Milk and the oral microbiome

My social media feed could be a psychology graduate’s thesis dream. Clearly it reads my mind, which adds what one would call an unhinged algorithm. Recently, the raw milk world entered the chat and shockingly, as I found out, gets more people riled up than discussions about war. My mind started thinking about milk and the mouth (sans the mustache), and here lies the research.

Milk can be a useful food for oral health, but not all milk products affect the mouth the same way. When discussing the oral microbiome, the real issue is not simply whether milk is “good” or “bad,” but how its composition influences plaque metabolism, acid production, enamel demineralization, and microbial ecology. Traditional dairy milk generally supports a more tooth-friendly oral environment than many sweetened beverages and some plant-based milk alternatives, while differences between skim milk, whole milk, heavy cream, soy milk, oat milk, almond milk, and coconut milk come down mostly to sugar availability, protein composition, fat content, pH, and mineral delivery.^1-5

One reason dairy milk tends to be relatively oral-friendly is that it contains calcium, phosphate, and casein proteins, all of which are relevant to enamel integrity. Milk is not a probiotic beverage in the way yogurt or kefir may be, but it can still influence the oral environment by making it less favorable for net mineral loss. Casein and casein-derived phosphopeptides help stabilize calcium and phosphate ions near the tooth surface, where those minerals may support remineralization and reduce enamel softening after acid exposure.^1,2,6 Bovine milk is considered low cariogenic—not because it avoids sugar entirely, but because its casein-rich, mineral-dense matrix helps counterbalance acid production and support enamel integrity in ways most beverages do not.^1,2,6,7

The primary sugar in dairy milk is lactose, which is fermentable, but generally considered less cariogenic than sucrose. Oral bacteria can metabolize lactose, but lactose typically produces a less aggressive cariogenic response than added sugars that rapidly feed organisms such as Streptococcus mutans.^3,7,8 Milk also has buffering capacity and a mineral-rich matrix that may reduce the net harm of dietary acid or carbohydrate exposure.^3,6,7

Most dairy milks are close to neutral pH, usually around 6.5 to 6.8, and many plant-based milks also fall in a similar range. However, oral health is influenced not just by pH, but by titratable acidity, sugar type, frequency of exposure, buffering capacity, and remineralization potential. That is why a beverage with a near-neutral pH can still be more cariogenic if it delivers more fermentable carbohydrate and less protective protein-mineral support.

Skim milk versus whole milk

Skim milk and whole milk are quite similar in terms of protein, lactose, calcium, and phosphate, so both can reasonably be viewed as compatible with oral health. The major difference is the fat content. Whole milk contains more milk fat, which may modestly slow oral clearance and preserve the natural dairy matrix a bit better than skim. In theory, that could slightly reduce the speed with which fermentable substrate is available to plaque bacteria, although this effect is likely modest in day-to-day use. If someone is choosing between the two strictly for oral health, whole milk may have a slight practical edge, but not enough to make skim milk a poor option. Skim milk is still a much better oral-health choice than most sweetened beverages or flavored “healthy” drinks.

Heavy cream

Heavy cream behaves differently. It is much higher in fat and lower in lactose per serving than standard milk, meaning it is less readily fermentable for oral bacteria. On paper, that sounds favorable. However, heavy cream is not usually consumed as a primary beverage, and it does not function the same way in the diet as milk. It may be less cariogenic, but that does not necessarily make it “better” for the oral microbiome or more useful for enamel support in real life. A more accurate way to frame heavy cream is this: it is likely less fermentable, but less functionally relevant as a routine oral-health beverage.

Soy milk

Soy milk is generally one of the better plant-based alternatives from an oral-health standpoint, especially when it is unsweetened and fortified. Compared with oat milk, soy milk is typically higher in protein, lower in starch-derived sugars, and often closer to neutral pH, which may make it less favorable to an acidogenic, caries-promoting biofilm.^5,9 That does not mean soy milk is equivalent to dairy milk. Even when fortified with calcium and vitamin D, soy milk still lacks the casein-rich dairy matrix that helps stabilize calcium and phosphate at the tooth surface. Dairy milk also tends to have stronger evidence behind its low-cariogenic and remineralization-supportive profile.^1-3,6 Still, if someone does not consume dairy, unsweetened soy milk is likely one of the more tooth-friendly plant-based options, and in many cases a better oral-health choice than sweetened oat, rice, or flavored nut milks. The problem is not soy itself—it is the added sugars, flavorings, and frequent sipping behavior that often come with commercial milk alternatives.^5,9

Oat milk

This is where people often get misled. Oat milk is not automatically oral-friendly just because it is plant-based. Many oat milks contain added sugars, enzymatically generated simple carbohydrates, and starch-derived substrates that may be more favorable to acid-producing oral bacteria than plain dairy milk. Even “unsweetened” oat milk can still present a more cariogenic carbohydrate profile than cow’s milk, depending on processing and formulation.^5,9 Oat beta-glucans have been shown to improve postprandial glucose regulation by slowing carbohydrate absorption and enhancing glycemic control.¹⁰ However, many commercial oat milks are enzymatically processed, reducing beta-glucan viscosity and breaking starch into simpler sugars. As a result, these products may produce a higher postprandial glucose response compared to intact oats, particularly in individuals with insulin resistance or impaired glucose metabolism.⁹ Many oat milks are fortified with calcium and vitamin D, which helps nutritionally, but fortification doesn’t recreate dairy milk’s casein-mineral matrix. That’s a major biological difference. You can add calcium to a carton, but you cannot simply duplicate the protective interactions of dairy proteins, lipids, and minerals. If an oat milk is sweetened or sipped frequently throughout the day, it may be substantially worse for caries risk than plain cow’s milk.^5,9

Almond milk

Almond milk is often perceived as a “healthy” alternative, but its oral-health impact is highly formulation dependent. Unsweetened almond milk is typically low in fermentable carbohydrate and near neutral in pH, which makes it relatively nonacidogenic compared with many sweetened beverages.^5,9 However, almond milk is also low in protein and lacks casein, meaning it does not provide the same remineralization supportive matrix as dairy milk. Even when fortified with calcium, it does not replicate the casein-calcium-phosphate interactions that help stabilize minerals at the tooth surface.^1,2,6 The real issue is that many commercial almond milks are sweetened or flavored, which significantly increases cariogenic potential. When consumed frequently or sipped over time, these versions can contribute to an acidogenic oral environment, like other sweetened beverages.⁵ From an oral microbiome perspective, unsweetened almond milk can be considered a relatively neutral option, but it is not functionally equivalent to dairy milk for enamel support and should not be assumed to provide protective effects.

Coconut milk

Coconut milk and coconut-based beverages vary widely in composition, and their oral-health impact depends heavily on the form consumed. Beverage-style coconut milks (carton products) are typically low in protein, variable in carbohydrate content, and often include stabilizers or added sugars, which can increase their cariogenic potential if consumed frequently.^5,9

Coconut milk derives its fat primarily from coconut oil, which is rich in lauric acid, a medium-chain fatty acid studied for antimicrobial properties in laboratory settings. However, these effects have not translated into meaningful clinical evidence for oral health. Coconut milk is not considered fermentable in the same way as carbohydrate-containing beverages, but current evidence does not support it as a functional oral-health beverage for enamel protection or microbiome modulation. Coconut milk is best viewed as composition dependent and generally neutral to potentially cariogenic if sweetened, rather than protective.

What about raw or unpasteurized milk?

This needs to be said plainly: raw milk is not a smarter oral-health choice just because it is less processed. Some people claim raw milk is “better for the microbiome” because it contains naturally occurring microbes and enzymes. That sounds appealing, but there is no credible clinical evidence showing raw milk provides superior oral microbiome benefits over pasteurized milk. Public health agencies, including the Centers for Disease Control and Prevention and the U.S. Food and Drug Administration, continue to warn that raw milk can contain pathogens such as Campylobacter, Salmonella, E. coli, Listeria, and Brucella, even when produced on farms with good hygiene practices.^11,12 Pasteurization does not meaningfully strip milk of its calcium, phosphate, or protein value in a way that would make it inferior for teeth. If someone is trying to choose the better oral-health option, pasteurized milk wins on safety without sacrificing the main features that matter for enamel and cariogenicity. Raw milk may sound “natural,” but microbiologically, it is a gamble—and not a necessary one.

If the goal is to support the oral environment and protect enamel, plain dairy milk generally performs better than oat milk and far better than most sweetened beverages. Among dairy choices, whole milk is probably the best all-around option, skim milk is still solid, and heavy cream is low in fermentable carbohydrate but less useful as a practical beverage. Among plant-based alternatives, unsweetened soy milk is likely the most favorable option, while almond and coconut milks are generally neutral unless sweetened, and oat milk is more formulation dependent and often more cariogenic. Raw milk, meanwhile, does not offer proven oral microbiome advantages and introduces unnecessary safety risk.

Editor’s note: This article first appeared in RDH eVillage newsletter, a publication of the Endeavor Business Media Dental Group. Read more articles and subscribe.

References

1. Giacaman RA, Maturana CA, Molina J, Volgenant CMC, Fernández CE. Effect of casein phosphopeptide-amorphous calcium phosphate added to milk, chewing gum, and candy on dental caries: a systematic review. Caries Res.2023;57(2):106-118. doi:10.1159/000530638
2. Ma X, Lin X, Zhong T, Xie F.Evaluation of the efficacy of casein phosphopeptide-amorphous calcium phosphate on remineralization of white spot lesions in vitro and clinical research: a systematic review and meta-analysis. BMC Oral Health.2019;19(1):295. doi:10.1186/s12903-019-0977-0
3. Castro RJ, Giacaman RA, Arthur RA, Maltz M. Cariogenicity of a milk-based drink used as a dietary supplement for older adults using a root caries experimental model. Caries Res.2019;53(1):76-83. doi:10.1159/000489569
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8. Moynihan P. Foods and factors that protect against dental caries. Nutr Bull.2000;25(4):281-286. doi:10.1046/j.1467-3010.2000.00088.x
9. Cui L, Jia Q, Zhao J, Hou D, Zhou S. A comprehensive review on oat milk: from oat nutrients and phytochemicals to its processing technologies, product features, and potential applications. Food Funct. 2023;14(13):5858-5869. doi:10.1039/d3fo00893b
10. Hossain MM, Tovar J, Cloetens L, Geraldi MV, Venuti C, Nilsson A. Oat beta-glucans consumed at breakfast improve glucose tolerance acutely and after a subsequent lunch – a randomized dose-response study in healthy young adults. Food Funct. 2025;16(10):4161-4171. doi:10.1039/d5fo00353a
11. Raw milk. Centers for Disease Control and Prevention. January 31, 2025. Accessed April 1, 2026. https://www.cdc.gov/food-safety/foods/raw-milk.html
12. Food safety and raw milk. U.S. Food and Drug Administration. Updated March 5, 2024. Accessed April 1, 2026. https://www.fda.gov/food/buy-store-serve-safe-food/food-safety-and-raw-milk