The query under way in the nutrition world is, how great are grapes?

Resveratrol, found in grape skins and red wine, has stirred interest in animal studies that show potential to lengthen life span, reduce heart disease, counter cancer, and prevent neurological disorders, among other health benefits.

While some critics dispute its potential for humans, research is planned to see whether the polyphenol -- a chemical substance in plants that also exists in peanuts, mulberries and knotweed -- has the same impact in people as occurs in yeast, worms, rats and apes.

And should resveratrol match its advertisements, Pittsburgh could become the seat of research and the center for development of supplement forms that include other polyphenols to multiply the effects of red wine on human health.

"I think this is the most interesting and compelling story of our adult lives," said Dr. Bryan Donohue, chief of the Division of Cardiology and medical director of the Cardiac Catheterization Laboratory at UPMC Shadyside. "There's an incredibly auspicious group of people, all accomplished in their own gigs, who have come together because of a mutual interest in resveratrol. However this comes out, it will have a Pittsburgh stamp on it."

Dr. Donohue said he's ready to begin human clinical trials on resveratrol's impact on heart contractions and heart disease.

Another local player is Dr. Joseph Maroon, a University of Pittsburgh Medical Center neurosurgeon, whose new book, "The Longevity Factor: How Resveratrol and Red Wine Activate Genes for a Longer and Healthier Life," acknowledges its potential to extend life span. Atria Books is the publisher.

"The longevity factor may literally have been under our noses all the time and activated in the very same plants with which we have coexisted and coevolved for millions of years," his book's introduction says. "This is one of the most absorbing stories in contemporary biology and the latest chapter in that search, and in the exciting emerging research that may significantly contribute to a longer, stronger and healthier human life span."

But not everyone agrees, due in part to high quantities of resveratrol used in animal studies, the lack of human clinical trials, dosage uncertainty and the small percentage of resveratrol that ends up in the blood when taken orally. Dr. Maroon said blood levels are low because it goes straight from the gut into the liver, where it produces metabolites.

Roger Mason of Youngagain.com, a supplement retailer who says he sells only supplements supported by scientific evidence, describes resveratrol as "useless junk with zero science based on overdosed rats." Noting high prices for low concentrations of the supplement, he said the growing market for resveratrol might exploit people's hopes for profit.

But Dr. Maroon, former president of the Congress of Neurological Surgeons and team neurosurgeon for the Pittsburgh Steelers, said he helped conduct one of the first human trials in May that provided resveratrol, quercetin and other grape polyphenol compounds to 90 sedentary adults. Results of the blind study, presented to the American College of Sports, showed the mixture improved endurance, verbal memory and reaction time.

Dr. Maroon said resveratrol shows no toxicity nor problems with human tolerance. He's been taking 500 milligrams of it each day for two years, while Dr. Donohue said he takes 1,000 milligrams a day.

Dr. Maroon, 68, has competed in more than 50 triathlons, including three Ironman Championships in Hawaii. He said resveratrol seems to have enhanced his memory, endurance and reaction time.

"For yeast, worms and mice and all species tested, it shows positive results," he said. "It's not a stretch that we will see the same effects in humans, but that clearly needs to be proven in human studies."

In laboratory tests resveratrol prevented development of various types of cancer and reduced plaque buildup in arteries and inflammation, which could make it valuable in treating Alzheimer's and diabetes.

But its greatest potential is longevity through the same mechanism as calorie restriction. Both reportedly activate the SIRT1 gene in mammals to lengthen life span.

Dr. Maroon's book offers history, research, pros and cons of resveratrol and an evaluation of available products. Careful not to encourage alcohol abuse, he recommends a daily glass of wine to benefit health.

Resveratrol's potential has prompted a Pittsburgh-based company, Xenomis, to develop a supplement that combines a form of resveratrol with other polyphenols. The company plans to sell the supplement online in coming months. Dr. Donohue said he's involved with the company.

"There are reasons to be hopeful that this line of natural therapy addresses aspects of illness that had not been perfectly addressed through traditional means," he said.