How Breastfeeding Protects Against Tooth Decay

This is a topic that has been bothering me since I had Aristotle…

When I was in dental school, we were told to discourage parents from night time bottle feeding because it leads to “nursing bottle tooth decay”. This happens because when your child falls asleep, the milk pools around the teeth. Since salivary flow slows down when you’re asleep, it can’t wash away the residual milk as easily. Bacteria then break down the milk sugars in the pooled milk around the teeth creating acid that dissolve the teeth and lead to the formation of cavities (tooth decay).

The assumption is that this happens regardless of whether your child takes formula or breastmilk. I can understand how formula milk causes tooth decay because a lot of milk formulas have added sugars. The question that has been on my mind is why would breastmilk – the first source of nutrition to a child intended by nature – have such a detrimental effect on their teeth? Especially when it has been found that night time breast milk is specially designed to make your baby sleep:

“melatonin, the sleep hormone, is undetectable in breastmilk during the day and peaks during the night”

“concentrations of sleep-inducing nucleotides to be stronger after dark than during the day”

The first tooth comes out on average at about 6 months and it is recommended that we breastfeed until our babies are at least 2 years old or more. Aristotle was nursing to sleep until about 3 years old. Hercules is 3 and he still nurses to sleep sometimes. In the primate world, some animals are nursing until 6 years.

If nature intended for babies and young children to consume milk before sleep, why would it serve something that would cause the teeth to decay? It makes no sense. It would be like evolutionary suicide.

It’s no coincidence that breastfed babies have less incidence of decay compared to formula-fed babies. Is it because of the method of delivery or is there something inherent in the breast milk that prevents decay? Well, it’s both.

Method of delivery: when a baby suckles directly from the breast, the milk enters the mouth behind the teeth and is swallowed. There is no pooling of milk in the mouth which can lead to tooth decay. If the baby falls asleep and stops suckling, the milk stops flowing. This suggests that it would actually be better to nurse directly from the breast at night rather than be bottle fed expressed breast milk. 

Breast Milk Properties: Breast milk contains lactoferrin which kills the bacteria that cause tooth decay.

“Before the use of the baby bottle, dental decay in baby teeth was rare. Two dentists, Dr. Brian Palmer and Dr. Harold Torney, have done extensive research on human skulls (from 500-1000 years ago) in their study of tooth decay in children. Of course these children were breastfed, probably for an extended length of time. Their research has led them to conclude that breastfeeding does not cause tooth decay.” – KellyMom

I thought it was also interesting to note that early studies were only the effects of lactose (the sugar in milk) on teeth, not on the effects of “complete” breastmilk on teeth.

So we can nurse our children to sleep without having to worry about causing their teeth to decay. And breastfeeding trumps again.

Further reading:

Published by Shen-Li

SHEN-LI LEE is the author of “Brainchild: Secrets to Unlocking Your Child’s Potential”. She is also the founder of (a website on parenting, education, child development) and (a website on Right Brain Education, cognitive development, and maximising potentials). In her spare time, she blogs on Forty, Fit & Fed, and Back to Basics.

2 thoughts on “How Breastfeeding Protects Against Tooth Decay

  1. Many thanks for your investigations, Shen-Li! If it wasn´t for your article, I would probably follow the advice given by my dentist today when she told me that my daughter has 5 teeth with caries and that it was due to the breastfeeding at night (although she first suspected the bottle feeding at night and only changed route when I told her my girl was breasfed 😉 But I completely agree with you that it doesn´t make sense a) there is no milk intake if the baby doesn´t work to get the milk out, so any milk intake will be stopped the moment the baby falls asleep b) the intake takes place is AFTER the teeth, not before! Wouln´t have ocurred to me without your blog entry though so THANK YOU for saving my daughter from being weaned unnaturally just because of some ill advice of an dentist!


    1. My pleasure. Glad to be able to help correct the misconception. 🙂 I hope we can spread this information so that nursing mothers don’t wean their children early because they are concerned about tooth decay.


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