A Friend or Foe: Understanding the Physiological Significance, Therapeutic Uses, and Potential Risks of Glycerophosphocholine—A Narrative Review

Glycerophosphocholine (GPC) is a well-known choline-containing compound commonly found in nature and has demonstrated potential therapeutic effects in aging-related conditions, such as neurodegenerative disorders, skeletal muscle performance, and eye disorders. Despite being widely used as a supplement, the mechanism by which GPC is absorbed and metabolized in the digestive system remains elusive. Furthermore, growing evidence suggests that high intake of choline-containing compounds, including GPC, is linked with trimethylamine N-oxide (TMAO) production, a metabolite associated with atherosclerosis progression. However, there has been an inconsistency that is not commonly discussed, and thus, the adverse effect of TMAO remains debatable. These warrant a better understanding of the physiological significance and metabolism of GPC in the body and how it is linked to TMAO and its potential risk. Through a comprehensive literature search, this narrative review aims to fill these gaps by providing a summary of the physiological significance and supplementation evidence of GPC. Further, the review also highlights the absorption mechanisms and relationship of GPC with intestinal microbiota and its relationship with TMAO production. Lastly, this review addresses and discusses the challenge of GPC supplementation and provides a brief view on future perspectives on GPC as a bioactive compound.