Dark chocolate contains health-promoting properties that researchers attribute to the presence of certain flavanoids, called flavanols, originating from the cocoa seeds of the Theobroma cacao tree. According to the World Cocoa Foundation, these flavanols, which impart a pungent flavor to cocoa, may lose their potency during processing. In "Nutrition Reviews," researchers at Case Western Reserve University relayed that processing of cacao beans, including fermentation, may directly affect flavanol concentration in the final chocolate product. Dark chocolate, an underfermented, bitter-tasting chocolate, may possess more flavanols and thus exert more health benefits, including cardiovascular function, greater insulin sensitivity and better brain function.
Cardiovascular Benefit
In the 2006 issue of "Heart," Swiss researchers identified that dark, but not white, chocolate was effective in reducing platelet activation and improving endothelial functioning two to eight hours after ingestion in a sample of healthy smokers. The higher flavanol concentration in the dark chocolate was presented as one possible reason for the difference. In July 2008, Yale researchers published findings in "The American Journal of Clinical Nutrition" that suggested the level of sugar in your chocolate may affect the ultimate health benefit, wherein a higher sugar content might attenuate and a lower sugar content could enhance these heart-healthy effects.
Diabetes and Dark Chocolate
Researchers have also discovered that the confection known as dark chocolate could exert anti-diabetic properties. Italian researchers published their findings of this relationship in "The American Journal of Clinical Nutrition" in March 2005. Fifteen healthy subjects were given either 100 g of dark chocolate or 90 g of white chocolate for 15 days, with a seven-day cocoa-free washout period before and afterward. Subjects who had taken 90 g then took 100 g and vice versa for another 15 days. Researchers found improved insulin sensitivity and decreased blood pressure in those taking dark chocolate.
Better Brain Function
Epidemiological research suggests that high flavonoid consumption correlates with a lower incidence of certain brain disorders, including Alzheimer's disease and Parkinson's disease. The research identifying a potential benefit of dark chocolate as it relates to brain function is in its infancy but seems promising. The theory, as proposed by McShea and colleagues in "Nutrition Reviews" in 2008, is that the flavanols in dark chocolate could promote better blood flow to the brain. Dark chocolate may possess compounds with an affinity for iron, known as iron-chelating compounds. Many of the amyloid precursor proteins responsible for amyloid plaque formation, a physiological manifestation in Alzheimer's disease, are possibly genetically regulated by iron-regulatory proteins. More research is needed to identify these possible iron-chelating compounds in dark chocolate and their role in brain health.
How Much is Too Much?
Chocolate of any kind can be laden with fat, calories and sugar, the so-called nutritional triumvirate of poor dietary selection. However, the type of fat in dark chocolate is not necessarily all bad. In the 2009 issue of "Circulation," Corti and colleagues reported that the fat in dark chocolate is mostly oleic acid, the healthy monounsaturated fat found in olive oil, and stearic acid, a saturated fatty acid that does not seem to exert untoward effects such as lowering HDL cholesterol. However, many processed chocolate products do contain milk fats and other artificial fats that may counteract the health-promoting effects of the flavonoid-rich dark chocolate. Cleveland Clinic and others recommend consuming dark chocolate in moderation, a couple of 1-oz. servings per week.