Why Can’t You Shake Breast Milk? [Myth Or Truth To It?]

Breast milk is made up of living cells that are susceptible to physical damage. For example, when you vigorously shake breast milk, it denatures the molecules. As a result, it breaks up the proteins into parts, exposing your baby’s gut to infections and gut lining inflammation.

Yes, when proteins are denatured, they won’t properly perform their function even though some proteins like those found in breast milk are much harder to denature than others.

To break down the protein molecules in breast milk, you’d have to apply a significant amount of force, the equivalent of when you have to whip heavy cream.

Debunking the myths about shaking breast milk 

Dad is noting down baby's feeding schedule, next to 2 bottles of breastmilk.

Unsurprisingly, breastfeeding is one area where there’s plenty of advice given to new mothers after delivery, and one of the pieces of advice is surprisingly strict; Swirl, never shake.

Human milk separates after expression and needs to be remixed before feeding to the baby. 

Slightly shaking by hand is unlikely to damage breast milk; however, it is entirely believable that vigorous shaking could denature and change how the proteins are folded in the milk. 

Scientifically, there are functional cells and proteins in milk, and the correct structure of these proteins is critical for their function. Still, for nutritional purposes, a denatured protein is just as good as a non-denatured protein.

Preparing your child’s bottle of breast milk requires pumping out the milk from the breast and eventually pouring it into a bottle. This whole process in itself already agitates breast milk in many ways without breaking down the proteins, and shaking a bottle of breast milk is no different.

It doesn’t reduce the breast milk nutritional value for your tiny human, nor does it break down the protein present.

Safe thawing of breast milk

The following are ways to safely thaw your expressed stored breast milk without having to upset it in any way.

  • Always thaw and serve the oldest breast milk first. Apply the principle of first in first out because the quality of breast milk can decrease over time.
  • Shaking breast milk might not destroy its nutrients but microwaving can destroy all the nutrients and create hotspots that can burn your baby’s mouth.
  • If you thaw breast milk in the refrigerator, let it settle and use it within 24hrs. The 24 hr count starts when the breast milk is completely thawed, not from the time you took it out of the freezer.
  • Once expressed breast milk is brought to room temperature or warmed, use it within 2 hours.
  • Never refreeze breast milk after it has thawed.

Safe serving of breast milk

A newborn baby is lying down drinking breastmilk from a bottle.

To safely serve your baby breast milk, you should…

  • Swirl the breast milk to mix the fat which may have separated. 
  • Serve the breast milk at room temperature. Breast milk does not need to be warmed.

Here are some tips if you decide to warm breast milk:

  • Keep the container sealed.
  • Immerse the sealed container into a bowl of warm water or hold it under warm running water for a few minutes but not hot water.
  • Before feeding it to your child, test the breast milk’s temperature by putting a few drops on your wrist.
  • Do not heat breast milk directly in the microwave or on the stove. 
  • If your baby doesn’t finish the bottle, use the leftover milk within 2 hours of the baby finishing feeding. After 2 hours, the leftover breast milk should be discarded.

Frequently asked questions

Does shaking breast milk cause gas?

When you vigorously shake breast milk before giving it to your baby, you will introduce air into the milk, and if your little one swallows too much air, she may develop excessive gas.

This may not bother the older babies, but the very young ones tend to be more sensitive to gas.

Does breast milk bubble when shaken?

Shaking of breast milk may change the physical appearance and quality of the milk, but it doesn’t impact its nutrition.

What happens if a baby drinks spoiled breast milk?

It could cause diarrhea and vomiting, which is very dangerous for your baby if they happen to consume spoiled breast milk.

If you did not use it until after it was thawed, it would still be ok for a few more days in the fridge, but breast milk is still safe as long as part of it remains frozen.


There is no published evidence to support that shaking breast milk damages the milk cells compared to swirling. Many of the issues that came up identifying with shaking are better described as myths 

It would be an awesome idea if an in-depth study could be conducted by having women shake and swirl breast milk with active sensors on the hand and in the milk cup, measure the hand’s acceleration, and then analyze the milk.

I suspect we wouldn’t find much damage but until then, enjoy feeding your baby.

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Hello, I am Emelda from Nairobi, Kenya. They simply call me mama Lilly. A fun of long road trips and a very good cook, along with my mommy duties to a super active girl. She inspires and challenges me in equal measure, and that is how I get to share with you our journey of triumph as we grow and tag you along.

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