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Fish odor syndrome is an unusual metabolic disorder found in people who lack enzymes to digest trimethylamine, an organic compound that is a byproduct of digestion. This compound builds up in the body instead of being broken down, and is expressed in sweat, urine, and other body fluids. The strong odor can be noticeable, especially when the patient is sweating heavily, and may cause social discomfort. Additionally, certain foods can result in a high heart rate and increase in blood pressure as the body's metabolism struggles to cope with them.
Known formally are trimethylaminuria, this condition is recessive. People need to inherit two copies of the gene for it to express, and individuals with fish odor syndrome will pass on a copy of the defective gene to their children. The children will become carriers, unless the other parent has a copy of the gene to pass on as well. It is also quite rare; a very small percentage of the population has this condition.
It is not possible to correct the metabolism to make it possible to digest trimethylamine and resolve fish odor syndrome, but there are ways to keep the strong smell down. Patients may be advised to eat a low protein diet, avoiding foods with trimethylamine precursors like carnitine, sulfur, choline, and nitrogen. The strong odor can be exacerbated by bacteria in the gut, as the balance of organisms in the digestive tract can be thrown off when a patient's metabolism isn't working right. Taking medications to kill some of the bacteria can sometimes be helpful. Patients also sometimes experience relief by consuming activated charcoal to cut down on the odor.
Detergents with a high pH can be helpful for removing the smell from clothing and keeping odors down when patients with fish odor syndrome sweat. People may also choose to live in cool climates and limit activities known to induce heavy sweating. Fish odor syndrome has been associated with psychological distress in some patients, and it may be helpful to see a mental health professional for talk therapy and access to medications to balance the brain chemistry and address suicidal thoughts and depression.
This condition tends to be more noticeable in women than in men. Some researchers theorize that this is the result of female hormones such as estrogen. Women can experience cyclical changes in the strength and nature of the odor, strongly suggesting that it is linked with fluctuating hormone levels. Using deodorants to manage smell can be beneficial, although patients may want to be careful with scented products, as the scent may react with the trimethylamine and produce a strong and unpleasant odor.