The Root Cause: Indigestible Wax Esters
At the heart of the controversy surrounding escolar is a simple biological fact: the fish contains high levels of naturally occurring, indigestible wax esters. This substance, often called gempylotoxin, is what gives escolar its rich, buttery flavor and texture, making it a desirable—and deceptively delicious—catch. However, unlike other fish, escolar's digestive system cannot process these waxy oils, so they are stored in its flesh. Humans similarly lack the necessary enzymes to break down these wax esters. When a person consumes a significant amount of escolar, the indigestible oils pass through the digestive system undigested, leading to the infamous side effects. While the name 'gempylotoxin' sounds alarming, it is not actually a toxin that poisons the body; rather, it is an oil that acts as a powerful, and often uncontrollable, laxative.
What is Keriorrhea?
The medical term for the primary symptom of eating too much escolar is keriorrhea, from the Greek word for 'flow of wax'. It is characterized by the sudden and often uncontrollable rectal leakage of oily, orange or yellow discharge. Symptoms typically appear within 30 minutes to 36 hours after consumption and can last for up to two days. While embarrassing and highly uncomfortable, it is not considered life-threatening and does not lead to significant fluid loss like typical diarrhea. The intensity of the symptoms often depends on the amount of fish consumed and an individual's own sensitivity.
Key symptoms of keriorrhea include:
- Oily, orange or yellow discharge from the rectum, sometimes occurring without notice.
- Abdominal cramps and stomach gurgling.
- Nausea and occasional vomiting.
- Headaches.
International Regulations and Bans
The digestive distress caused by escolar has led various countries to implement strict regulations or outright bans on its sale. The regulatory approach differs significantly around the world, creating a patchwork of legality that can confuse consumers.
Global Regulations on Escolar
| Country | Regulation | Reason | Status |
|---|---|---|---|
| Japan | Banned since 1977 | Public health concerns over severe gastrointestinal distress. | Sale prohibited |
| Italy | Banned | Consumer complaints about the purgative side effects. | Sale prohibited |
| United States | Legal, FDA Advisory | FDA informally advises against marketing in interstate commerce but does not enforce a ban. | Legal with caution |
| Canada | Legal, Warning Labels | Requires clear labeling and provides consumer fact sheets noting potential adverse effects. | Legal with warnings |
| Hong Kong | Advisory | Advised clear labeling and consumer awareness of potential health effects. | Legal with advisories |
The Widespread Problem of Mislabeling
A significant problem contributing to consumer illness from escolar is mislabeling, whether through ignorance or deliberate fraud. Because of its mild, buttery flavor, escolar is frequently sold under more appealing, and often incorrect, names to unsuspecting consumers.
Common mislabeled names for escolar include:
- "White Tuna" or "Super White Tuna"
- "Butterfish" (a different species entirely)
- "Walu"
- "Oilfish"
- "Sea Bass"
Studies by organizations like Oceana have revealed how pervasive this issue is. For instance, a 2013 study found that a high percentage of "white tuna" samples tested in US sushi restaurants were actually escolar. This deception poses a direct health risk to consumers who may eat a larger portion than is considered 'safe,' unaware of the fish's potent effects.
Additional Health Concerns: Mercury Levels
As a large, deep-water predatory fish, escolar can also have elevated levels of mercury. This is a concern for all large predatory species, as mercury bioaccumulates up the food chain. While the digestive issues from the wax esters are immediate and obvious, the risks from mercury exposure are chronic and build over time. Health Canada, for example, issues consumption advice for escolar and other fish to minimize mercury exposure.
How to Mitigate the Risks
For those in regions where escolar is legal and sold, the key to avoiding its undesirable side effects lies in cautious consumption. For first-time eaters or those with sensitivities, the Queensland Government in Australia recommends avoiding it entirely.
- Practice Portion Control: A consensus among health advisories is to limit intake to a small portion, typically under 6 ounces (170 grams), especially if you are unsure of your sensitivity.
- Modify Preparation: While not foolproof, some reports suggest that preparing the fish in ways that drain the oil, such as grilling, and discarding the liquid can reduce the effects. Deep skinning is also mentioned, but results are inconsistent.
- Verify the Species: When ordering "white tuna" or "butterfish," particularly at a sushi restaurant, ask for clarification. Reputable vendors and restaurants should correctly identify the fish as escolar. A pinkish-white fillet is likely real albacore tuna, whereas a pure white, buttery fillet could be escolar.
Conclusion
The reason escolar is banned or heavily regulated in various countries is not because it is a deadly toxin, but because its indigestible wax esters lead to severe, unpleasant gastrointestinal distress for many who eat it. The problem is compounded by widespread mislabeling, deceiving consumers into accidentally eating a larger, more problematic portion. While some people can eat small amounts without issue, the potential for an embarrassing and painful episode of keriorrhea, combined with the additional risk of higher mercury content, makes it a controversial menu item. Consumers are best served by being aware of the risks, questioning ambiguous menu descriptions, and erring on the side of caution.
For more information on seafood labeling and fraud, you can visit the Food and Drug Administration's website.
Frequently Asked Questions
Q: Is escolar toxic? A: No, the wax esters found in escolar are indigestible, not toxic. They cause a powerful laxative effect rather than actual poisoning.
Q: What is keriorrhea? A: Keriorrhea is an oily, orange or yellow diarrhea caused by the body's inability to digest the wax esters in escolar and oilfish.
Q: Why is escolar sometimes called 'ex-lax fish'? A: The nickname is a result of the fish's strong and unpredictable laxative effect, which can result in embarrassing accidents if overconsumed.
Q: Is escolar banned in the United States? A: No, escolar is not formally banned in the US. However, the FDA has informally recommended against its marketing in interstate commerce and encourages clear labeling.
Q: Does cooking remove the wax esters from escolar? A: No, the wax esters are not affected by cooking, though preparation methods like grilling can help drain some of the oil.
Q: How can I identify escolar to avoid it? A: Be cautious of fish labeled ambiguously as "white tuna," "super white tuna," or "butterfish." If the fillet is pure white and has a notably buttery, oily texture, it may be escolar.
Q: What should I do if I get keriorrhea after eating escolar? A: Keriorrhea is usually self-limiting and resolves on its own within one to two days. Staying hydrated is recommended. If symptoms are severe or persist, seek medical advice.
