Chocolate' s Health Benefits—Trick or Treat?

Special Report

OCTOBER 2007

IS THERE a health benefit to that Halloween chocolate treat? Mount ing evidence has indicated so, linking certain forms of chocolate to improved cardiovascular health, lower blood pressure, enhanced glucose tolerance, even stronger teeth. Candy-makers as well as “health-oriented” companies have even developed chocolate products they claim are good for us.

But not so fast, says Jeffrey B. Blumberg, PhD, director of the Antioxidants Research Laboratory at Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA). Before you scarf down everything in the kids’ or grandkids’ Halloween goodie-bag, Blumberg cautions, it’s important to note that not all forms of chocolate have health benefits. Dark chocolate with a cocoa content of at least 70% has been shown to be the most beneficial.

And though Blumberg acknowledges the growing number of chocolate studies, and has participated in research here and abroad that shows some healthful benefits of cocoa in the diet, he warns that it’s still important to consume the confection in moderation.

“Chocolate is not a health food,” Blumberg emphasizes. “A health food would be one with positive attributes, which we know chocolate has, but that is absent the negative attributes. When we look at chocolate, we need to acknowledge the fat and the calories. The question is: Can we really get the benefits without paying the price in calories and fat?”

Some producers of chocolate products would like us to think so. In 2003, Mars Inc., the maker of M&Ms and Snickers, launched the CocoaVia snack bar, and began marketing the product as packed with cocoa flavonols—naturally occurring antioxidants that have been associated with cardiovascular health (see the February 2005 Health - letter). The company has since gone on to produce CocoaVia chocolate bars, a candy product that delivers 100 milligrams of cocoa flavonols plus 1.1 grams of canola sterol esters in its 100 calories per serving.

Now a new product, “The Doctor’s Chocolate,” promises to “lower daily stress and tension” and reduce sugar cravings while delivering a sweet load of antioxidants and amino acids—at only 20 calories per diabetic-friendly piece of raspberry-flavored chocolate.

The flavonol factor

This drive to produce something delicious and delightfully marketable stems not only from the average person’s willingness to swallow a bite of chocolate instead of, say, a clump of sautéed kale, but also from the rash of hopeful reports linking the sweet treat with health benefits. One recent study, published in the Journal of the American Medical Association (JAMA), showed that eating about 30 calories a day of dark chocolate was associated with lowering of blood pressure, without weight gain or other adverse effects (see box, next page).

“Cocoa is a good source of magnesium and contains many phytochemicals, including plant sterols and theobromine,” Blumberg notes, “but most of the excitement is directed to its flavonoid content.” For example, he adds, dark chocolate is rich in proanthocyanidins that are potent antioxidants—but blueberries, cranberries and tea are likewise rich in proanthocyanidins.

The focus of Blumberg’s work with chocolate has been on the antioxidants, specifically in dark chocolate high in fla vonol-rich cocoa. “In one Italian study, for instance, we saw a significant decline in LDL (‘bad’) cholesterol,” he says.

It’s the flavonol factor, he notes, that is behind the promising findings of a recent Spanish study in which cocoa was found to increase antioxidant activity in all body tissues. Notably, the cocoa flavonols strengthened the thymus, an organ situated in the upper part of the chest that plays a role in the body’s immune response.

Publishing their findings in the Journal of Agricultural and Food Chemistry, researchers from the University of Barcelona reported that feeding a cocoa-enriched diet to rats boosted the animals’ antioxidant enzyme defenses. While the researchers wrote that more study is needed to determine if there would be the same result in humans, the initial findings are promising. (And it probably wouldn’t be hard to find humans willing to sign on to take part in such research!)

Variety for vitality

But Blumberg cautions that it’s best to obtain our nutrients from a varied, healthful diet, getting a wide range of flavonoids from many sources—particularly those that don’t have the fats and calories of chocolate. “I don’t think there’s a ‘best’ flavonoid,” he says. “To focus on just a couple of them is short-sighted. It’s important to get a wide range of them into our diet, and the best way to do that is to eat whole variety of antioxidant-rich foods, like green tea, fruits and vegetables, and red wine if you enjoy that.” He suggests consuming “the darkly colored fruits and vegetables which contain high amounts of those desirable phytonutrients.”

But a bite of high-quality dark chocolate, even on a regular basis, can indeed be a good thing. “It’s certainly worth having for the healthful components, like the flavonols,” Blumberg says. “I think it’s reasonable to say that cocoa and high-quality dark chocolate can be beneficial when included in the diet as some of one’s discretionary calories. It’s a lovely indulgence that can contribute to a whole healthy diet.”

And, he adds, allowing ourselves a small, regular treat can offer another bonus—helping to keep us on the healthful diet bandwagon. Recent Tufts research suggests that weight-loss success comes from controlling the frequency of giving in to cravings—such as for chocolate—rather than trying to suppress cravings entirely (see page 7).

Having that small reward can make staying on a healthful diet feel like less of a sacrifice,” Blumberg says. “It’s a treat, after all, and that makes us feel good!”

Chocolate News to Smile About

Have some chocolate each day to keep the dentist away? It seems to fly in the face of common sense: A cocoa extract is more effective at protecting teeth than fluoride? But that’s the word from researchers who found that an ingredient in chocolate can fight cavities and promote dental health.

Arman Sadeghpour, PhD, led the Tulane University arm of the research team, which also included scientists from the University of New Orleans and Louisiana University’s School of Dentistry. They compared a cocoa extract versus fluoride, side-by-side on the enamel surface of human teeth.

The key to cocoa’s dental benefits, according to Sadeghpour, is a substance called theobromine. A water-insoluble, crystalline bitter powder, theobromine is an alkaloid of the cacao plant, and is therefore found in chocolate along with teas and other foods. Its chemical makeup is similar to caffeine. Theobromine helps harden tooth enamel, making teeth less susceptible to decay.

The cocoa extract could offer the first major innovation in commercial toothpaste since manufacturers began adding fluoride in 1914. Sadeghpour has since started up a biotech company, Theodent, and created a prototype of peppermint-flavored toothpaste with the cavity-fighting cocoa extract. “We are now working on the steps for approval” toward a marketable product, he says. His cocoa-enhanced toothpaste could hit supermarket shelves within two to four years.

In the meantime, Sadeghpour adds that consuming foods containing theobromine also boosts dental health. “Consumers do receive some benefit to all their bone tissue just from eating chocolate, thanks to the theobromine,” he says.

Chocolate candy doesn’t come close to matching the hoped-for benefits of Sadegh - pour’s toothpaste, however. You get only about 3% theobromine even in high-quality dark chocolate, he explains, which is far outweighed by the tooth-decaying effects of sugar.

A Bite of Dark Chocolate Helps Blood Pressure

Worried about your blood pressure? It might not be a bad idea to pop an occasional piece of dark chocolate. A new study found that small amounts of the candy were as effective at lowering blood pressure as other non-pharmaceutical interventions. While not a substitute for hypertension medications, a small daily dose of chocolate brought results significant enough to be considered clinically beneficial to overall health, the researchers said.

In previous short-term studies, consumption of 100 grams of cocoa daily has been shown to improve the function of the endothelial cells lining blood vessels—thereby reducing blood pressure. Polyphenols—specifically flavonols—in the cocoa are thought to be responsible.

In the latest research, scientists at the University Hospital of Cologne, Germany, studied 24 women and 20 men, ages 56-73, who were prehypertensive (blood pressure 130/85 to 139/89) or Stage 1 hypertensive (140/90 to 160/100). The subjects ate 30 calories’ worth about one-quarter ounce—of either dark or white chocolate daily for 18 weeks.

Writing in the Journal of the American Medical Association (JAMA), lead author Dirk Taubert, MD, PhD, and colleagues reported that at the end of the test period, those who had consumed the dark chocolate saw modest reductions in their systolic and diastolic pressures. The improvements averaged only two to three “points.” But Dr. Taubert noted, “On a population basis, it has been estimated that a 3-mm HG reduction in systolic BP would reduce the relative risk of stroke mortality by 8%, of coronary artery disease mortality by 5%, and of all-cause mortality by 4%.”

The blood-pressure benefit was not accompanied by weight gain or other related bodily changes, such as elevated lipids or sugar in the blood.

The researchers suggested the positive blood-pressure results were due to the cocoa’s flavonols. These naturally occurring compounds promote the production of nitric oxide in the cells lining the vascular system, leading to better blood-vessel dilation

But subjects who ate white chocolate saw no changes in their blood pressure or other beneficial markers in their blood. White chocolate is made from cocoa butter—the natural fat of the cacao bean —and lacks the beneficial polyphenols of cocoa.

The most intriguing finding, Dr. Taubert added, was that simple commercial dark chocolate was as effective at lowering blood pressure as much more comprehensive dietary modifications. Dark chocolate, in fact, yielded results similar to the DASH (Dietary Approaches to Stop Hypertension) diet plan. And a small dose of chocolate each day might just make it easier and, well, tastier for hypertensive patients to stay on board with a method of intervention.

“Whereas long-term adherence to complex behavioral changes is often low and requires continuous counseling, adoption of small amounts of flavonol-rich cocoa into the habitual diet is a dietary modification that is easy to adhere to,” the researchers wrote, “and therefore may be a promising behavioral approach to lower blood pressure in individuals with above-optimal blood pressure.”

Don’t expect your doctor to start writing prescriptions for Godiva. But at least chocolate lovers with minor blood-pressure concerns can feel better about occasionally indulging in a guilty pleasure.

http://www.tuftshealthletter.com/ShowArticle.aspx?rowId=412

 



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