The treatment of small intestinal bacterial overgrowth with enteric-coated peppermint oil: a case report - Peppermint Oil

Alternative Medicine Review,  Oct, 2002  by Alan C. Logan,  Tracey M. Beaulne

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Abstract

Recent investigations have shown that bacterial overgrowth of the small intestine is associated with a number of functional somatic disorders, including irritable bowel syndrome (IBS), fibromyalgia, and chronic fatigue syndrome. A number of controlled studies have shown that enteric-coated peppermint oil (ECPO) is of benefit in the treatment of IBS. However, despite evidence of strong antimicrobial activity, ECPO has not been specifically investigated for an effect on small intestinal bacterial overgrowth (SIBO). A case report of a patient with SIBO who showed marked subjective improvement in IBS-like symptoms and significant reductions in hydrogen production after treatment with ECPO is presented. While further investigation is necessary, the results in this case suggest one of the mechanisms by which ECPO improves IBS symptoms is antimicrobial activity in the small intestine.

(Altern Med Rev 2002;7(5):410-417)

Introduction

The small intestinal microflora of a healthy adult normally contains relatively small numbers of microorganisms. Total counts are generally [10.sup.4] or less/mL of fluid, except for the distal ileum where the numbers can rise to [10.sup.6] per mL. (1) Small intestinal bacterial overgrowth (SIBO) has been described as any condition in which the proximal part of the small intestine contains greater than [10.sup.5] microorganisms per mL for extended periods. (2) Direct measurement of microbial numbers in the small intestine is difficult and invasive so other methods of detection such as the lactulose hydrogen breath test (LHBT) have become relatively reliable indicators. (3-6) Lactulose is a non-absorbable disaccharide fermented by intestinal bacteria causing hydrogen production.

Expansion of colonic bacteria into the small intestine is often due to intestinal stasis and/ or hypochlorhydria. (7) The elderly, in particular, can be susceptible to SIBO due to both a lack of gastric acid (8) and the consumption of a disproportionately large number of drugs that can cause hypomotility. (9) Symptoms of SIBO can resemble those of irritable bowel syndrome (IBS) and functional dyspepsia (such as bloating, diarrhea, abdominal pain, and constipation), (10) and symptoms commonly observed in chronic fatigue syndrome (CFS) (11) and fibromyalgia (FM). (12) Patients with SIBO can have difficulty with proper absorption of proteins, fats, carbohydrates, and B vitamins and other micronutrients due to bacterial interference. (13-16) Excess bacteria can successfully compete for nutrients, produce toxic metabolites, and cause direct injury to enterocytes in the small intestine. (2)

The presence of SIBO has been investigated in three distinct but overlapping illnesses known as functional somatic disorders: IBS, FM, and CFS. In the case of IBS (n=202), 78 percent of subjects had bacterial overgrowth as measured by the LHBT. (10) In a separate study, FM patients (n=123) had the same high rate of SIBO at 78 percent, (17) and in a third study 77 percent of CFS patients (n=31) were diagnosed with SIBO. (18) In all three studies antibiotics were administered to patients with SIBO, leading to marked subjective improvements in about half of those with overgrowth. Eradication of bacteria was measured by LHBT approximately 10 days after a course of antibiotics (most often Ciprofloxacin 500 mg po bid or Flagyl 500 mg po tid, for 10 days). Successful eradication of SIBO was significantly correlated with a reduction in gastrointestinal complaints. Interestingly, in the CFS study, eradication led to significant improvements in memory, concentration, pain, and depression. Decreased nutrient levels have been observed among CFS patients (19) and SIBO may be a contributing factor.

The similar rates of SIBO across all three patient populations are not entirely surprising given the clinical overlaps. (20) Research shows that 92 percent of CFS patients and 77 percent of FM patients have a history of IBS. (21) Patients reporting chronic fatigue (not the syndrome) have a high rate of IBS (73%), according to a one-year retrospective study. (22) A separate study found that 70 percent of FM patients had IBS and 65 percent of IBS patients met FM criteria, leading the authors to suggest they are different expressions of a common pathogenic process. (23) Indeed, a delay in gastric emptying has been observed in both IBS (24) and CFS. (25) Intestinal microbial overgrowth may play a direct role in altering intestinal transit via an effect on the migrating myoelectric complex, which controls transit time. (26)

The Potential of Enteric-Coated Peppermint Oil

There are a number of studies demonstrating that aromatic oils from plants can act as broad-spectrum antimicrobial agents. (27-29) Peppermint oil is one such agent that has been shown, at least in vitro, to inhibit the growth of at least 22 bacterial strains, including gram-positive cocci and rods and gram-negative rods. (30-33) While menthol, the key active ingredient in peppermint oil (constituting 36%), is effective against a number of bacteria, the entire peppermint oil is a more effective anti-microbial agent than menthol alone. (31) In addition to inhibiting the growth of bacteria, peppermint oil has a bactericidal activity against pathogenic bacteria, including E. coli 015:H7, H. pylori, and S. enteritidis. The antibacterial activity was apparent even when tested against pathogenic, antibiotic-resistant strains. (34)