Nutrition Can Impact Impact Dental Health

What Causes Dental Caries?

The Role of Carbohydrates

Improving National Oral Health

When it comes to cavities, traditional wisdom holds that sweets and snacks are the biggest culprits. But research shows that the cavity-causing power, or cariogenicity, of a food depends on multiple factors including composition of the total diet, frequency of consumption of the food, stickiness and how long the food remains in the mouth. By understanding the role sugars and other fermentable carbohydrates play in oral health, nutritionists and other educators can help lessen the instances of dental caries.

Nutrition has two distinct roles in oral health. Nutrients consumed affect the development and maintenance of oral tissues and the mouth's natural protective mechanisms. Also, a food's properties and nutrient composition influence dental plaque and the stimulation of salivary flow.

Diet most certainly is a modifiable risk factor in preventing dental caries. The American Dietetic Association position paper on role of diet and nutrition in oral health states: "Diet and nutrition have a direct influence on the progression of tooth decay, a preventable oral infectious disease. Major components of a preventive dental regimen include nutrition counseling, fluoride therapy, use of sealants, and control of cariogenic bacteria...The primary risk factors to consider in determining the cariogenic, cariostatic, and anticariogenic properties of the diet are food form (liquid, solid and sticky, long lasting), frequency of consumption of sugar and other fermentable carbohydrates, nutrient composition, sequence of food intake, and combination of foods."

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What Causes Dental Caries?

Bacteria, saliva, minerals, and foods eaten all play a role in helping or hindering the progress of dental caries. Cariogenic bacteria are at the heart of the disease, causing progressive destruction of tooth enamel. The decaying action of the bacteria depends on their ability to adhere to tooth surfaces, the degree to which they colonize, and how the food residues influence the amount of acid produced by the bacteria.

Saliva serves an important protective function. The amount of saliva available in the mouth and its fluoride, calcium and phosphorus content enable remineralization of affected tooth surfaces. Good nutrition is essential to produce sufficient quantities of saliva to neutralize acid produced by the bacteria and return minerals to the teeth, beginning the repair process.

Of those foods impacting caries, only fermentable carbohydrates can be consumed by the caries-promoting bacteria (Streptococcus mutans or Lactobacillus acidophilus) to produce acid and subsequent decay. Acid conditions below pH 5.5 cause dissolution of calcium and phosphate from tooth enamel or the dentin below. Decay occurs when periods of challenge to the tooth (demineralization) exceed periods of recovery (remineralization).

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The Role of Carbohydrates

Americans eat more carbohydrates now than ever before. In fact, carbohydrates are an integral part of our diet, accounting for 50 percent of daily intake. This is in line with expert advice as both the Dietary Guidelines and the Food Guide Pyramid recommend carbohydrates as the foundation of a healthful diet. It is ironic, however, that fermentable carbohydrates have been identified as the largest food contributor to dental caries. Sugars such as sucrose and glucose do play a role, but recent studies show that cooked carbohydrates such as bread, crackers, potato chips or pasta also contribute to decay.

Studies show that differences in foods' cariogenicity depends not only on the amount of fermentable carbohydrate they contain, but on their frequency of consumption and how long they remain in the mouth. Researchers have found that cooked starches remain longer in the mouth, increasing the amount of time the bacteria can feed on them.

Dr. Shelby Kashket of the Forsyth Dental Center in Boston says retention in the mouth is the biggest indicator of cariogenicity. "The cariogenicity of foods, whether high in sugars (like sucrose, glucose or fructose) or starch, depends on the length of time in the mouth. A more relevant issue is the number of meals or eating sessions each day."

The order in which foods are eaten also affects their cariogenicity. For example, the caries-causing potential of a carbohydrate may be reduced if it is followed by eating food with anti-cariogenic properties. Foods such high in fiber, certain cheeses and some flavorings increase salivary flow, thereby decreasing their time in the mouth and making them unavailable to plaque bacteria. Alkaline foods, like most seafoods, buffer the acids produced by the carbohydrates as they ferment, lessening potential damage. Fats also may help by coating the teeth so that acid does not reach the teeth's plaque.

The effect of consuming a soft drink under different situations demonstrates how food intake can impact dental health. Soft drinks have a high content of fermentable carbohydrates but can be less detrimental when consumed rapidly than sucking a hard candy for an extended time. Drinking a soft drink slowly throughout the day poses more risk than drinking it quickly. This is because oral pH levels drop for an extended period of time, allowing a longer period of for the bacterial acids to demineralize tooth surfaces. Drinking a soft drink at a meal lessens risk because other food properties such as fiber, fat and minerals interfere with the drink's cariogenic potential.


Some research shows that the source of the carbohydrate has no effect on its cariogenicity. Prof. Martin Curzon of Leeds Dental Institute in England says there is little difference between the cariogenicity of "extrinsic" and "intrinsic" sugars. Curzon and his colleagues compared the effect of whole fruit with that of homogenized juices on acid production and changes in plaque pH using apples, oranges and bananas. Curzon found no significant difference in the acid produced from the different forms of each fruit. "The concept of intrinsic and extrinsic sugars is not practical since [most] foods are not eaten whole," Curzon says. Professor Curzon believes the way we eat has more impact on caries than what we eat, and that decay results from bad diets, not "bad" foods."

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Improving National Oral Health

The U.S. Department of health and Human Services considers the improvement of oral health in America one of the greatest achievements of the public health service in this century. Measures such as fluoridation of the water supply, increased professional dental services and treatments like dental sealants have dramatically reduced the incidence of caries among children and young adults.

To continue this trend, Dr. Kashket advises nutritionists to counsel patients about the importance of reducing snacking or 'grazing' habits. "The advice to limit sugary foods is one part of the answer. However, there are clearly very few non-cariogenic foods. People will eat what tastes good. The answer is to eat less frequently, giving the teeth a chance to remineralize."

Good oral hygiene practices such as brushing with a fluoride dentifrice, flossing regularly, routine dental visits, and attention to when and what food is consumed will continue to produce enormous improvements in oral health.

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