Eirini Dimidi, RD and Prof Whelan of King's College London recently reviewed food supplements in irritable bowel syndrome (IBS). Here are the key takeaways:
Aloe vera is a plant which has been shown to have immunomodulatory properties. Aloe vera may also have a prebiotic potential as it contains glucomannans, acemannan, and mannose. Studies have investigated whether Aloe vera could improve IBS symptoms. These studies have shown aloe vera to be ineffective in improving IBS‐related symptoms and quality of life. In clinical practice, data thus far do not suggest aloe vera will have a large impact, if any at all, on symptoms in IBS. If it does, then the effect is likely to be too small to warrant widespread use in clinical practice.
Peppermint oil has been shown to be anti‐inflammatory and causes intestinal smooth muscle relaxation, potentially reducing abdominal discomfort. However, it also relaxes the lower esophageal sphincter, which may lead to gastro‐esophageal reflux (GERD). Enteric‐coated peppermint formulations bypass release in the upper gastrointestinal tract to avoid reflux symptoms, but release peppermint oil in the lower gastrointestinal tract where it can exhibit its smooth muscle relaxant properties.
Studies suggest that peppermint oil is safe and may relieve symptoms of IBS, including abdominal pain. However, peppermint oil appears to exhibit a localized physiological effect in the gut, with small‐intestinal‐release formulations being optimal for relief of abdominal pain, discomfort, and IBS symptoms.
Probiotics are “live microorganisms that, when administered in adequate amounts, confer health benefits to the host”. Probiotics may improve IBS symptoms by inducing changes in the gut microbiota and their metabolite production, and may interact with the intestinal immune system, and the central and enteric nervous system. Therefore, they may modulate gut motility, inflammation, and visceral hypersensitivity.
Evidence suggests that specific probiotic strains or probiotic combinations may improve IBS symptoms. However, it remains unclear which strains, strain combinations, dose, and treatment duration are effective in IBS.
Fiber and prebiotics
Fiber modulates the gut microbiome, increases fecal bulk by increasing microbial biomass or via water retention, and regulates gut motility. Fibers vary considerably in their chemical structure which determines their degree of solubility, viscosity, and fermentability by the gut microbiota. Thus, different fiber types exert different physiological effects in the gut.
Psyllium, a soluble fiber, improves symptoms of IBS, although more research is needed to understand its impact in different IBS subtypes. While prebiotics can enrich certain microbiome bacteria, associated with health benefits, there is currently limited and inconsistent evidence of improving IBS symptoms.
Ref: Dimidi, Eirini, and Kevin Whelan. "Food Supplements and Diet as Treatment Options in Irritable Bowel Syndrome." Neurogastroenterology and Motility, 2020.
Medically reviewed by Onyx Adegbola, MD PhD, founder, Casa de Sante