Keriorrhea is the production of oily, orange or yellow-colored stools that occurs after consuming certain foods. This physiological response is characterized by an oily discharge or leakage from the rectum, sometimes without traditional stool material. The condition is often considered uncomfortable and embarrassing due to the nature of the leakage and the difficulty in flushing the oily residue. Keriorrhea is typically a temporary, self-limiting condition that is not medically severe.
Identifying the Specific Fish and Oils
The foods most frequently responsible for causing keriorrhea belong to the Gempylidae family of fish, commonly known as snake mackerels. The two primary culprits are Oilfish (Ruvettus pretiosus) and Escolar (Lepidocybium flavobrunneum). These deep-sea species store large quantities of a specific type of fat that the human body cannot properly process.
These fish are often mislabeled in markets and restaurants, sometimes being sold as “white tuna,” “codfish,” or “butterfish.” Due to the adverse effects, the sale of Oilfish and Escolar is restricted or banned entirely in several countries, including Japan, Italy, and South Korea. The amount of fish consumed directly relates to the likelihood and severity of the symptoms; consumption of over 140 grams often triggers a reaction.
Other sources of indigestible fats, such as certain dietary supplements or fat substitutes, can also potentially lead to similar oily stool symptoms. However, the most commonly reported outbreaks are directly linked to the consumption of Oilfish and Escolar. Their high concentration of indigestible fats makes them the most potent cause of the condition.
Why Certain Fats Cause Keriorrhea
The underlying mechanism of keriorrhea involves a specific type of fat called wax esters. These compounds are naturally present in the fish species mentioned, accumulating in their muscle tissue and making up almost 20% of their body weight in some cases. Wax esters are formed when a fatty acid combines with a fatty alcohol.
The human digestive system is uniquely unprepared to handle these wax esters. Digestive enzymes known as lipases, which break down most dietary fats, are unable to effectively process these specific compounds. Since the wax esters cannot be broken down or absorbed in the small intestine, they pass through the digestive tract largely intact.
The undigested, oily material accumulates in the rectum, leading to the characteristic leakage and discharge. This physiological response can be accompanied by an osmotic laxative action in the colon, contributing to a sensation of false diarrhea. The condition is sometimes referred to as gempylid fish poisoning, due to the presence of these indigestible fats, sometimes called gempylotoxins.
Symptoms and Resolution
The most distinct symptom of keriorrhea is the passage of an oily, orange or yellowish liquid, which often floats on the toilet water due to its low density. The discharge can occur with or without solid stool material and is frequently accompanied by an unpleasant odor. Anal leakage and occasional fecal incontinence are also commonly reported issues.
The onset of symptoms typically occurs rapidly, often within a few hours to a day after eating the fish. While the primary symptom is the oily discharge, some individuals may also experience mild gastrointestinal distress, such as stomach cramping or nausea. These additional symptoms are non-severe.
Keriorrhea is a self-limiting condition that resolves spontaneously without medical intervention. Symptoms usually disappear completely within 24 to 72 hours once the indigestible esters have been fully passed through the system. Management involves remaining hydrated and being aware of the potential for unexpected bowel movements until the episode concludes.