A mid-life crisis for aging theory

From yeast to mice, limiting food intake slows aging and extends lifespan. Activators of the sirtuins, enzymes famously linked to this process, promise a wealth of new drugs, but the sirtuin hypothesis is now coming under fire. The lifespan was dramatically extended in yeast bearing an extra copy of a sirtuin, the conserved enzyme class. Sirtuins have been shown to extend lifespan in many other organisms, but a schism in the field has erupted over the role that these proteins play in the aging process. Sirtuins are responsible for the health, and longevity, enhancing effects of calorie restriction, a treatment that extends healthy lifespan 40% or more in many organisms, including mice and rats. Drugs such as resveratrol and the antidiabetic drug, SRT501 could treat diseases related to aging.