The dentist always says the same thing: floss every day, brush twice per day, don’t eat too many sweets. It seems no matter how well you follow this advice, your teeth continue to rot. You believe you’re genetically cursed, like I used to believe about myself, but the reality is there are a multitude of science-driven actions you can take to keep your teeth sturdy for good. By reading this, you’ll save yourself the physical pain of scary metal tools and the financial pain of burning thousands of dollars on procedures. You’ll also be equipped to ask your dentist more probing questions and really get your money’s worth on consulting their expertise.

Part 1: Acidity and Saliva

Acid Damages Enamel, Saliva Protects It

You already know the common dietary factors impacting oral health: sugary, starchy, and acidic foods. Sugars don’t directly damage teeth; instead, they feed bacteria that promote an acidic environment in the mouth, and those acids erode tooth enamel. Starches are broken down into simple sugars within the mouth, creating the same effect. And of course, acidic foods/beverages like citrus fruits and coffee or soda can similarly damage teeth, even when they are sugar-free. A 2004 paper with hundreds of citations at this time of writing describes much of this common knowledge, but it also highlights a lesser-known secret:

A very important biological parameter is saliva. Several salivary protective mechanisms come into play during an erosive challenge: dilution and clearance of an erosive agent from the mouth, neutralisation and buffering of acids, and slowing down the rate of enamel dissolution through the common ion effect by salivary calcium and phosphate [Zero and Lussi, 2000].

Saliva is a protective agent against foods that typically erode teeth, working preventatively to buffer against acids and remedially to remineralize enamel once damaged. It’s a defensive measure we tend to ignore because it’s not usually considered to be something we can control. On the contrary, as you’ll see below, it very much is.

Besides well-known food and hygiene practices, saliva is important

Metabolism

I’m going to pitch a fascinating idea right now: the ability for saliva to protect teeth depends on overall metabolic health. This animal study demonstrates that a stressful high-sugar diet impairs salivary gland function; not only does salivary flow rate decrease, but the protein content of the saliva decreases, reducing its protective capacity. Note that the presence of oxidative damage to salivary glands suggests that the effect isn’t specifically due to sugar, but can be caused by any diet that promotes an unfavorable redox balance, i.e., any diet where nutrient value is insufficient to combat the oxidation created from energy intake and other external sources (oxidized oils, environmental pollution, smoking, etc.). The same is true for many chronic diseases, and is a recurring theme in this blog; an unfavorable redox balance compromises the functions of bodily systems, promoting various diseases due to the body’s adaptation to a stressed state.

That means we should also expect human subjects with metabolic diseases to experience tooth decay at higher rates than healthy ones, which is exactly what we see in observational data. Here is a study of middle-aged Japanese men, comparing those who suffered from tooth decay with those who didn’t. Those with tooth decay were much more likely to have metabolic syndrome, even after other variables like age, smoking status, and amount of physical activity were controlled for. Granted, observational studies can’t control for every variable, but combining this data with the aforementioned animal study concocts a strong argument: metabolically unhealthy people are much more likely than healthy ones to have problems with tooth decay because their saliva is sparse and weak. Some estimates calculate as many as 88.2% of American adults to be metabolically unhealthy; no wonder teeth are a constant societal struggle.

A stressful diet, in addition to causing other metabolic diseases, impairs the protective effects of saliva.

Saliva Man
Your saliva needs to hit the gym

Drugs

A long list of medications can cause dry mouth as a side effect, making teeth more vulnerable; consumers should check labels and consult medical professionals. Two common non-prescription drugs, caffeine and alcohol, act as diuretics and can also lead to increased mouth dryness. The 85% of Americans who consume at least one caffeinated beverage per day should be aware of this and make sure to stay hydrated while keeping their caffeine intake moderate.

Part 2: You Have Not Enough Minerals

Vegetarians Have More Tooth Decay

This is fascinating: a simple observational study comparing the dental health of vegetarians and non-vegetarians. On one hand, the vegetarians had better gum health than the non-vegetarians, but the typical flaw in vegetarian versus non-vegetarian studies is we’re not actually comparing vegetarians with meat-eaters; we’re comparing people who are selective about their eating with people who are not. Additionally, the vegetarians in this study were more educated, suggesting socioeconomic advantages. Yet despite those advantages, and better gum health, the vegetarian group still had significantly more tooth decay and erosion; quite a surprising result! The goal is not to pick on vegetarians specifically, but to ask what it is about this eating pattern, or closely-related ones, that might promote tooth decay. I dove into published research and reached a very interesting conclusion about something that no one is talking about.

Something mysterious in human diets is a likely reason why vegetarians have more tooth decay than omnivores.

Modern Diets and Mineral Absorption

For decades, dietary trends have promoted using grains, nuts, seeds, and legumes as the primary foundation of a diverse and healthy human diet. As a funny side note, these foods are all different types of seeds, so what looks diverse on the surface is not very diverse after all. But what’s important to know is that many of these foods contain phytic acid (PA), an antinutrient that reduces the absorption of dietary minerals like zinc, calcium, magnesium, and iron; all of which are critical for strong teeth. The presence of antinutrients makes sense biologically to help certain plants avoid unwanted predation, yet antinutrients remain oft-overlooked components of nutritional planning. We should especially pay attention to people who are consuming large quantities of these foods every day, while at the same time limiting nutrient-rich foods like meat, eggs, and fish because of lifestyle choices or pop culture headlines. Societies in the distant past discovered brilliant preparation methods to reduce antinutrient presence in plants, but those processes are rarely used in basic modern cooking. Opinions about antinutrients vary among nutrition enthusiasts; on one end are people who claim they are insignificant, and on the other are those who avoid them like the plague. Both extreme groups have strong biases towards their own eating habits, happily cherry-picking and distorting research findings to sell an image or a product. What I’ve found in my own investigation into phytic acid is that its presence doesn’t always matter, but when it does, it can be significant.

This Oxford-published article analyzes the impact of PA on the absorption of different dietary minerals. I’ll summarize the analysis of these minerals one by one, while also presenting additional evidence.

Many modern foods are high in phytic acid, and the traditional ways of preparing them are rarely used in basic cooking.

Phytic Acid and Calcium

We know definitively that PA impairs calcium absorption, but there’s no good evidence that this impact is meaningful in a human diet. Measuring adequate calcium intake isn’t an exact science because blood levels of calcium depend on many factors. Luckily, measurements like bone mineral density (BMD) can be used to get a rough idea. Here is a paper published analyzing BMD in vegetarians compared with omnivores. While there is some research to suggest vegetarian BMD to be modestly lower, the degree is not clinically significant, and the results are inconsistent between studies. So presumably, PA is not impactful on calcium levels within realistic dietary boundaries.

Phytic Acid and Magnesium

PA has been shown to impair magnesium absorption in humans, but that is offset by the magnesium concentration in PA foods. That’s why we see comparable magnesium status of people on plant-centric and control diets; plant-centric diets are higher in PA, but they usually contain more magnesium. This is clearly another case where PA intake is not impactful.

Phytic Acid and Zinc

Zinc is different. A number of studies like this one plainly state:

We observed a high prevalence of imminent or manifest zinc deficiency among vegetarians and vegans.

Is the deficiency an abundance problem or an absorption one? Several plant foods, like oats, include an abundance of zinc, so most plant-focused eaters should not have a problem eating enough in theory. However, zinc’s bioavailability in plant foods is reduced to the point where getting enough is challenging. As cited in the Oxford paper:

PA is the major determinant of Zn absorption, especially for diets with a low animal protein content.

Not only is PA hugely impactful on the absorption of zinc, but a couple of other nuances compound the problem. First, a bit of irony: although calcium is another mineral that is important for teeth, it works synergistically with PA in the gut to impair zinc absorption even further. Second, vegetarians consume little to no animal protein, which means a lack of peptides to promote zinc absorption even when PA is not considered. Finally, this study concretely demonstrates zinc’s importance on the integrity of tooth enamel. Therefore, the conclusion that zinc-deficient people have weak enamel and are more susceptible to tooth decay bridges perfectly with the observation that vegetarians, who are often zinc-deficient due to high PA consumption, are at greater risk of tooth decay compared with their omnivorous peers.

Phytic Acid and Iron

Iron deficiency worldwide is extremely common, and vegetarians have repeatedly been shown to have lower iron stores than omnivores. The reason is twofold: first, dietary iron comes in two forms: heme and non-heme. Heme iron, found in meats, is absorbed 3.7x more easily than non-heme iron, found in plants. Second, PA is a major contributor to reduced iron absorption. Human observations, animal experiments, and in-vitro analysis all align to show iron’s impact on tooth decay. Iron-deficient children were observed to have a huge 10.77x increased likelihood of severe cavities compared to a control group, and iron has been repeatedly shown to impact enamel strength directly.

Phytic Acid Conclusion

Phytic acid is an underreported detriment to dental health; It binds to zinc and iron in quantities that are impactful on enamel. Vegetarians are a useful proxy in research to represent people consuming a high-PA diet, and have been shown to have higher levels of tooth decay than omnivores, even in cases when their overall health is better. That means anyone who consumes an abundance of grains, nuts, seeds, and legumes, vegetarian or not, needs to be wary. They should take extra care of dental hygiene, supplement when needed, and prepare high-PA plant foods to reduce their PA content via techniques like soaking, sprouting, fermentation, and cooking. The simplest approach is shifting the diet to favor animal foods more, creating balance and reducing the need for tedious micromanagement. That strategy bolsters overall nutrient intake while keeping PA levels too low to cause any harm.

Part 3: Useful Tricks

Technology

The year is 2026, and yet most people still brush and floss like it’s 2026 BC. The study results on electric toothbrushes are neutral to positive; some show a positive effect on plaque removal while others show no benefit. Even so, electric brushes are easier to use and reduce the possibility of incorrect technique. Even more impactful is water flossing: research consistently supports water flossing in favor of string flossing, and it’s also easier.

Honey

Eating honey is much better for teeth than eating table sugar. How is that possible when honey is almost pure sugar? Remember, the sugar itself is not what damages teeth. Instead, sugar feeds oral bacteria that produce acid, and the acid is what causes the damage. Because honey is antibacterial, it helps fight acid-producing bacteria that cause cavities. Luckily, honey is non-perishable, so finding good-quality honey is easy, whether locally or online. I have personally consumed large amounts of honey for months at a time with no detriment to my teeth, so believing the research is easy for me. Although it’s more of a footnote here, honey is something I plan to write more deeply about in the future.

Chewing

Modern foods generally tend to be much softer than traditional ones, reducing the amount of chewing required. Besides helping the jaw develop normally, chewing also increases saliva production, helping to protect teeth. That’s why chewing sugar-free gum can help prevent decay, even more so when xylitol gum is used. Choosing real foods that require heavy chewing like roast beef, firm fruits, and fibrous vegetables is also a good strategy for people like me who don’t want to start a gum-chewing habit.

Saltwater Rinses

Rinsing with saltwater after eating might have a mildly positive effect. Research is mixed, but it can offer mild protection against cavity-causing bacteria, while also dislodging food particles. I asked my dentist and he said it’s not a bad idea. At the very least, it’s easy and harmless, even if not super impactful.

Part 4: Final Thoughts

Why I Wrote This

My teeth have not always been perfect, especially back when I was eating a diet heavy in junk food and taking prescription stimulants. Back then, I brushed my teeth twice every day and flossed every day, yet still frequently got cavities. The dentist didn’t offer any advice other than to brush and floss better. Once I improved my health, so did my teeth, but eating a diet heavy in some foods that were high in phytic acid, like nuts, still contributed to the occasional cavity. These days, I’ve been enjoying a comfortable cavity-free life, and studying the research has helped me understand why.

My Own Protocol

I focus on a nutritious diet centered around animal foods, complemented with carbohydrates that usually come from fruit and honey. I prefer chewier cuts of meat for the lower cost, and the increased chewing also adds enamel protection as a bonus. My consumption of phytic acid is very low because I don’t eat grains, seeds, nuts, or legumes too frequently. I use an electric toothbrush once per day in the evening (I know twice per day is recommended) prefaced by water flossing. Those nutrition and hygiene habits have helped keep me cavity-free for a long time now, and my twice-yearly professional dental cleanings are easy because my plaque buildup is low. My eating strategy wasn’t originally designed with tooth protection in mind, but studying the research has provided sensible answers that describe why it works so well. I’m sharing my own protocol not to say that everyone needs to do the exact same thing, but to help readers understand how the principles I have outlined in the research apply to real life. I hope for others to think critically about these ideas and make appropriate adjustments in their lives that work for them.

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