Health Perspectives

Is Candy Dandy

For Your Heart?

Mary Ann Ryan

Recent research has cast chocolate in a new antioxidant-rich light.

Chocolate lovers of the world, listen up: Your day of vindication may be at hand. You have no doubt been indulging your cravings despite everything you know about the junk-food status of those candy bars, death-by-chocolate cakes, and hot fudge sundaes you eat. But now comes news—from the past American Chemical Society (ACS) National Meeting in Anaheim, CA, and other sources—that holds out the hope that chocolate might not be all bad.

Papers entitled “Chocolate: A Rich Source of Polyphenol Antioxidants in the American Diet” (Abstract No. 095), “Capacity of Polyphenolic-Rich Beverages [including cocoa] to Inhibit LDL Oxidation” (Abstract No. 039), and “Potential Cardiovascular Health Benefits of Oligomeric Procyanidins [a subclass of polyphenol antioxidants] Present in Chocolate and Cocoa” (Abstract No. 093) were presented at the Anaheim meeting.

These findings are intriguing because a considerable body of published research on fruits and vegetables suggests that the antioxidant compounds found in these foods in abundance provide protection against cancer and cardiovascular disease. Teas and wine also have been identified as excellent sources of antioxidants. And now chocolate, considered sublime for its taste and texture but cursed (from a health standpoint) for the accompanying fat and sugar, is shown to be high in compounds with antioxidant activity. Could this boost chocolate up a few notches in the health column?

A search of the literature on chocolate unearthed some additional information guaranteed to put a smile on the faces of chocoholics. How about “Chocolate Lovers May Live Longer,” an Associated Press article reporting on a Harvard University School of Public Health study finding that people who consume candy live, on average, almost a year longer than those who do not (1)? Or several publications based on research at the Pennsylvania State University showing that stearic acid, the main saturated fatty acid in chocolate, does not raise blood cholesterol levels as other saturated fats do (2)? And, finally, how about a few reports that cast doubt on some firmly entrenched, negative beliefs about chocolate concerning caffeine content, migraine headaches, allergies, and addictive effects (see box, Misconceptions about Chocolate, p. 58)?

Reading these various reports, you might feel as though you were being transported back in time to Woody Allen’s 1973 movie Sleeper. The main character, Miles Monroe, is the owner of The Happy Carrot Health Food Store in Greenwich Village before he is frozen for 200 years. He wakes up after his long sleep to find that the new health foods are hot fudge, steak, and cream pies.

Although it is unlikely we will be elevating chocolate to health-food status anytime soon, the new findings about chocolate are interesting enough to prompt a further look into what is known about it and how consumption of it might affect health.

Some Basics about Chocolate
Chocolate comes from beans harvested from the cocoa tree (Theobroma cacao), native to Central America. The beans are fermented, dried, roasted, and pressed to give a “chocolate” liquor, which consists of about a 50/50 mix of cocoa particles and cocoa butter.

If the chocolate liquor is further pressed to extract more of the cocoa butter (all but 10–25% of it), and the remaining paste cooled, ground, and sifted, cocoa powder results. The primary nutrients in cocoa—besides the fats and fatty acids from the cocoa butter that remains in it—include various carbohydrates (a portion of which is the dietary fiber cellulose) and protein. Also present in smaller quantities are mineral salts (of Mg, P, Na, K, Ca, Fe, Zn, Cu, and Mn), theobromine (the principal alkaloid of the cocoa bean), caffeine, polyphenols, and water.

A combination of cocoa and cocoa butter with other ingredients produces the delectable forms of chocolate we find in candy bars and other foods. Nutrition information from the Mayo Clinic (“Ask the Mayo Dietitian,” www.mayohealth.org) describes the different forms of chocolate as follows:

Unsweetened chocolate is a mixture of cocoa powder and refined cocoa butter. It is too bitter to eat and is used mainly in baking.

Dark chocolate (bittersweet and semisweet) contains cocoa, cocoa butter, and varying amounts of sugar.

Milk chocolate has milk as well as cocoa, cocoa butter, and varying amounts of sugar. Flavorings such as vanilla are sometimes added.

White chocolate contains no chocolate liquor, but only cocoa butter, sugar, milk, and flavorings.

Misconceptions about Chocolate Chocolate is high in caffeine. The amount of caffeine in a 1-oz piece of chocolate (sweet, semisweet, dark, or milk) ranges from 10 to 20 mg. By comparison, a 6-oz cup of regular brewed coffee contains 105 mg, a cup of tea 35 mg, and 12 oz of cola 35–50 mg. (Mayo Clinic Web site, www.mayohealth.org.) Chocolate causes migraine headaches. A double-blind, placebo-controlled study of chocolate’s ability to induce headaches in 63 women with chronic headache was conducted at the University of Pittsburgh Pain Evaluation and Treatment Institute in 1997. The conclusion: “Contrary to the commonly held belief of patients and physicians, chocolate does not appear to play a significant role in triggering headaches in typical migraine, tension-type, or combined headache sufferers” (Cephalalgia 1997, 17 (8), 855–862). Chocolate is addictive. Although many people experience cravings for chocolate, there is little evidence from existing studies that these are due to addiction. The Mayo Clinic Health Letter (February 1995) says, “It’s more likely chocolate cravings occur simply because chocolate tastes so good.”

Most of the ingredients of chocolate have been known for some time. Of greater interest are the new findings that chocolate contains substantial amounts of antioxidants in the form of complex mixtures of phenolic compounds, and that these may have beneficial effects on health. Some background on what is known about dietary antioxidants in general may be helpful before we look at those in chocolate.

Benefits of Dietary Antioxidants
Why should antioxidants be important to health? Cells in the body are constantly exposed to reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂), superoxide anion (O₂^–), hydroxyl radical (OH^–), and hypochlorous acid (HOCl), which are capable of causing cellular damage. Most ROS are produced in the course of ordinary biological processes and are prevented from doing harm by the body’s internal antioxidant defense systems, that is, antioxidant enzymes within the cells. However, the defense system is not perfect, and some ROS escape it. Furthermore, illnesses, aging, or external factors such as air pollution, smoking, or the effects of ultraviolet radiation can lead to additional ROS and overwhelm the internal defenses. This is when food sources of antioxidants become important, because they form a second line of defense to scavenge free radicals and prevent damage.

Consumption of fruits and vegetables—good sources of antioxidants—has been found to correlate positively with protection against cardiovascular disease, cancer, and cataracts, as well as slowing the effects of aging. In addition to fruits and vegetables, tea and wine are high in antioxidant compounds. Some researchers believe that it is the antioxidants in wine that are responsible for the “French paradox,” the finding that moderate wine consumption correlated with the lower mortality rate from heart disease in certain people in France despite their intake of foods high in saturated fat. Phenolic antioxidants have been shown to inhibit the oxidation of low-density lipoprotein (LDL) cholesterol, and mounting evidence suggests that it is the oxidized form of LDL that leads to the buildup of fatty plaques in arteries.

Vitamins C and E and beta-carotene are antioxidants. However, these substances are only part of a much larger mix of antioxidant compounds found in fruits and vegetables. Therefore, much of the recent research has reported total antioxidant activity or total antioxidant capacity of specific foods or beverages. (See box, Foods and Beverages High in Antioxidants.)

Foods and Beverages High in Antioxidants In addition to chocolate, the following foods and beverages are high in antioxidant content. Beverages: tea (green and black); red wine; grape, tomato, orange, apple juice. Top 10 vegetables: garlic, kale, spinach, brussels sprouts, alfalfa sprouts, broccoli flowers, beets, red bell peppers, onions, corn [J. Agric. Food Chem. 1996, 44 (11), 3426–3431]. Top 10 fruits: strawberry, plum, orange, red grapes, kiwi fruit, pink grapefruit, white grapes, banana, apple, tomato [J. Agric. Food Chem. 1996, 44 (3), 701–705].

Antioxidants in Chocolate
The excitement over antioxidants in chocolate appears to have been started by a letter published in the medical journal Lancet in 1996 (3). Researcher Andrew Waterhouse and colleagues at the University of California–Davis, Department of Viticulture and Enology, had noticed in analyzing the cocoa bean that it was a rich source of phenols. Phenols occur in most plant products but had been found to be especially abundant in fruit, vegetables, wine, and tea. To determine whether chocolate products are also rich in phenols, the researchers took cocoa powder and baking chocolate from the kitchen and a milk chocolate candy bar from a vending machine to analyze them using a standard test for phenols in wine. They also tested cocoa extract for its antioxidant activity by determining its ability to inhibit oxidation of LDL cholesterol purified from human blood. Among their findings from this preliminary experiment were that of the three forms of chocolate, cocoa had the highest levels of phenols, followed by baking chocolate and milk chocolate; that a standard 1.5-oz milk chocolate bar had approximately the same quantity of phenols as a 5-oz glass of red wine; and that cocoa powder extract was a potent antioxidant for LDL oxidation.

The antioxidants [chocolate] contains are likely to be positive for health . . .

More recently, Joe Vinson at the University of Scranton (PA), who has been studying total polyphenols in foods and beverages in the American diet, has found even higher levels of antioxidants in chocolate. His studies have shown that on a weight basis, “the concentration of polyphenols in milk chocolate is higher than in red wines and black or green teas. It is 20 times higher than in tomatoes, 2 times higher than in garlic, and over 3 times higher than in grapes.” He also notes that dark chocolate provides more than twice the level of polyphenols as milk chocolate per serving, and that white chocolate has no antioxidant content.

Harold Schmitz, group manager for the Analytical and Applied Sciences Group at M&M/MARS (Hackettstown, NJ), says that an important next step in studying antioxidants in chocolate and other foods will be to gain an understanding of the biological effects of different fractions of the polyphenolic compounds, rather than just looking at total polyphenols. His group, working in collaboration with researchers at the University of California–Davis, developed an analytical method based on HPLC/MS for separating and identifying procyanidins, a diverse subgroup of polyphenols (4). The researchers are finding not only that procyanidins collectively have antioxidant activity and possible cardiovascular benefits, but also that different fractions of procyanidin oligomers (e.g., dimers, trimers, tetramers) have different antioxidant potentials and, therefore, probably different biological potentials.

This last point raises an important issue. Because little is known about the physiological effects of specific antioxidants in the complex mixtures found in chocolate, fruits, vegetables, and other sources, and because these mixtures do not contain exactly the same compounds (there is some overlap, but there are many differences), it is wise to follow the standard advice of dietitians: Health is best served by eating a wide variety of foods and a balanced diet. In other words, don’t start substituting chocolate for broccoli thinking you will get the identical antioxidant benefit.

Chocolate Candy Consumption Americans eat a lot of chocolate in the form of candy (about 4.6 kg/year per person, or 10 lb), but not as much as people in some northern European countries. In Switzerland, the country with the highest consumption, estimated chocolate intake is 9.9 kg/yr (22 lb) for each person, more than double the U.S. amount (Am. J. Clin. Nutr. 1994, 59, 10605–10645. A typical milk chocolate bar (1.4 oz) has a mass of 40 g, so U.S. consumption would approximate 114 candy bars a year for every inhabitant (if we simplify things by assuming that all chocolate candy intake is in the form of such bars). Each bar contains approximately 210 calories, 13 g of fat (7 of which are saturated), 23 g of carbohydrate, and 3 g of protein (source: www.hersheyfoods.com).

So, How Much Can You Eat?
Taking into consideration all that has been said above about chocolate, we are still left with the question of whether it is generally a good food for health. As with many questions in life, this one does not have a simple answer. Chocolate is usually consumed in forms that have a high sugar and fat content, and for this reason should be limited in the diet. Yet the antioxidants it contains are likely to be positive for health, although more in vivo research needs to be done to confirm this. Julie Seed, a dietitian at the Francis Stern Nutrition Center of Tufts University (Medford, MA), assessed chocolate’s place in the diet in light of its high antioxidant content. She said, “We would still need to consider whether it is the preferred source of these compounds, which are also abundant in fruits and vegetables.” There is no definitive answer. But at least we have more evidence than we did a few years ago that chocolate is a more complex and interesting food than we may have thought, and that it may have some health benefits.

References
(1) Lee, I-M.; Paffenbarger, R. S., Jr. Br. Med. J. 1998, 317, 1683–1684.

(2) Kris-Etherton, P. M.; Derr, J. A.; Mitchell, D. C. Metabolism 1993, 42, 121–134.

(3) Waterhouse, A. L.; Shirley, J. R.; Donovan, J. L. Antioxidants in Chocolate. Lancet 1996, 348(9030), 834.

(4) Hammerstone, J. F.; Lazarus, S. A.; Mitchell, A. E.; et al. J. Agric. Food Chem. 1999, 47, 490–496.

Mary Ann Ryan writes on health and science topics. She holds an M.S. degree in analytical chemistry and a Ph.D. in chemical education from the University of Virginia. Her e-mail address is maryannryan@compuserve.com.

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Copyright © 1999 by the American Chemical Society.