One of the best pieces of news to emerge over the last several years is that chocolate may help you live longer, probably by reducing cardiovascular events like heart attacks and stroke. After all –- how often is a remedy this easy to take? But which type of chocolate is really the healthiest?
Cocoa and the Kuna Indians: Chocolate has been used for medicinal effect for thousands of years, but its recent recognition as a possible heart-healthy food came to light in the early 1990s. Harvard Medical School researchers, led by Norman Hollenberg, investigated why Kuna Indians, living in the San Blas Islands off the Caribbean coast of Panama, had low blood pressure, even with increasing age. This was true despite a high level of salt consumption, which exceeded that of most Western populations.
If the Kunas had their genetic makeup to thank for healthy blood pressure, moving to an urban environment on the mainland shouldn’t make any difference. But it did –- migration to cities corresponded with a rise in blood pressure, with increasing age. Further investigation showed island-dwelling Kunas also lived longer than their mainland cousins, with low rates of cardiovascular disease and cancer. After allowing for factors like stress and lack of pollution, Hollenberg and his team concluded the most striking difference in the Kuna Indians’ island environment was dietary, including a dramatic average daily consumption of more than 5 cups of cocoa, per person.
There’s a big difference between the cocoa the Kunas drink, and the cocoa and chocolate people usually purchase in a grocery or specialty store -- mostly due to how it’s processed and its formulation.
Processing: Cocoa beans grow as the seed of the berry-like fruit of the cacao tree. After shelling and roasting, the beans are ground into a suspension called cocoa liquor, made up of cocoa butter (fat) and solids. Pressing removes most of the cocoa butter, resulting in a hard, dry cake, which is ground into what we use as cocoa powder.
This powder contains most of the flavanols, a family of flavonoids, or antioxidants, that have since been credited with most of chocolate’s health benefits. Flavanols affect the way nitric oxide is produced in the body, helping blood vessels to relax, and thereby improving blood flow to the heart, the brain, and extremities. They also may reduce inflammation, and the proliferation of dangerous free radicals produced in regular cell metabolism.
At this stage, cocoa powder remains quite bitter. As a result, it’s often processed by treatment with alkali -- most commonly sodium bicarbonate, or baking soda -- to make it darker, less acidic, and easier to mix into beverages. Unfortunately, this 200-year-old method, also known as "Dutch-processing," has been shown to destroy the active flavanol content by as much as 80%. Thus, the percentage of cocoa contained in a piece of chocolate, whether it’s 60%, 70% or higher, is no indication of its flavanol content, argues Hollenberg in a 2007 editorial in the journal Circulation. He and other nutrition researchers have argued for labeling chocolate products with flavanol values instead.
The Kuna Indians drink largely homegrown, unprocessed cocoa powder, containing very high flavanol levels.
Formulation: Cocoa butter’s unique property of having a melting point that matches human body temperature –- allowing it to literally “melt in your mouth” –- makes it delicious. Its fat content, however, puts chocolate-lovers at risk of weight gain if they don’t compensate for those calories elsewhere. A 3.5 oz (100g) bar of chocolate contains more than 500 calories (compared with just 12 calories in a tablespoon of unsweetened cocoa). Obesity increases the risk of cardiovascular disease, diabetes, and cancer, so don’t try to extend your life by eating chocolate if it results in gaining weight. Indeed, a very small amount of chocolate may be sufficient for improved longevity.
Bottom line: Research on the indigenous Kuna Indian population of Panama suggests that unprocessed cocoa may be the healthiest form, due to its high flavanol content. Since flavanols are destroyed through chemical Dutch-processing, or alkalization, look for cocoas labeled "natural," as they have not been treated with alkali.
Andres-Lacueva C., et al. “Flavanol and flavonol contents of cocoa powder products: influence of the manufacturing process.” J Agric Food Chem. 2008. May 14;56(9):3111-7. Epub 2008 Apr 16.
Claims About Cocoa. US National Institutes of Health Information Sheet. Accessed January 27,2011.http://newsinhealth.nih.gov/issue/aug2011/feature1
Kenneth B. Miller et al. Impact of Alkalization on the Antioxidant and Flavanol Content of Commercial Cocoa Powders. J. Agric. Food Chem., 2008, 56 (18), pp 8527–8533. DOI: 10.1021/jf801670p.
Norman K. Hollenberg, MD, PhD and Naomi D.L. Fisher, MD. “Is It the Dark in Dark Chocolate?” Circulation. 2007; 116: 2360-2362.http://circ.ahajournals.org/content/116/21/2360.full
K. Hollenberg N. Vascular action of cocoa flavanols in humans: the roots of the story. J Cardiovasc Pharmacol. 2006;47 Suppl 2:S99-102; discussion S119-21.