Dr. Christoph Westphal, Sirtris’s chief executive, replied to this objection with a question: “Is it too good to be true that when you are young you get no disease?”

He believes that activation of the sirtuins is what keeps the body healthy in youth, but that these enzymes become less powerful with age, exposing the body to degenerative disease. That is the process that he says is reversed by resveratrol and, he hopes, by the more powerful sirtuin-activator drugs that his company is developing, though many years of clinical trials will still be needed to demonstrate whether they work and are safe to use.

The developing buzz over sirtuin activators has captivated some scientists who do research on the aging process, several of whom are already taking resveratrol themselves. Dr. Sinclair has said that he has been swallowing resveratrol capsules for three years, and that his parents and half his lab staff do the same.

So does Dr. Tomas Prolla at the University of Wisconsin. “The fact that investigators in the field are taking it is a good sign there is something there,” he said.

But many others believe taking the drug now is premature, including Dr. Leonard Guarente of M.I.T. whose 15-year study of the sirtuins laid the basis for the field of study. It was after working in Dr. Guarente’s lab as a postdoctoral student that Dr. Sinclair found in 2003 that resveratrol was a sirtuin activator.

Though resveratrol has long been known to be a component red wine and other foods, it is present there in only minuscule amounts, compared with the very large doses used in experiments. Dr. Sinclair dosed his mice daily with 22 milligrams of resveratrol for each kilogram of weight, and Dr. Auwerx used up to 400 milligrams. No one could drink enough red wine to obtain such doses.

Resveratrol is now available in capsules that contain extracts of red wine and giant knotweed, a plant found in China. One manufacturer of such capsules is Longevinex, whose president, Bill Sardi, said today that demand for the product had increased by a factor of 2400 since Nov. 1. But even Longevinex’s capsules, which at present contain 40 milligrams of resveratrol each, would have to be gulped in almost impossible quantities for a human to obtain doses equivalent to those used in mice. “It’s like eating a whole bottle of Tums every day,” Dr. Evans said.