Studies related to Blood Flow and Cocoa Extract

Effect Of Cocoa Flavanols And Exercise On Cardiometabolic Risk Factors In Overweight And Obese Subjects

Effect Increase
Trial Design Double blind
Trial Length 1-6 months
Number of Subjects 49
Gender Both Genders
Age Range 18-29, 30-44, 45-64
Body Types Obese, Overweight
Notes for this study:
A beverage containing cocoa flavanols (451mg) versus control beverage (18mg) in overweight and obese sedentary subjects for 12 weeks alongside a modest exercise program (given to both groups) or without exercises noted that there were changes in blood flow in both high flavanol groups and no alterations in any lipid biomarker in any group.

During exercise, fat oxidation rates were not different between cocoa conditions and overall fat mass was not affected. There appeared to be a decrease in diastolic blood pressure, but not systolic, without any statistically significant changes in heart rate (although a trend to reduce was noted).

Protective Effects Of Flavanol-rich Dark Chocolate On Endothelial Function And Wave Reflection During Acute Hyperglycemia

Effect Increase
Trial Design Double blind
Trial Length 1-7 Days
Number of Subjects 12
Gender Both Genders
Age Range 18-29
Body Types Average
Notes for this study:
Ingestion of 100g dark chocolate (flavonoid dose not specified) for three days prior to an oral glucose tolerance test, compared to the placebo group given flavonoid free chocolate, appeared to be associated with no alterations in blood pressure or blood flow despite the expected increases (from the oral glucose tolerance test) occurring in the white chocolate group.

Neither group experienced changes in parameters of insulin sensitivity or secretion.

Cocoa Consumption For 2 Wk Enhances Insulin-mediated Vasodilatation Without Improving Blood Pressure Or Insulin Resistance In Essential Hypertension

Effect None
Trial Design Double blind
Trial Length 1-2 Weeks
Number of Subjects 20
Gender Both Genders
Age Range 45-64
Body Types Obese
Notes for this study:
Twice daily consumption of a cocoa beverage containing 900mg polyphenols (174mg (-)-epicatechin) overall, for two weeks, failed to improve insulin sensitivity in hypertensives. While blood pressure and flow were also unaffected, there appeared to be an increase in insulin-mediated arterial diameter associated with cocoa.

Dark Chocolate Acutely Improves Walking Autonomy In Patients With Peripheral Artery Disease

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 22
Gender Both Genders
Age Range 65+
Notes for this study:
Ingestion of 40g dark chocolate (85% cocoa by weight) in people with peripheral artery disease is able to increase maximal walking distance (11%) and time (15%) when measured two hours after consumption. This was accompanied by a decrease in isoprostanes and increase in biomarkers of nitric oxide metabolism.

Dose-dependent Increases In Flow-mediated Dilation Following Acute Cocoa Ingestion In Healthy Older Adults

Effect Increase
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 23
Gender Both Genders
Age Range 45-64, 65+
Body Types Overweight, Average
Notes for this study:
Ingestion of cocoa powder in addition to a drink (placebo or 2, 5, 13, or 26g of additional cocoa) was able to, over the course of two hours of measurement, increase blood flow as assessed by FMD without affecting nitroglycerin induced vasodilation or heart rate. Blood pressure appeared to be spiked by 2-3mmHg, although it was similar in placebo.

Some other parameters measured did not differ between groups.

Cocoa Reduces Blood Pressure And Insulin Resistance And Improves Endothelium-dependent Vasodilation In Hypertensives

Effect Increase
Trial Design Double blind
Trial Length 1-2 Weeks
Number of Subjects 20
Gender Both Genders
Age Range 45-64
Body Types Obese
Notes for this study:
In subjects with essential hypertension (grade I, never treated) given dark chocolate at 100 grams a day (87mg flavanols) for 15 days, ingestion of the dark chocolate relative to white chocolate resulted in a decrease in blood pressure and increase in blood flow with minor benefits to insulin sensitivity (in response to an oral glucose tolerance test) and total and LDL cholesterol.

hsCRP and ICAM-1 unaffected in both normotensives (which did not experience the same myriad of benefits as the hypertensive subjects) and in the hypertensive subjects.

Effect Of Dark Chocolate On Arterial Function In Healthy Individuals

Effect Increase
Trial Design Cohort
Trial Length 24 hours
Number of Subjects 17
Gender Both Genders
Age Range 18-29
Body Types Average
Notes for this study:
In a single-blind study where flavanol rich dark chocolate (100 grams) was given acutely to otherwise healthy young subjects and then their arterial parameters measured, there appeared to be an increase in arterial function as assessed by aortic augmentation index (7.8% decrease) and increase in diameter (0.15-0.18mm increase) alongside a general increase in blood flow as assessed by flow mediated vasodilation (1.43% increase); however, these changes did not occur alongside changes in MDA or TAC in serum.

Dark Chocolate Consumption Improves Leukocyte Adhesion Factors And Vascular Function In Overweight Men

Effect Increase
Trial Design Cohort
Trial Length 2-4 Weeks
Number of Subjects 70
Gender Male
Age Range 45-64, 65+
Body Types Overweight
Notes for this study:
In a comparative study between a normal 58% cocoa product at 70g (259mg flavanols and 97mg (-)-epicatechin) and an enhanced product (1047mg flavanols with 349mg (-)-epicatechin) over four weeks both products seemed to perform equally against each other; there was no flavanol-free product to use as reference.

Relative to baseline values, both groups experiences a decrease in some cellular adhesion factors (leukocytes and neutrophils tested) and improved blood flow as assessed by FMD; the inflammatory response from an acute high fat test meal was attenuated in both groups.

A minor increase in blood glucose and free fatty acids seen in both groups was attributed to the caloric components of the test chocolate.

NOX2-mediated Arterial Dysfunction In Smokers: Acute Effect Of Dark Chocolate

Effect None
Trial Design Cohort
Trial Length 24 hours
Number of Subjects 40
Gender Both Genders
Age Range 18-29, 30-44
Body Types Average
Notes for this study:
Ingestion of 40 grams of dark chocolate can acutely improve blood flow in smokers secondary to reducing oxidative stress in serum (the oxidative stress, from increased NOX2 activity, suppressed nitric oxide signalling; antioxidant effects of (-)-epicatechin temporarily normalized these effects). This effect did not extend to nonsmoking controls.

The study was single-blinded with milk chocolate used as control, and nitric oxide was measured via proxy (nitrite/nitrate ratio).

NOX2-mediated Arterial Dysfunction In Smokers: Acute Effect Of Dark Chocolate

Effect Increase
Trial Design Cohort
Trial Length 24 hours
Number of Subjects 40
Gender Both Genders
Age Range 18-29, 30-44
Body Types Average
Notes for this study:
Ingestion of 40 grams of dark chocolate can acutely improve blood flow in smokers secondary to reducing oxidative stress in serum (the oxidative stress, from increased NOX2 activity, suppressed nitric oxide signalling; antioxidant effects of (-)-epicatechin temporarily normalized these effects). This effect did not extend to nonsmoking controls.

The study was single-blinded with milk chocolate used as control, and nitric oxide was measured via proxy (nitrite/nitrate ratio).

Blood Pressure And Endothelial Function In Healthy, Pregnant Women After Acute And Daily Consumption Of Flavanol-rich Chocolate: A Pilot, Randomized Controlled Trial

Effect None
Trial Design Double blind
Trial Length 1-6 months
Number of Subjects 44
Gender Female
Age Range 18-29
Body Types Overweight, Average
Notes for this study:
Chocolate consumption with either a high flavanol content () or low content for 12 weeks in pregnant women failed to increase blood flow (FMD) or influence systolic or diastolic blood pressure.

Women gained weight during their 12 weeks of pregnancy, but the rates did not differ between groups.

Effects of Dark Chocolate and Cocoa Products on Endothelial Function: A Meta-Analysis
Effect Increase
Trial Design meta
Trial Length na
Number of Subjects 454
Gender na
Notes for this study:
Blood flow assessed via flow mediated vasodilation (FMD) across 14 studies appeared to show a reliable increase in blood flow average around 2%, with slightly greater benefits in those with CVD risk factors (2.36%) relative to healthy persons (1.76%) and comparable effects following a single dose and chronic dosing up to 12 weeks.

Acute Effect Of Oral Flavonoid-rich Dark Chocolate Intake On Coronary Circulation, As Compared With Non-flavonoid White Chocolate, By Transthoracic Doppler Echocardiography In Healthy Adults

Effect Increase
Trial Design Double blind
Trial Length 1-2 Weeks
Number of Subjects 39
Gender Male
Age Range 18-29, 30-44
Body Types Average
Notes for this study:
Ingestion of dark chocolate (200kcal) containing 550mg polyphenols, relative to white chocolate control, appeared to increase coronary blood flow as assessed by transthoracic Doppler echocardiography in otherwise healthy adults after two weeks.

Flavonoid-rich Dark Chocolate Improves Endothelial Function And Increases Plasma Epicatechin Concentrations In Healthy Adults

Effect Increase
Trial Design Double blind
Trial Length 1-2 Weeks
Number of Subjects 21
Gender Both Genders
Age Range 18-29, 30-44
Body Types Average
Notes for this study:
Consumption of just under 50 grams of flavanol rich dark chocolate (conferring approximately 200mg procyanidins and 50mg epicatechin) daily for two weeks in otherwise healthy human subjects was able to improve blood flow to a small degree relative to placebo (low flavanol chocolate group) despite not having any influence on lipid, inflammatory, or oxidative parameters.

Blood Pressure Is Reduced And Insulin Sensitivity Increased In Glucose-intolerant, Hypertensive Subjects After 15 Days Of Consuming High-polyphenol Dark Chocolate

Effect Increase
Trial Design Double blind
Trial Length 1-2 Weeks
Number of Subjects 19
Gender Both Genders
Age Range 30-44, 45-64
Body Types Overweight
Notes for this study:
In essential hypertensives with impaired glucose tolerance given 50g of dark chocolate (1009mg phenols, 111mg epicatechin) twice a day for 15 days improved blood pressure (systolic, diastolic, and ambulatory) and improved insulin sensitivity as assessed by QUICKI and HOMA-IR; an improvement in beta-cell function appeared to also exist alongside modest improvements in cholesterol.

Blood flow (FMD) improved, but other serum parameters related to inflammation and methylation did not.
Funding issues for this study:
Napoleone Neri, Chairman, Sugar Company donated the chocolate bars, but had no part in funding; funding by USDA

Characterisation Of Hypertensive Patients With Improved Endothelial Function After Dark Chocolate Consumption

Effect Increase
Trial Design Cohort
Trial Length 1-7 Days
Number of Subjects 21
Gender Both Genders
Age Range 45-64
Notes for this study:
In hypertensive subjects, supplementation of dark chocolate (75g) daily for one week improved average blood flow but with more efficacy in subjects who had less severe symptoms (assessed by blood pressure, age, and Framingham risk score).

Consumption Of High-polyphenol Dark Chocolate Improves Endothelial Function In Individuals With Stage 1 Hypertension And Excess Body Weight

Effect Increase
Trial Design Cohort
Trial Length 2-4 Weeks
Number of Subjects 20
Gender Both Genders
Age Range 18-29, 30-44, 45-64
Body Types Obese, Overweight
Notes for this study:
In overweight or obese individuals given 50g of 70% dark chocolate daily for four weeks, supplementation appeared to improve blood flow as assessed by the reactive hyperemia index (RIH) without affecting other parameters of glucose or lipid metabolism, inflammation, or weight.

No placebo control was used in this four week study.

Dark Chocolate And Vascular Function In Patients With Peripheral Artery Disease: A Randomized, Controlled Cross-over Trial

Effect None
Trial Design Double blind
Trial Length 24 hours
Number of Subjects 21
Gender Both Genders
Age Range 65+
Notes for this study:
In subjects with PAD given 50 grams of dark chocolate and then measured two hours later at rest (a time where improvements in walking distance are seen with dark chocolate), there are no alterations in blood flow or biomarkers of circulatory health relative to baseline or white chocolate control.

Effects Of Dark Chocolate And Cocoa Consumption On Endothelial Function And Arterial Stiffness In Overweight Adults

Effect Increase
Trial Design Double blind
Trial Length 2-4 Weeks
Number of Subjects 30
Gender Both Genders
Age Range 30-44
Body Types Overweight
Notes for this study:
The addition of 37g of dark chocolate with a cocoa beverage (814mg of total flavanols) daily for four weeks, relative to visually similar chocolate products devoid of flavanols, was able to increase basal diameter and peak diameter of the artery by 6% and increase blood flow 22% relative to the no flavanol control.

Basal blood pressure was unchanged in these subjects, although an acute increase of 4mmHg was noted acutely after consumption that seemed to normalize afterwards.

An improvement in arterial stiffness was noted, but only in the women tested, and an increase of fasting insulin and insulin resistance was observed in the placebo condition but not in the group with high flavanol cocoa.

Sustained Benefits In Vascular Function Through Flavanol-containing Cocoa In Medicated Diabetic Patients A Double-masked, Randomized, Controlled Trial

Effect Increase
Trial Design Double blind
Trial Length 2-4 Weeks
Number of Subjects 41
Gender Both Genders
Age Range 45-64
Body Types Obese
Notes for this study:
In type II diabetics on medication, supplementation of dark chocolate (75, 371, or 963mg of flavanols; highest dose having 203mg epicatechin) was able to acutely increased blood flow in a dose-dependent manner. There were no changes in heart rate, blood pressure, or glycemic control. HbA1c did decrease, but evenly so in both groups.

30 days of ingestion at the highest dose (963mg, three doses of 321mg) improved blood flow 30% under basal conditions, while each dose acutely improved blood flow slightly more (but then normalized to 30% during the supplementation period).