What causes foul-smelling stools (feces)?

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From the Guidelines

Smelly poops are primarily caused by bacterial overgrowth in the digestive system, which can be triggered by various factors including diet, medical conditions, and medications. The breakdown of food by bacteria in the digestive system, particularly foods high in sulfur, can lead to the production of foul-smelling compounds 1. Common culprits include high-protein foods (meat, eggs), cruciferous vegetables (broccoli, cabbage), dairy products, and certain carbohydrates that aren't fully digested. Medical conditions such as malabsorption disorders like celiac disease, inflammatory bowel diseases, infections, or conditions affecting the pancreas can also cause particularly foul-smelling stool.

Key Factors Contributing to Smelly Poops

  • Diet: Foods high in sulfur, such as meat, eggs, and cruciferous vegetables, can contribute to smelly poops
  • Medical conditions: Malabsorption disorders, inflammatory bowel diseases, infections, and conditions affecting the pancreas can cause foul-smelling stool
  • Medications: Antibiotics can disrupt the gut bacteria balance, leading to changes in stool odor
  • Supplements: Certain supplements, such as those containing sulfur compounds like chondroitin sulfate, can increase stool odor

Reducing Smelly Poops

To reduce smelly poops, it is recommended to limit sulfur-rich and high-fat foods, stay hydrated, and maintain regular bowel habits. If you notice a sudden, persistent change in stool odor accompanied by other symptoms like diarrhea, blood in stool, or weight loss, it's essential to consult a healthcare provider as this could indicate an underlying health issue requiring treatment 1. In some cases, bacterial overgrowth can be treated with antibiotics, such as rifaximin, which is a nonabsorbable antibiotic choice, although careful patient selection is needed when treating with this or any antibiotic medication 1.

From the Research

Causes of Smelly Poops

  • Small intestinal bacterial overgrowth (SIBO) is a condition characterized by an excessive amount of bacteria in the small intestine, which can lead to symptoms such as bloating, pain, gas, and diarrhea 2.
  • SIBO can be caused by an overgrowth of pathogenic organisms, including Enterococcus, Escherichia coli, and Klebsiella, as well as Methanobrevibacter smithii, which can produce methane and contribute to constipation-predominant irritable bowel syndrome (IBS-C) 3.
  • Gut microbiome dysbiosis, which can lead to SIBO, can also cause increased intestinal permeability, dysmotility, chronic inflammation, autoimmunity, and decreased absorption of bile salts, all of which can contribute to smelly poops 3.
  • Probiotics have been shown to be effective in reducing symptoms of IBS and SIBO, including abdominal pain and bloating, and may help to decontaminate SIBO and reduce hydrogen gas production 4, 5.

Factors Contributing to Smelly Poops

  • Intestinal methanogen overgrowth (IMO) can contribute to smelly poops, particularly in individuals with constipation-predominant IBS 3.
  • Dietary factors, such as a high-fiber diet, can contribute to the production of smelly poops, as can certain medical conditions, such as gastroesophageal reflux disease (GERD) and inflammatory bowel disease (IBD) 6.
  • The use of broad-spectrum antibiotics can disrupt the balance of the gut microbiome and contribute to SIBO and smelly poops 2.

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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