Your breast milk might smell fishy due to high lipase activity, an enzyme that breaks down fats too quickly, especially in stored milk, making it smell soapy or fishy, though it's usually safe for the baby; or it could be your diet (fish/garlic) or poor hygiene/storage, but if it's consistently fishy even fresh, check for Trimethylaminuria (rare).
Is High Lipase Milk Dangerous to Your Baby? Dr. Chang points out that while excess lipase can change the taste of the milk, it does not make it harmful to the baby. In fact, it may even have benefits for your milk.
The longer milk is kept at room temperature or even in the refrigerator before being frozen, the more lipase activity it will have. Milk that has a high level of lipase can develop a soapy smell and taste, but is not harmful to the baby.
A fishy body odor in children can be caused by dietary factors, poor hygiene, or rare metabolic conditions like trimethylaminuria. Encourage regular bathing with gentle soap and wearing clean clothes. Monitor diet for foods that may contribute to odor, such as fish or certain vegetables.
Trimethylamine Responsible for Fishy Flavor in Milk from Cows on Wheat Pasture.
However, if there is an excess lipase activity in the milk, it can result in a fishy or soapy odor due to it breaking down the fats found within it. This can cause some babies to refuse to drink the milk that has been expressed. The rate at which this process occurs can vary widely from person to person.
Parents may hear that the "typical" breast milk smell is mild, subtle, and perhaps slightly sweet/appealing. First, though, it's crucial to note that there is no single "typical" smell. In reality, the smell and taste of breast milk varies from person to person.
Breast milk after being refrigerated and thawed may have various odors, such as soap-like, rancid, or fishy smells. To remove odors from frozen breast milk, mothers should follow all safe breast milk storage guidelines and try some of the suggested methods below for removing fishy odors from frozen breast milk.
Vaginal discharge can also provide information about what kind of vulvovaginitis your child may have. A watery discharge that's odorless may mean a yeast infection, for example, while a discharge that's thick and milky and smells fishy may indicate bacterial vaginosis.
If your baby's poop smells quite foul, almost like bile or rotten fish, it could mean they are fighting a GI bug. GI viruses that cause diarrhea are normally self-limiting. Continue nursing and/or feeding as usual, and take your baby to the clinic if they are not back to normal in about a week.
Unusual Taste or Odor
Under normal conditions, breast milk has a characteristic mild, slightly creamy flavor, without being overly salty or sweet. If it tastes fishy, sour, or has an unpleasant smell, the milk has likely spoiled, and its nutritional integrity is compromised.
The "4-4-4 rule" for breast milk is a simple storage guideline: fresh milk is good for 4 hours at room temperature (up to 77°F/25°C), for 4 days in the refrigerator (39°F/4°C or colder), and up to 4-6 months (or longer) in a standard freezer (0°F/-18°C). It's a handy mnemonic, though some organizations like the CDC recommend up to 6 months in the freezer and the AAP up to 9 months, with deeper freezers offering even longer storage.
We suggest that the ammonia content significantly increases in breasts with inflammation due to mastitis, and infants might be sensitive to a change in the odor of milk during mastitis. The perception of an ammonia odor in milk seems a reasonable explanation for refusing to suckle.
If you do have excess lipase activity in your breast milk, you might notice a difference in its smell and taste after pumping and storing, though how long this takes to develop can vary from person to person. Some possible changes include: Milk that has a soapy smell or taste. Milk that has a metallic smell or taste.
It's theorized that when there is a high amount of lipid activity in breast milk, it may change the scent of breast milk. This scent is usually described as soapy, but it's also been described as metallic or like milk that's gone sour.
Symptoms include:
An enzyme called flavin-containing monooxygenase 3 (FMO3) breaks down trimethylamine in the body, changing it to the odorless compound trimethylamine N-oxide. But if the enzyme isn't working as it should, trimethylamine accumulates in the body and can make a person produce a foul, rotting-fish aroma.
Trimethylaminuria (TMAU), also known as fish odor syndrome or fish malodor syndrome, is a rare metabolic disorder that causes a defect in the normal production of an enzyme named flavin-containing monooxygenase 3 (FMO3).
Yeast infection symptoms
High Lipase Milk is Safe
The odor might be mild, or it might be pretty strong and unpleasant. It is actually harmless though. It's perfectly safe to use this milk to feed your baby.
Description. Trimethylaminuria is a disorder in which the body is unable to break down trimethylamine, a chemical compound that has a pungent odor. Trimethylamine has been described as smelling like rotten or decaying fish.
If your milk smells “sour” or “rancid” this can be from oxidation. These changes may occur shortly after the milk is expressed, or it may occur after the expressed milk is frozen and then defrosted.
Enzyme activity.
But some people have overactive enzymes that move faster than normal. This can create a fishy or soapy odor in breast milk that you pump and save for later. It can even affect the taste. Sometimes your baby won't have a problem with the milk, but other times they may refuse to drink.
The "4-4-4 rule" for breast milk is a simple storage guideline: fresh milk is good for 4 hours at room temperature (up to 77°F/25°C), for 4 days in the refrigerator (39°F/4°C or colder), and up to 4-6 months (or longer) in a standard freezer (0°F/-18°C). It's a handy mnemonic, though some organizations like the CDC recommend up to 6 months in the freezer and the AAP up to 9 months, with deeper freezers offering even longer storage.
Can babies get sick from old breast milk? If your baby has had spoiled breast milk, they'll likely let you know. They may throw up, or have an upset stomach, diarrhea or fever. It's important to call your pediatrician if you think your baby may be sick from having spoiled breast milk.