Weston A Price found that some populations had remarkably low levels of cavities (see his book Nutrition and Physical Degeneration, available online here). Swiss villagers from the remote Loetschental Valley had cavities at a rate of 0.3 cavities per person if they were eating their traditional diet. By comparison, one class of Swiss boys living in St. Moritz had cavities at a rate of 9.8 cavities per person. While it seems likely that Weston Price cherry-picked statistics to exaggerate the difference, Price found a strong correlation between diet and cavities. Some (though not all) populations eating a traditional diet had incredibly low rates of cavities, with most people in those populations being cavity-free. Excellent dental health was achieved without fluoride, tooth brushing, or fillings.

Thanks to studies on animals and humans, scientists figured out why some diets have led to extremely low rates of cavities. Not only that, they discovered that cavities can heal on their own with improvements in diet. In particular, the work of the husband-and-wife team of Lady May Mellanby and Edward Mellanby stand out. Edward Mellanby is best known for his role in discovering the causes of rickets (biography), a skeletal disorder caused by poor nutrition. Few people realize however that rickets and cavities are both caused by the same set of nutritional deficiencies.

The nutritional science of cavities

The Mellanbys discovered that with proper nutrition, the secondary dentin of the tooth can naturally remineralize and form a protective surface on its outer layer. To visualize what this looks like, we can look at teeth that have been stained with silver nitrate. We now know that the secondary dentin in teeth are filled with tiny tubes/tubules (Google image search) that allow stains such as silver nitrate to penetrate. From Weston Price’s Nutrition and Physical Degeneration, there is a diagram that shows a decayed tooth versus a healthy tooth:

The tooth on the left (A) is heavily stained as the decayed dentin is highly permeable to silver nitrate. The healthy tooth on the right (B) was pulled three months after the same child was receiving improved nutrition. Because the decayed dentin became denser, the silver nitrate has not penetrated it deeply; the discoloration is far less. Edward Mellanby’s 1934 book Nutrition and Disease (available on Scribd or mirrored on this blog; available in HTML) also has pictures of remineralizing teeth. In the diagram below, note that:

The tooth’s surface becomes less irregular and less soft as the secondary dentin remineralizes.

The healthier teeth become more resistant to the pigment used.

The tooth in the top-left has an active cavity (caries). The other images illustrate the progression of healing at 6 months, 3 years, and with an arrested cavity.

Dietary factors

The Mellanbys discovered that the following factors affect the healing of cavities:

Calcium and phosphorous (in bioavailable form). Fat-soluble vitamins, especially vitamin D. Low levels of phytic acid, which is typically found in grains/cereals, nuts, plant seeds, and legumes. Roots and tubers contain small amounts of phytic acid that are usually insignificant.

Bones like teeth are made up of mostly calcium and phosphorus. Not surprisingly, we need to absorb these raw materials from our food. Vitamins are building blocks for the proteins and enzymes that the body produces; they are needed for the body to function properly. Phytic acid is an anti-nutrient that binds to minerals such as calcium and prevents the body from using it.

Through animal testing, scientists slowly put together the pieces of the puzzle to figure out the main factors affecting tooth decay. Then their ideas were extended to human trials. May Mellanby and her colleague C. Lee Pattison ran a series of investigations on sick children with tuberculosis being treated at a Sheffield hospital. With hospitalized children, the researchers could control the children’s entire diet without having to worry about whether or not the test subjects were following their prescribed diet; the children did not have the freedom to go off their diet. The most effective diet that they tested was described in their 1932 paper. It contained plenty of vitamin D, calcium, and did not contain any grains/cereals. They found that the children’s cavities exhibited a remarkable level of hardening while almost no new cavities developed/got worse:

Vitamin D and the removal of cereals were the most important variables in their investigations. Their findings on vitamin A were inconclusive.

By modern scientific standards, the experiment could have been improved with a randomized trial design with a proper control group. Also, a larger sample size would be highly desirable as there were only 22 children on the cereal-free diet. Nonetheless, the results clearly indicate that improved nutrition can heal cavities.

The best diet consisted of the following (average daily consumption, in grams):

Milk, whole fat. 1190.7 g (That’s 1.2 litres / 5.1 cups / 0.3 gallons of milk every day.)

Potatoes. 212.6 g

Vegetables other than potatoes. 212.6 g

Meat. 141.8 g

Butter and cream. 70.9 g

Eggs. 56.7 g

Sugar, jam, syrup. 56.7 g

Fish. 28.4 g

Bacon. 14.2 g

Cooking fat. 14.2 g

Cocoa. 14.2 g

Cod-liver oil. 8.6 g

Radiostol (vitamin D₂). 0.4 g

Fruit additional to above in each case.

The diet clearly reflects the food of the early 1930s, when meat was less affordable and food was cooked with animal fat rather than vegetable oils. The researchers noted that “the children did not like giving up bread”, reflecting taste preferences of that era. The children’s cavities healed despite eating sugar, jam, and syrup.

Curing tooth decay today

Many of the same nutritional principles should apply today. For good dental health, we require high levels of fat-soluble vitamins. Unfortunately, there are no human trials on the specific levels needed to achieve excellent dental health. May Mellanby never looked at whether or not the supplemental 0.4g of vitamin D₂ was necessary. Nonetheless, it seems that a high intake of animal products without supplements should be sufficient. The anthropology work of Weston A Price and Vilhjalmur Stefansson demonstrate that some ancestral populations had excellent health without vitamin D supplementation (or tooth brushing). In Stefansson’s Not by Bread Alone (available here and mirrored here), Stefansson describes Icelanders in the Middle Ages who were immune to cavities as they lived primarily on animal products and negligible amounts of bread (pages 92-93; pg 68 in the PDF).

To treat cavities today, here is a list of some animal products that are easily obtainable at supermarkets:

Dairy: whole-fat milk, cheese, butter, cream. Avoid fake ice cream- “frozen desserts” use vegetable oil rather than cream and do not taste as good.

Meat, bacon, etc.

Liver: animals store vitamins such as vitamin A in their liver. Liver is an extremely nutrient-dense source of vitamins.

Bone marrow: when eating chicken, the leg bones can be cracked open to eat the marrow inside. Pork and beef marrow can sometimes be purchased at ethnic and mainstream supermarkets.

Eggs

Fish and fish offal. While unpopular, the bellies, livers, brains, and eyes of fish are all nutritious. Whole fish can be obtained if you don’t mind cleaning your own fish.

Seafood.

Where possible, you may want to consider buying wild-caught and pasture-raised animals as better taste and nutrition sometimes go together. Wild-caught salmon, which you may find better-tasting than the typical farmed salmon, was found by one study to contain roughly four times the Vitamin D than the farmed version. However, note that food products marketed as “free range” aren’t always nutritionally superior in such a dramatic fashion. One study found that it is possible to raise free-range chickens that produce eggs with four times the vitamin D content. However, the same researchers found that free-range eggs from supermarkets had low vitamin D contents relative to the ideal free-range eggs. This is fairly consistent with another study which found that free-range and organic eggs at supermarkets had only 42% more vitamin D 3 than conventional eggs. Unfortunately, the nutritional content can vary widely depending on how an animal is raised while consumers have very little information on the nutritional content of such foods. One way to sidestep this issue is to eat an abundance of nutrient-dense foods, ensuring an adequate margin of safety against insufficient vitamins and minerals. Or, tinker with your diet until you figure out what works for you.

Dealing with phytic acid

The simplest way of avoiding the anti-nutrient effects of phytic acid is to significantly reduce its consumption. Phytic acid is generally found in the seeds of plants. Foods such as grains, nuts, and bread can be substituted for potatoes, yams, and/or other carbohydrate sources such as fruit. Potatoes actually contain low amounts of phytic acid. At the time, May Mellanby did not know that the cavity-inducing effect of grains/cereals was due to phytic acid, which ironically is found in low levels in potatoes. Note that May Mellanby’s best diet had excellent results despite the low levels of phytic acid in potatoes. (For a fuller story on phytic acid, see Mellanby’s 1949 48-page paper on the topic.)

It should be noted that a higher intake of calcium and other minerals can counteract the effect of some phytic acid. Edward Mellanby wrote in his 1949 paper:

A diet which contains vitamin D and is rich both in calcium and phytate is compatible with perfect bone formation, but this is not the case when the diet is rich in both vitamin D and phytate and relatively (but not absolutely) low in calcium.

For this reason, Mellanby noted that adding milk to the diet can be more beneficial than an equivalent amount of butter when it comes to bone health. According to the USDA website, milk has roughly 5 times the calcium content than butter (125 versus 24 mg for every 100 grams). Both are still good sources of calcium; May Mellanby fed both milk and butter to children in her experiments. Also note that muscle meat and bone broths can be poor sources of calcium, so you may not want to rely on them as your only sources of calcium. Ribeye steak has 11 mg of calcium per 100g; eating 2500 calories of ribeye, which is enough to feed most adults, results in 94.5 mg of calcium or slightly less than a tenth of the recommended daily intake of 1000 mg. Meat-only bone broths have between 1.5 to 5.4 mg of calcium per 100g (see Table 1 on page 4 of this study), which is roughly 1/23 to 1/83 of the calcium content of milk. Adding vegetables to broths can increase their calcium content.

Another approach to dealing with the effects of phytic acid is to use different food preparation techniques to destroy the phytic acid in food. For example, the traditional methods of making sourdough bread involves fermenting it for at least a day. This process greatly reduces the amount of phytic acid in the bread, likely due to enzymes (phytases) in the bread that break down phytic acid over time. Differences in food preparation explain why Weston Price observed very good dental health in certain populations despite their consumption of whole-grain rye bread. (Whole-grains contain significantly more phytic acid before the breadmaking process begins as phytic acid is concentrated in the outer bran layer. The bran is removed in white bread.) However, preparing food using traditional techniques is time-consuming and less convenient that simply substituting away problematic foods.

Convenience tips

Modern diets have certainly provided a large degree of convenience thanks to restaurants, fast food, take-out, delivery, microwaved dinners, and processed food products. For those with busy lifestyles, here are some tips on making nutritious eating easier.

Eating out:

The bun in a burger can be substituted for a lettuce wrap at some chains. The In and Out chain refers to this as “protein style”. Or simply ask for no bun. Many fast food restaurants will allow you to order a bunless burger with extra patties, cheese, bacon, etc.

Easy cooking ideas:

Potatoes: it takes very little work to wrap a potato (or yam) in tinfoil and bake it. Eat it with butter and/or cheese. With a little more effort, potatoes can be boiled to make mashed potatoes. Mash in large amounts of butter for taste.

For foods that lose very little taste when frozen (e.g. mashed potatoes), prepare a large batch and freeze some of it for later consumption. This cuts down on food preparation time.

Slow-cooked broths and soups: use leftover bones, marrow bones, and/or meat scraps as the main ingredient (especially meat with lots of connective tissue such as skin, tendon, trimmings, etc.). Add potatoes, carrots, onions, beets, and/or tomatoes as desired. Cook everything for several hours with a slow cooker, crockpot, a pot in an insulated container, or a pot simmering on a stove. Cook at 70-100°C (158°F to 212°F). The long cooking time will make tendons and connective tissue tender enough to eat.

Bake meat/fish on a bed of onions, mushrooms, and/or vegetables. Any added butter or meat juices will drip onto the vegetables and add flavour to them. This is easy to clean up if you line the cooking container with a piece of aluminium foil.

If you don’t know how to cook, see my primer on basic cooking skills.

Other:

Snack on cheese instead of candy or potato chips.

Drink some of your food via whole-fat milk.

Why you should eat fat

Many people nowadays believe that fat and saturated fat cause obesity and/or heart disease. Mellanby’s diet certainly consists of foods that might be considered unhealthy today: cooking fat, bacon, meat, butter, cream, and whole-fat milk. However, randomized trials don’t support this misconception. The largest trial ever conducted on saturated fat versus vegetable oil, the Minnesota Coronary Experiment, found no difference between saturated fats versus vegetable oil. The results also suggested that a lowering of cholesterol correlates with higher rather than lower risk of death.

You may find it difficult to believe that health authorities have been spreading misinformed advice for a long time. But that’s why real science is beautiful. By performing controlled experiments, we can discover truths about our world and sort out conflicting information. See my post on fat (“Fat: one of the most studied areas of nutrition“) as it goes over randomized trials studying fat and saturated fat.

In fact, the way that the Mellanbys discovered the importance of fat-soluble vitamins was through the removal of fat from milk. In doing so, milk was stripped of its fat-soluble vitamins. The resulting nutrient deficiency allowed animal test subjects to develop cavities. Similarly, researchers also used lean meat (rather than fatty meat) and peanut oil as a replacement for cod-liver oil to induce nutritional deficiencies. In other words, the researchers had to remove nutritious fats from the diet to cause cavities.

(For a fuller story on how the scientific conclusions were reached, see Mellanby’s 1949 48-page paper on the topic.)

Other minor factors that affect cavities

Overly aggressive dentists

The determination as to what is and isn’t a cavity is actually subjective. Dentists will vary in their opinion as to what is and isn’t a cavity. Some dentists may be overly aggressive in diagnosing cavities because it is in their financial interest to do so. Tooth abnormalities identified by a dentist may not necessarily be a cavity or turn into a cavity. If you’ve never had a cavity in your life and a new dentist tells you that you have several cavities… you may benefit from a second opinion.

Fluoride and brushing

Once we get into the world of mainstream dentistry, the effectiveness of dental treatments drop off dramatically. Modern outcomes are not very good compared to what May Mellanby achieved with better nutrition. Nonetheless, the evidence is that some modern dental treatments slow down the rate at which cavities develop.

In general, fluoride-based treatments have a small impact on cavities. Here are what various reviews by the Cochrane Collaboration say about fluoride treatments:

Fluoride toothpaste (review): For the most common concentration of fluoride in toothpaste (1000/1055/1100/1250 parts per million), the cavity reduction effect was roughly 23% . Higher concentrations (2400/2500/2800 ppm) of fluoride had a stronger effect ( 36% ) while weaker concentrations (440/500/550 ppm and below) did not have a statistically significant effect. Note that there is some risk of fluorosis (imperfect tooth structure) when children under 6 years use fluoride toothpaste as some children will swallow it.

(review): For the most common concentration of fluoride in toothpaste (1000/1055/1100/1250 parts per million), the cavity reduction effect was roughly . Higher concentrations (2400/2500/2800 ppm) of fluoride had a stronger effect ( ) while weaker concentrations (440/500/550 ppm and below) did not have a statistically significant effect. Note that there is some risk of fluorosis (imperfect tooth structure) when children under 6 years use fluoride toothpaste as some children will swallow it. Fluoride varnishes (review): There was roughly a 43% reduction in cavities, although study results vary dramatically.

(review): There was roughly a reduction in cavities, although study results vary dramatically. Water fluoridation (review): The reviewers found that the available research isn’t very good. They concluded that the research suggests that water fluoridation is effective at reducing cavities in children. Surprisingly, they did not evidence for the same effect in adults. A Newsweek article on this Cochrane review contains some colorful comments from scientists:

Sheldon [dean of the Hull York Medical School in the UK] says that if fluoridation were to be submitted anew for approval today, “nobody would even think about it” due to the shoddy evidence of effectiveness and obvious downside of fluorosis.

As far as tooth brushing goes, I couldn’t find a Cochrane review on the topic. One review on the topic of personal hygiene (which combines brushing with flossing) found that personal hygiene alone, without fluoride, “failed to show a benefit in terms of reducing the incidence of dental caries”. However, you may want to take the review with a grain of salt as the authors misrepresent evidence in order to promote their pet theories on ‘dental defects’ and topical fluoride being effective because it is absorbed by the body. Regardless of whether or not brushing is actually effective, you should probably be more concerned about the combination of brushing and fluoride toothpaste- it is unlikely that you’d apply fluoride toothpaste without brushing. The evidence does point towards fluoride toothpaste as slowing down the rate at which cavities develop.

Flossing

One review states that there “have been no trials showing that flossing prevents caries [cavities] in adults in real-world clinical situations”. A more recent review additionally argues that flossing does not reduce plaque or gingivitis.

Sugar

From 1945 to 1954, researchers ran experiments on people with mental handicaps institutionalized at Vipeholm Hospital. While these studies are controversial today due to ethical considerations (e.g. lack of informed consent), they do add to our knowledge of dental decay. Here are some of the results of this research:

Sugar given in sticky form (especially toffee and caramel) and eaten between meals significantly increased cavities. However, this did not happen if the sugar was eaten with meals.

meals significantly increased cavities. However, this did not happen if the sugar was eaten with meals. Cavities still developed even when the diet contained as little sugar (natural or refined) and other carbohydrates as possible. (!!!) Contrary to mainstream dental theory, it seems that not all cavities are caused by sugar.

(See The Vipeholm Dental Caries Study: Recollections and Reflections 50 Years Later.)

The Vipeholm results strongly suggest that sugar isn’t very damaging to your teeth unless it is consumed between meals. Sticky sugars like toffee and caramel are more damaging than chocolate.

Acidic food and drink, e.g. soda

Scientists know that acids can slowly dissolve teeth when extracted teeth are tested outside of an animal’s body. However, scientists don’t fully understand why some foods dissolve teeth faster than others. One study looked at how quickly enamel dissolved in popular sodas and common beverages. There was little relationship between the acidity of the drink (as measured on the pH scale) and enamel loss. The chart below shows enamel loss in red, with pH in blue (lower is more acidic):

The researchers did not find any correlation between acidity (as measured by pH) and how quickly the enamel broke down in the various beverages.

Scientists also aren’t entirely sure if these laboratory experiments apply to living teeth in a human being. There is however anecdotal evidence that particular acids strongly correlate with dental problems:

Stomach acid from gastric reflux (GERD), or stomach acid from eating disorders where purging is involved.

Crystal meth, which leads to a condition dentists call “meth mouth”. Some dentists believe that this recreational drug is problematic due to its acidity, while others argue that it is due to dry mouth (xerostomia).

Mountain Dew, a specific brand of soda.

Professional wine tasting.

However, there are also anecdotes that provide conflicting evidence. One examination of professional wine tasters found that while wine tasters generally have more erosive wear, some wine tasters had no erosive wear.

As there is a surprising lack of animal and human studies, we simply haven’t even begun to research why some foods seem to be unusually bad for our teeth. We could feed dogs/cats/rats various soft drinks and sodas, yet we simply haven’t done so. While the Mellanbys did this type of experimental work and discovered how to cure rickets and cavities, that type of nutritional research simply hasn’t continued.

Despite the lack of good research, perhaps my own anecdotal experience may be helpful. As somebody who used to experience sensitive teeth (it went away after changing my diet), I have noticed that certain drinks would cause my teeth to become slightly painful within a few minutes. Consistent with the laboratory study discussed earlier on the enamel dissolving effects of various beverages, I found that A&W Root Beer was fine for my teeth while other sodas weren’t. Weirdly enough, competing root beer brands were damaging whereas A&W was not. If you experience teeth sensitivity like I did, you might also find that certain foods and drink trigger pain. I also found that consuming problematic foods/drink was not so bad if they were ingested in the middle of a meal. Rinsing my mouth with water did not have the same effect as eating a small amount of food. If you have sensitive teeth, this type of self-experimentation will allow you to quickly figure out what does and doesn’t make your teeth hurt. You don’t need a randomized clinical trial to figure it out.

Ultimately, there is very little quality research as to why some acidic substances seem to be bad for teeth while others aren’t nearly as bad. Regardless, we are fairly certain that (some) acids damage teeth. Dentists sometimes use acid etching to create a rough tooth surface so that adhesives will form a stronger bond to teeth. One of the acids used for etching is phosphoric acid at a very high concentration (30%). Phosphoric acid is a common ingredient in soft drinks and is found in Coca-Cola and A&W Root Beer. For whatever reason, Coca-Cola would trigger my tooth sensitivity but A&W Root Beer would not. Perhaps one day scientists will be able to explain why. Until that day comes, I would say that there is currently some degree of evidence that avoiding highly acidic/erosive foods can improve your dental health. Tea, coffee, milk, and A&W Root Beer can be substitutes for soft drinks and acidic fruit juices such as orange juice.

Recap / TL;DR

In our modern world, the most important factors to having cavity-free teeth are:

Eat plenty of nutrient-dense foods such as milk, dairy, meat, offal, etc.

Minimize consumption of grains and plant seeds by substituting such foods (e.g. bread) for potatoes, yams, etc.

If you’re not sure about what to eat, model your diet after the diet that May Mellanby used (hit Crtl + F and search for “the best diet”). *You don’t need to copy the consumption of sugar, jam, and syrup.

If you’re vegan, scroll down for Appendix B of this post.

And finally, I wish you the best when it comes to your dental health. May your secondary dentin be well-mineralized and decay-free.

Appendix A: Links to additional resources

Treating cavities

Stephen Guyenet’s old blog:

For whatever it’s worth, Guyenet has since changed his mind on phytic acid and doesn’t think that it’s as important as he originally thought.

Perhaps the most notable figure in treating cavities with nutrition is the late Ramiel Nagel, who has written about the importance of fat-soluble vitamins (and avoiding grains, etc. etc.). He has various ideas on “natural” (holistic) treatments of dental problems, promotes certain supplements, and heavily criticizes conventional dental treatments. I don’t agree with everything that he says as I don’t believe in holistic/alternative/functional medicine. Nonetheless, I would not have researched the Mellanbys’ science and curing cavities had I not stumbled across his website CureToothDecay.com.

More anecdotes about diet success can be found among the experiences of those on the keto diet, which happens to be fairly good for cavities as it cuts out most sources of phytic acid (with the exception of almond flour). Search reddit’s r/keto community with this link.

For the American Dental Association’s views, you can refer to the 2018 article “Options for dealing with tooth decay” or the 2013 patient handout “Tackling tooth decay“. I would note that Cochrane reviews of the scientific literature don’t support the claims that these articles make on water fluoridation and flossing.

History

Martin Renner has written an excellent phD thesis on the history of “conservative” nutrition, or nutrition that emphasizes traditional and proven ways of eating that have led to good health. He talks about the Mellanbys and briefly discusses how mainstream dentistry marginalized their views because they were seen as outsiders.

A different historical narrative by Malcolm Nicolson and Gillian S Taylor looks at the controversy surrounding the Mellanbys in their day. Mainstream dentistry at that time pushed forward the theory that fibre-containing food had a ‘detergent’/cleaning effect on the mouth, which got rid of bacteria that causes cavities. This theory is not taken seriously today. Nicolson and Taylor seem to suggest that leading dentists defended their theories (and attacked the work of the Mellanbys) to save face:

The leading British dentists found themselves in a position in which their claim to professional status and their claim to distinctive therapeutic and preventive expertise were both under intense scrutiny. It is in this context that the adoption of a form of discourse that emphasised their possession of a special sort of authority, primarily clinical but secondarily scientific, was particularly advantageous.

Appendix B: For vegans

If you are vegan, emulating the diet that May Mellanby used obviously won’t work due to the many animal products used. And just as unfortunately, there are few proven models of healthy vegan eating. The anthropology work of Weston A Price and Vilhjalmur Stefansson did not uncover vegetarian (let alone vegan) societies with excellent dental health. I haven’t come across studies on how to optimize nutrition for dental health while on a vegan diet. Nonetheless, if you want to try to make veganism work for you, here’s what I could find.

Denise Minger, a health blogger who was vegan for years, has a page full of tips for those looking to maximize their health on a vegan diet. She suggests getting vitamin D (specifically, vitamin D 3 rather than D 2 ) from vegan supplements. Note that added vitamin D 3 typically comes from animal sources, so make sure that the supplement is vegan. Her preference for D 3 over D 2 is to sidestep concerns over the lower bioavailability of D2 (D2 may not be converted into usable vitamin D as readily). Eating non-sentient bivalves such as oysters is another option for vitamin D. Minger also provides some tips on how to prepare food to reduce their phytate content (phytate refers to phytic acid and its various forms when it binds to minerals).

Ramiel Nagel (now deceased) wrote an article on how to reduce phytic acid levels in foods with different food preparation techniques. Nagel’s website also has a page for vegans.

Some additional notes: