Trimethylaminuria is a rare recessive genetic condition which causes people to have a fishy body odor. This condition is not harmful to physical health, although some people with trimethylaminuria experience emotional distress and social hardships as a result of the smell, which can sometimes be quite strong. It is not possible to cure this condition, but it can be managed, and there are a number of ways in which people can reduce the fishy odor if it becomes an issue.
In order to have trimethylaminuria, someone must inherit both copies of the defective gene. The condition is actually a metabolic disorder, caused by lack of the enzyme which breaks down trimethylamine. Because the body cannot break it down, trimethylamine is expressed in body fluids like sweat, urine, and mucus, and this compound is responsible for the fishy smell. Some people who carry one copy of the gene may experience body odor problems, but usually both copies are needed for symptoms to appear.
This condition appears to be more common in women, although it is not sex linked. Researchers have theorized that female hormones could make trimethylaminuria worse or more noticeable, and that men who have the condition may not always be aware of it because the symptoms are low level. A doctor can diagnose trimethylaminuria by testing the urine for trimethylamine, performing genetic testing to look for the rogue gene responsible, or subjecting the patient to a challenge test in which a large dosage of trimethylamine is given and followed through the body.
Controlling the diet is the most effective way to cut down on the fishy smell, by reducing foods which contain precursors to trimethylamine. Foods rich in sulfur, nitrogen, and choline such as eggs, fish, and beans should be avoided or eaten in moderation. Some patients also have success with activated charcoal tablets, which appear to reduce the odor for many patients. A doctor or nutritionist can help a patient find foods which are safe to eat while balancing nutritional needs.
People with trimethylaminuria can experience psychological hardship as a result of their body odor, and some doctors recommend going to counseling in addition to pursuing measures to control the disorder. Patients may find it beneficial to attend therapy so that they can talk about their experiences and develop coping techniques for social situations. Young children especially can benefit from therapy, as their classmates may tease them for their body odor.