Napa, Calif. -- Dr. Roger Corder's book, The Red Wine Diet, shakes up the discussion about what it is in wine that provides the often-observed protection against heart disease, diabetes and other illnesses. While much of the discussion in the wine world in recent years has been about resveratrol as the key healthful ingredient, Corder makes the case for another compounds, procyanidins.

While it's been reported that resveratrol reduces heart problems in laboratory rats, Corder says that finding is based on rats consuming amounts of resveratrol that humans will not be able to replicate by drinking wine. "Resveratrol in the amount of wine that people typically consume is inert in our systems," he said during a lunch at The Hess Collection Winery to promote the U.S. release of his book.

The lab rats typically consumed 1.5 grams per day of resveratrol, while the amount in wine varies from about 1 to 2 milligrams per bottle, or .1% of that given to the rats.

Corder is a professor of experimental therapeutics at the William Harvey Research Institute in London, and has studied cardiovascular function and the link between diabetes and heart disease for 25 years. His initial results on the topic were published in the respected journal Nature in 2001, and The Red Wine Diet was released last year in the United Kingdom.

The book cover and title invite the impression that it's another pop diet plan, yet the book carefully details the research that led him to conclude that yes, red wine does have more heart healthy properties than white wine and rosé; that it comes from the red polyphenols that give wine color and much of its flavor; and further, that certain types of red wine contain more of the polyphenols called procyanidins that he found to be critical in the human body.

His work narrows the "French Paradox," and may weaken the widely held view that it is primarily the alcohol in wine that gives the biggest heart-protection benefit. The French Paradox, made famous by a "60 Minutes" television report in 1991, offered regular red wine consumption as the main reason why French people who eat lots of animal fat and may have other "bad" habits had a much lower heart disease incidence than Americans and many other populations.

Corder said he began his research by identifying regions of the world where people lived the longest, and soon zeroed in on the Gers area in the southwest of France, where despite diets heavy with cassoulet, foie gras and other foods full of artery-clogging animal fat, the local population lives very long lives. Gers has double the national average of men aged 90 or more, Corder found. And what wine do they drink?

"The wines are the most procyanidin-rich I have encountered," he wrote. "The explanation seems to be the Tannat grape, which is grown widely here."

Malbec wines, especially grown at high altitudes, are also high in procyanidin, and so can be Cabernet Sauvignon, again especially if it's mountain grown, and not overly ripened. The "soft" tannins that often lead to the highest ratings for California wines don't have as much of the health-giving polyphenols as Cabernets harvested at more traditional, lower sugar levels, he said.

The Red Wine Diet also stresses moderation and a balanced diet, including foods and other beverages that are high in procyanidins. The book is published by Avery, and is available in soft cover at $15.95. See the-red-wine-diet.com for more details.