithium, oral corticosteroid, anti-psychotic drugs, weight loss medications, nitrate, or digitalis

Medical History Exclusion Criteria:

  • Active or prior CVD (e.g., stroke, heart attack, percutaneous transluminal coronary angioplasty, coronary artery bypass graft, congestive heart failure, symptomatic ischemic heart disease [angina], or arteriosclerotic cardiovascular disease-related therapeutic procedure)
  • Diabetes mellitus
  • Cancer diagnosis or treatment in the 2 years prior to study entry (note: people with non-melanoma skin cancer, localized breast cancer, or localized prostate cancer can enroll if they did not require systemic chemotherapy)
  • Active inflammatory bowel disease, malabsorption, or major gastrointestinal resection
  • Renal insufficiency as determined by a serum creatinine greater than 1.2 mg/dL for women or greater than 1.4 mg/dL for men (these participants can enroll if their estimated glomerular filtration rate is greater than 40 mL/min by either the Cockcroft-Gault equation or the simplified Modification of Diet in Renal Disease equation)
  • Emergency room visit or hospital stay for asthma or chronic obstructive pulmonary disease in the 6 months prior to study entry
  • Any serious illness not otherwise specified that would interfere with participation

Laboratory Exclusion Criteria:

  • Fasting LDL cholesterol greater than 220 mg/dL and triglycerides greater than 750 mg/dL
  • Fasting blood glucose greater than 125 mg/dL
  • Serum transaminase greater than 2 times the upper range of normal, or a clinical diagnosis of hepatitis
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00608049

Locations
United States, Maryland
Johns Hopkins Medical Institutions
Baltimore, Maryland, United States, 21205
United States, Massachusetts
Brigham and Women's Hospital
Boston, Massachusetts, United States, 02115
Sponsors and Collaborators
Brigham and Women's Hospital
Investigators
Principal Investigator: Frank M. Sacks, MD Brigham and Women's Hospital, Boston
Study Director: Lawrence J. Appel, MD Johns Hopkins Medical Institutions, Baltimore
  More Information

No publications provided

Responsible Party: Frank M. Sacks, Frank M. Sacks, MD, Brigham and Women's Hospital
ClinicalTrials.gov Identifier: NCT00608049     History of Changes
Other Study ID Numbers: 481, R01HL084568, R01 HL084568
Study First Received: January 23, 2008
Last Updated: July 3, 2014
Health Authority: United States: Federal Government

Keywords provided by Brigham and Women's Hospital:
Blood Pressure
Diabetes
Nutrition
Dietary Carbohydrate
Lipoproteins
Insulin Resistance

Additional relevant MeSH terms:
Cardiovascular Diseases
Overweight
Body Weight
Signs and Symptoms

ClinicalTrials.gov processed this record on September 29, 2014