A sweet scent from human waste may seem unusual, yet some individuals encounter it. While often benign, a change in stool odor can occasionally signal an underlying issue within the body. Understanding factors influencing stool smell provides insight into digestive health, covering common harmless reasons for a sweet scent and potential health concerns.
How Poop Gets Its Smell
The typical odor of human stool results from complex interactions of gut bacteria during the digestive process. As undigested food passes into the large intestine, microorganisms break down remaining carbohydrates, proteins, and fats through fermentation and putrefaction. This bacterial activity produces various volatile compounds and gases.
Key compounds contributing to stool odor include skatole and indole, byproducts of protein breakdown, along with sulfur-containing gases like hydrogen sulfide and methane. The specific mix and concentration of these compounds determine the unique smell of an individual’s bowel movements. Variations in diet or gut microbiome composition can naturally alter this odor.
Everyday Reasons for a Sweet Scent
Sweet-smelling stool is common in infants, especially breastfed ones. Breast milk’s easy digestibility and an infant’s immature digestive system lead to different fermentation byproducts, often resulting in a sweet, sometimes mustard-like or seedy, odor. Formula-fed infants may also produce sweet-smelling stools, though their odor can strengthen as their gut microbiome develops.
As babies transition to solid foods, their stool odor typically becomes more pungent, reflecting changes in their diet and gut bacterial populations. For adults, consuming foods high in sugar or certain artificial sweeteners can influence the gut microbiota. This alteration may lead to the production of different compounds during digestion, resulting in a sweeter smell.
Sweet Poop as a Sign of Something Else
While often harmless, a sweet odor in stool can sometimes point to underlying health conditions. A Clostridioides difficile (C. diff) infection can produce a distinctive, often sickeningly sweet or “horse barn” smell in stool. This bacterial infection often follows antibiotic use, which disrupts the normal balance of gut bacteria, allowing C. diff to proliferate.
Carbohydrate malabsorption is another potential reason for sweet-smelling stool. Conditions like lactose intolerance or fructose malabsorption prevent the proper digestion and absorption of sugars in the small intestine. These undigested sugars then travel to the large intestine, where they ferment excessively, producing gases and compounds that can give stool a sweet or fruity odor, often accompanied by symptoms like bloating, gas, and diarrhea. In rare instances, sweet-smelling stool might also be associated with very high blood sugar levels, such as those seen in uncontrolled diabetes, where the body produces ketones that can alter the smell of bodily waste.
When to Consult a Doctor
Changes in stool odor, including a sweet smell, do not always require medical attention, especially if they are temporary or related to diet. However, if the sweet odor persists or is accompanied by other concerning symptoms, seeking professional medical advice is a reasonable step.
Symptoms that warrant a doctor’s visit include persistent or severe diarrhea, abdominal pain or cramping, unexplained weight loss, nausea, or fever. Changes in stool consistency or color, such as very watery stools, blood in the stool, or dark and tarry stools, should also prompt a medical evaluation. These signs, when present alongside a sweet-smelling stool, can indicate an underlying gastrointestinal issue that requires diagnosis and management.