In the book Kiss Your Dentist Goodbye, Ellie Phillips DDS recommends ending each meal with a "tooth healthy" food such as milk or cheese which neutralizes acid loving bacteria that contribute to tooth decay. Most parents believe that milk is vital for healthy teeth (this belief is probably based on the fact that milk contains calcium and that calcium is a necessary nutrient for strong bones)

On the other hand, the Mayo Clinic counts "milk" among foods that cling to your teeth and cause tooth decay.

..the following factors can increase risk.. Certain foods and drinks.. Foods that cling to your teeth for a long time — such as milk, ice cream..

Besides for the Mayo Clinic's reasoning, there's another reason to doubt the assumed cariostatic nature of milk. Among experts there's a strong consensus that tooth decay is caused by the acid (mainly lactic acid) produced by the S. mutans bacteria that harbor the oral cavity which feed on fermentable carbohydrates.

Streptococcus mutans is capable of metabolizing pyruvate (pyruvic acid) further, to generate yet more energy and more acid byproducts. When excess sugars are available, they favor the lactate dehydrogenase pathway to produce lactic acid. This causes the pH in the immediate environment of the tooth to decrease rapidly, making saliva and the interbacterial fluid in dental plaque more acidic

Lactic acid is the major end-product of glycolysis by Streptococcus mutans under conditions of sugar excess or low environmental pH.

Since milk contains lactose which is converted to lactic acid by S.mutans, doesn't this support the argument that milk is actually cariogenic? The PH of lactic acid is 2.43 and the teeth begin to demineralize at a PH of 5.5. Moreover, the level of demineralization increases by ten fold for each additional 1 point drop in PH according to Ellie Phillips in her own book. Thus, a PH of 2.43 should be highly damaging to the teeth.

What scientific studies exist that analyze whether milk is cariostatic or actually cariogenic?

  • 1
    Those two claims aren't contradictory. Milk may be both a buffer and a food for harmful microbes. If milk is drunk but not left on teeth (for example if the teeth are brushed afterwards), milk would have the beneficial effect but not the harmful effect. If milk is drunk after brushing teeth (or when the teeth are not coated in acid), it would have the harmful effect but not the beneficial effect. In other words, the claims are that there is an immediate positive effect and a longer term negative effect. I would suggest questioning the first claim alone.
    – piojo
    Commented Jan 5, 2021 at 4:28
  • Like @piojo, I am worried this is a false dilemma. How can we fix it? (Likes to the definitions of cariostatic and cariogenic would be a start.)
    – Oddthinking
    Commented Jan 5, 2021 at 11:42
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    As @piojo said, it definitely depends on the time for which milk remains in contact with the teeth. Milk has cariostatic agents eg. casein proteins, calcium phosphates. However milk can be cariogenic if it remains in contact with the teeth for some time, as seen in infants when they sleep with their milk bottles, known as nursing bottle caries.
    – Ojasvi
    Commented Jan 5, 2021 at 12:16
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    Potential answers should consider that growing teeth in children might be affected differently then set teeth in adults.
    – user11643
    Commented Jan 5, 2021 at 16:02
  • I'd prefer not trimming the claim down. That's how we get misleading answers and how urban myths grow. If you want "what effects does milk have on teeth" seems the same question to me, but perhaps more neutral.
    – user11643
    Commented Jan 5, 2021 at 16:04

1 Answer 1


The book may actually be correct and Mayo (surprisingly) rather wrong here. According to a 2020 review:

Several published reviews have concluded that milk is of very low cariogenicity and may have some caries protective potential. For example, WHO reviewed the strength of the evidence in 2003 and concluded that a “decreased risk” of dental caries from milk was “possible.” The evidence comes from several types of study: epidemiological studies (interventional and observational), animal experiments, plaque pH studies, and in vivo and in vitro enamel and dentine slab experiments. More recent observational epidemiological studies have adjusted for potential confounders and have reported that milk consumption is associated with lower caries experience or incidence. Other types of study generally support this conclusion. Reasons for these favourable caries-related properties include the lower acidogenicity of lactose compared with other dietary sugars and the protective effects of calcium, phosphate, proteins, and fats.

The most detailed controlled studies were alas done in (deslivated) rodents or in vitro on enamel slabs...

A severe test of the cariogenic or cariostatic properties of milk was developed by Bowen et al. [68, 69], using desalivated rats which are therefore much more caries-susceptible. In these experiments, the rats given milk or lactose-reduced milk remained essentially caries-free, while those given sucrose or lactose in water developed caries. The authors concluded “that (cow’s) milk does not promote caries, even in the highly caries-conducive environment engendered,” and “that milk or lactosereduced milk can be used safely by hyposalivatory patients as a saliva substitute.” Peres et al. [70] and Bowen and Lawrence [71], also using desalivated rats, concluded that “cow’s milk was not cariogenic” and “cow’s milk is essentially noncariogenic”, respectively.

Caution is always needed when extrapolating the findings of animal experiments to the human situation, and this is important when dietary phosphate is thought to play a caries-preventive role [3, 72] as is the case with milk. Although some caution is advisable, the results of the above numerous animal experiments give considerable weight to the evidence that bovine milk is noncariogenic and may be anti-cariogenic.

Several studies, in human volunteers, have shown that the fall in plaque pH after drinking milk is negligible compared with the fall in pH after drinking solutions of sucrose or lactose, and that the falls for lactose were smaller than for sucrose [73–80]. While plaque pH studies are a useful guide to the fermentability of sugars in foods, such experiments do not consider the presence and effect of substances in foods which may protect against dental caries, such as, for example, calcium, phosphate and casein in milk.

Artificial caries-like lesions can be induced in small slabs of enamel by exposing their surface to acid buffers or by covering the slab with a biofilm which is then challenged with a variety of substrates. This method has been used both in the laboratory (in vitro) and in the mouth (in vivo), where they are held by a purpose-built intra-oral appliance, to examine the ability of foods to demineralize or remineralize tooth enamel. The early experiments of Weiss and Bibby [81] and Bibby et al. [82] examined the in vitro effect of bovine milk (raw, pasteurized, whole or skimmed) and found that all the milks “reduced the solubility of enamel,” while similar results were obtained by Thomson et al. [83–85] using an enamel slab intra- oral device. Jensen et al. [86], using a similar system, showed that milk (with 3 levels of fat content) was not cariogenic for enamel or dentine. Gedalia et al. [87] and Walker et al. [88, 89] reported that milk remineralized previously demineralized enamel slabs in vivo.

In addition to the plaque pH studies mentioned above, Jenkins and Ferguson [73] conducted in vitro comparisons of 4% lactose solutions and cow’s milk. They concluded that, within the limits of their experiments, their results “gave no grounds for suggesting that milk has a local effect on the teeth which would favour caries,” and suggested that the negligible fall in plaque pH was partly due to milk’s high buffering power and that the low level of dissolution of test enamel was due to the protective action of milk’s high levels of calcium and phosphate. Rugg-Gunn et al. [77] also reported that both cow’s milk and human milk protected enamel from dissolution in in vitro experiments, compared with sucrose or lactose, but that human milk was less protective than cow’s milk, as would be expected from their different calcium and phosphorus contents.

Eight further in vitro studies have investigated the caries inducing or caries preventive effect of milk and showed that (a) demineralization of enamel was reduced by intermittent exposure to milk [90, 91, 92], and (b) that milk aided the remineralization of demineralized enamel [90, 93]. Ivancakova et al. [94] and Arnold et al. [95] reported that milk reduced the rate of root caries progression.

Not all in vitro studies have suggested that milk resists demineralization or encourages remineralization. Prabhakar et al. [96] incubated enamel slabs with human or bovine milk in vitro and concluded that plain bovine milk was relatively cariogenic in the absence of saliva. Likewise, Muñoz-Sandoval et al. [97] and Giacaman and Muñoz-Sandoval [98] report that bovine milk caused demineralization of enamel and dentine slabs and concluded that “Whole milk… may be less cariogenic than sucrose but not anticariogenic.” These differences may be explained by differences in experimental methods. While the studies discussed in the previous paragraph used cell-free demineralization, the 3 studies discussed in this paragraph used active biofilms, for example, of Streptococcus mutans, which might result in a greater challenge.

Although there is no total agreement in the conclusion drawn, both in vitro and in vivo enamel slab experiments suggest that bovine milk has little ability to cause demineralization and, indeed, is capable of remineralizing previously demineralized enamel. The calcium, phosphate and casein components would appear to be crucial determinants of these favourable properties of bovine milk.

And an older (2002) review that was mainly focused on mechanisms, but which is open access says in its abstract:

The mechanisms involve several milk components and effects. Caseins and peptides thereof, i.e. casein glycomacropeptide (CGMP) and casein phosphopeptide (CPP), reduce the adhesion of cariogenic mutans streptococci in situ and seem to reduce colonization in the rat. They block adhesion in solution (clearance), as well as when bound to tooth surfaces. CGMP binds to the tooth as micelle-like structures, which do not bind bacteria. CPP binds as minor complexes with calcium and phosphate, buffering calcium and phosphate when hydroxyapatite solubility increases by decreasing pH, and possibly explaining the acid-buffering effect from milk and cheese. Further, peptides in the whey fraction, i.e. proteose-peptones, provide protection against tooth tissue demineralization, and other milk peptides, such as kappacin (a k-casein-derived peptide), lactoferrin, lactoperoxidase and lysozyme, possess innate immunity-like functions. Using milk components as a caries-prophylactic measure has not been studied in humans, but epidemiological studies conrm associations between milk:cheese intake and protection against caries. However, the impact of possible confounders cannot yet be fully evaluated.

Similar 2004 article.

  • Upvoted, excellent analysis. Would you concur that the anticariogenic properties of milk exist even if the milk is not ingested, rather the teeth are merely exposed to it? If this is the case, someone who is lactose intolerant may still be able to benefit from the potential anticariogenic properties of milk by swishing it around in their mouth a couple times a day..
    – S.O.S
    Commented Jan 6, 2021 at 0:02
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    @S.O.S Probably just better to use a wash designed for that ...
    – user11643
    Commented Jan 9, 2021 at 16:25
  • @fredsbend According to the research above, milk may prevent tooth decay in a different way than mouthwash does. So someone may want to take advantage of the benefits of both milk + mouthwash (not at the same time!). Or if someone wants a "natural" mouthwash, milk may be the answer. There seems to be some conflict in the data above in this regard, but the data suggests this possibility.
    – S.O.S
    Commented Jan 10, 2021 at 1:21

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