Thursday, May 20, 2010

Miss-Information, or The False Equation of Breastmilk with Cavities

I'm going to interrupt the sewing posts on this blog for a rant on breastfeeding and the misperception that prolonged breastfeeding is directly linked to cavities (dental caries) in young children.

Today I was at the dentist and a dental tech came up to me and talked to me as I was waiting to schedule the next appointment for the kids, which was to include the boy. It happened that I was wearing the sling with T riding in it and she asked if he liked it and my comment was that he seems to want to be in it more since he just weaned himself. Her response to that was that it was a good thing he had, since he was now a year old.

Me: "Why's that?"

Her: "Because breast milk causes cavities because it has so much sugar in it."

I'm not going to repeat the rest of the conversation here, mostly because I don't want to bore readers but also because I want to put forth my own argument on this ridiculous perception.

There are so many logical arguments that you can make against the statement "breast milk causes cavities and shouldn't continue past a year" which require only common sense and no scientific support so I'm going to go through those before talking about what science tells us.

1. Dentists are not the same as doctors. I hate to say this because they are doctors in the sense that they have higher degrees in their area of specialization. However, they don't go through the same kind of training that pediatricians do. The American Association of Pediatrics recommends that breastfeeding is the ideal way to feed the baby for the first year and that it should continue after the first year as long as it's beneficial for mother and child. So in other words, as long as you and your baby both want to do it.

They have taken this position because dozens and dozens of studies have shown the many benefits of breastfeeding for both mother and infant. These benefits continue beyond the first year, and they seem to far outweigh any risk for dental caries that you assume by extended nursing. Since these benefits have long-lasting effects, there is evidence to suggest that it's more beneficial to risk getting cavities in your baby's baby teeth than for him or her to be at risk for obesity or other health problems because you stopped nursing after the first year. Baby teeth fall out, your body remains the same.

Additionally, the American Association of Pediatric Dentistry makes the claim that breastfeeding should "be avoided after the first primary tooth begins to erupt and other dietary carbohydrates are introduced". (Policy on Early Childhood Caries (ECC): Classifications, Consequences, and Preventive Strategies, AAPD Reference Manual V31, No. 6, p. 41) This is in direct contradiction to the AAP recommendation, given that a child's first tooth could erupt as early as 3 months, thereby making the recommendation that mothers stop nursing far before the 1 year mark. Moreover, one has to draw the (obviously false) conclusion that mothers who breastfeed should stop when the child's first tooth appears and begin bottle feeding with formula when using the AAPD's logic, since their issue is with the breastmilk and not the breast itself. This is clearly a ludicrous idea but, because the AAPD approaches the problem of dental caries solely from the point of view of oral health and not from overall health, they persist in the belief that breastmilk is a direct cause of caries and that cutting it from a child's diet will prevent a huge portion of the infant population from getting cavities. Further, it doesn't seem to mesh with the idea that dentists have put forward that prolonged sucking on a more rigid object such as a bottle's nipple or pacifier will damage tooth alignment; the breast is designed with a baby's mouth in mind.

2. Babies do most of their exclusive breastfeeding prior to having teeth. Teeth which have not erupted cannot get cavities. It has been shown that babies do most of their exclusive nursing between birth and 6 months of age. On average, an infant's first tooth appears somewhere between the age of 4 and 6 months. So even if breastmilk were a direct cause of dental caries, this means that the exposure to breastmilk gets lower as the child ages, thereby lowering the risk of dental caries from it.

3. Around the same time that babies get their first tooth, solids are introduced. As the baby gets older, more and more foods are introduced and ingested and less breastmilk. The simple fact is that there are many different substances that have varying amounts of sugar in them - some more sugar than breastmilk. For example, fructose's purpse is a sweetener and it's what makes strawberries, apples, etc. taste nice. Lactose, which is found in breastmilk doesn't just have the purpose of making the milk taste good (it's in cow's milk, too, by the way) but rather it helps the baby's immature digestive system most effectively absorb calcium and other important nutrients. So to say that breastmilk is the sole cause of cavities in infants and young children is absurd because by the time they have 2 or more teeth, most of them are consuming more than breastmilk and water.

4. If extended breastfeeding really was a direct cause of dental caries, babies in Africa and in most third world countries would have extremely poor dental health. Extended breastfeeding used to be the norm everywhere in the world because there was no such thing as formula or bottles or even baby food. While the invention of formula and baby bottles was a lifesaver for children who couldn't nurse for various reasons, it completely changed the way we feed our infants and what we perceive as normal maternal-child interaction. Now only children born in Third World countries are breastfed for extended periods of time and, generally speaking, they don't seem to have an overwhelming problem with dental health and caries in their children. What's more, these are countries whose dental care is far less established than that in the US or Europe, so it would be normal for these children to have significantly poorer dental health and yet this does not seem to be the case. According to a study published in the journal Pediatrics, children in South Africa demonstrated no significant increase in risk for dental caries when extended nursing occurred:

"The American Academy of Pediatric Dentistry currently recommends weaning from bottle or breastfeeding by the age of 12 to 14 months and discourages bedtime infant feeding, especially after the eruption of the first tooth, to prevent ECC.(33) Although Roberts et al,(23) in their study of 1- to 4-year-old South African children, reported that children who were breastfed for 12 months had a lower level of caries than those bottle fed or bottle and breastfed for <12 months, the current study provides no evidence that breastfeeding for >1 year decreases or increases the risk for ECC or dfs counts. Moreover, interpretation of the results of the current study relevant to this issue is further limited in a number of ways. For example, the quantity and quality of supplemental feedings, the quantity of breastfeeding, and information about other factors, such as bedtime breastfeeding or bottle feeding, are not available from NHANES data, and, thus, it is not known how these factors might differ among those breastfed for >1 year and those breastfed for a shorter duration. Several other studies have investigated these factors; however, the results of such studies remain inconclusive.(5,6,16,34,35)"

So, the study even shows that children who were nursed for less than a year had more cavities than those who nursed for the entire first year of life. As anecdotal evidence, my oldest daughter nursed until about 1.5 months past her 2nd birthday. She has excellent oral health and has never had a cavity as of today. She will be 10 in August. So much for extended nursing causing cavities.

5. It is well-known that the main cause of dental caries is bacteria, NOT sugar. Here's where we come to the scientific part. The American Association of Pediatric Dentistry says that, "Caries results from an overgrowth of specific organisms that are part of normally-occurring human oral flora. Mutans streptococci (MS) is considered to be a principal indicator group of bacterial organisms responsible for dental caries." (Guideline on Infant Oral Health Care, rev. 2009, American Academy of Pediatric Dentistry) So clearly, pediatric dentists already know that bacteria is the true culprit when it comes to the cause of cavities. It would be fair to say that the average mother knows that pretty much everything her child touches is potentially harboring all kinds of bacteria. New mothers are admonished to wash their hands before they touch their babies, sterilize bottle nipples, clean off dropped pacifiers before allowing the child to suck on them again. However, we cannot completely sterilize our environments. Children crawl on various surfaces and touch everything within reach, putting their fingers and hands, or even the objects that they touch, in their mouths and in this way transfer myriad types of bacteria to their mouths. I submit that direct transmission of bacteria to a child's mouth is a much more common way for bacteria to be introduced and therefore a much more likely direct cause of dental caries.

So, if the AAPD is aware that the main cause of dental caries is bacteria, why aren't dentists and hygienists telling parents this and using it as a way to emphasize the importance of maintaining oral hygiene by brushing and flossing when children are very young? Instead they tell people that nursing is to blame and probably cause some mothers to stop nursing before they want to or before their child is ready.

6. People with softer tooth enamel are, in general, more susceptible to cavities. We're all unique individuals and we each have varying amounts of enamel hardness. Any good dentist can tell you that softer enamel is more susceptible to being worn down by bacteria and acids. Children with serious GERD issues often have softer enamel because of the exposure to acid due to reflux. Acid alone can cause enamel erosion and in someone whose enamel is soft to begin with, this provides an excellent opportunity for bacteria to set up house and get to work causing cavities.

7. The AAPD, in its Guideline on Infant Oral Health Care states that "Caries is a disease that is, by and large, preventable." It goes on to list things that can be done to help prevent caries, including the fact that, since it has been shown that bacterial levels in the mother's mouth can directly influence the bacterial levels in the child's mouth prenatally: "Oral hygiene: Tooth-brushing and flossing by the mother on a daily basis are important to help dislodge food and reduce bacterial plaque levels.". Presumably this is to reduce the amount of MS existent in the mother's saliva prenatally. Further, recommendations for post-partum care of infants' teeth begins with: "Oral hygiene measures should be implemented no later than the time of the eruption of the first primary tooth. Cleansing the infant's teeth as soon as they erupt with either a washcloth or soft toothbrush will help reduce bacterial colonization." It goes on to say how often children's teeth should be brushed and how much toothpaste should be used and adds that routine flossing should begin when there are 2 or more teeth adjacent to each other. (p. 96) Further, in Policy on Early Childhood Caries (ECC): Classifications, Consequences, and Preventive Strategies, the AAPD lists preventive measures for ECC. This list consists of 5 practices that parents can follow to decrease the risk of ECC. First on the list is reducing familial levels of Mutans streptococci during the prenatal period. Oral hygiene comes in at the #3 position and includes cleaning the teeth of children who fall asleep while feeding before putting them to bed; brushing the child's teeth twice daily with fluoridated toothpaste; and flossing. Included in #3 are recommended amounts of toothpaste by age. It is not until the last practice that we see mention of 'ad libitum' nursing. Clearly, extended nursing is not nearly as big of a problem as parents are made to believe if it is last on the list.

8. More emphasis should be placed on bottles and sippy cups and their contents. The AAP makes the recommendation that children should not be put to bed with a bottle or sippy cup. The AAPD mentions this, too, but I feel that more emphasis needs to be given to bottles and sippy cups because, more often than not, the beverage inside is not harmless water but juice or other sugary drinks, particularly when the child is older than 12 months. This is more common in homes on the lower end of the socio-economic spectrum and most notable in homes where the average level of education is lower. I have personally seen small children eating lollipops and drinking carbonated drinks like Sprite or non-carbonated but highly-sugared drinks such as Hi-C. It is becoming more and more common to see an 18-month-old child eating a Happy Meal at McDonalds and while fast-food restaurants have made efforts to provide healthier alternatives for children (apple slices instead of fries, milk to drink) the fact of the matter is that the children most in need of the healthy options usually don't get them and they end up with the carbonated drink and the fries. Given these extenuating factors it seems ridiculous to lay the blame for ECC at the feet of breastmilk before other causes.

9. The AAPD misses the boat completely when it comes to other major causes for ECC. According to the afore-mentioned study in the journal Pediatrics, other causes for ECC include maternal smoking and ethnicity.

"Although breastfeeding was not found to be associated with either an increased or decreased risk of ECC, decreased family income and prenatal maternal smoking, both strongly associated with decreased rates of breastfeeding as demonstrated in previous studies, (12) were both found to be independently associated with an increased risk. Maternal smoking during pregnancy is well recognized to be associated with myriad negative perinatal health outcomes in children,(24–27) in addition to early termination of breastfeeding.(28,29) In this study, children whose mothers reported smoking during pregnancy were less likely to be breastfed, but maternal smoking during pregnancy also was independently associated with increased rates of ECC and higher numbers of caries in multivariable analyses that controlled for breastfeeding. It is not possible from these data to disentangle whether it is prenatal, postnatal, or both prenatal and postnatal tobacco smoke exposure that is associated with an increased risk of ECC, because women who smoke during pregnancy are likely to continue smoking postnatally. Also, whereas it is possible that maternal smoking during pregnancy may simply be a marker for a mother's unhealthy choices for diet and oral hygiene practices, the association between secondhand tobacco smoke exposure and increased risk for dental caries in children in this and previous studies (17,30,31) indicates a clear need to establish the possible causal nature of the association of exposures to maternal smoking in utero and postnatally and ECC."

Ethnicity is a prominent factor when it comes to risk for ECC, though it is unclear whether this is a genetically-linked problem or if it is simply that minorities are more likely to earn less than their white counterparts and therefore be poor. The Pediatrics study showed that:

"Consistent with previous studies, children living in poverty and Mexican American children were at significantly increased risk for both ECC and S-ECC.(13,16,32) Although it is well recognized that socioeconomic factors and ethnicity influence dietary and oral health-related behaviors, as well as access to dental care, it remains unclear why poor and Mexican American children are at increased risk for ECC. Mexican American children in this nationally representative sample were more likely to breastfeed longer (both overall and exclusively) than other ethnic/racial groups. Ramos-Gomez et al(21) found higher rates of ECC among Mexican-American rural migrant children in California, but nursing patterns, such as duration, frequency or bedtime bottle/breastfeeding were not found to be independently associated with increased rates. Interestingly, in the current study, breastfed Mexican American and breastfed poor children had higher rates of ECC than non–Mexican American children or those living at 200% of the FPL who were never breastfed. The reasons for this could not be investigated because of limitations of the data. The NHANES 1999–2002 lacks, for example, information about nursing patterns, as well as other potentially cariogenic factors that might have been associated with poverty or being Mexican American, such as the level of oral cariogenic microorganisms, frequency of carbohydrate intake, or personal oral hygiene habits. These findings do suggest, however, that breastfeeding does not eradicate the increased risk for ECC among Mexican American children and those living in poverty."

In short, the AAPD needs to re-examine its position on extended breastfeeding and place a much greater emphasis on targeting children who are more likely to develop ECC, rather than simply demonizing extended breastfeeding. Additionally, I'm fairly certain that part of this reluctance to accept extended nursing is society's overall sexualization of women's breasts and its inability to reconcile this view with the actual purpose of the breast: to feed one's children.


  1. Well, you are right in your various points. And also:

    Dentists are not the same as doctors.

    And remember, DOCTORS sometimes get stuff wrong too! Like, oh...:

    "Oral hygiene: Tooth-brushing and flossing by the mother on a daily basis are important to help dislodge food and reduce bacterial plaque levels.".

    Right. THE MOTHER. Got that? Daddy, don't worry, you've already worked so hard. Put your feet up and let me get you that gin and tonic and I'll continue to cater to EVERY detail of our children's care.

    I nursed my kids until age 3 and 2. One of them has had dental issues and the other does not. As you mention there are hereditary factors at play and of course, different children have different diets and their teeth seat differently in the jaw (making cavities more or less of an issue) - and enamel softness, as you say, which some members of my family seem to have an issue with and others do not.

    I predict people who already have anti-breastfeeding bias or have consumed erroneous science will IGNORE the examples of prolonged breastfeeding and healthy dental outcomes. But in this case, this woman could PREDICT that had your child nursed any longer you would have had SO much more dental trouble. That's not something you can prove AT ALL but she can just say it, can't she, and walk away and continue to spout ignorance? Ugh.

  2. Actually, I assumed that when I read it and if it comes off that way in what I wrote, I made it sound wrong. What they're talking about is that bacterial levels in the mother's mouth can affect the level of bacteria in the fetus/neonate, so if the mother brushes HER mouth and lowers the bacteria count, the count the the child is likely to be lower, too.

    What irked me so much was that she's supposed to be the "dental professional" , the one with the knowledge and she was so clearly biased that it made me want to be über knowledgeable, too. And clearly I am, since most of what I wrote I actually said to her, though without the documentation to back it up.