I take 1 gram (1,000 mg) of NMN every morning, along with 1 gram of resveratrol (shaken into my homemade yogurt) and 1 gram of metformin.7 • I take a… - David A. Sinclair

Trading reproduction for repair, the sirtuins order our bodies to "buckle down" in times of stress and protect us against the major diseases of aging: diabetes and heart disease, Alzheimer's disease and osteoporosis, even cancer. They mute the chronic, overactive inflammation that drives diseases such as atherosclerosis, metabolic disorders, ulcerative colitis, arthritis, and asthma. They prevent cell death and boost mitochondria, the power packs of the cell. They go to battle with muscle wasting, osteoporosis, and macular degeneration. In studies on mice, activating the sirtuins can improve DNA repair, boost memory, increase exercise endurance, and help the mice stay thin, regardless of what they eat. These are not wild guesses as to their power; scientists have established all of this in peer-reviewed studies published in journals such as Nature, Cell, and Science.

Over fifty years, Goldman estimated, the potential economic benefits of delayed aging would add up to more than $7 trillion in the United States alone. And that's a conservative estimate, based on modest improvements in the percentages of older people living without a disease or disability. Whatever the dollar figure, though, the benefits "would accrue rapidly," Goldman's team wrote, "and would extend to all future generations,"

A study of more than 41,000 metformin users between the ages of 68 and 81 concluded that metformin reduced the likelihood of dementia, cardiovascular disease, cancer, frailty, and depression, and not by a small amount. In one group of already frail subjects, metformin use over the course of nine years reduced dementia by 4 percent, depression by 16 percent, cardiovascular disease by 19 percent, frailty by 24 percent, and cancer by 4 percent.22 In other studies, the protective power of metformin against cancer has been far greater than that.