Dark chocolate consumption was associated with a reduced risk of two cardiovascular diseases
Cardiologists from Shaoxing and Zhuji hospitals in China's Zhejiang Province, along with medical colleagues from Shaoxing University, used Mendelian randomization to examine the causal relationship between dark chocolate consumption and the risk of cardiovascular disease (CVD). The results of the study are described in an article for the journal Scientific Reports.
Recall that diseases of the heart and blood vessels include coronary heart disease, arterial hypertension, cerebrovascular disease, cardiomyopathies, congenital and acquired heart defects, heart rhythm and conduction disorders, pulmonary hypertension, venous thromboembolic complications, peripheral vascular disease, myocarditis, heart failure and some other types of CVD. This group is considered the main cause of death and disability in the world, so experts continue to look for factors that influence the likelihood of developing such ailments and ways to protect.
Dark chocolate has long been favored by scientists in the context of CVDs. Because of its higher cocoa content, it has a bittersweet flavor and, unlike milk or white chocolate, is rich in beneficial - including cardiovascular - substances: flavanols (procyanidin, catechin and epicatechin) and methylxanthines.
Previous studies have shown that moderate consumption of dark chocolate can improve endothelial function and vasodilation (smooth muscle relaxation) of coronary arteries, inhibit platelet adhesion and aggregation, and lower blood lipid levels. But the quality of these scientific papers remained questionable due to differences in the amount of dark chocolate, lack of placebo, short observation periods, and small samples.
This time, the medics looked at two-sample studies based on Mendelian randomization and comprehensively examined the causal relationship between genetically predicted dark chocolate consumption and the risk of 12 cardiovascular diseases. The data was originally taken from the UK Biobank and covered 64,945 people of European descent.
To predict dark chocolate consumption, the Chinese researchers identified 21 independent DNA sequence differences the size of a nucleotide in the genome - single nucleotide polymorphisms. The scientists then obtained information on more than 524,000 cases of coronary heart disease (CHD), atrial fibrillation, heart failure, stroke, essential hypertension (a form of arterial hypertension, a chronic disease), non-rheumatic heart valve defects, non-ischemic cardiomyopathy, transient ischemic attack, venous thromboembolism, myocardial infarction and deep vein thrombosis.
The results of the analysis revealed that dark chocolate consumption did not affect the risk of developing all of the above conditions, except for essential hypertension (odds ratio was 0.73) and venous thromboembolism (0.69, but in this case the scientists did not establish a causal relationship).
"Dark chocolate does have a positive effect on the cardiovascular system. However, the pathophysiologic mechanisms underlying the onset and progression of CVD are too complex; previous studies have only identified individual risk factors and certain aspects of CVD pathogenesis that are affected by dark chocolate consumption. We cannot conclude that its consumption reduces the likelihood of cardiovascular disease, so its cardiovascular benefits may not be sufficient," the cardiologists warned.
Nevertheless, they recommended that people at risk of essential hypertension replace unhealthy snacks with dark chocolate (55 to 70 percent cocoa). Further research will have to be done to fully clarify the cause-and-effect relationship and confirm the findings.