# One-carbon metabolism

One-carbon metabolism is a linked set of chemical cycles (the folate and methionine cycles) that shuttle single carbon atoms around your cells. Your body uses those carbons to build DNA's building blocks, to convert homocysteine back into methionine, and to make SAM (S-adenosylmethionine), the universal 'methyl donor' for tagging DNA, RNA, histones, and fats. The network runs on diet. It draws on folate, choline, betaine, methionine, and vitamins B2, B6, and B12, so its output is sensitive to what you eat. With age, this system can go off-balance, which shows up as high blood homocysteine, broadly under-methylated DNA, and weaker epigenetic upkeep. That ties it directly to two hallmarks of aging: epigenetic changes and genome instability.

## Sources

- Ducker GS, Rabinowitz JD. (2017). One-carbon metabolism in health and disease. Cell Metabolism. https://doi.org/10.1016/j.cmet.2016.08.009
- Mentch SJ, Locasale JW. (2016). One-carbon metabolism and epigenetics: understanding the specificity. Annals of the New York Academy of Sciences. https://doi.org/10.1111/nyas.12956

---

_Canonical: https://longevity-switzerland.com/en/glossary/one-carbon-metabolism · Part of Longevity Cities · Updated 2026-06-22_