Moderate Amounts May Help Heart Health and More, Researchers Find
By Kathleen Doheny
WebMD Health News
Reviewed by Brunilda Nazario, MD
March 29, 2012 (San Diego) -- Chocolate is increasingly shedding its reputation as a sweet treat only. More research is uncovering health benefits when the dark stuff is eaten in moderation.
At the annual meeting of the American Chemical Society here, a three-hour symposium was devoted to cocoa science and technology. Cocoa researchers from around the world gathered to share their latest findings, passing chocolate bars around the audience as they talked science.
Here is an update on questions chocolate lovers may have.
While some heart benefits of chocolate are solid, others are still under debate, says Eric Ding, PhD, instructor of medicine and nutritional epidemiologist at Harvard Medical School. At the symposium, he discussed his review of 24 published studies on chocolate.
The studies included more than 1,100 people. Researchers looked at how their chocolate-eating habits affected their heart disease risk factors such as high blood pressure.
"The blood pressure-lowering effect is well known," he says. His team found that, on average, systolic blood pressure declined slightly, less than two points on average, in chocolate eaters. Systolic blood pressure is the top number of a blood pressure measurement, and in people older than 50, this can be a stronger risk factor for heart disease than the lower, or diastolic, measurement.
There is also solid evidence that chocolate can increase HDL or "good" cholesterol, Ding and his colleagues found. In general, the lower your LDL and the higher your HDL, the better your chances of preventing heart disease and other chronic conditions.
With chocolate, insulin resistance improved, a benefit if you have diabetes or want to avoid it, Ding says.
Blood flow also improved with a bit of chocolate, another benefit, he says.
"Altogether the results suggest strong benefits against cardiovascular disease," Ding tells WebMD.
The report is published in TheJournal of Nutrition.
Other studies on the health benefits of chocolate are in earlier phases and are preliminary.
Chocolate may help those with type 2 diabetes minimize the ill effects of high blood sugar levels after eating, says Stephen L. Atkin, MD, a researcher at the Hull York Medical School in the U.K. He gave 10 patients with type 2 diabetes small amounts of chocolate an hour before he gave them glucose to simulate a meal.
He found improvements in their blood vessel functioning, which in turn could help reduce heart disease risk.
Chocolate may help patients with congestive heart failure, says Francisco Villarreal, MD, PhD, a professor at the University of California, San Diego, who also spoke at the symposium. In congestive heart failure, the heart doesn't pump enough blood to meet the body's needs.
In a small study with five patients, he gave them about 100 milligrams of a flavonol called epicatechin, found in chocolate, every day for three months.
He measured a substance called nitric oxide, which regulates the contractibility of the blood vessels and affects blood pressure. He found "a very significant increase" in nitric oxide levels.
Other research, which has not yet progressed to people, is looking at the potential of chocolate to treat migraine as well as inhibit colon cancer.
The cocoa scientists think not. They've formed the International Society of Chocolate and Cocoa in Medicine. It has scheduled its first international meeting for 2012.
A flavonol called epicatechin, an antioxidant, turns up in much chocolate research.
"The flavonol epicatechin warrants further study,'' Villarreal says. It seems to have an effect on the powerhouse of the cell, known as the mitochondria. "Many diseases, including Alzheimer's, seem to have a mitochondrial component," he says.
He suspects the antioxidant properties aren't the whole reason epicatechin has benefits.
The doses used in studies are all over the place. However, scientists involved in cocoa research seem to love the words "in moderation." At this point, there is no established serving size of chocolate for heart health. A moderate portion size of chocolate is about 1 ounce.
In his studies, Villarreal has found that half a square is the ''sweet spot" for good effects.
Dark chocolate is most often studied and found to have health effects.
A serving a day would be considered moderate, says Rene D. Massengale, PhD, a food chemist in Bloomington, Ind., and a spokesperson for the Institute for Food Technologists. She reviewed the findings but was not involved in the research. She has consulted in the past for Hershey's.
Perspective is crucial, she says. "Eating a lot of chocolate because you think you are going to get the health benefit, but having a 3,000-calorie diet, is not going to do you any good," she tells WebMD.
Eating chocolate definitely won't lower your body mass index (BMI), Ding tells WebMD. He disputes the conclusion of a research letter published this week in the Archives of Internal Medicine, finding that regular chocolate eaters have lower BMIs.
His review of 24 rigorous studies, he says, finds no effect. "The cocoa flavonoids absolutely yield no BMI or weight change," he says.
And those chocolate bars that were passed around at the meeting?
By any chocolate lover's standard, they would have to be described as teeny.
SOURCES: Shrime, M. The Journal of Nutrition, Nov. 1, 2011.Golomb, B. Archives of Internal Medicine, March 26, 2012.American Chemical Society annual meeting, San Diego, Calif., March 25-29, 2012.Eric Ding, PhD, nutritional epidemiologist and instructor of medicine, Harvard Medical School, Boston.Stephen L. Atkin, MD, researcher, Hull York Medical School, U.K.Francisco Villarreal, MD, PhD, researcher, University of California, San Diego.
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