By LEE BOWMAN,
Scripps Howard News Service
BOSTON (February 17, 2002 9:04 a.m. EST) - There's more evidence that cocoa rich in cholesterol-battling antioxidants helps ward off some of the factors associated with heart attacks and stroke, scientists lecturing here Friday during the annual meeting of the American Association for the Advancement of Science said.
The antioxidants in chocolate are called flavonoids, potent plant compounds also found in tea, red wine and some fruits and vegetables. Studies show that flavonoids slow the processing of "bad" LDL cholesterol into material that clogs the arteries, and at the same time make blood platelets less likely to clump and cause clots.
"What we're finding, though, is that all flavenoids are not created equal. There are some foods that are richer in them, and seem to be more biologically active, and cocoa is right up there," said Carl Keen, chairman of the nutrition department at the University of California-Davis.
Keen compared the reactions of platelets to a flavanol-rich cocoa drink and a blood-thinning, 81-milligram dose of aspirin, and found similar reactions in a group of 20- to 40-year-olds.
"What we don't know is just what the dose-effect of this might be over a longer period of time," Keen said. "We have some research that shows eating foods high in flavanols is good for the arteries, but we don't yet know what the minimum amount is you can consume to have the effect you want, or what happens if you consume at these levels for weeks or months."
Another chocolate researcher, Dr. Norman Hollenberg of Brigham and Women's Hospital here, reported findings that flavanols may be associated with controlling another chemical that regulates the arteries, nitric oxide.
The compound is critical for healthy blood flow and pressure, Hollenberg said. "If our research results continue to support a link between consumption of flavanol-rich cocoa and nitric oxide
synthesis, there could be significant implications for public health." Both Keen and Hollenberg used a special experimental cocoa supplied by the Mars candy company that is not yet available to the public.
Dark chocolate, which is typically a bit more expensive and not quite as sweet, is richest in flavonoids because of the way it's processed. Milk chocolate, which also has added butterfat, contains fewer flavonoids, while cocoa powder and chocolate syrups are currently processed with a method that removes most of the flavonoids.
As far as the fat in dark chocolate goes, it's mostly a saturated vegetable fat that behaves in an artery-friendly way, like olive and canola oils. Hollenberg began studying the effects of cocoa as part of a high blood pressure study on members of the Kuna tribe of Panama. He noted that members of the tribe who lived on the isolated islands almost never developed hypertension as they aged, while those who moved to urban Panama City did develop age-related high blood pressure. His team learned that in their homelands, the Kuna consume large amounts of cocoa.
And it was observed that the island-dwelling Kuna had significantly higher levels of nitrite-nitrate in their blood, which helps keep pressure down.
Back in Boston, people in a study group have nitric oxide numbers pretty much like those seen in the urban-dwelling Kuna. Hollenberg's team tried having them consume either high-flavanol or low-flavanol cocoa, and saw a significant response in the nitric oxide flow over a short time.
Now the scientists are preparing for a more specific study of the active ingredient of the compounds to conclusively determine if regulating nitric oxide with flavanols has a positive impact.
Keen noted that while early studies of flavanols showed they were beneficial, "it's only been in the last few years that we've been able to isolate some of the active components of flavanols and do the biochemistry that's needed to understand the mechanisms.
"Of course, it's still possible that flavanols are greater than the sum of their parts, and that they work well in the blood precisely because they are together," Keen said.
