Unrefined vs. Refined Carbohydrates and Dental Cavities

There's a definite association between the consumption of refined carbohydrates and dental cavities. Dr. Weston Price pointed this out in a number of transitioning societies in his epic work Nutrition and Physical Degeneration. Many other anthropologists and dentists have observed the same thing.

I believe, based on a large body of anthropological and medical data, that it's not just an association-- sugar and flour cause cavities. But why? Is it that they lack micronutrients-- the explanation favored by Price-- or do they harm teeth by feeding the bacteria that participate in cavity formation? Or both?

I recently found an interesting article when I was perusing an old copy of the Journal of Dental Research: "A Comparison of Crude and Refined Sugar and Cereals in Their Ability to Produce in vitro Decalcification of Teeth", published in 1937 by Dr. T. W. B. Osborn et al. (free full text). I love old papers. They're so free of preconceptions, and they ask big questions. The authors begin with the observation that the South African Bantu, similar to certain cultures Dr. Price visited, had a low prevalence of tooth decay when eating their native diet high in unrefined carbohydrate foods. However, their decay rate increased rapidly as modern foods such as white flour and refined sugar became available.

To test whether refined carbohydrates have a unique ability to cause tooth decay, the investigators took pieces of teeth that had been extracted for reasons other than decay (for example, crowding), and incubated them with a mixture of human saliva and several different carbohydrate foods:

• crude cane juice
• refined cane sugar
• whole wheat flour
• white wheat flour
• whole corn meal
• refined corn meal

After incubating teeth in the solutions for 2-8 weeks at 37 C (human body temperature), they had trained dentists evaluate them for signs of decalcification. Decalcification is a loss of minerals that is part of the process of tooth decay. Teeth, like bones, are mineralized primarily with calcium and phosphorus, and there is a dynamic equilibrium between minerals leaching out of the teeth and minerals entering them.

The researchers used teeth incubated in saline solution as the reference. The dentists were "blinded", meaning they didn't know which solution each tooth came from. This is a method of reducing bias. Here are some of the results. Cane juice vs. refined sugar:

Unrefined cane juice was not very effective at causing decalcification, compared to refined sugar. This was a surprise to me. Here is the result for wheat:Note that the scale is different on this graph. Wheat, and particularly refined wheat, is very good at decalcifying teeth in vitro. Corn:

Refined corn is much more effective at decalcifying teeth than whole meal corn. Next, the investigators performed an experiment where they compared the three types of refined carbohydrate to one another:
As one would predict from the graphs above, refined wheat is worse than refined corn, is worse than refined sugar. This is really at odds with conventional wisdom.

It's important to keep in mind that these results are not necessarily directly applicable to a living human being, who wouldn't let a mouthful of wheat porridge sit in his mouth for five weeks. But it does show that refining carbohydrates may increase their ability to cause cavities due to a direct effect on the teeth (rather than by affecting whole-body nutritional status, which they do as well).

The authors tested the acidity of the different solutions, and found no consistent differences between them (they were all at pH 4-5 within 24 hours), so acid production by bacteria didn't account for the results. They speculated that the mineral content of the unrefined carbohydrates may have prevented the bacterial acids from leaching minerals out of the teeth. Fortunately for us, they went on to test that speculation in a series of further investigations.

In another paper, Dr. T. W. B. Osborn and his group showed that they could greatly curb the decalcification process by adding organic calcium and phosphorus salts to the solution. This again points to a dynamic equilibrium, where minerals are constantly leaving and entering the tooth structure. The amounts of calcium and phosphorus required to inhibit calcification were similar to the amounts found in unrefined cane sugar, wheat and corn. This suggests the straightforward explanation that refined sugar and grains cause decay at least in part because most of the minerals are removed during the refining process.

However, we're still left with the puzzling fact that wheat and corn flour decalcify teeth in vitro more effectively than cane juice. I suspect that has to do with the phytic acid content of the grains, which binds the minerals and makes them partially unavailable to diffusion into the teeth. Cane juice contains minerals, but no phytic acid, so it may have a higher mineral availability. This explanation may not be able to account for the fact that refined sugar was also less effective at decalcifying teeth than refined wheat and corn flour. Perhaps the residual phytic acid in the refined grains actually drew minerals out of the teeth?

No, I'm not saying you can eat sugar with impunity if it's unrefined. There isn't a lot of research on the effects of refined vs. unrefined sugar, but I suspect too much sugar in any form isn't good. But this does suggest that refined carbohydrates may be particularly effective at promoting cavities, due to a direct demineralizing effect on teeth subsequent to bacterial acid production. It also supports Dr. Price's contention that a food's micronutrient content is the primary determinant of its effect on dental health.

Reversing Tooth Decay
Preventing Tooth Decay
Dental Anecdotes

The Identity Politics of Breasts: Male Lactation and the Political Economy of Wo/Man (part 2)

Is it to men that nature confided domestic cares? Has she given us breasts to feed our children?”
--Pierre-Gaspard Chaumette quoted in "Why Mammals are Called Mammals"[*]

Experience may tell you that producing milk and nursing youngsters is a job for the female mammal, not the male. But your experience is probably limited, and the potential of biology--and medical technology--is vast.
--Jared Diamond "Father's Milk"[*]

"For those who claim male lactation is "unnatural," I would have to ask: how natural is canned formula from Nestle' or pacifiers made from petrolium byproducts? If milk production in men were truly unnatural, it wouldn't exist.”
--Laura Shanley "Milkmen: Fathers who Breastfeed"[*]

3. Male Lactation: An Unnatural Act?
The identity politics of human breasts come to full fruition in the question of male nipples. As male children we are taught that girls have “boobs” and boys have “chests,’ but the question of male nipples cannot be evaded. For thousands of years breasts have been one of the most significant markers of one’s gender, and hence male breasts and their nipples pose an existential dilemma to those who identify as male. This has never been truer than within the present visual culture that fetishizes the (female) breast.

Take for example the reception of the 2006 Nickelodeon film Barnyard. While critics had diverse opinions on the film, nearly all their reviews shared one particular quip: the protagonist of the film, a steer, had utters. As one late reviewer ranted:

Every single review whether by a critic or just your average John Q. Moviefone seems to be possessed by the urge to point out their extensive knowledge of bovine anatomy and remind the reader that male cattle do not, in fact, have udders.[22]

While filmgoers often suspend disbelief during films, especially animated features, the audiences could not suspend “the truth” about male anatomy. And, of course, there is also the double standard. Female pigs (who have ten or more nipples) and chickens (who don’t have any mammary glands) are often represented with a pair of giant breasts in cartoons yet male reviewers say nothing—they probably are not even conscious of these transgressions. The existence of DD breasts on a chicken somehow seem quite natural, but udders on a male, no! (But if male goats can grow udders, why not steers?)[*]Read more »