The proposed study Dose And Response to Cocoa (DARC), will examine variation in dose of cocoa-containing product consumption over an 8-week period and assess effects on blood pressure, endothelial function and arterial stiffness. The randomized, controlled, modified Latin square parallel design will compare the effects of two doses of cocoa consumption on blood pressure, endothelial function and arterial stiffness in 120 adults with stage 1 hypertension.

Hypothesis #1 To verify the efficacy of an 8-week course of cocoa-containing product consumption on blood pressure in adults with stage 1 hypertension. Specifically, to demonstrate at least 3.5 mmHg improvement in 24-hour mean systolic blood pressure following 8 weeks of treatment with cocoa- containing products when compared to placebo. Our hypothesis is that cocoa-containing product consumption will result in clinically significant improvement of systolic blood pressure at the conclusion of an 8-week course of treatment.

Hypothesis #2 To identify a dose-response relationship in which increasingly higher doses of cocoa powder in cocoa-containing products will demonstrate correspondingly greater beneficial effects on blood pressure over an 8-week period in individuals with stage 1 hypertension. Specifically, to investigate the effects of the variation of dose of cocoa powder in cocoa-containing products (i.e. 5 grams or 10 grams of cocoa powder) for 8 weeks on blood pressure. We hypothesize that increasingly higher doses of cocoa powder in cocoa-containing products will demonstrate correspondingly greater beneficial effects on blood pressure.

Hypothesis #3 To assess the effects of different doses of cocoa-containing product consumption over an 8-week period on 24-hour diastolic blood pressure, endothelial function, arterial stiffness, serum lipids, theobromine, CRP, glucose, insulin, body weight, and waist circumference in adults with stage 1 hypertension. We hypothesize that consumption of cocoa-containing products will lower diastolic blood pressure; improve endothelial function of our participants; reduce arterial stiffness; improve serum lipids; theobromine; and will have no clinically meaningful effects on body weight and waist circumference, CRP, glucose, or insulin.

Inclusion Criteria:

• men and women age 18-75 years
• stage 1 hypertension (i.e. 140-159/90-99 mmHg) without anti-hypertensive medication or with only one anti-hypertensive medicaion
• body mass index < 35 kg/m²
• willing to discontinue the use of chocolate/cocoa products at least 4 weeks prior to intervention.

Exclusion Criteria:

• anticipated inability to complete or comply with study protocol
• use of lipid-lowering or aspirin unless stable on medication for at least 1 month and willing to refrain from taking medication for 12 hours prior to endothelial function scanning
• severe hypertension (systolic blood pressure >160mmHg or diastolic blood pressure >100 mmHg), or use more than one anti-hypertensive medications
• allergic to cocoa products (chocolate or cocoa powder)
• regular use of vitamin C, vitamin E, fish oil, flax seed oil, omega-3 fatty acids, Coenzyme Q10, fiber supplements, garlic pills, arginine, red yeast rice, and/or any kind of antioxidant and unwilling to discontinue supplementation for at least 4 weeks prior to study initiation and for the study duration. Use of a multi-vitamin containing no more than two times the recommended daily allowance for vitamins C and E is permissible
• diagnosed eating disorder
• on any specific diet, weight control diet, and/or vegan diet
• substance abuse (chronic alcoholism and/or other chemical dependency)
• any unstable medical condition that would limit the ability of a subject to participate fully in the trial (e.g., cancer, AIDS, tuberculosis, psychotic disorder)
• current or impending pregnancy. In premenopausal women, pregnancy will be excluded by pregnancy test at the time of each study visit.