Fishy body odor (trimethylaminuria)

Originally Published: September 11, 2009 - Last Updated / Reviewed On: January 9, 2015
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Dear Alice,

After many years of confusion, I have been diagnosed with trimethylaminuria. It is an awful disease that has caused much emotional pain in my life. I was hoping that if the disease was discussed on your site that people's awareness may increase and perhaps people would not be quite so quick to judge others. I would appreciate it if you could post my message for this reason. Also, if the disease is caused by the lack of a certain hormone in my body, then would an injection of this hormone be a possible solution? In all of my research, I have not seen this discussed.

Dear Reader,

You are not alone in feeling pained by this unusual disorder. Many people who suffer from trimethylaminuria also suffer from depression as a result of disruptions this condition can cause to social life, relationships, or career. Though there may not be a definitive cure or treatment, seeking out the assistance of your health care provider and perhaps a counselor may help you reduce your symptoms and find ways of dealing with feelings of social isolation and embarrassment this genetic condition can sometimes trigger.

Trimethylaminuria is a condition that’s been around for centuries, but has only really gained recognition in the scientific world within the past three decades. It’s an uncommon genetic disorder that occurs when the body can't break down trimethylamine, a naturally occurring dietary compound. The condition is related to mutations in the FMO3 gene, which normally produces an enzyme that converts fishy-smelling trimethylamine into an odorless molecule. But when the FMO3 gene isn't working properly and trimethylamine is not processed, it can accumulate and cause the body, breath, sweat, and urine to smell strongly like fish.

Trimethylaminuria seems to be more common in women than in men. Some scientists chalk this up to female sex hormones like progesterone and/or estrogen. Several reports suggest that the condition worsens around puberty, before and during menstrual periods, while taking oral contraceptives, and during menopause — all times when female hormones are high. It is also believed that the condition is genetic, meaning both mom and pop were carriers of the altered FMO3 gene and passed it along (interestingly, some carriers may experience mild or episodic versions of the condition). Both the type of FMO3 mutation and lifestyle factors such as stress and diet seem to influence the duration and severity of symptoms. To help decrease the symptoms of trimethylaminuria, you may want to try a few of these treatments under the supervision of your health care provider:

  • Avoiding foods containing trimethylamine and its precursors like:
    • Milk obtained from wheat-fed cows
    • Eggs
    • Liver
    • Kidney
    • Peas
    • Beans
    • Peanuts
    • Soy products
    • Brassicas (e.g., Brussels sprouts, broccoli, cabbage, and cauliflower)
    • Lecithin and lecithin-containing fish oil supplements
    • Seafood (freshwater fish have less trimethylamine N-oxide)
  • Taking low doses of antibiotics and/or using laxatives to reduce the amount of trimethylamine produced in your gut
  • Taking activated charcoal or other supplements to decrease the concentration of trimethylamine in your pee
  • Using body soaps with a moderate pH (between 5.5 and 6.5)
  • Taking riboflavin (vitamin B2) supplements to enhance FMO3 enzyme activity
  • Recommended intake is 30 to 40mg taken three to five times per day with food
  • Avoiding activities and conditions that might make you sweat (e.g., exercise and stress)

List adapted from the National Human Genome Research Institute.

Although the condition is caused largely by a missing enzyme, at this time, replacement therapy for FMO3 is not currently an option. The good news is that managing trimethylamuinuria doesn’t mean you have to go it alone — it’s wise to partner up with your health care provider. Mixing medications and supplements may have undesirable or unintended results and dietary restrictions can result in nutritional deficits. It’s recommended for pregnant and breast-feeding women who have this condition to consult with their health care providers before restricting their diets to temper the effects of trimethylamuinuria.

Dealing with trimethylamuinuria can also be emotionally painful and isolating, but therapy and appropriate medical treatment can prove really helpful in alleviating some of its symptoms and repercussions. You've made great progress already by investing time to solve your mystery, dealing with some of the emotional issues, and seeking to share information and your experience. All the best going forward!

Alice