Escolar is not toxic or poisonous, but it carries a well-known digestive side effect that has led several countries to ban or restrict its sale. The fish contains high levels of waxy compounds that humans cannot properly digest, and eating too much in one sitting can cause oily, orange diarrhea that lasts up to 48 hours. Most people can eat small portions without problems, but the risk is real enough that you should know exactly what you’re dealing with.
Why Escolar Causes Digestive Problems
Escolar meat is rich in wax esters, a type of fat made from long-chain fatty acids bonded to long-chain fatty alcohols. These compounds make the fish taste buttery and rich, but your body lacks the specific enzymes needed to break them down. Your pancreatic lipase, the main fat-digesting enzyme, struggles with wax esters because they repel water so effectively that the enzyme can’t access them properly. Even your bile salts, which normally help dissolve dietary fats, are far less effective at breaking up wax esters compared to the triglycerides found in most foods.
The result is that wax esters pass through your digestive tract largely intact. When enough of them accumulate in your intestines, they act as a lubricant and come out the other end as an oily, orange discharge. This condition has a clinical name: keriorrhea.
What Keriorrhea Looks and Feels Like
Keriorrhea typically involves one to three oily, orange, mucus-like bowel movements that may or may not contain solid stool. Symptoms usually start within two hours of eating escolar, though the window ranges from 20 minutes to four hours. The episode generally resolves within 24 to 48 hours, and normal bowel movements return on their own without any treatment.
The experience is uncomfortable and inconvenient, but it is not medically dangerous. There’s no damage to your intestines, no infection, and no lasting effects. The biggest risks are social embarrassment and the fact that the oily discharge can be difficult to control, sometimes leaking without warning. Some people also experience abdominal cramps, nausea, or bloating alongside the oily stools.
How Much You Can Safely Eat
California Sea Grant, a research program affiliated with the University of California, recommends eating no more than six ounces of escolar at a time to avoid the laxative effects. That’s roughly the size of two decks of playing cards. Many people tolerate this amount without any symptoms at all, while others are more sensitive and react to smaller portions. There’s no reliable way to predict your individual tolerance in advance.
There are also no well-proven cooking methods that eliminate the wax esters from the fish. Grilling can separate some of the oil from the meat, and discarding the cooking liquid afterward may reduce the risk to some extent. But no preparation technique guarantees a symptom-free experience. Skinning the fish and avoiding the belly portion, where fat content is highest, are common-sense approaches, though they haven’t been rigorously studied.
You Might Be Eating It Without Knowing
One of the bigger concerns with escolar is that it’s frequently sold under misleading names. In sushi restaurants, escolar commonly appears on menus as “white tuna,” “super white tuna,” or “butterfish.” A widely cited investigation by the ocean conservation group Oceana found that 84% of fish samples labeled “white tuna” at sushi restaurants were actually escolar. True white tuna is albacore, a completely different fish with none of these digestive side effects.
This mislabeling is a genuine safety issue. If you think you’re eating albacore tuna, you might order a generous portion or eat it multiple times during a meal. Someone who unknowingly eats a large amount of escolar at dinner could find themselves dealing with uncontrollable oily discharge later that night with no idea why. If you’ve ever had an unexplained episode of orange, oily diarrhea after eating sushi, escolar mislabeled as white tuna is a likely explanation.
How Different Countries Handle Escolar
Regulations vary widely around the world. Japan and Italy have banned the sale of escolar entirely. Several other countries require specific labeling and consumer warnings when escolar is sold. The United States does not ban escolar, but the FDA issued an advisory in the 1990s recommending against its sale and has import controls targeting foreign processors that fail to meet seafood safety regulations. In practice, escolar is widely available in American restaurants and fish markets, often without any warning about its effects.
Canada and Hong Kong both allow the sale of escolar but require that it be properly labeled and that consumers be informed about the potential for digestive symptoms. Australia and New Zealand have also issued formal advisories. The inconsistency in global regulation reflects the fact that escolar isn’t dangerous in the traditional sense. It won’t poison you or cause lasting harm. But it can cause a distinctly unpleasant few hours if you eat too much or don’t know what you’re getting into.
Who Should Avoid It Entirely
People with irritable bowel syndrome, inflammatory bowel disease, or other chronic digestive conditions may want to skip escolar altogether. The undigested wax esters can aggravate an already sensitive gut, and the resulting symptoms can be more severe and prolonged than in someone with healthy digestion. Young children and older adults, who may be more vulnerable to dehydration from diarrhea, are also better off choosing a different fish.
For everyone else, escolar is a calculated risk. If you enjoy the taste and keep your portion to six ounces or less, you’ll likely be fine. But go in with your eyes open, especially at sushi restaurants where the fish may not be labeled honestly. Asking your server directly whether the “white tuna” is albacore or escolar is the simplest way to know what you’re actually eating.