Sugar and Tooth Decay: Does The Association Imply That Calories Don't "Count" After All?

The relationship between sugar and tooth decay has been long documented by physicians and dentists. We all know that 'sugar rots your teeth' and that, in general, if you want to take good care of your mouth, teeth, and gums, you should avoid snacking on lollypops and hard candies all the time. This is not news to most people.

But this relationship between sugar and tooth decay actually has profound implications, particularly when we consider that tooth decay strongly associates with other so called "diseases of civilization," including obesity and diabetes.

Why do dental problems closely associate with diseases like overweight and cancer?

The Caloric Balance Hypothesis cannot explain this relationship unless its defenders somehow contrive a viable mechanism by which "excess calories" themselves can cause dental diseases. This is probably impossible, since calories are nothing more than units of energy.

The Lipophilia Hypothesis provides a neater and more plausible explanation. It tells us that carbohydrate consumption drives both fat accumulation and tooth decay. In other words, eating sugar gives us tooth decay, makes us fat, and makes us sick.

Okay, two different ideas about why we get fat and why obesity associates with tooth decay. But what does the evidence in the real world tell us? Are carbohydrates -- as opposed to proteins and fats -- uniquely capable of causing tooth decay and dental disease?

Physicians and dentists alike tell us that carbs do appear to be uniquely bad for our teeth. This relationship between sugar and tooth decay is not at all controversial.

1. Consider this quote from WebMD[1], of all places (WebMD has a very pro-Caloric Balance Hypothesis slant):

"Tooth decay occurs when foods containing carbohydrates (sugars and starches) such as breads, cereals, milk, soda, fruits, cakes, or candy are left on the teeth. Bacteria that live in the mouth digest these foods, turning them into acids. The bacteria, acid, food debris, and saliva combine to form plaque, which clings to the teeth. The acids in the plaque dissolve the enamel surface of the teeth, creating holes in the teeth called cavities or caries."

2. To fortify the idea that obesity and tooth decay occur together, check out this article from 'Relationship between obesity and dental decay in children.'[2]

So to summarize. We have two theories about what makes us fat. We see a relationship between sugar and tooth decay. We also see a relationship between overweight and dental disease. Our first theory -- the idea that overeating and under exercising make us fat -- tells us nothing about why this relationship occurs. Our second theory -- the idea that 'carbohydrate disease' drives both overweight and tooth decay -- seems to do a far more efficient job of explaining the evidence.

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1. Reviewed by Darren R. Williams, DDS. Preventing Tooth Decay (March 15 2009).

2. Siobhan Gallagher; Tufts University 'Relationship between obesity and dental decay in children.' Medical News Today (09 Dec 2005).

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