Effect of Amount and Type of Dietary Carbohydrates on Risk for Cardiovascular Heart Disease and Diabetes
Summary
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.
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.
Study Design
Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Investigator, Outcomes Assessor), Primary Purpose: Prevention
Conditions
Overweight
Intervention
High carbohydrate and low glycemic index (GI) diet, Low carbohydrate and low GI diet, High carbohydrate and high GI diet, Low carbohydrate and high GI diet
Location
Johns Hopkins Medical Institutions
Baltimore
Maryland
United States
21205
Status
Recruiting
Source
National Heart, Lung, and Blood Institute (NHLBI)
Results (where available)
Links
- Source: http://clinicaltrials.gov/show/NCT00608049
- Information obtained from ClinicalTrials.gov on July 15, 2010
Medical and Biotech [MESH] Definitions
Diet, Carbohydrate-restricted
A diet that contains limited amounts of CARBOHYDRATES. This is in distinction to a regular DIET.
Diabetic Diet
A diet prescribed in the treatment of diabetes mellitus, usually limited in the amount of sugar or readily available carbohydrate. (Dorland, 27th ed)
Ketogenic Diet
A course of food intake that is high in FATS and low in CARBOHYDRATES. This diet provides sufficient PROTEINS for growth but insufficient amount of carbohydrates for the energy needs of the body. A ketogenic diet generates 80-90% of caloric requirements from fats and the remainder from proteins.
Diet, Mediterranean
A diet typical of the Mediterranean region characterized by a pattern high in fruits and vegetables, cereals and bread, potatoes, poultry, beans, nuts, olive oil and fish while low in red meat and dairy and moderate in alcohol consumption.
Diet
Regular course of eating and drinking adopted by a person or animal. This does not include DIET THERAPY, a specific diet prescribed in the treatment of a disease.
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