People’s diets can have a profound effect on their oral health. Eating certain types of sugary or starchy foods contributes to oral health problems such as tooth decay and gum disease. In addition, poor nutrition has negative effects on oral health, including premature tooth loss and bad breath (halitosis).

For most people, tooth decay and gum disease are the chief oral health dangers associated with a poor diet. Normally, the mouth contains bacteria that rest on a person’s teeth in a sticky film called dental plaque. Plaque constantly forms on the teeth. Bacteria in plaque feed on the food particles, creating an acid that eats away at the enamel of a person’s teeth for 20 minutes or more after eating. This erosion is the major cause of dental problems such as tooth decay and gum disease. The only way to stop this process is to brush and floss the teeth regularly, preferably as soon after eating as possible.

The bacteria in plaque especially thrive on sugary and starchy foods known as fermentable carbohydrates. Some carbohydrates break down into simple sugars (glucose, fructose, maltose and lactose) in the digestive tract. However, fermentable carbohydrates break down into simple sugars in the mouth. When bacteria feed on these sugars, they dissolve the minerals inside the tooth enamel (demineralization). Saliva, fluoride and foods such as vegetables and milk can help replenish these minerals (remineralization). However, in some cases minerals are lost faster than they are regained. The result is tooth decay.

Today, Americans appear to be eating record amounts of sugary sodas, processed foods, fruit drinks and snacks. The average American eats about 147 pounds (67 kilograms) of sugar every year, according to the National Institutes of Health (NIH). People who consume such foods regularly put themselves at much higher risk for developing tooth decay and gum disease.

Frequent snacking is particularly bad for oral health, because the cycle of acid creation and destruction of enamel repeats with each snacking session. The more often a person eats – and the longer the food remains in the mouth – the greater the risk of destruction of the enamel.

In addition, foods that are especially sticky (e.g., candies) stay in the mouth longer and create more damage. Foods that pack tightly into tooth crevices – such as potato chips – also can wreak havoc with dental health. The molars are particularly likely to be affected by these foods. Soft drinks, sweetened coffee and other sugary liquids that are sipped during the day provide an almost constant source of food for oral bacteria, leaving the teeth under attack for long periods at a time. In addition, soft drinks are acidic and usually contain phosphorus, both of which erode the tooth enamel and contribute to the development of more tooth decay than sugars.

Although sugary foods like candies, cookies and sodas are especially bad for the teeth, healthier foods also contain sugars and starches that can promote dental problems. Certain fruits, bread and cereal all contain these substances. This does not mean these foods should be avoided. However, it is best to try to eat these foods during meals, limit snacking and to brush soon after meals when possible.

On the other hand, some foods actually decrease the risk of tooth decay. Fats alter the surface properties of tooth enamel, hamper the ability of sugar to dissolve and are toxic to oral bacteria. Proteins affect the ability of plaque to metabolize and increase salivary urea levels. Foods such as aged cheese help buffer acid when eaten soon after sugary or starchy foods.