Source: Mursu J, et al. Dark chocolate consumption increases HDL cholesterol concentration and chocolate fatty acids may inhibit lipid peroxidation in healthy humans. Free Radical Biol Med 2004;37: 1351-1359.
Abstract: Cocoa powder is rich in polyphenols and may contribute to the reduction of lipid peroxidation. The aim of this trial was to study the effects of long-term ingestion of chocolate, with differing amounts of polyphenols, on serum lipids and lipid peroxidation ex vivo and in vivo. The authors conducted a three-week clinical supplementation trial of 45 nonsmoking, healthy volunteers. Participants consumed 75 g/d of either white chocolate (WC), dark chocolate (DC), or dark chocolate enriched with cocoa polyphenols (HPC). An increase in serum HDL cholesterol was observed in the DC and HPC groups (11.4% and 13.7%, respectively), whereas there was a small decrease (-2.9%, P < 0.001) in the WC group. The concentration of serum LDL diene conjugates, a marker of lipid peroxidation in vivo, decreased 11.9% in all three study groups. No changes were seen in the total antioxidant capacity of plasma, in the oxidation susceptibility of serum lipids or VLDL + LDL, or in the concentration of plasma F2-isoprostanes or hydroxy fatty acids. Cocoa polyphenols may increase the concentration of HDL cholesterol, whereas chocolate fatty acids may modify the fatty acid composition of LDL and make it more resistant to oxidative damage.
Comments by Mary L. Hardy, MD
I was especially interested in discovering that chocolate (a key food group from Halloween to Easter—all those chocolate-giving holidays!) could be a healthy food choice. I put my heart and soul into this and it looks like my heartfelt wish may have come true—sort of. Luckily, cocoa does have a long history of use as a healthy beverage. A chocolate liquid made from the roasted cacao "beans" was a health-promoting drink of the Mayans more than 500 years before the Spanish came to the new world.1 However, we wouldn’t recognize their hot chocolate today if it were sold at Starbucks. The traditional drink, still brewed in Central America today, was unsweetened and often included hot spices like chili or black pepper, resulting in a spicy, bitter complex drink.2 This life-giving beverage was precious in Mayan culture. It was offered as a sacrifice to the gods and its consumption was limited to priests and royalty. The sacred nature of the plant is reflected in its Latin name, Theobroma cacao, literally food of the gods.1,2 Modern phytomedical investigations have identified some significant health effects of chocolate, largely related to its flavonoid content.
Theobroma cacao, a tropical tree, yields a melon-sized fruit that contains in its pulp, the "cocoa bean," which is really a seed. Although this tree originally was native to tropical Mesoamerica, 90% of commercial cocoa now comes from West Africa. After roasting and/or fermentation, the seeds are pressed to extract the cocoa butter, leaving behind the cocoa cake. Once this cake has been dried and ground, it is called cocoa powder. Variations in taste, color, texture, and phytochemical structure result from differences in the varieties of plants, climate conditions, and processing. Cocoa powder contains approximately 20% fat, up to 3% methylxanthine alkaloids (mainly theobromine), and is rich in flavonoids. This powder is blended with sugar, cocoa butter, and other ingredients to make chocolate products.3
Chocolate is a rich source of dietary flavonoids, accounting for 20% of the total flavonoids present in the Dutch diet.4 Flavonoids are potent antioxidants and are thought to protect against heart disease and cancer. It recently has been determined that chocolate is a good source of epicatechin, the main flavonoid found in green tea, a beverage with well-known health benefits. Chocolate also contains additional phenolic compounds such as procyanidins.3 The polyphenol content of chocolate is highest with dark chocolate and decreases with milk chocolate. In one analysis, dark chocolate had a higher catechin content than milk chocolate or black tea (54 mg/100 g vs. 15.9 mg/100 g vs. 13.9 mg/100 g, respectively).4 The total phenolic content of dark chocolate was twice that of red wine and triple that of green tea and black tea.5 The values for antioxidant capacity were similar as well. So, dark chocolate can be a good dietary source of healthful flavonoids with a strong antioxidant capacity.
Mursu et al conducted a trial to determine the ability of cocoa powder to affect components of the lipid profile in humans.6 They fed non-smoking, healthy volunteers 75 g/d of either white chocolate (WC), dark chocolate (DC), or dark chocolate enriched with added cocoa polyphenols (HPC). The energy density of the test chocolates was roughly 560 kcal but the total amount of catechins varied from a total of 0 mg in the 75 g sample for WC, to 366 mg for the DC sample, to a maximum of 557 mg in the HPC sample. The 45 subjects enrolled in the study were allowed to choose the type of chocolate they wished to eat. After three weeks eating the chocolate of their choice, the lipid levels and LDL oxidation were measured. HDL levels were unchanged in the WC group but rose about 10% in the DC group and 13% in the HPC group (P < 0.001). No changes in total cholesterol or LDL were observed. The dark chocolates also decreased lipid peroxidation by 12%, measured by the formation of a byproduct of oxidation found in the blood. Unfortunately (for me), a small but statistically significant weight gain was recorded in the DC group.
Although chocolate has been shown to be an important source of dietary flavonoids, concern must still be taken to account for the energy density of this food. Health-conscious consumers interested in maximizing their polyphenol intake would be best advised to eat dark, not milk, chocolate in doses that do not lead to calorie excess and consequent weight gain. To address this energy concern while maintaining a health benefit, we already are starting to see the development of isolated chocolate polyphenols as dietary supplements in capsule form, much like the green tea capsules already available. Some manufacturers have started to incorporate chocolate catechins with baby aspirin to capitalize on the heart-healthy effects.
I think I can be justified in looking at chocolate as a relatively healthy vice—in moderation, at least! That may be good enough to get me through chocolate season.
Dr. Hardy, Associate Director, UCLA Center for Dietary Supplement Research: Botanicals Medical Director, Cedars-Sinai Integrative Medicine Program Los Angeles CA, is on the Editorial Advisory Board of Alternative Therapies in Women’s Health.
1. Dillinger TL, et al. Food of the gods: Cure for humanity? A cultural history of the medicinal and ritual use of chocolate. J Nutr 2000;130(8S Suppl):2057S-2072S.
2. Lee R, Balick MJ. Chocolate: Healing food of the gods’? Altern Ther Health Med 2001;7:120-122.
3. DerMarderosian A, Beutler J, eds. The Review of Natural Products. St. Louis, MO: Facts and Comparisons; 2002.
4. Arts IC, et al. Chocolate as a source of tea flavonoids. Lancet 1999;354:488.
5. Lee KW, et al. Cocoa has more phenolic phytochemicals and a higher antioxidant capacity than teas and red wine. J Agric Food Chem 2003;51:7292-7295.
6. Mursu J, et al. Dark chocolate consumption increases HDL cholesterol concentration and chocolate fatty acids may inhibit lipid peroxidation in healthy humans. Free Rad Biol Med 2004;37:1351-1359.