Dietary Geraniol Helps Relieve Symptoms of Irritable Bowel Syndrome

by | Feb 25, 2019 | 2018, Digestive Health, Irritable Bowel Syndrome

Written by Angeline A. De Leon, Staff Writer. Geraniol improved dysbiosis and significantly improved inflammation in the participating patients with irritable bowel syndrome.

With more than 200,000 cases in the U.S. each year, irritable bowel syndrome (IBS) can be a debilitating disease in that it can directly impact quality of life and productivity 1. Common symptoms of the disorder include abdominal pain, gas, and bloating. Diseases such as gastro-esophageal reflux, non-celiac wheat sensitivity and fibromyalgia may co-exist with IBS 2. Although various mechanisms have been proposed for the pathogenesis of IBS, recent research has identified a key role of gut microbiota dysbiosis, referring to a disturbance in the balance of gut flora 3. IBS dysbiosis can involve, for example, decreases in beneficial bacteria like Lactobacilli and Bifidobacteria bacteria and increases in bacteria associated with disease such as Streptococci 4. Although their mechanism of action is still unclear, essential oil (EO) mixtures demonstrate the ability to modulate gut microbiota, suggesting their potential as a therapy option for IBS 5. In particular, geraniol (ge-OH), a component of EO extracted from lemongrass, rose, and other aromatic plants, shows significant antimicrobial, antioxidant, and anti-inflammatory properties 6 and has been found to improve symptoms of colitis and microbial dysbiosis in mice 7. Oral administration of geraniol also appears to reduce inflammation in the colon specimens of colitic mice 8. In a pilot study 9 conducted by Rizzello and colleagues at the University of Bologna in Italy (2018), the anti-inflammatory and anti-dysbiotic properties of geraniol were tested in a group of IBS patients.

A total of 19 Italian IBS patients (mean age = 38.84 years) were enrolled in an exploratory prospective, non-controlled, open label trial. Subjects underwent a 4-week treatment period in which they were administered geraniol (using a delayed release formulation designed to reach the colon) at a maximum daily dose of 8 mg kg (-1) body weight. At baseline, the end of Week 4, and at a 4-week follow-up, blood and fecal samples were collected for cytokine and microbiota analysis (control group for fecal microbiota analysis based on publicly available rRNA gene sequence data from a group of 12 healthy Italian subjects with a mean age of 33 years). Researchers also administered the Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS) and evaluated IBS symptomology at each time point.

Gut microbiota biodiversity (measured based on Simpson index value) was confirmed to be significantly lower in the IBS group, compared to healthy controls (p = 9 x 10-6). After four weeks of treatment with geraniol, microbiota diversity in IBS patients was seen to increase, although the change failed to reach statistical significance (p = 0.40). Geraniol was associated with a significant increase in relative abundance of Collinsella and Faecalibacterium (p = 0.04 for both), low levels of which are associated with IBS 10,11 and decreased percentages of Bacteroides and Prevotella trending towards significance (p < 0.2). At the end of Week 4, a significant decrease in circulating MIP-1β (a macrophage inflammatory protein found at high levels in IBS patients 12 was also observed (p = 0.032), along with a significant decrease in VAS-IBS score (from 309.95 to 216.47, p < 0.001).

Altogether, evidence from the study supports the therapeutic use of geraniol to improve gut dysbiosis and inflammation in patients with IBS. Treatment with geraniol was found to increase ecosystem biodiversity, specifically promoting the presence of favorable bacteria, Collinsella and Faecalibacterium. Based on observed decreases in MIP-1β, a pro-inflammatory circulating cytokine, geraniol also showed anti-inflammatory effects, consistent with the literature, and appeared to diminish IBS symptomology, according to the VAS-IBS questionnaire. Notable limitations of the study include its relatively small sample size and the absence of a double-blind placebo arm. Nonetheless, as the first study to confirm the clinical utility of geraniol in human subjects with IBS, the study provides novel evidence pointing to the capacity of geraniol to modulate the intestinal microbial ecosystem. Limitations are the potential placebo effect and the absence of a double-blind placebo arm. A placebo controlled study on a larger population is warranted to validate these findings.

Source: Rizzello F, Ricci C, Scandella M, et al. Dietary geraniol ameliorates intestinal dysbiosis and relieves symptoms in irritable bowel syndrome patients: a pilot study. BMC Complementary and Alternative Medicine. 2018; 18: 338. DOI: 10.1186/s12906-018-2403-6.

© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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Posted February 25, 2019.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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