Lifespan: Why We Age—and Why We Don't Have To

Lifespan argues that aging is a single underlying condition rather than a collection of separate diseases, and that the condition is a loss of information. Sinclair's information theory of aging holds that the genome is the digital data and the epigenome the analog reader, that the reader degrades as cells repeatedly respond to damage, and that if the lost instructions can be preserved or restored, aging can be slowed and possibly reversed in part.

The supporting mechanisms run through sirtuins, NAD+ availability and the enzymes that consume it, and through cellular reprogramming — the observation that partially resetting a cell's epigenetic state can restore youthful gene expression and function in animal models. Sinclair also makes the case that aging should be classified and treated as a disease, and describes his own regimen of NMN, resveratrol and metformin.

It is written for a general reader and it is, whatever else is true of it, an unusually effective piece of science communication. It brought a serious research question to a large audience.

On evidence, precision matters here. The epigenetic framing and the reprogramming work are genuinely interesting and continue to be pursued by many independent laboratories. Other central claims are contested. The resveratrol findings that made Sinclair's name — the case for it as a direct sirtuin activator — have been challenged on methodological grounds and have not replicated cleanly, and the human data on resveratrol supplementation is unimpressive. NMN and NAD+ precursors raise NAD+ levels in humans but have not been shown to extend healthspan or lifespan in people. Metformin's role as a longevity drug is still being tested rather than established. The book's confidence about translation to humans runs ahead of the clinical data, and Sinclair holds commercial interests in the sector. Read it for the hypothesis; treat the supplement recommendations as untested.