Reported by Kittu Jindal Garg, M.D., ABC News Medical Unit:
If your doctor has said you have prehypertension, he or she likely recommended a low-salt diet and exercise to avoid taking blood pressure medication.
Given a new study's findings of the effects of chocolate on blood pressure, however, some doctors may start prescribing cocoa to patients at risk for hypertension.
But not everyone is convinced that this study, published Tuesday in the Cochrane Library, is the "tipping point" for such a bold move.
The study has little to do with the merits of a favorite candy bar. It looked at the substances in cocoa - flavanols - and their potential benefits for blood pressure.
Flavanols are natural compounds found in cocoa beans, which have been previously proposed as a route to improved heart health. Flavanols are found at varying levels in cocoa products, and studying the amount of flavanol itself rather than the amount of cocoa might be the key.
"Based on this study," said Dr. Randal Thomas, an internist at the Mayo Clinic, "I'll mention to my patients that a small amount of chocolate may help reduce cardiovascular risk by reducing blood pressure."
Keith-Thomas Ayoob, associate professor of pediatrics at Albert Einstein College of Medicine, agreed, saying he would "tell patients that a little - emphasis on little - dark chocolate may be a good thing … and cocoa powder is probably the best way to get their flavanols."
Cardiologist Thomas said that while previous studies had found that chocolate intake was associated with a reduced risk of certain heart-related ills, "this study provides new information that suggests that the mechanism for reducing the risk may be related to its effect on lowering blood pressure."
In the current study, Dr. Karin Ried and colleagues at the University of Adelaide in Australia reviewed 20 studies between 2003 and 2011 to examine the effects of cocoa on blood pressure.
Across these trials, 856 for the most part healthy individuals were given an average of 545.5mg of flavanol. They ingested a certain amount of cocoa contingent on the ideal amount of flavanol daily over a minimum of two weeks, and had their blood pressure checked before and after the study was completed.
What they found was that the people who had been consuming high flavanol-containing cocoa had a two- to three-point reduction in their blood pressure compared with the participants who drank nonflavanol-containing cocoa.
Flavanols form a chemical called nitric oxide in the blood, which is known to relax blood vessels. Several blood pressure medications affect levels of nitric oxide in the blood, which strengthens the case that flavanols are having some kind of therapeutic effect. "It follows sound reasoning that dilated blood vessels could lower blood pressure," Ayoob said.
"[This study] likely represents the best data analysis to date of the topic," said Dr. Scott Wright, cardiologist at the Mayo Clinic. "This has the potential for a significant public health impact, for if further science supports the use of flavanol-enriched foods, we can substitute chocolate for some of the sodium-enriched foods we eat for pleasure and thus improve blood pressure in both ways."
Still, some experts advise caution.
Dr. Carol Horowitz, an internist at Mount Sinai Medical Center, believes the "impact is small and extremely short-lived." She said she would tell her patients to enjoy small amounts of chocolate if it's a food they like, "but eat it if you love it, not because it will make you healthier, as it may not."
"The thorough Cochrane analysis … shows a disappointingly small effect of chocolate consumption on blood pressure," said Dr. Franz Messerli, director of the hypertension program at St. Luke's and Roosevelt Hospitals in New York. "The health benefits of chocolate, similar to those of red wine, may be multifactorial."
But for anyone who is a few blood pressure points shy of hypertension, chocolate might be the answer.
"The drop in blood pressure is not huge, but it's certainly important for people with borderline hypertension," Ayoob said, speculating that adjusting one's diet to exclude salt and include cocoa "might even have enough positive effects to prevent at least some people from needing medication."