5 Benefits of Probiotics (Explained at the Molecular Level)
Irritable bowel syndrome (IBS) is one of the most frequent gastrointestinal disorders estimated to affect millions of people universally. The mechanisms responsible for the generation of IBS include variation in gut motility, inflammation, small-bowel bacterial overgrowth, the leaky gut phenomenon and a meddling with the gut-brain axis, hypervigilance to pain, and last but not the least when the gut ecology goes haywire.
Live, healthy bacteria (probiotics) have a wide array of potential health benefits in various GI diseases, predominantly IBS. Why are probiotics an effective addition in IBS?
Here are the 5 benefits of ingesting healthy bacteria in IBS!
1. Induce the Expression of Pain-Alleviating Receptors in the Gut
What are the most potent painkillers? They are opioids and to our surprise, probiotics exert morphine-like effects once ingested. Experts have been capable of figuring out that probiotics, particularly the Lactobacillus strains induce the expression of pain-relieving receptors in the gut.  This reduces the pain hypersensitivity in IBS.
2. Eradicate Small-Intestinal Bacterial Overgrowth (SIBO)
One of the several triggers of IBS is SIBO. Normally, our small intestines contain a fewer number of microbes in contrast to the colon. However, when a gargantuan amount of bacteria inhabits our small intestine, it alters the normal gut microbiota, giving rise to a condition, called SIBO. In addition to interfering with the normal digestion and absorption of nutrients, SIBO can also contribute to IBS hallmarks like abdominal pain, bloating, gas, and diarrhea. Studies show that probiotics are effective at easing the chronic bloating and diarrhea associated with SIBO and subsequently diarrhea-predominant IBS. In fact, in some instances, probiotics have been found to be more useful than antibiotics.  
3. Modulate the Immune System
There is a speculation that IBS might be the result of the production of mediators from inflammatory cells. The anti-inflammatory properties of probiotics, specifically Lactobacillus reuteri  dampen down the inflammation and IBS features.
4. Aid in the Leaky Gut Phenomenon
Our intestine consists of tight junctions – so named because they are glued together to prevent the leakage of certain substances into the bloodstream. Loss of these tight junctions is followed by the seepage of harmful substances into the blood. This leaky gut contributes to a plethora of systemic illnesses, including IBS. Probiotics reinforce these tight junctions, curtailing the escape of harmful substances into your system. The restitution of a healthy gut barrier ameliorates the IBS symptoms. 
5. Normalize the Gut-Brain Axis
An altered gut flora in IBS has a negative impact on the mood and cognitive function – the gut-brain-microbiota axis. Reciprocally, psychological stress can perturb the balanced community of intestinal bacteria, exacerbating the functional bowel disorder/IBS. Probiotics not only stabilize this axis,  yet also mitigate anxiety and depression, and hence, banish the major risk factors for IBS.
Dr. Rasheed Huma
- Ringel-Kulka T, Goldsmith JR, Carroll IM, et al. Randomized Clinical Trial: Lactobacillus Acidophilus NCFM Affects Colonic Mucosal Opioid Receptors Expression in Human Patients with Functional Abdominal Pain. Alimentary pharmacology & therapeutics. 2014;40(2):200-207. doi:10.1111/apt.12800.
- Chen WC, Quigley EMM. Probiotics, prebiotics & synbiotics in small intestinal bacterial overgrowth: Opening up a new therapeutic horizon! The Indian Journal of Medical Research. 2014;140(5):582-584.
- Soifer LO, Peralta D, Dima G et al. [Comparative clinical efficacy of a probiotic vs. an antibiotic in the treatment of patients with intestinal bacterial overgrowth and chronic abdominal functional distension: a pilot study]. Acta Gastroenterol Latinoam. 2010;40(4):323-7.
- Ma D, Forsythe P, Bienenstock J. Live Lactobacillus reuteri Is Essential for the Inhibitory Effect on Tumor Necrosis Factor Alpha-Induced Interleukin-8 Expression. Infection and Immunity. 2004;72(9):5308-5314. doi:10.1128/IAI.72.9.5308-5314.2004.
- Rao RK, Samak G. Protection and Restitution of Gut Barrier by Probiotics: Nutritional and Clinical Implications. Current nutrition and food science. 2013;9(2):99-107.
- Smith CJ, Emge JR, Berzins K, et al. Probiotics normalize the gut-brain-microbiota axis in immunodeficient mice. American Journal of Physiology – Gastrointestinal and Liver Physiology. 2014;307(8):G793-G802. doi:10.1152/ajpgi.00238.2014.