Nature's pharmacopoeia contains numerous proven natural treatments for people with irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) backed by scientific studies.
What are IBS and SIBO?
IBS is a functional gastrointestinal disorder characterized by abdominal pain and altered bowel patterns that is divided into several subclassifications, including constipation-predominant IBS (IBS-C), diarrhea-predominant IBS (IBS-D) and mixed IBS (IBS-M). IBS represents a diagnosis of exclusion, meaning that other organic causes of gastrointestinal pathology must first be ruled out.
Small intestinal bacterial overgrowth (SIBO), on the other hand, represents an abnormal accumulation of bacteria in the small intestine that generates symptoms similar to IBS. Although SIBO is formally defined as greater than or equal to 10^5 CFU of bacteria/mL found in the proximal jejunal aspirate, obtained by intubation and aspiration acquired from multiple sites within the intestine, this procedure is not frequently performed due to its invasiveness (Bures et al., 2010; Gasbarrini et al., 2009). Instead, hydrogen-methane breath testing is used, with the glucose breath test (GBT) having superior specificity (meaning it detects few false positive) (Ghoshal et al., 2014). Some meta-analyses have revealed that SIBO is present in up to 38% of IBS patients versus 12% of healthy controls (Ford et al., 2009).
Traditionally, IBS is treated with pharmaceutical treatments such as antispasmodics, muscle relaxants, bulking agents, proton pump inhibitors, antidiarrhoics, and antidepressants, and SIBO is treated with antibiotics and prokinetics, all of which are accompanied by a litany of adverse sequelae. However, natural medicine offers a treasure trove of alternatives to these conventional therapies.
Peppermint Oil: A Viable Option for Symptomatic Relief
In one study, two enteric-coated peppermint oil capsules were administered to patients with IBS twice a day for four weeks. Only 38% of the people in the placebo group exhibited a greater than 50% reduction in their symptom score compared to 75% of those in the peppermint oil (Cappello et al., 2007). In fact, symptom improvement was elicited for diarrhea, constipation, pain at defecation, incomplete evacuation of stool, abdominal bloating, pain or discomfort, flatulence, mucus excretion, and urgency at defecation in those receiving peppermint oil (Cappello et al., 2007).
These results were replicated in a second study of children with IBS. After two weeks of receiving enteric-coated peppermint oil, 76% of those subjects receiving peppermint oil improved compared to only 19% of those receiving placebo. The researchers conclude, "Peppermint oil may be used as a therapeutic agent during the symptomatic phase of IBS" (Kline et al., 2001).
Another prospective, randomized, double-blind, placebo-controlled clinical trial administered enteric-coated peppermint oil to patients with IBS symptoms approximately half an hour before meals for one month (Liu et al., 1997). 79% experienced improvement in abdominal pain, 83% had less abdominal distention, and 79% experienced less gas (Liu et al., 1997). In addition, 73% in the peppermint group had fewer instances of borborygmi, or the rumbling and gurgling sounds resulting from passage of fluid and gas in the intestines, and 83% experienced decreases in stool frequency (Liu et al., 1997).
How Does It Work?
Peppermint exerts an antispasmodic effect. Researchers hypothesize that menthol, one of the active constituents in peppermint, disrupts the movement of calcium across the cell membrane which is required for muscular contraction, causing intestinal smooth muscles to instead relax (Hills & Aaronson, 1991). In addition, this spasmolytic effect may be responsible for the reduction in diarrhea, as it extends the oro-cecal transit time and helps restore normal rates of motility (intestinal transit) (Grigoleit & Grigoleit, 2005). Not only that, but "antispasmodics in fact may decrease the functional obstruction caused by increased phasic colonic contractions that may be present in constipation" (Cappello et al., 2007).
Lastly, the reduction in gas, bloating, and abdominal distention peppermint produces may be due to its antimicrobial effects on enteric flora. In other words, peppermint may "weed" the overgrown small intestinal bacteria that occurs in SIBO, a potential root cause of IBS. This notion is supported by evidence that peppermint oil decreases the production of hydrogen, a bacterial byproduct in patients with SIBO (Logan & Beaulne, 2002). In nearly half of subjects in one study, the therapeutic effects of peppermint oil extended at least a month after the study concluded, suggesting that the benefits may be related to a culling back of the microbiota (Cappello et al., 2007).
Herbal Combinations for Enhanced Efficacy
To step things up a notch, peppermint essential oil may be combined with caraway seed, which in animal models, has been demonstrated to decrease the visceral hypersensitivity implicated in the pathophysiology of IBS (Adam et al., 2006). Visceral hypersensitivity occurs when innocuous stimuli are perceived as painful due to sensitization of nociceptors (pain receptors) (Chiu et al., 2013). In a prospective, randomized, double-blind, multi-center trial, this combination has also been shown to decrease the symptoms of dysmotility type dyspepsia (indigestion) or essential/idiopathic dyspepsia in combination with IBS (Freise & Kohler, 1999).
Another agent proven to decrease visceral hypersensitivity in animal models is Iberogast, an herbal formula used extensively in Europe (Liu et al., 2004; Muller et al., 2006). Containing various botanicals including iberis amara, angelica, chamomile, caraway fruit, celandin, St. Mary's thistle, lemon balm leaves, licorice root, and peppermint leaves, Iberogast is used as a frontline therapy in Europe and has been used for half a century. A double-blind, randomized, placebo-controlled, multi-centre trial confirmed that Iberogast is effective in significantly reducing abdominal pain in IBS subjects compared to controls (Madisch et al., 2004).
In addition, another randomized clinical trial demonstrated that Iberogast has equivalent efficacy to the prokinetic drug cisapride in patients with dysmotilitiy type dyspepsia (Rösch et al., 2002). Given its propensity to accelerate gastric emptying, researchers speculate that Iberogast is useful for impaired gastrointestinal motility. Iberogast may also be helpful for SIBO by increasing activity of the migrating motor complex (MMC), or the between-meals electromechanical activity observed in gastrointestinal smooth muscle that sweeps undigested food and errant bacteria through the digestive tract to clean it out.
Another randomized, double-blind, placebo-controlled study showed that Iberogast resulted in significantly superior improvement in terms of resolving symptoms of functional dyspepsia compared to placebo (Ottillinger et al., 2013). Not only that, but those who received Iberogast remained recurrence-free longer than patients who had received placebo. Renowned functional gastroenterologist Dr. Gerard Mullin recommends 20 drops in a beverage 2-3 times daily for symptomatic relief (Ottillinger et al., 2013).
Of course, of equal utility is unearthing the root cause of functional bowel disorders such as IBS and dyspepsia, such as post-infectious damage to the MMC resulting in SIBO, mild mucosal inflammation, alterations in ileocolonic transit, food sensitivities, stress, disruptions in neuromuscular function, and dysbiosis. To explore a root cause resolution approach to IBS that addresses these underlying causes, see a certified functional medicine practitioner.
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