Here’s my opinion after studying baby bottles, breast feeding and breast feeding mechanics:
Negative air pressure or vacuum is created when baby sucks milk out of the bottle. Do a simple experiment; grab a can that contains liquid like juice or milk, make one small hole about 1/8” diameter on one side of the top and tilt or turn can upside down, you’ll notice that the liquid doesn’t come out. Now make another small hole on the opposite side of the can and tilt; you’ll notice the liquid pours out without problems. Make another experiment when you drink from a plastic water bottle; create a seal around the opening and start sucking, you’ll notice the bottle begins to deform as you drink; the longer you suck, the more it deforms. It’s also difficult to swallow and the bottle is pulling liquid out of your mouth back into the bottle. This phenomenon is due to negative air pressure or vacuum.
Air-vents are an opening or one-way valve that allows air to enter a closed container like a baby bottle to reduce vacuum created when liquid leaves. Traditional baby bottles have air-vents to prevent a vacuum and the resulting effects; difficulty feeding, nipple collapsing and excessive air bubbles. The reason most babies are colicky after feeding from a traditional bottle is because they swallow the air entering the bottle through the air-vents. You may not see bubbles, but air is constantly mixing in with milk. It’s known that air ingestion causes gas and colic in babies.
A baby bottle with no air-vents would need to shrink in size to compensate for the negative air pressure created as liquid is sucked out. Think of a syringe that delivers medicine directly to your veins. There’s a piston inside the syringe that moves up as the medicine leaves the syringe, delivering air-free medicine. Similar to a syringe, a BARE bottle’s milk chamber automatically reduces in size as the baby sucks out the contents; preventing the build-up of negative air pressure and dispensing air-free milk. Breast-milk is contained in little sacs called milk lobes, inside the mother’s breast; as the baby sucks the milk, these lobes shrink in size as well. It is known that the less air the baby swallows, the less discomfort baby will suffer from gas and colic.
Not all non-vented bottles offer benefits to a baby. A traditional baby bottle with no air-vents is the most primitive of its kind. As baby sucks contents, he’s also building negative air pressure leading to nipple collapsing and difficult feeding. When baby lets go of the nipple air enters thru the nipple creating and ingesting air bubbles that leads to gas, colic.
This comparison is based on published articles, factual statements and user testing.
1 It is known that air-swallowing may cause gas / colic in babies. The less air ingestion the less gas in babies
2 Nutrients are lost when milk is mixed with oxygen in the air, BARE allows the user to expel the air and maintain an air-tight container to inhibits bacteria growth, due to the lack of oxygen, resulting in longer nutrient retention than baby bottles that allow air. A baby bottle with collapsible lines allows user to expel air but doesn’t maintain an air-free environment, air goes back in almost immediately as gravity pulls liquid down.
3 Because BARE works with suction as opposed to gravity, baby is able to start feeding as soon as he/she can bring the bottle to his/her mouth. Other bottles require baby to turn the bottle upside down which can delay the self-feeding milestone. 4 breastfeeding directly is proven to have innumerous benefits for mom and baby rather than bottle-feeding breast milk to learn more about the advantages of breastfeeding go to http://aappolicy.aappublications.org/cgi/content/full/pediatrics;115/2/496