New Parents, Cross This Off Your List of Things to Worry About



Does shaking breast milk actually damage the nutritional value? Research is scant, but this Ph. D says most likely not
Since the fat in breastmilk rises to the top, my husband's first impulse was to give the mason jar a good shaking before turning it into a bottle for our son. My mother, who saw him do this—and who I should mention is not at all the nagging type—stepped out of character for a moment and told him not to shake the jar. And if you have ever done any reading online about how to handle breast milk, you have probably encountered the same warnings that breast milk should be gently swirled, not shaken, because it may damage the proteins it contains. However, the scientific research in support of this advice borders on non-existent.
Most of what you'll find online links back to two sources: Lactation Consultant Linda Smith, who published a short and citation-less essay entitled, “Don’t Shake the Milk,” vs. Anthropologist Elizabeth Quinn Ph. D, who wrote a very lengthy and reasonable analysis of the available scientific data on her blog.
Because there are no studies that specifically look at what happens to human breast milk when shaken, Dr. Quinn went about gathering data points from other scientific resources in order to answer this question. Here’s a look into her thought process:
“The idea that shaking denatures proteins is based on the shear force the proteins would be exposed to during shaking.  We need two pieces of information here: what level of force is generated by shaking and what level of force denatures proteins."
How she calculates the force a human arm can generate vs. the force a protein can tolerate is pretty interesting, and she goes into great detail about it on her blog if you're interested. Long story short, once she compared the figures, the conclusion was pretty clear:
“It is unlikely that the human arm is capable of generating enough force to damage the cells in the milk.”
And although there are no human studies, she goes on to cite the closest research available, which looked at leukocyte levels in animal milk.  (You may remember that we also encountered leukocytes last week when we looked at another feeding myth about storing breast milk in glass. Leukocytes are the beneficial antibodies mothers pass on to their babies to help build their immune systems):
“A study of leukocytes exposed to shear forces in a rat model, found that leukocytes incurred very little damage from shear forces.  Breast milk cells are likely exposed to high shear force at multiple points in their normal life course – from milk ejection to swallowing to digestion, and may be more resistant to cell damage.”
So, could you mix breast milk like a martini? Maybe. There’s not enough research to know for sure. We’ll probably still mix milk on the gentle side, but it’s nice to know this isn’t an issue worth worrying about too much.

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@faustisland just bought a pack of Mason Bottle Silicone Nipples, and then combined one with a classic blue mason jar she had at home. Extra adorable!

@valeryphalon.photography uses Mason Bottle Silicone Sleeves to make toddler training cups for her big girls.

@headygrimm gets a Mason Bottle + Silicone Sleeve ready for her little one. She got the whole bottle including the jar as part of the Essential Mason Bottle Gift Set, but you can also make your own with jars from home using the Mason Bottle DIY Kit.

@loveandcovenant uses the 8 oz DIY Kit in combination with their mason jars from home.

@eyecreate_ gave her little lade The Original Mason Bottle. The width of mason jars makes them easy to hold for little hands.

@headygrimm got the Essential Mason Bottle Gift Set for her little one. It comes with both size bottles, both sleeves, and set of extra set of Medium Flow Nipples.

Paola used Mason Bottle with her son Max from the day they brought him home from the NICU. Though he didn't take to the preemie nipples in the hospital, he latched onto his Mason Bottle immediately!

@sriesland stocked up on mason jars for pumping at work, then she got a Mason Bottle DIY Kit to turn those jars into baby bottles.

@MasonBottle we like to use our 4 oz. sleeves with baby food portions.





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