Dietary Glycine Supplementation Extends Lifespan of Genetically Heterogeneous Mice

Preliminary experiments suggested lifespan extension by glycine supplementation (GlyS) without the growth inhibition seen with methionine restriction in Fisher 344 rats. This suggested that the benefit GlyS, rather than owing to increased methionine clearance (as was originally envisioned), was attributable to increased levels of glycine itself, acting via the glycine receptor. The glycine receptor is a glycine-gated chloride channel that is widespread among cell types, including macrophages, and GlyS has been shown by others to exhibit anti-inflammatory and anti-cancer properties in several rodent models, and even to reverse Type 2 diabetes in a human trial. GlyS has also recently been found by others to restore the youthful mitochondrial phenotype in senescent cultured human fibroblasts, whose senescence was linked to epigenetic down-regulation of the principal pathways of endogenous glycine synthesis. The present study set out to replicate the life extension previously observed in rats, in large, repro...