Effects of Dark Chocolate on Insulin Sensitivity in People With High Blood Pressure

NCT00099476 | Completed Phase 1

• 2 other identifiers: 05004705-AT-0047
• Study Type: interventional
• Target: 65
• Locations: 1 country
• Sites: 1

Brief Summary

This study will examine whether dark chocolate affects the way patients with hypertension (high blood pressure) respond to insulin, a hormone secreted by the pancreas that regulates blood glucose (sugar) levels. In many people with hypertension, insulin is not as effective in helping the body use glucose. This is called insulin resistance. Insulin also increases blood flow into muscle by opening inactive blood vessels. Laboratory studies suggest that eating dark chocolate may improve blood pressure. This study will determine whether dark chocolate improves insulin resistance or changes how blood vessels react to insulin in hypertensive people. People between 21 and 65 years of age who have high blood pressure and are not pregnant may be eligible for this study. Candidates are screened with a medical history, physical examination, and blood and urine tests. Participants refrain from eating foods containing chocolate or cocoa for 1 week and then come to the clinic on three separate occasions 3 weeks apart for a glucose clamp test and contrast ultrasound, described below. At the first glucose clamp test, subjects are randomly assigned to drink either a cocoa drink with high anti-oxidant content or one with a very low content of anti-oxidant. Each drink will be taken twice a day for 2 weeks. At the end of the 2 weeks, they return for a second glucose clamp test. At the second test, they stop taking the cocoa drink for 1 week and then start again for another 2 weeks. For this 2-week period, those who were given the high anti-oxidant content cocoa drink the first 2 weeks will take the placebo, very low anti-oxidant drink this time, and those who took the placebo will now have the high anti-oxidant cocoa drink. After this 2 weeks of taking the cocoa drink or placebo, they then take the third and last glucose clamp test. Glucose clamp test: This test measures how the body responds to insulin. Subjects fast the night before each test and do not eat until the test is over, usually in the early afternoon. For the test, the subject lies in a bed or reclines in a chair. A needle is placed in a vein in each arm - one for collecting blood samples and the other for infusing glucose, insulin, and a potassium solution. Blood glucose and insulin levels are measured frequently during the test and the rate of the glucose infusion is adjusted to keep blood glucose at the baseline (fasting) level. Blood samples are tested for blood count, electrolytes, liver function...

Conditions

Hypertension

Keywords

Epicatechin; Polyphenols; Chocolate; Insulin Resistance; Endothelial Dysfunction; Hypertension

Interventions

Effects of dark chocolate BEHAVIORAL

Eligibility Criteria

• Age: 21 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Hypertensive subjects between the ages of 21 - 65 years in good general health except for mild to moderate hypertension (blood pressure between 140/95 and 170/110 off medication), on no medication or nutritional supplements except for antihypertensive agents, anti-cholesterol drugs or birth control agents. Subjects will be taken off all antihypertensive OTC supplements and anti-cholesterol drugs for one week prior to study and for the duration of the study. Women on birth control will remain on their regime. During the time subjects receive no antihypertensive therapy, their blood pressure will be monitored at least daily (either at home, in the clinic, or at another convenient facility). If a subject's blood pressure exceeds 170/110 on three determinations over a period of at least 15 minutes, the subject will be withdrawn from the study and appropriate antihypertensive therapy resumed. In addition, if the subject's blood pressure exceeds 160/100 during measurements on three consecutive days, the subject will be withdrawn from the study and appropriate antihypertensive therapy resumed.

You may not qualify if:

• Subjects will be excluded if they have diabetes, pregnancy, liver disease, pulmonary disease, renal insufficiency, coronary heart disease, heart failure, peripheral vascular disease, coagulopathy, actively smoked tobacco within last two years, in treatment for any form of cancer, positive tests for HIV, hepatitis B or C, or take systemic corticosteroids. These conditions are all known to adversely influence insulin sensitivity.
• Subjects will be excluded if they have a history of malignant hypertension, aortic aneurysm or stroke.
• Subjects with known hypersensitivity to octafluoropropane or with known cardiac shunts will also be excluded from participating because of potential adverse effects from microbubble contrast agent.
• Subjects will be excluded if they are unable to give informed consent for all procedures.
• Children are excluded from this study because children are not typically hypertensive.

Sponsors & Collaborators

• National Center for Complementary and Integrative Health (NCCIH): lead

Study Sites (1)

National Institutes of Health Clinical Center, 9000 Rockville Pike

Bethesda, Maryland, 20892, United States

Location

Related Publications (4)

• Ferrannini E, Buzzigoli G, Bonadonna R, Giorico MA, Oleggini M, Graziadei L, Pedrinelli R, Brandi L, Bevilacqua S. Insulin resistance in essential hypertension. N Engl J Med. 1987 Aug 6;317(6):350-7. doi: 10.1056/NEJM198708063170605.

  PMID: 3299096 BACKGROUND

• Modan M, Halkin H, Almog S, Lusky A, Eshkol A, Shefi M, Shitrit A, Fuchs Z. Hyperinsulinemia. A link between hypertension obesity and glucose intolerance. J Clin Invest. 1985 Mar;75(3):809-17. doi: 10.1172/JCI111776.

  PMID: 3884667 BACKGROUND

• Zavaroni I, Mazza S, Dall'Aglio E, Gasparini P, Passeri M, Reaven GM. Prevalence of hyperinsulinaemia in patients with high blood pressure. J Intern Med. 1992 Mar;231(3):235-40. doi: 10.1111/j.1365-2796.1992.tb00529.x.

  PMID: 1556520 BACKGROUND

• Muniyappa R, Hall G, Kolodziej TL, Karne RJ, Crandon SK, Quon MJ. Cocoa consumption for 2 wk enhances insulin-mediated vasodilatation without improving blood pressure or insulin resistance in essential hypertension. Am J Clin Nutr. 2008 Dec;88(6):1685-96. doi: 10.3945/ajcn.2008.26457.

  PMID: 19064532 DERIVED

MeSH Terms

Conditions

Hypertension; Insulin Resistance

Condition Hierarchy (Ancestors)

Vascular Diseases; Cardiovascular Diseases; Hyperinsulinism; Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases

Study Design

• Study Type: interventional
• Phase: phase 1
• Purpose: TREATMENT
• Sponsor Type: NIH

Study Record Dates

• First Submitted: December 14, 2004
• First Posted: December 15, 2004
• Study Start: December 10, 2004
• Study Completion: April 16, 2009
• Last Updated: July 2, 2017

Record last verified: 2009-04-16

Locations

US (1)