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By Adriane Fugh-Berman, MD
In the movie sleeper, woody allen wakes up in the 21st century to find many things changed, including the news that hot fudge sundaes are good for you. The data are not in on the ice cream, but chocolate may well be a health food in the next century. It turns out that chocolate is extremely high in antioxidants, with dark chocolate besting milk chocolate (which contains milk and more sugar than dark chocolate).
The Origins of Chocolate
Chocolate comes from the beans of the cacao tree (Theobroma cacao, family Sterculiaceae), a 20-foot evergreen that originated in South America and was brought into Mexico by the Mayas before the 7th century AD. Its species name, Theobroma, is Greek for "food of the Gods." The words chocolate and cocoa are derived from the Aztec; chocolate is a version of xocoatl, which means "bitter water" in Nahua. "Cocoa" is an 18th century corruption of the tree’s name "cacao." Cacao beans were used as currency in Mexico until 1887 (100 beans could buy a slave or a canoe). This currency was even counterfeited by scooping out the pulp and replacing it with wax or dirt; such was punishable by death.1
Several anthropologists believe that they have discovered the "Cradle of Chocolate" in the Ulua river valley in northwestern Honduras, an area known to be one of the first places where cocoa was cultivated. John S. Henderson, PhD, and Rosemary A. Joyce, PhD, uncovered pieces of pottery dating back to 1600 BC that are thought to be vessels for chocolate.
Originally used only as an unsweetened beverage flavored with chili peppers, Europeans invented the sweet form of hot chocolate. The use of chocolate in confectionery dates only from 1828, when the use of a screw press to separate cocoa butter from chocolate became popular. Defatted cocoa powder was one result of this innovation, and the other was cocoa butter, which could now be added to chocolate to create the smooth candies that are so popular today.2
Most chocolate today comes from Africa, although South America is also a source, and Hawaii has recently entered the market with a unique variety.
Chocolate contains the methylxanthines theobromine, theophylline, and caffeine. The caffeine content of chocolate is much lower than that in tea or coffee; by weight, the caffeine content of cocoa is 0.009%; coffee 0.04%; black tea 0.06%; and green tea 0.01%.3 Chocolate also contains three unsaturated N-acylethanolamines that may act as cannabinoid mimics (see Alternative Therapies in Women’s Health, March 1999, pp. 28-29) and flavonoid polyphenols. It is these flavonoids that are antioxidants, and their presence in chocolate makes it unnecessary to add preservatives. One of the flavonoid polyphenolics in chocolate is (-)-epicatechin. Because catechins are the primary flavonoids in tea, sometimes they are called tea flavonoids. Catechins (as well as other flavonoids) are strong antioxidants and are thought to have a protective effect against cardiovascular diseases.
A recent study compared the catechin content of dark chocolate, milk chocolate, and black tea.4 Dark chocolate contained the most catechins (53.5 mg/100 g); milk chocolate contained 15.9 mg/100 g, and an infusion of black tea (1 g/100 ml water) contained only 13.9 mg/100 ml. The type of catechins present was also found to differ. For example, chocolate contained only (+)-catechin and (-)-epicatechin. Whereas tea contained only low concentrations of those catechins, tea contained other types of catechins, including high concentrations of (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate, as well as low concentrations of (-)-epigallocatechin and (+)-gallocatechin.
EGCG is the major tea polyphenol, and its levels in green tea are three to eight times higher than in black tea.5 It would have been useful for the researchers to compare green tea and black tea; both come from the Camellia sinensis, but are processed differently, which results in different levels of catechins. It is unclear whether different catechins have different effects.
Chocolate may also have immunoregulatory effects; cacao liquor polyphenols inhibited reactive oxygen species (hydrogen peroxide and superoxide anion in activated granulocytes and human peripheral blood lymphocytes).6
Because people tend to consume larger amounts of tea than chocolate on a daily basis, the researchers also estimated the total intake of catechins from chocolate and tea in a representative sample of the Dutch population. Tea was the most important source of catechins, supplying 55% of the total daily intake, but chocolate was an important source as well, contributing 20% of total intake.3
For those concerned about fat intake, cocoa contains almost no fat but retains antioxidant effects. Cocoa powder has more phenols by weight than bakers (unsweetened) chocolate, which in turn has more phenols than milk chocolate. A 41 g (1.5 oz) piece of milk chocolate contains 205 mg phenol, equivalent to the 210 mg phenol found in a 140 ml (5 oz) serving of red wine. An in vitro experiment found that cocoa phenols inhibited human LDL oxidation by 75%.7 The authors suggest that the pairing of red wine and chocolate may have cardiovascular as well as gustatory benefits.
The antioxidant effect of cocoa has been confirmed in vivo. LDL oxidation lag time was measured in the blood of 12 male volunteers, who then consumed 35 g of cocoa.3 Prior to cocoa ingestion, LDL oxidation lag time was 61.2 min. Two hours after cocoa intake, oxidation lag time was prolonged to 70.3 min; four hours after ingestion, oxidation lag time had returned to 64.4 min. This is significant because there is evidence that the susceptibility of LDL cholesterol to oxidation is a factor in the development of atherosclerosis.
Chocolate Innocent in Migraines
Although chocolate is thought to trigger headaches, especially migraines, a double-blind study has cast doubt on this belief. Sixty-three women with chronic headache (50% migraine, 37.5% tension-type, and 12.5% mixed) followed a diet restricted in vasoactive amine-rich foods for two weeks before undergoing provocative trials with two samples of chocolate and two samples of carob presented in random order.8 Subjects maintained diaries throughout the study, recording diet and headache. Chocolate was no more likely to provoke headache than was carob in any of the headache groups. Subjects’ belief in whether chocolate ingestion was related to headache did not correlate with the results.
Potential Adverse Effects
If you’re trying to increase your daily ingestion of chocolate—for medicinal use, of course—you may want to steer clear of hot chocolate vending machines. When a number of employees in a Minneapolis manufacturing plant became ill after drinking hot chocolate from a machine, significant amounts of Bacillus cereus were isolated from dispensed beverages.9 Citywide testing of vending machines dispensing hot chocolate found that seven of 39 licensed machines tested were contaminated; two machines had levels high enough to cause illness.
Also, it is possible that chocolate could contribute to renal stone formation in susceptible individuals, although no cases have been reported. One study found that a single chocolate bar caused less pancreatic islet cell stimulation than sucrose (as determined by glucose, insulin, and C-peptide levels) but caused a significant increase in triglyceridemia, calciuria, and oxaluria.10
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2. McGee H. On Food and Cooking: The Science and Lore of the Kitchen. New York, NY: Collier Books, 1997.
3. Kondo K, et al. Inhibition of LDL oxidation by cocoa. Lancet 1996;348:1514.
4. Arts IC, et al. Chocolate as a source of tea flavonoids. Lancet 1999;354:488.
5. Dreosti IE. Bioactive ingredients: Antioxidants and poly-phenols in tea. Nutr Rev 1996;54(11 Part 2):S51-S58.
6. Sanbongi C, et al. Polyphenols in chocolate, which have antioxidant activity, modulate immune function in humans in vitro. Cell Immunol 1997;177:129-136.
7. Waterhouse AL, et al. Antioxidants in chocolate. Lancet 1996;348:834.
8. Marcus DA, et al. A double-blind provocative study of chocolate as a trigger of headache. Cephalalgia 1997;17:855-862.
9. Nelms PK, et al. Time to B. cereus about hot chocolate. Public Health Rep 1997;112:240-244.
10. Nguyen NU, et al. Increase in calciuria and oxaluria after a single chocolate bar load. Horm Metab Res 1994;26:383-386.