Can cocoa lower your heart disease risk?

In a recent study published in Nutrients, researchers reviewed the effects of cocoa consumption on anthropometric measurements, blood pressure, and glycemic and lipid profiles to elucidate its impact on the risk of cardiovascular disease (CVD).

Study: Effects of Cocoa Consumption on Cardiometabolic Risk Markers: Meta-Analysis of Randomized Controlled Trials. Image Credit: iprachenko / Shutterstock.com

CVDs and the need for dietary interventions

Current estimates indicate that CVDs claim over 17.9 million lives each year, thus making these diseases the leading global cause of human mortality. In Brazil, over 397,000 individuals died due to CVDs in 2019, 43% of whom succumbed to coronary artery diseases.

The Framingham Heart Study is considered the pioneer of cardiometabolic research, as a significant portion of current cardiometabolic risk stratification has been based on its concepts. This study stratifies CVD risk based on age, sex, systolic and diastolic blood pressure, cholesterol, body mass index (BMI), and behaviors, including smoking and alcohol dependence. Notably, many of these factors have shown strong associations with diet, with a growing body of literature highlighting the role of healthy diets, such as the Mediterranean diet, in reducing CVD risk.

Cocoa is a fruit that is rich in polyphenols, the majority of which are flavonoids that have been shown to reduce the risk of both CVDs and artherosclerosis by reducing inflammation, improving endothelial function, and lowering blood pressure. More specifically, cocoa appears to activate nitric oxide (NO) and neutralize free radicals, thereby reducing oxidative stress and protecting cells from damage.  

To date, previous studies aimed at revealing the potential benefits of cocoa consumption on the Framingham risk score, a measure of cardiometabolic risk, have produced mixed results.

About the study

The present study involved a systematic review and meta-analysis of randomized control trials (RCTs) evaluating the associations between cocoa consumption and cardiometabolic risk markers.

RCTs that included individuals 18 years of age and older that used cocoa, its extracts, or dark chocolate, with a cocoa content of 70% or higher, were eligible for review inclusion. Studies conducted on pregnant or post-menopausal women, animal models, and those investigating the association between cardiometabolic risk and other comorbidities like cancer were excluded from the study.

Relevant publications were identified using six electronic scientific databases including MEDLINE, Web of Science, EMBASE, SciELO, LILACS, and Cochrane. The Rayyan reference manager was used for study data extraction and management.

Data on the reviewer, author, journal, publication year, country, methodology, cohort size, and participant details, including age, sex, amount of cocoa supplementation, follow-up period, and reported outcomes, were collected. The Cochrane risk of bias (RoB) tool was used to calculate bias risk between included studies.

The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool was used to determine the strength of evidence of each included study against other studies in a paired-effects fashion. Higgins (I²) was used to test the degree of heterogeneity of included publications.

Study findings

Of the 3,807 studies initially identified in the database search, 31 met the study inclusion criteria and were included in the meta-analysis. Taken together, these studies included a cohort size of 1,110 cases and 876 controls.

Thirteen studies assessed the effects of cocoa supplementation on healthy participants, three on participants with metabolic syndrome, two on hypertension or pre-hypertension, seven with T2D, one on insulin resistance, and four on dyslipidemia or excess weight.

Cocoa consumption had no statistically significant effects on total body mass, waist circumference, or BMI. While abdominal circumference was reduced following cocoa supplementation interventions, these findings were borderline and were associated with high heterogeneity.

However, cocoa polyphenol consumption was found to reduce adverse lipid profiles, fasting blood glucose levels, and blood pressure, with the degree of reductions positively correlated with the dosage of cocoa intake. These findings may explain previously contrasting reports between studies, as cocoa elicited cardioprotective effects despite showing no improvements in some historic CVD risk markers.

Taken together, cocoa consumption, including cocoa supplements and dark chocolate, appears to impart protective effects on cardiometabolic risk markers and have a clinically significant impact on CVD risk reduction.

We suggest that the consumption of polyphenol-rich cocoa could be part of a strategy aimed at promoting cardiovascular health.”