Health Benefits of Dark Chocolate

Theobroma cacao, the cocoa tree, has been cultivated in Central and South America for over 3000 years. Cocoa is derived from the tree’s seed, also known as the cocoa bean.

Chocolate is a product of the processed cocoa bean. Sweet chocolate is chocolate combined with sugar. Milk chocolate is sweet chocolate combined with milk powder or condensed milk. Dark chocolate typically has no added dairy products, has at least 65% cocoa content, and has much more of the potentially healthy chemicals from the cocoa bean as compared with milk chocolate. White chocolate is cocoa butter (aka cacao fat), milk solids, and sugar without the cocoa solids or mass; in many countries it is not considered chocolate.

It’s been a little over 10 years since we first read in a medical journal about cocoa and chocolate as potential sources of antioxidants for health. What have we learned since then?

Phytochemicals are chemicals produced by plants, and there are hundreds of thousands of them. Polyphenols are a subset of phytochemicals. Flavonoids, with strong antioxidant properties, are a subset of polyphenols. And a subset of flavonoids, called flavonols, have particularly potent biological effects in humans. Prominent flavonols in dark chocolate are flavan-3-ol, catechin, and epicatechin. Also metabolically active are proanthocyanidins, which are polymeric condensation products of flavan-3-ol.

Are you bored yet? Have I convinced you of my authority on the subject? Say yes, or I’ll keep going! [Please say yes: I’m boring myself!]

Note that some chocolate manufacturers process the cocoa beans to remove some of the polyphenols, which reduces bitterness or pungency.

Other rich sources of flavonols are wine, tea, and various fruits and berries.

How could dark chocolate, especially its flavonoids, be healthful?

  • Flavonoids are antioxidants that protect from injury caused by free radicals
  • Enhanced nitric oxide production, leading to relaxation of arteries (vasodilation), leading to reduced blood pressure: up to 6 mmHg systolic and 3 mmHg diastolic
  • Elevation of HDL cholesterol, with no effect on total and LDL cholesterol
  • Inhibition of platelet aggregation and activation, leading to fewer blood clots that cause heart attacks and strokes
  • Decreased inflammation
  • Reduction of C-reactive protein, a marker of inflammation
  • Decreased neutrophil (white blood cell) activation. White blood cells play a role in inflammation
  • Decreased LDL cholesterol oxidation, leading to fewer atherosclerotic complications
  • Improved function of the cells that line blood vessels (endothelium)
  • Possible enhanced insulin sensitivity
  • May act as anti-carcinogens and neuro-protective agents
  • May act as an antidepressant

Note also that low-fat natural non-alkalized cocoa powder is also a rich source of antioxidant flavonoids.

Bottom line? Dark chocolate, especially because of flavonoids, may well be protective against cardiovascular disease such as heart attacks and strokes.

[Did you notice I’m waffling . . . may be protective.]

What’s in dark chocolate other than flavonoids?

A 40 gram serving of a fine dark chocolate bar has:

  • Calories: 200
  • Calories from fat: 150
  • Fiber: 4.5 grams (dark chocolate is a good source of fiber on a “per calorie” basis)
  • Sugar: 11 grams
  • Saturated fats: 10 grams

But aren’t saturated fats bad for me?

The fats in dark chocolate are 1/3 oleic (healthy monounsaturated, as in olive oil), 1/3 stearic (saturated, but no effect on cholesterol levels, unlike some other saturated fats), and 1/3 palmitic (saturated, and could increase cholesterol levels and heart risk). So it’s sort of a wash.

[I’m not getting into the diet-heart hypothesis now. Don’t bait me.]

What’s the healthy “dose” of dark chocolate?

No one is sure. It’s certainly no more than 100 grams (3.5 ounces) a day, and the optimal dose may be as low as 20 grams every three days. If you eat too much, it will make you fat. 100 grams is 500 calories; that’s probably way too much. Even if you start eating 20 grams – 100 calories – every three days, you will gain weight unless you give up some other food or exercise a little more.

Parker, why are you waffling?

Because no one has ever done a study to see if adding dark chocolate actually reduces death rates or sickness from specific diseases in humans. I think it probably does, but who knows for sure? Nobody. What we need is a randomized, controlled trial of dark chocolate as a supplement in 10,000 middle-aged adults followed over the course of 10 years. I’d sign up for that in a heartbeat. Just don’t give me the placebo.

Steve Parker, M.D.

Additional Resources:

Clay Gordon, author of the book Discover Chocolate, kindly critiqued an early version of this blog post here. If the link doesn’t work, go to The Chocolate Life and search “Health Benefits of Chocolate” in the Forums.


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Farouque, H.M, et al. Acute and chronic effects of flavanol-rich cocoa on vascular function in subjects with coronary artery disease: a randomized double-blind placebo-controlled study. Clinical Science, 111 (2006): 71-80.

Heptinstall, S., et al. Cocoa flavanols and platelet and leukocyte function: recent in vitro and ex vivo studies in healthy adults. Journal of Cardiovascular Pharmacology, 47 supplement 2 (2006): S197-205.

Keen, C.L., et al. Cocoa antioxidants and cardiovascular health. American Journal of Clinical Nutrition, 81 supplement 1 (2005): 298S-303S.

Mehrinfar, R. and Frishman, W.H. Flavanol-rich cocoa: a cardioprotective nutraceutical. Cardiology Reviews, 16 (2008): 109-115.

Engler, M.B, and Engler, M.M. The emerging role of flavonoid-rich cocoa and chocolate in cardiovascular health and disease. Nutrition Reviews, 64 (2006): 109-118.

Lippi, G. et al. Dark chocolate: consumption for pleasure or therapy? Journal of Thrombosis and Thrombolysis, September 23, 2008 (Epub ahead of print).

Hooper, L, et al. Flavonoids, flavonoid-rich foods, and cardiovascular risk: a meta-analysis of randomized controlled trials. American Journal of Clinical Nutrition, 88 (2008): 38-50.

Cooper, K.A., et al. Cocoa and health: a decade of research. British Journal of Nutrition, 99 (2007): 1-11. Epub August 1, 2007.

Aron, P.M., and Kennedy, J.A. Flavon-3-ols: nature, occurrence and biological activity. Molecular Nutrition and Food Research, 52 (2008): 79-104.

Buijsse, B, et al. Cocoa intake, blood pressure, and cardiovascular mortality [in men]: the Zutphen Elderly Study. Archives of Internal Medicine, 166 (2006): 411-417.

Ding, E.L., et al. Chocolate and prevention of cardiovascular disease: a systematic review. Nutrition and Metabolism, 3 (2006): 2.

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