The lore surrounding chocolate -- from its use as an aphrodisiac among the Aztecs to its mood elevating properties -- can seem as complex and variable as the confection itself. Scientific studies, however, may provide a prudent excuse to indulge in the sweet treat.
Decades of research have shown that chocolate has several beneficial physiological effects, most notably on heart health.
A new study presented today at the International Headache Congress meeting in Philadelphia suggested that cocoa powder has a healing effect on inflamed cells related to migraine headaches in rats.
But many of the studies on chocolate are inconclusive, showing neither significant health advantages nor disadvantages. And the results of today's IHC study on cocoa powder contradicts previous theories that chocolate triggers migraines in some people.
While research continues, so does chocolate consumption. Parsing chocolate fact from fiction could be the key to guilt-free snacking.
"It's reasonable for a natural food, reasonably unrefined, to have some good qualities to it," said Keith-Thomas Ayoob, director of the nutrition clinic at the Albert Einstein College of Medicine in New York City. "Most people are probably already realizing these benefits."
Dark chocolate, which should be at least 60 percent cocoa by weight, is one of the richest sources of the bioflavonoid antioxidants that counteract cell damage.
Dr. David Katz, director of the Prevention Research Center at Yale University, said part of the reason why so many people love chocolate is because eating it stimulates the brain's pleasure centers. The xanthine compounds in chocolate -- a group of chemicals that includes caffeine -- aid that reaction.
"It's absolutely magic food," Katz said. "Because it's so good, it almost feels a little naughty."
Milk chocolate, which contains a much lower percentage of cocoa, confers less than half of the benefits of dark chocolate and white chocolate has no such health benefits because it lacks cocoa.
And there has been compelling evidence that eating dark chocolate has positive cardiovascular effects. Studies have found that chocolate can lower blood pressure, reduce the risk of blood clots and improve blood flow through veins and arteries in humans.
A study in the September issue of the Journal of Internal Medicine showed that heart attack survivors can reduce their risk of a second heart attack by eating chocolate several times per week.
But experts caution that if chocolate is eaten in large amounts, its fat and calorie content could negate the positive effects of its antioxidants and other chemicals.
"If we're going to make this a 'food as medicine' [issue], the public does need guidance," Katz said. "Some is good for you, more is bad for you ... there is a sweet spot in a certain range, like alcohol."
But some may continue to avoid chocolate due to its reputation for triggering migraines in some people who may be sensitive to the chemicals.
As yet there is no solid evidence of what chocolate's relation is to headache, including today's study from the IHS, an animal study that may not translate to humans and only postulates that the anti-inflammatory properties of cocoa could have an indirect effect on migraine headaches, which is an inflammatory disease.
But new theories about what causes migraines could do something to relieve the notoriety chocolate has gained in the field.
"If we go back and look at what we assume would trigger a migraine, a lot of those things were not triggers at all but were, in the case of food, cravings that occurred as part of the migraine but were misinterpreted as the cause," said Dr. Joel Saper, director of the Michigan Headache and Neurological Institute..
In other words, eating chocolate an hour before an imminent migraine might lead a person to believe that the chocolate caused the migraine.
"The human body might crave things because we know it will alleviate [pain]," said Paul Durham, director of the Center for Biomedical and Life Sciences at Missouri State University and author of the study on cocoa powder preventing cellular inflammation in rats. "When we tried to stimulate the [pain] nerves, compounds or chemicals in cocoa might block that pain."
Doctors aren't prescribing chocolate bars to heart patients or migraine sufferers yet, but Katz said he can envision a recommendation to habitually eat dark chocolate.
"It's not just giving people a license to do what they're already doing," Katz said. Americans already eat about 12 pounds of chocolate per year, most of which is the less beneficial milk chocolate. "But if they need a nudge to switch over to the dark side, this is a place science provides us to go."
No guidelines have yet been determined about how to consume dark chocolate to maximize the health benefits. It is not clear how often and how much chocolate people should eat before the excess calories, sugar and subsequent weight gain becomes a problem, and this is one area where research could move forward.
Other areas for further research include expanding on some preliminary studies on how the antioxidants in chocolate could be harnessed to fight chronic diseases and cancer, as well as how food combinations -- like chocolate eaten with fruits and nuts -- might affect health.
"This is tougher because there are no surrogate markers [of improvement] like there are with heart studies," Katz said. "In general, foods that are good for us are really just foods that are good for us and you can't take care of just one organ at a time. If you're cultivating health, you are reducing the risk of all the bad stuff."