But in the intervening years, enough evidence has accumulated that most cardiologists will now admit to the potential cardiovascular benefits of chocolate.
What Is The Evidence That Chocolate Improves Heart Health?Several studies have now documented an association between chocolate consumption and improved cardiovascular health. These generally have been observational studies, and while their conclusions are useful for developing theories, they cannot prove cause-and-effect relationships.
Nonetheless, virtually every study that has examined the issue has reported an association between chocolate consumption and cardiovascular health. Several of these studies have shown that chocolate consumption is associated with reduced blood pressure. At least one study showed that women who ate chocolate had a significantly reduced risk of developing heart failure.
Most recently, a meta-analysis of seven studies was published in the British Medical Journal, showing that chocolate consumption was associated with a 39% reduction in cardiovascular disease and a 29% reduction in stroke.
Again, these studies do not prove that eating chocolate directly improves cardiac health -- but they do demonstrate that there is a convincing association between the two.
What Is It About Chocolate That Is Beneficial?Investigators theorize that it is the flavonols in chocolate that cause vascular improvement. These flavonols can make blood vessels more elastic, improve insulin sensitivity, reduce the "stickiness" of platelets and reduce blood pressure.
Dark chocolate contains more flavonols than lighter chocolate, so most of the published studies have reported on dark chocolate. However, the recent meta-analysis mentioned earlier found that chocolate in any form -- dark or light; in the form of chocolate bars, chocolate drinks or chocolate confections -- was associated with cardiovascular benefit.
How Much Chocolate Is Beneficial?The correct "dose" of chocolate to achieve a cardiovascular benefit has not been determined. The studies that have reported a heart-health benefit from chocolate, however, generally described a range between 100 grams of chocolate per day and consuming some form of chocolate "more than once a week."
Most investigators who have studied this question have concluded that most of the benefit (if there indeed is a benefit) can be obtained by eating chocolate once or twice per week.
What Is the Downside of Chocolate for Heart Health?There are several possible disadvantages to adding chocolate to your diet for the potential cardiovascular benefits. These include:
- Observational studies are often misleading. Once randomized clinical trials are finally completed, it may turn out that chocolate does not actually produce much of a cardiac benefit after all.
- Notably, 100 grams of chocolate equals about 500 calories. So, adding 100 grams of chocolate to your daily diet (the upper dose suggested by available studies) will cause you to gain about a pound of weight per week. Such a result does not seem like it would really be heart-healthy.
- If you religiously adhere to one of those popular but mutually-exclusive dietary philosophies (that is, low fat vs. low carb), be aware that chocolate products come packed with both fat and carbohydrates. It therefore violates both of these dietary dogmas, and its consumption will reduce you to a state of dietary sin.
Buitrago-Lopez A, Sanderson J, Johnson L, et al. Chocolate consumption and cardiometabolic disorders: systematic review and meta-analysis. BMJ 2011; DOI:10.1136/bmj.d4488.
Mostofsky E, Levitan EB, Wolk A, Mittleman MA. Chocolate intake and incidence of heart failure: A population-based, prospective study of middle-aged and elderly women. Circ Heart Fail 2010; DOI:10.1161/CIRCHEARTFAILURE.110.944025.