Vegetarianism a Cause of Tooth Decay? Um, No. Not Exactly.

Did you hear the one about the “new” study finding “that vegetarians are much more likely to suffer from tooth decay, lower (more acidic) salivary pH levels, and lower stimulated saliva flow than control subjects that were matched by sex and age”?

We did (thank you, Google Alerts). Only the study’s not new. And that’s not exactly what its author found.

But at least the post included a link to the study (PDF) in question, originally published in the American Journal of Clinical Nutrition not last week or even in 2011 but in 1988.

The article – “Health Aspects of Vegetarian Diets” by Johanna T. Dwyer, DSc, of the New England Medical Center (now Tufts Medical Center) – is a literature review, not a dedicated study of the dental impact of a vegetarian diet. Of the nearly 350 citations it includes, just a handful focus on this issue. Looking at them as a whole, Dwyer found, “There is little evidence that vegetarians have better dental health than do nonvegetarians….Vegetarian diets do not provide any distinct dental advantage over nonvegetarian diets.”

No better dental health. No advantage.

So how do we get from there to the headline “New Study: Vegetarians Have More Tooth Decay” (emphasis added)?

One study Dwyer looked at did find a higher rate of “dental erosions on some tooth surfaces, lower salivary pH levels, and lower stimulated saliva flow” among lactovegetarians (i.e., vegetarians who eat dairy). Other studies noted how fruit juices and acidic foods can erode teeth, which is hardly news these days. Yet, according to another study Dwyer cites,

If acid fruits and vegetables are eaten in conjunction with or after other foods rather than frequently between meals and their consumption is coupled with good oral hygiene, they pose little danger to dental health….

To then conclude that vegetarianism in general increases tooth decay is quite a leap.

Bottom line: A vegan diet is neither inherently better or worse for your teeth than a diet that includes meat, dairy, fish and eggs. What matters is the specific composition of the diet – along with eating and hygiene habits, as we noted in our previous post on raw food diets and tooth decay:

We regularly see new clients who eat a raw food diet to enhance their health. Yet when we examine their teeth, it is not uncommon to find a lot of decay. This often comes as a surprise to the client. Indeed, it seems counterintuitive when you consider that a raw food diet forgoes all processed foods and is often rich in fruits, vegetables, nuts and seeds. Why should these clients suffer dental problems?

Part of the cause can be dietary – such as a high sugar intake from an overabundance of fruits, especially in dried form. But part is also behavioral. In fact, there is one commonality we see amongst all raw foodists with tooth decay: a tendency to “graze,” eating small portions throughout the day. This habit – regardless of the type of diet one consumes – greatly increases the risk of developing tooth decay, especially around the gumline.


Carbohydrates tend to cling to tooth enamel more than fats and proteins do – especially around the base of the teeth, where food particles more easily can get stuck. There, they feed the oral microbes that form the biofilm often still called “plaque.” As these microbes colonize, their metabolic byproducts acidify the oral environment. Ideally saliva neutralizes it, but when biofilm covers the oral surfaces, it can’t do the job.

These acidic conditions peak for about 20 to 30 minutes, but if a person is grazing throughout the day, they’re effectively nursing the problem, ensuring that conditions remain acidic and the biofilm is allowed to proliferate. Together, these greatly increase the risk of cavity formation.

That grazing is an issue was pounded home to us a while back, when a woman brought her twin boys to us for their dental care. One of the boys had excellent teeth while the other had rampant caries (cavities). Yet both ate the same diet, which included a muffin a breakfast each morning. How each boy ate it made all the difference: the one with no caries ate his muffin all at once, while the other saved his to nibble from throughout the day.

Same diet. Different eating behaviors. Different outcomes.

[See also “Making the Good Look Bad (& the Worse Look Better).”]

Good dental health – like good systemic health – depends on eating a nutrient-rich and varied diet. All the nutrients most essential to dental health – antioxidants, calcium, magnesium, zinc, trace minerals, vitamin D and protein – can be found in both plant and animal sources. Both vegans and meat-eaters alike should control the amount of sugars, high-acid foods and sugars they eat. Both groups should, at minimum, brush and floss after meals and avoid grazing through the day.

The moral of the story? Read carefully. And with curiosity. Follow links. Learn more.

Image by Judy Baxter, via Flickr

Published by The Verigin Dental Health Team

A humanistic, holistic dental practice in Northern California, providing integrative, biological, mercury-free dentistry

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