Health by chocolate? Sorry, no

On the surface, it all sounds very promising. Research has suggested that chocolate might be able to reduce blood pressure, improve blood vessel function, keep blood platelets from aggregating and forming clots, and even lower blood cholesterol. In other words, chocolate might be able to reduce the risk of heart disease.

It's the latest incarnation of chocolate, dark chocolate in particular, as a health food. It has already been touted as a cavity preventer, a skin-care product, and everything in between.

None of the earlier claims have ever panned out. Now, the chocolate-heart disease prevention theory has been put to a number of different tests. For instance, in one investigation, the blood pressure of people who were given a daily chocolate ''dose" started falling after just 10 days. In another research project, chocolate appeared to have an effect on blood similar to that of baby aspirin, which some doctors recommend for their patients to prevent blood clotting. Yet another study suggests that chocolate improves blood vessel function by widening arteries.

Still, hold the chocolate bunnies. Despite such findings, the buzz about chocolate's ability to improve heart health is way ahead of the science.

All of the studies to date are small, and none looked at chocolate's ability to stave off a cardiac event such as a heart attack or stroke. Rather, they looked at various biomarkers that suggest but do not prove anything about chocolate's ability to prevent heart disease, death or disability. And they looked at them for only a short period of time -- weeks, days, or even hours.

''It's an intriguing area of scientific inquiry," said Frank Sacks, a Harvard heart disease researcher, but ''consumers should not say, 'I should eat some chocolate because it might be good for my heart.' "

There are still a lot of unknowns. For instance, Sacks said, some studies suggest that compounds in chocolate can relax blood vessel linings, which supposedly would be a good thing for the heart. But, he said, estrogen does the same thing, and while it was thought for decades that the estrogen in hormone replacement therapy protected against heart disease, we now know that estrogen is bad for heart health -- one of the main reasons women are now generally steered away from hormone therapy at menopause.

Harold Schmitz, director of science at chocolate giant Mars Inc., which funds much of the chocolate research, said that, to his knowledge, no long-term clinical trials looking at chocolate are planned, so it would be years, at the earliest, before any bottom-line answers could come in.

Even if chocolate were eventually found to be heart protective, incorporating it into the American diet could worsen the country's obesity problem, and in turn the risk of heart disease. In a country where two in three adults are overweight, the most important thing most people can do for their heart health is to subtract calories from their diets.

Mars notes in press materials that 100 grams of chocolate contain four times the concentration of catechins -- a specific class of antioxidants theorized to benefit the heart -- as a cup of tea. But 100 grams of chocolate have more than 500 calories. Tea has no calories.

In studies suggesting chocolate has a health benefit, researchers take pains to make sure test subjects eating chocolate consume no more calories than participants who don't eat chocolate. But that's not what happens in the real world. ''We're Americans," said Jeffrey Blumberg, director of the Antioxidants Research Lab at Tufts University and an investigator on one of the chocolate studies. ''We don't know how to enjoy quality without quantity."

Much of the reason the hope for chocolate is bigger than concerns about its calories, and bigger than any proof behind claims for its benefits, is the spin Mars has been putting on the science. Schmitz said Mars is ''concerned with any marketing that is misleading to the consumer," and feels it is irresponsible.

But consider a press kit from Mars's public relations firm, Fleishman Hillard, that said a Harvard study ''specifically looked at chocolate consumption and longevity" and found that subjects ''who consumed chocolate at least three times a month lived longer than those who abstained." That is not true. First, the researchers looked at overall candy consumption, noting that they could not tease out chocolate from other types of candy. Second, the results of that research, published in the British Medical Journal in 1998, showed that people who ate candy one to three times a month enjoyed greater longevity than others, but the death rate increased for people who ate candy more often.

Mars also refers to the blood pressure research mentioned earlier as a study when, in fact, it was reported simply as a letter to the editor of a medical journal. That means the research didn't go through peer review so that scientists looking it over could ask questions about methodology -- and keep it from getting published if they felt it wasn't conducted rigorously enough.

Furthermore, Mars is now marketing to both consumers and physicians a chocolate-containing product that it boasts can lower cholesterol. Its evidence -- one unpublished study of the product funded by Mars. Called Cocoa Via, it is more granola bar than chocolate. And while it does contain compounds called phytosterols that have been shown to help keep down blood cholesterol, they are not in chocolate naturally; they have to be added during manufacturing. In fact, instead of eating 180 calories' worth of Cocoa Via bars a day, you can buy phytosterol soft-gel capsules that are virtually calorie-free and confer the same effect.

Even compounds found naturally in chocolate that are being singled out for possible health benefits -- flavonols -- are rarely found in concentrations as high as in the research that points to possible benefits. ''Most people are not getting a flavonol boost" even if they eat dark chocolate, said Mars's Schmitz. Only a couple of products out there are known to have the levels used in research.

Which is part of the reason William Connor, a noted heart disease researcher at Oregon Health and Science University, said that the hype about chocolate ''is misleading the public" and ''deceptive advertising at its worst."

Lawrence Lindner can be reached at lindner@globe.com.