Metformin decreases bacterial trimethylamine production and trimethylamine N-oxide levels in db/db mice

Janis Kuka (Coresponding Author), Melita Videja, Marina Makrecka-Kuka, Janis Liepins, Solveiga Grinberga, Eduards Sevostjanovs, Karlis Vilks, Edgars Liepinsh, Maija Dambrova

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


The current study aimed to explore whether metformin, the most widely prescribed oral medication for the treatment of type 2 diabetes, alters plasma levels of cardiometabolic disease-related metabolite trimethylamine N-oxide (TMAO) in db/db mice with type 2 diabetes. TMAO plasma concentration was up to 13.2-fold higher in db/db mice when compared to control mice, while in db/db mice fed choline-enriched diet, that mimics meat and dairy product intake, TMAO plasma level was increased 16.8-times. Metformin (250 mg/kg/day) significantly decreased TMAO concentration by up to twofold in both standard and choline-supplemented diet-fed db/db mice plasma. In vitro, metformin significantly decreased the bacterial production rate of trimethylamine (TMA), the precursor of TMAO, from choline up to 3.25-fold in K. pneumoniae and up to 26-fold in P. Mirabilis, while significantly slowing the growth of P. Mirabilis only. Metformin did not affect the expression of genes encoding subunits of bacterial choline-TMA-lyase microcompartment, the activity of the enzyme itself and choline uptake, suggesting that more complex regulation beyond the choline-TMA-lyase is present. To conclude, the TMAO decreasing effect of metformin could be an additional mechanism behind the clinically observed cardiovascular benefits of the drug.

Original languageEnglish
Article number14555
JournalScientific Reports
Issue number1
Publication statusPublished - 1 Dec 2020


  • L-carnitine
  • intestinal microbiota
  • gamma-butyrobetaine
  • metabolism
  • choline
  • phosphatidylcholine
  • metagenome

Field of Science*

  • 3.1 Basic medicine

Publication Type*

  • 1.1. Scientific article indexed in Web of Science and/or Scopus database


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