Homocysteine

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 [1] [2].
  • Schizophrenia: Homocysteine as gut-microbiome-modulated biomarker for treatment response [3].
  • CRC: Mucosal metabolomics show altered homocysteine pathway [4].
  • ESRD: Homocysteine accumulation in end-stage renal disease with mycobiome alterations [5].

Cross-References

References (5)

  1. Aiping Liu, Wei Zhou, Liuhong Qu et al. (2019). Liu 2019 — Altered Urinary Amino Acids in Children with ASD. Frontiers in Cellular Neuroscience. doi:10.3389/fncel.2019.00007
  2. K.A. Bala, M. Dogan, T. Mutluer et al. (2016). Bala 2016 — Plasma Amino Acid Profile in ASD. European Review for Medical and Pharmacological Sciences
  3. Yuan X, Wang Y, Li X et al. (2021). Gut Microbial Biomarkers for the Treatment Response in First-Episode, Drug-Naive Schizophrenia: A 24-Week Follow-Up Study. Translational Psychiatry. doi:10.1038/s41398-021-01531-3
  4. Loke MF, Chua EG, Gan HM et al. (2018). Metabolomics and 16S rRNA Sequencing of Human Colorectal Cancers and Adjacent Mucosa. PLOS ONE. doi:10.1371/journal.pone.0208584
  5. Yi Ren, Lei Chen, Ruochun Guo et al. (2024). Altered Gut Mycobiome in Patients with End-Stage Renal Disease and Its Correlations with Metabolomes. Journal of Translational Medicine. doi:10.1186/s12967-024-05004-1

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