Reversal of visceral hypersensitivity in rat by Menthacarin ® , a proprietary combination of essential oils from peppermint and caraway, coincides with mycobiome modulation

Neurogastroenterol Motil. 2018 Jun;30(6):e13299. doi: 10.1111/nmo.13299. Epub 2018 Jan 31.


Background: Irritable bowel syndrome (IBS) is a common gastrointestinal disorder associated with altered gastrointestinal microflora and increased nociception to colonic distension. This visceral hypersensitivity can be reversed in our rat maternal separation model by fungicides. Menthacarin® is a proprietary combination of essential oils from Mentha x piperita L. and Carum carvi. Because these oils exhibit antifungal and antibacterial properties, we investigated whether Menthacarin® can reverse existing visceral hypersensitivity in maternally separated rats.

Methods: In non-handled and maternally separated rats, we used the visceromotor responses to colorectal distension as measure for visceral sensitivity. We evaluated this response before and 24 hours after water-avoidance stress and after 7 days treatment with Menthacarin® or control. The pre- and post-treatment mycobiome and microbiome were characterized by sequencing of fungal internal transcribed spacer 1 (ITS-1) and bacterial 16s rDNA regions. In vitro antifungal and antimicrobial properties of Menthacarin® were studied with radial diffusion assay.

Key results: Menthacarin® inhibited in vitro growth of yeast and bacteria. Water-avoidance caused visceral hypersensitivity in maternally separated rats, and this was reversed by treatment. Multivariate analyses of ITS-1 and 16S high throughput data showed that maternal separation, induced changes in the myco- and microbiome. Menthacarin® treatment of non-handled and maternally separated rats shifted the mycobiomes to more similar compositions.

Conclusions & inferences: The development of visceral hypersensitivity in maternally separated rats and the Menthacarin® -mediated reversal of hypersensitivity is associated with changes in the mycobiome. Therefore, Menthacarin® may be a safe and effective treatment option that should be tested for IBS.

Keywords: IBS; abdominal pain; bacteria; fungi; microbiome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Anti-Bacterial Agents / administration & dosage
  • Anti-Bacterial Agents / isolation & purification
  • Antifungal Agents / administration & dosage
  • Antifungal Agents / isolation & purification
  • Drug Combinations
  • Hyperalgesia / drug therapy*
  • Hyperalgesia / microbiology
  • Hyperalgesia / psychology
  • Male
  • Maternal Deprivation
  • Mentha piperita
  • Mycobiome / drug effects*
  • Mycobiome / physiology
  • Oils, Volatile / administration & dosage*
  • Oils, Volatile / isolation & purification
  • Plant Oils / administration & dosage*
  • Plant Oils / isolation & purification
  • Rats
  • Rats, Long-Evans
  • Visceral Pain / drug therapy*
  • Visceral Pain / microbiology
  • Visceral Pain / psychology


  • Anti-Bacterial Agents
  • Antifungal Agents
  • Drug Combinations
  • Oils, Volatile
  • Plant Oils
  • peppermint oil
  • caraway oil