Overview
Homocysteine is a sulfur-containing amino acid intermediate in the methionine cycle. Elevated plasma homocysteine (hyperhomocysteinemia) is an established risk factor for cardiovascular disease, endothelial dysfunction, and neurodegenerative disease. The gut microbiome modulates homocysteine metabolism through B-vitamin (B12, folate, B6) production, methionine cycling, and one-carbon metabolism.
Microbiome Connection
- B12/folate production: Gut bacteria (Bifidobacterium, Lactobacillus, Propionibacterium) synthesize B12 and folate — essential cofactors for homocysteine remethylation to methionine. Dysbiosis-driven loss of B-vitamin producers increases homocysteine levels.
- ASD: Altered urinary amino acid profiles including homocysteine pathway metabolites liu 2019 urinary amino acids asd biomarkers bala 2016 plasma amino acid profile asd.
- Schizophrenia: Homocysteine as gut-microbiome-modulated biomarker for treatment response yuan 2021 gut microbial biomarkers treatment response schizophrenia.
- CRC: Mucosal metabolomics show altered homocysteine pathway loke 2018 metabolomics 16s crc mucosa.
- ESRD: Homocysteine accumulation in end-stage renal disease with mycobiome alterations ren 2024 altered gut mycobiome esrd metabolomes.
Cross-References
- vitamin b12 — essential cofactor for homocysteine remethylation
- cardiovascular disease — homocysteine as CVD risk factor
- endothelial dysfunction — homocysteine-mediated endothelial damage
- oxidative stress — homocysteine generates ROS via auto-oxidation