By now, most people have heard that chocolate is heart healthy … as long as it comes in the form of dark chocolate.
We've reported some of this hearty evidence, and studies linking dark chocolate to enhanced gut health, skin health, and more ... see the “Cocoa, Tea & Coffee” section of our news archive.
Cardiovascular benefits are also associated with cocoa powder that has not been treated with alkali … an unnecessary process called “Dutching”, used to make cocoa look darker and taste a bit less bitter.
It's quite clear that the vascular benefits of chocolate and natural, non-Dutched coca stem from their flavonoid-type polyphenols, especially the sub-class called flavanols.
As the authors of a prior evidence review wrote, “… cocoa can be particularly rich in a sub-class of flavonoids known as flavanols … flavanol-containing cocoa products have demonstrated improvements in endothelial and platelet function, as well as blood pressure. These studies provide direct evidence for the potential cardiovascular benefits of flavanol-containing foods and help to substantiate the epidemiological data” (Erdman JW Jr et al. 2008).
Most dark chocolate – that is, chocolate containing 65% or more cocoa – is made with natural, non-Dutched cocoa solids.
But most cocoa powder is Dutched (treated with alkali), which reduces its flavanol content drastically … by 80 percent or more. Read cocoa labels to see if they list alkali or clearly indicate that alkali has or has not been used.
Evidence review affirms heart benefits of chocolate
Researchers from Britain's University of Cambridge analyzed the results of seven population studies, which involved 114,009 people.
The authors looked for reductions in “cardio-metabolic disorders,” including cardiovascular disease (coronary heart disease and stroke), diabetes, and metabolic syndrome.
Compared with those who reported the lowest levels of chocolate consumption, people who reported eating the most chocolate were 37 percent less likely to develop cardiovascular disease and 29 percent less likely to suffer a stroke.
This link between higher levels of chocolate consumption and lower risk of cardio-metabolic disorders persisted even after the results were adjusted for other factors that could affect heart risks … including age, physical activity, body mass index, smoking, diet, education, and drug use.
One study, conducted in Japan, found that those who ate the most chocolate were 31 percent less likely to have diabetes.
No link was found between chocolate consumption and the risk of congestive heart failure (CHF). However, CHF typically occurs after many years of cardiovascular disease, so it would be surprising if chocolate could help at that late stage.
“Higher levels” of consumption were defined in different ways by the authors of the seven studies. Most defined it as eating chocolate one to five times a week or more, and one defined it as eating an average of one quarter ounce (7.45 grams) daily.
As the authors wrote, “Based on observational evidence, levels of chocolate consumption seem to be associated with a substantial reduction in the risk of cardio-metabolic disorders” (Buitrago-Lopez A et al. 2011).
The results of this kind of review cannot be conclusive, since only controlled clinical trials can prove a cause-and-effect relationship between a food or drug and a health outcome.
But the results are meaningful both because of the large number of people involved, and because lab studies consistently find that chocolate exerts beneficial cardiovascular effects in animals and humans.
The authors of an earlier evidence review put it this way:
“The body of short-term randomized feeding trials suggests cocoa and chocolate may exert beneficial effects on cardiovascular risk via effects on lowering blood pressure, anti-inflammation, anti-platelet function, higher HDL, decreased LDL oxidation” (Ding EL et al. 2006).
Buitrago-Lopez A, Sanderson J, Johnson L, Warnakula S, Wood A, Di Angelantonio E, Franco OH. Chocolate consumption and cardiometabolic disorders: systematic review and meta-analysis. BMJ. 2011 Aug 26;343:d4488. doi: 10.1136/bmj.d4488.
Corti R, Flammer AJ, Hollenberg NK, Lüscher TF. Cocoa and cardiovascular health. Circulation. 2009 Mar 17;119(10):1433-41. Review.
Ding EL, Hutfless SM, Ding X, Girotra S. Chocolate and prevention of cardiovascular disease: a systematic review. Nutr Metab (Lond). 2006 Jan 3;3:2.
Erdman JW Jr, Carson L, Kwik-Uribe C, Evans EM, Allen RR. Effects of cocoa flavanols on risk factors for cardiovascular disease. Asia Pac J Clin Nutr. 2008;17 Suppl 1:284-7. Review.
Ghosh D, Scheepens A. Vascular action of polyphenols. Mol Nutr Food Res. 2009 Mar;53(3):322-31. Review.
Janszky I, Mukamal KJ, Ljung R, Ahnve S, Ahlbom A, Hallqvist J. Chocolate consumption and mortality following a first acute myocardial infarction: the Stockholm Heart Epidemiology Program. J Intern Med. 2009 Sep;266(3):248-57.
Selmi C, Cocchi CA, Lanfredini M, Keen CL, Gershwin ME. Chocolate at heart: the anti-inflammatory impact of cocoa flavanols. Mol Nutr Food Res. 2008 Nov;52(11):1340-8. Review.