Many of us bathe on a regular basis to eliminate bad body odor and control the spread of disease. Despite rigorous bathing, some of us still emit odors that go beyond stinky armpits. Smelling like rotting fish, sweaty feet, or boiled cabbage can be a sign of rare medical conditions that can compromise our overall health.

In SciShow's video, "3 Diseases That Make You Stink," host Hank Green explains unusual body signs are often a sign of a bigger problem, specifically, a defect in the way the body is breaking down, or metabolizing, food. The three medical conditions that can influence our overall health include: trimethylaminuria, also known as "fish odor syndrome"; isovaleric acidemia, which causes some people to smell like sweaty feet; and hypermethioninemia, which produces a boiled cabbage-like smell. Symptoms of these conditions can be pungent, and sometimes extremely dangerous.

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Trimethylaminuria "Fish Odor Syndrome"

People with this condition are identified by their unique decomposing fish smell. Their bodies do not break down the compound trimethylamine, which emits the smell of fishiness. Typically, everyone's body produces trimethylamine in the gut, where bacteria excretes it, while helping us digest foods like eggs, liver, and fish. Copious amounts of trimethylamine in the body is not a problem, because it's converted into an odorless molecule due to flavin-containing monooxygenase, a special enzyme in the liver. However, those with the disorder can't metabolize the smelly compound because they have mutations in the gene that produces that enzyme.

Without a signfiicant amount of the enzyme, trimethylamine builds up, and has no where to go but out with bodily fluids, including in your sweat, urine, and even your breath. It’s best to avoid broccoli and brussel sprouts so there are fewer of the precursor chemicals that get broken down into trimethylamine. Infusions of antibiotics can also help wipe out some of the bacteria that are making the trimethylamine.

Isovaleric Acidemia

This disease can cause signfiicant brain damage, and even death, especially in young children. A genetic mutation leads to an enzyme deficiency in isovaleric-coenzyme A dehydrogenase. It helps break down the amino acid leucine, but without it, leucine can only be broken down part-way. The compound left over from this process, isovaleric acid, starts to build up. It smells like cheese, and it's the same chemical that makes your sweaty feet smell.

Although it's not clear why, a build up of isovaleric acid can dramatically affect the central nervous system, and in large amounts, it's toxic to neurons, and can lead to developmental delays. It makes it difficult to digest breast milk or formula, with symptoms appearing very soon after birth. There's no cure for isovaleric acidemia, but some treatments like avoiding foods rich in leucine, and taking supplements of other, non-threatening amino acids, can help keep patients safe.


This condition occurs when there is too much of a different amino acid, methionine. It's a rare amino acid that contains sulfur, and when methionine isn't metabolized properly, it can result in large amounts of dimethylsulfide, which produces a smell similar to boiled cabbage. It can occur because you ate too much methionine, which is in protein-rich foods, like meat and cheese.

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If it's genetic, it can be due to mutations in one of several genes that are responsible for making the enzymes that help break down methionine. Without those enzymes, patients sometimes have that cabbagey smell in their sweat, breath, or urine. Not everyone with the disease has symptoms; in fact most people don't.

In severe cases, the inability to produce the enzyme can lead to neurological problems and muscle weakness, among other problems in the nervous system. Again, treatment involves avoiding foods containing methionine and taking supplements.

These three medical conditions are some of the many diseases that can lead to peculiar body odors.

See Also:

How Do Our Noses Identify Different Odors?

Longevity Measured By Sense Of Smell Spells Bad News For The Noseblind