Breast milk has natural scents. While some changes in smell are normal, others signal a specific cause. Understanding these factors provides clarity for caregivers.
Understanding Normal Breast Milk Smells
Breast milk’s scent naturally varies based on a mother’s diet, hydration, and the time of day it is expressed. Common smells include a subtly sweet aroma, a creamy or fatty scent, or a faint metallic undertone. A mild nutty or slightly soapy smell is also common, as these are part of the milk’s natural composition. These variations are not a cause for concern.
Common Reasons for Distinct Smells
One common reason for a noticeable smell in breast milk, particularly after it has been stored, is the presence of high lipase levels. Lipase is an enzyme naturally found in breast milk that plays a beneficial role in breaking down fats, making them easier for an infant to digest. However, when lipase activity is high, it can continue to break down milk fats over time, resulting in a soapy, metallic, or even rancid odor. Despite the altered smell, milk affected by high lipase is safe and nutritious for consumption.
Improper storage and handling can also lead to distinct smells in breast milk. If milk is left at room temperature for too long, not cooled rapidly enough after expression, or stored in unsterilized containers, bacterial growth can occur. This microbial activity can cause the milk to develop a sour, spoiled, or “off” odor, indicating it is spoiled. Adhering to proper storage guidelines is important to maintain milk quality and safety.
The foods a mother consumes can directly influence the scent of her breast milk. Strong-smelling ingredients such as garlic, onions, certain curries, or pungent spices contain volatile compounds that can be absorbed into the bloodstream and subsequently transferred into breast milk. This transfer can impart a noticeable odor to the milk, which, while distinct, is harmless and does not affect the milk’s safety. Babies consume milk with these altered scents without issue.
Some medications, vitamins, or herbal supplements taken by the mother can also change the scent and taste of breast milk. These substances may be excreted into the milk, temporarily altering its characteristics. If a mother notices a new or unusual smell after starting a particular supplement or medication, it could be a contributing factor.
Infection within the breast, such as mastitis, can cause a foul or pus-like odor in expressed milk. Mastitis is an inflammation of breast tissue that can involve infection, and it presents with other symptoms. These signs include breast pain, redness, swelling, and a feeling of warmth in the affected area.
Addressing and Preventing Smell Issues
For breast milk affected by high lipase, scalding the milk before freezing is a strategy. Scalding involves heating the milk to approximately 180 degrees Fahrenheit (82 degrees Celsius) until small bubbles appear around the edges, but not boiling. This brief heat treatment deactivates the lipase enzyme, preventing further breakdown of fats and preserving the milk’s original smell and taste during storage. After scalding, the milk should be quickly cooled before freezing.
To prevent smells related to storage and handling, it is important to follow established guidelines for breast milk storage temperatures and durations. Freshly expressed milk can be stored at room temperature (up to 77°F or 25°C) for up to four hours, in a refrigerator (39°F or 4°C or colder) for up to four days, and in a freezer (0°F or -18°C or colder) for six to twelve months. Always use clean, sterilized containers and pumping equipment to minimize bacterial contamination.
If dietary influences are suspected, parents can observe if certain strong-smelling foods correlate with changes in their milk’s odor. While these smells are harmless, a mother can consider temporarily reducing her intake of specific foods if she is concerned about the milk’s scent. Maintaining good hydration by drinking plenty of water and eating a balanced diet also supports overall milk quality.
When to Consult a Healthcare Professional
It is advisable to consult a healthcare professional if breast milk develops a foul, pus-like, or spoiled odor, especially when accompanied by maternal symptoms. These symptoms include fever, intense breast pain, redness, warmth, or flu-like feelings, which can indicate a breast infection like mastitis. Prompt medical attention can help address the underlying issue and prevent complications.
Seeking professional guidance is also recommended if an infant consistently refuses milk with an altered smell or shows signs of discomfort or illness after consuming it. While many smell variations are benign, a baby’s persistent refusal or adverse reaction warrants investigation. A doctor or lactation consultant can assess the situation and provide tailored advice. If a distinct or concerning smell persists despite common remedies, or if the cause remains unclear, consult a healthcare provider.