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Sponsored by: |
National Heart, Lung, and Blood Institute (NHLBI) |
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Information provided by: | National Heart, Lung, and Blood Institute (NHLBI) |
ClinicalTrials.gov Identifier: | NCT00608049 |
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 |
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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: | Prevention, Randomized, Double Blind (Subject, Investigator, Outcomes Assessor), Crossover Assignment, Efficacy Study |
Official Title: | Optimal Macronutrient Intake - Carbohydrate |
Estimated Enrollment: | 160 |
Study Start Date: | February 2008 |
Estimated Study Completion Date: | February 2012 |
Estimated Primary Completion Date: | February 2011 (Final data collection date for primary outcome measure) |
Arms | Assigned Interventions |
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1: Experimental
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
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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.
|
2: Experimental
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.
|
3: Experimental
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.
|
4: Experimental
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.
|
5: Experimental
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.
|
6: Experimental
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.
|
7: Experimental
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.
|
8: Experimental
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.
|
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.
Ages Eligible for Study: | 30 Years and older |
Genders Eligible for Study: | Both |
Accepts Healthy Volunteers: | Yes |
Inclusion Criteria:
Medication Exclusion Criteria:
Medical History Exclusion Criteria:
Laboratory Exclusion Criteria:
Contact: Patricia Copeland, RD | 617-732-5500 | pcopeland2@partners.org |
Contact: Jeanne Charleston | 410-281-1600 | jeannec@jhmi.edu |
United States, Maryland | |
Johns Hopkins Medical Institutions | Recruiting |
Baltimore, Maryland, United States, 21205 | |
Contact: Jeanne Charleston | |
Principal Investigator: Lawrence J. Appel, MD | |
United States, Massachusetts | |
Brigham and Women's Hospital | Recruiting |
Boston, Massachusetts, United States, 02115 | |
Principal Investigator: Frank M. Sacks, MD |
Principal Investigator: | Frank M. Sacks, MD | Brigham and Women's Hospital, Boston |
Study Director: | Lawrence J. Appel, MD | Johns Hopkins Medical Institutions, Baltimore |
Responsible Party: | Brigham and Women's Hospital, Boston ( Frank M. Sacks, MD ) |
Study ID Numbers: | 481, R01 HL084568 |
Study First Received: | January 23, 2008 |
Last Updated: | August 4, 2008 |
ClinicalTrials.gov Identifier: | NCT00608049 |
Health Authority: | United States: Federal Government |
Blood Pressure Diabetes Nutrition |
Dietary Carbohydrate Lipoproteins Insulin Resistance |
Body Weight Signs and Symptoms Heart Diseases Diabetes Mellitus |
Overweight Insulin Resistance Insulin |
Cardiovascular Diseases |