1. Individuals taking certain medications
People taking cough suppressants should not eat fish, especially deep-sea fish, to avoid causing histamine allergic reactions, which can lead to symptoms such as skin flushing, conjunctival congestion, dizziness, rapid heartbeat, and urticaria. Many deep-sea fish contain histamine substances. Once the amount of histamine in the human body exceeds the standard, this substance enters the blood circulation, causing a histamine allergic reaction. The reason why people do not experience the above-mentioned discomfort symptoms when eating deep-sea fish normally is because there is a substance in the human stomach and liver that inhibits histamine activity—monoamine oxidase. It prevents histamine from entering the blood. However, some cough suppressants contain monoamine oxidase inhibitors, which inhibit the secretion of monoamine oxidase by the stomach and liver. At this point, eating deep-sea fish can easily lead to the rapid accumulation of histamine substances in the body.
In addition to cough suppressants, other medications can also inhibit monoamine oxidase. These include antibiotics such as furazolidone (e.g., Furazolidone), ketoconazole, and griseofulvin; antihypertensive drugs such as pargyline; selegiline for treating Parkinson's disease; antidepressants such as moclobemide; and antitumor drugs like procarbazine. Traditional Chinese medicine also contains drugs that inhibit monoamine oxidase, such as deer antler, hawthorn, and fo-ti.
2. Patients with cirrhosis
Cirrhosis makes it difficult for the body to produce clotting factors, and low platelet counts can easily lead to bleeding. Consuming sardines, mackerel, tuna, and other fish rich in eicosapentaenoic acid can worsen the condition dramatically, adding insult to injury.
3. Pregnant women
Pregnant women should not consume sea fish frequently. Regular consumption of seafood can lead to excessive intake of methylmercury. The higher the amount of mercury the fetus is exposed to in the womb, the greater the risk of mild delays in the development of other functions such as attention, memory, and language abilities. Scientists also warn that even if the mother's mercury intake is low, the fetus's brain development may still be delayed. Therefore, pregnant and breastfeeding women should eat less seafood, a maximum of 1-2 times per week, each time less than 100 grams. They should avoid eating high-mercury sea fish like tuna and swordfish and can choose to eat farmed fish from uncontaminated ponds.
4. Patients with bleeding disorders
Patients with bleeding disorders such as thrombocytopenia, hemophilia, and vitamin K deficiency should eat less or no fish. This is because eicosapentaenoic acid (EPA) in fish can inhibit platelet aggregation, thereby worsening the bleeding symptoms of patients with bleeding disorders.
5. Tuberculosis patients
When taking isoniazid, consuming certain fish can easily cause allergic reactions. Mild cases include nausea, headache, skin flushing, and conjunctival congestion, while severe cases can involve palpitations, numbness and swelling of the lips and face, rash, diarrhea, abdominal pain, difficulty breathing, elevated blood pressure, and even hypertensive crises and cerebral hemorrhage.
6. Gout patients
Because fish contains purine substances, and gout is caused by a disorder in the body's purine metabolism.