Healthy Foods



Researchers have some news for chocolate lovers: it may be good for you. Scientists reported preliminary evidence recently that cocoa and other chocolates may keep high blood pressure down, your blood flowing and your heart healthy.

The research, the latest which correlates eating flavonoid-rich foods with a reduced risk of cardiovascular disease, was presented in February at the American Association for the Advancement of Science's (AAAS) annual meeting in Boston.

One study found that a substance in cocoa helps the body process nitric oxide (NO), a compound critical for healthy blood flow and blood pressure. Another study showed that flavonols in cocoa prevent fat-like substances in the bloodstream from oxidizing and clogging the arteries, and make blood platelets less likely to stick together and cause clots. Flavonoids are plant compounds with potent antioxidant properties; so far, scientists have found more than 4,000 kinds. Cocoa beans contain large quantities of flavonoids, and so do red wine, tea, cranberries, peanuts, strawberries, apples and many other fruits and vegetables. The flavonoids in chocolate are called flavonols.

Generally, science has found that dark chocolate is higher in flavonoids than milk chocolate. The way that cocoa powder and chocolate syrups are manufactured removes most flavonoids.

Nitric Oxide

In the first study, researchers gave Boston volunteers cocoa with either a high or low amount of flavonols. Those who drank cocoa with more flavonols showed more nitric oxide activity.

"Nitric oxide plays such an important role in the maintenance of healthy blood pressure and, in turn, cardiovascular health," said lead researcher Dr. Norman K. Hollenberg, physician and professor of medicine at Brigham and Women's Hospital and Harvard Medical School.

The residents of an island called Kuna in Panama prompted Hollenberg's study. These indigenous people rarely develop high blood pressure, although they drink about 5 cups of cocoa each day and include it in many recipes. But if they leave the island, the risk of high blood pressure increases, and studies found it wasn't related to salt intake or obesity.

Next, Hollenberg's team will determine if regulating nitric oxide with flavonols has a positive impact.

"If our research results continue to support a link between consumption of flavonol-rich cocoa and nitric oxide synthesis, there could be significant implications for public health," said Hollenberg.

Promotes Blood Flow

The other study compared how blood platelets responded to a flavonol-rich cocoa drink with 25 grams of semi-sweet chocolate pieces and a blood-thinning, 81-milligram aspirin dose. The research found similar reactions to the two from a group of 20- to 40-year-olds: both the drink and the aspirin prevented platelets from sticking together or clotting, which can impede blood flow.

In other words, flavonol-rich cocoa and chocolate act similarly to low-dose aspirin in promoting healthy blood flow. Reducing the blood's ability to clot also reduces the risk of stroke and heart attacks.

Lead study author Dr. Carl Keen cautioned that his team isn't suggesting that people eat a couple of candy bars instead of taking their daily dose of aspirin.

"We're not advocating that people consume flavonol-rich foods in place of aspirin," stressed Keen, who is also the University of California-Davis nutrition department chairman. For people who cannot take aspirin, however, he said eating flavonol-rich foods "may be a useful approach."

He noted one important difference between aspirin and flavonol-rich foods: "The effects you see in aspirin are longer-lasting than the effects you see in flavonols," he said.

Although the trial involved just 40 people, Keen called the results "remarkably robust" and said the platelet effect may be related to the nitric oxide benefits found by Hollenberg's study.

Keen's team currently has an article under review in which they show a direct comparison to low-dose aspirin using the same study group.

"The next thing on our agenda is to look at chronic effects," said Keen. "What happens when a person has a high flavonol intake for two weeks? Do you still see the same effects? Many times...the body adapts or adjusts and you don't necessarily see the same thing after two or three weeks."

Chocolate's Benefits?

A true chocoholic could do a little research and argue that there are several bioactive compounds in chocolate that promote alertness, lessen pain and promote well-being.

For example, the stimulants theobromine, caffeine, tyramine and phenylethylamine (PEA) provide a much-needed lift. Tryptophan, an essential amino acid, lessens anxiety by producing the neurotransmitter serotonin; endorphins, the body's natural opiates, reduce sensitivity to pain.

Anandamide acts like a cannabinoid to promote relaxation. And last but certainly not least, chocolate is a natural analgesic, and high-fat, chocolate foods trigger the brain's production of natural opiates.

So let's sum up. Chocolate gives you an energy lift, less anxiety, a reduction in pain-who wouldn't recommend something that did all that? Well, a nutritionist or biochemist could argue that chocolate doesn't contain much of these ingredients.

For example, while caffeine does encourage alertness, there is less caffeine in chocolate than there is in a cup of coffee. (There are about 30 milligrams of caffeine in your average chocolate bar, while a cup of coffee contains 100 -150 mgs.)

Another example: PEA causes blood pressure and blood sugar to rise, and you'll feel alert and content for awhile. But those good feelings are likely to be followed by a sugar-induced drop in energy that leaves you more tired than before you ate the candy.

Cannabinoids are substances that mimic marijuana. The chemical in marijuana that makes people "high" - tetrahydrocannabinol (THC) - binds to certain receptors in the brain. The anandamide in chocolate can bind to the same receptors, producing a "high."

Antioxidant Power

Here's an argument you could win with the nutritionist: Studies show that cocoa powder, dark chocolate and milk chocolate have higher Oxygen Radical Absorption Capacity (ORAC) values than many common foods, such as prunes and blueberries. (ORAC values measure how powerful an antioxidant a substance is. An antioxidant is a substance that inhibits oxidation or reactions promoted by oxygen and peroxides, and that include many held to protect the living body from the deleterious effects of free radicals. Examples include beta-carotene, vitamin C, and alpha-tocopherol.

Dark chocolate has more than 13,000 ORAC units and milk chocolate has about 6,700, according to the Chocolate Manufacturers Association in McLean, Va. Unsweetened powdered cocoa starts out with almost twice as much antioxidants as dark chocolate, but when it's diluted with water or milk and sugar to make hot chocolate, the flavonoid total per serving plummets to about half that in milk chocolate.

In different terms, a 40-gram serving of milk chocolate contains about 400 milligrams of antioxidants, the same as a glass of red wine, according to research published by Joe A. Vinson of the University of Scranton, Pa. Vinson's team's results were also supported by ACRI.

Vinson and his colleagues found that the flavonoids in chocolate are more powerful than vitamins such as ascorbic acid in protecting circulating lipids from oxidation. Atherosclerosis studies suggest that oxidation of lipoproteins is part of the process that creates the plaque that clogs artery walls.

"Chocolate just stands out," Vinson said. "It's much higher than anything else."

If that doesn't convince your doctor, try this: researchers from the Harvard School of Public Health found that those who eat chocolate and sweets up to three times each month live almost a year longer than those who eat too much or those who steer clear of junk altogether.

Industry-funded Research

Both studies presented at the February AAAS meeting used an experimental cocoa supplied by Mars Incorporated, and the candy company commissioned the research as well. Mars Incorporated makes M&Ms and Mars, Snickers and Dove bars, among other candies.

For the last few years, Mars Incorporated and the American Cocoa Research Institute (ACRI) in McLean, Va., have jointly funded research to try to find health benefits in the delectable dessert. Mars Incorporated external affairs director Marlene Machut said the studies began as "flavor research" but shifted to health benefits as evidence grew.

One problem with that was alluded to in an AAAS symposium on chocolate held in 2000: Why should consumers trust data on chocolate when it comes from industry-funded research?

"That's a valid question," acknowledged John W. Erdman, professor of food science and human nutrition at the University of Illinois at Urbana-Champaign and cochair of that symposium. But he also said in a recent interview that if the candy industry hadn't funded the research, "it would have been very difficult to get off the ground otherwise."

Erdman said the situation is similar to Quaker Oats' preliminary funding of research that showed oats' lowered serum cholesterol, or to Midwestern soy farmers funding most of the initial studies which showed that proteins and antioxidants in soy fight heart disease. Later clinical research done by independent labs around the world confirmed those smaller studies' conclusions and expanded upon them, he said.

"It's often necessary for a lot of promising, peer-reviewed, industry-financed studies to be done before government steps in with financial support for larger-scale research," Erdman said. "Nowadays the FDA wants preliminary information before they fund a major project."

Rather than questioning the data, Professor Keen believes people should applaud the industry for investigating the nutritional value of their products.

"Responsible food companies have a responsibility to fund research into the potential value of nutrients in those foods," he said. "If [these] companies help fund research at independent campuses and universities, and generate exciting data, that tells the NIH, 'This is a worthwhile area in which to invest precious taxpayer dollars.'"

Conclusive Evidence?

So does chocolate contribute to disease prevention? Should we eat chocolate for its health benefits as well as for its terrific taste?

When asked to choose how far along the preliminary-conclusive continuum this research is, Erdman said, "It's moving along. People are starting to say, 'There's something here.' Scientists are finding similar results with compounds in fruits and vegetables, tea, red wine and tomatoes."

Keen agreed, pointing out that the tea, grape and chocolate industries are just a few of the groups exploring antioxidants' potential benefits.

"I think one should view it from a collective perspective," he suggested. "There are a number of industries with very different types of food products who are saying, 'It looks like these compounds may have some potential health benefits,'" he said.

Of course, people should always be "skeptical" until results are repeated and published in peer-reviewed journals, Keen said.

The USDA Food Composition Laboratory is already sold: They're developing a database reporting the levels of flavonoids in plant foods, and cocoa will be included along with fruits, berries and other foods that provide health benefits, said Machut. In addition, the lab adopted Mars Incorporated's methods for looking at the flavonol levels in food products.

Methods Matter

"The cacao bean and its bran have the highest polyphenol levels," nutritionist Angela Miraglio noted in a May 2001 article in Nutrition Notes. "Processing the beans destroys some polyphenols; temperature, chemical changes and duration of exposure contribute to the loss. So the level of polyphenols in the final product vary. Cocoa processors and chocolate manufacturers are beginning to take precautions to minimize the losses."

Mars recently developed a proprietary method for processing cocoa beans called Cocoapro?, which preserves polyphenols by changing the way the beans are selected, fermented, dried, as well as how they're processed and formulated, said external affairs director Machut. Some Mars candy bars feature the CocoaPro label.

"That's how consumers can identify chocolates that retain much of a cocoa bean's initial flavonoid riches," said Machut.


Both Keen's and Hollenberg's teams plan future research into the benefits of cocoa. As you might expect, Mars Incorporated plans more, too.

But the surest sign of the candy company's faith in its main product is the fact that they're "working with several pharmaceutical companies to isolate and develop cocoa components as cardiovascular pharmaceuticals." In other words, they're trying to develop a drug based on chocolate's cardiovascular health benefits.

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Copyright (c) 2009 David Arthur.

This page was last updated on December 9, 2009