It has been 220 years since Thomas Jefferson penned the following words to John Adams: "The superiority of chocolate, both for health and nourishment, will soon give it the same preference over tea and coffee in America which it has in Spain." These prophetic words seem to resurface repeatedly in the consciousness of consumers and the food industry—and in the world of medical nutrition.

Montezuma is said to have presented Cortez in 1519 with chocolatl, a warm liquid extract from cocoa beans. The Spaniards found this "food from the gods" bitter (high in potassium), and mixed it with cane sugar as a sweetener. The resulting concoction quickly became tremendously popular and was spiked with vanilla and cinnamon once it reached Europe. Finally, in 1876, milk was added, and chocolate production took off at an unprecedented rate.

In a recent survey, 52% of adults in the United States proclaimed chocolate their favorite flavor (Arabe, 2005). At this point, it is accepted that 65% of Americans prefer milk chocolate, which of course requires whole milk and cocoa butter. American consumers represent about one-third of the chocolate market, which seems ironic in light of the health risks associated with easy excesses of nonessential calories in dessert foods such as chocolate. These risks, reflected in the "metabolic syndrome" and in cardiovascular disease, are associated with annual health care costs in excess of $300 billion.

Lest we panic about chocolate, there is some emerging good news: Epidemiological studies in Finland, the Netherlands, and the U.S. and clinical evidence suggest that dietary flavonols (epicatechin and catechin) and oligomeric procyanidins from tea, wine, and cocoa may promote cardiovascular health and reduce the risk of mortality from ischemic heart disease (Murphy et al., 2003).

Several short-term clinical studies among a limited number of healthy adults 25–50 years of age and those with essential hypertension but otherwise healthy indicated that the consumption of dark chocolate (88–500 mg of flavonols) improved insulin sensitivity and decreased blood pressure following the dietary intervention period (Grassi et al., 2005a, b; Engler et al., 2004). These studies suggest that the flavonol components in dark chocolate improve endothelial function, a nitric oxide–dependent vasorelaxation. The importance of these findings resides in the fact that this function is impaired in type 2 diabetes and is a significant contributor to cardiovascular disease.

The clinical relevance of these preliminary findings from the consumption of flavonol-rich dark chocolate—namely, a decrease in systolic blood pressure, improved vascular relation, and enhanced insulin sensitivity—may mean that cocoa is good for heart health and nourishment, as penned by Jefferson.

It is important to remember that the flavonol content of much of the chocolate on the store shelves today is quite variable. Thus, the potential health benefits may not be realized from the routine consumption of cocoa-containing products. Modifications of cocoa technology and bean processing will be necessary to retain most of the flavonols while maintaining the desirable sensory characteristics of chocolate.

Chocolate has a rich history associated with its medicinal value. Cardinal Richelieu, Prime Minister of France, drank chocolate to treat his spleen, and women drank it to regain their strength during particularly exhausting days. It is incumbent on us to remember that while chocolate and cocoa impart pleasure, they are rich in fat and calories. These kinds of products can be part of a prudent diet, but their intake should be limited. Meanwhile, additional large-scale clinical trials that either confirm or refute these actions of dark chocolate or other flavonol-containing foods are essential.

It may be that medical evidence, nutritional science, and food technology will soon validate Jefferson’s insightful words.


Keen, C.L., Holt, R.R., Oteiza, P.I., Fraga, C.G., and Schmitz, H.H. 2005. Cocoa antioxidants and cardiovascular health. Am. J. Clin. Nutr. 81(Suppl.): 298S-303S.

Steinberg, F.M., Bearden, M.M., and Keen, C.L. 2003. Cocoa and chocolate flavonoids: Implications for cardiovascular health. J. Am. Dietet. Assn. 103: 215-223. 

by Roger Clemens, Dr.P.H.,
Contributing Editor
Director, Analytical Research, Professor, Molecular Pharmacology & Toxicology, USC School of Pharmacy, Los Angeles, Calif.
[email protected]

by Peter Pressman, M.D.,
Contributing Editor
Attending Staff, Internal Medicine, Cedars-Sinai Medical Center, Los Angeles, Calif.
[email protected]


Arabe, K.C. 2005. A chocolate fix. Ind. Mkt. Trends, Feb. 14.

Engler, M.B., Engler, M.M., Chen, C.Y., Malloy, M.J., Browne, A., Chiu, E.Y., Kwak, H-K., Milbury, P., Paul, S.M., Blumberg, J., and Mietus-Snyder, M.L. Flavonoid-rich dark chocolate improves endothelial function and increases plasma epicatechin concentrations in healthy adults. J. Am. Coll. Nutr. 23: 197-204.

Grassi, D., Lippi, C., Necozione, S., Desideri, G., and Ferri, C. 2005a. Short-term administration of dark chocolate is followed by a significant increase in insulin sensitivity and a decrease in blood pressure in healthy persons. Am. J. Clin. Nutr. 81: 611-614.

Grassi, D., Necozione, S., Lippi, C., Croce, G., Valeri, L., Pasqualetti, P., Desideri, G., Blumberg, J.B., and Ferri, C. 2005b. Cocoa reduces blood pressure and insulin resistance and improves endothelium-dependent vasodilation in hypertensives. Hypertension 46: 398-405.

Murphy, K.J., Chronopoulos, A.K., Singh, I., Francis, M.A., Moriarty, H., Pike, M.J., Turner, A.H., Mann, N.J., and Sinclair, A.J. 2003. Dietary flavonols and procyanidin oligomers from cocoa (Theobroma cacao) inhibit platelet function. Am. J. Clin. Nutr. 77: 1466-1473.