In recent years resveratrol has clearly fallen below the dividing line for work that is useful from a longevity perspective - if it could extend life significantly in mice, that would have been demonstrated by now. You might compare with the size of the effects on mouse lifespan for rapamycin to provide an example of a compound that is worth investigating. There is, however, a lot of money sunk into work on resveratrol and the underlying mechanisms of sirtuins, so don't expect that to halt any time soon. Research and developer institutions are prone to inertia, just like all other fields of human endeavor. In any case, here is some of the latest work on SIRT1: "If resveratrol needs SIRT1 to improve health, then animals lacking the gene should not get any benefits from the chemical. His lab published that experiment in yeast in 2003. But mice lacking SIRT1 die in the womb, or they are born with developmental defects such as blindness. To get around that problem, [researchers] engineered 'conditional knockout' mice whereby SIRT1 can be inactivated in adulthood. ... It took us two weeks to do the experiment in yeast, and five years in mouse, but finally we're there ... In normal mice, resveratrol combated the effects of a high-fat diet by boosting the efficiency of energy-generating organelles called mitochondria in skeletal muscle tissue. This effect vanished in adult mice without a working version of SIRT1. Yet SIRT1 wasn't responsible for all the beneficial effects of resveratrol ... Resveratrol stabilized the blood glucose levels of both normal and SIRT1-lacking mice on fatty diets. The chemical also improved liver health in mice without SIRT1. [The researchers also contend] that a lot the confusion over how resveratrol works comes down to dosage. At very high doses it binds other proteins besides SIRT1 ... For instance, a signalling protein called AMPK is also important to resveratrol's beneficial effects on metabolism. ... low doses of resveratrol boosted AMPK levels in various cells that expressed SIRT1, but not cells without the sirtuin. Much higher doses of resveratrol, however, activated AMPK irrespective of whether the cells expressed SIRT1."