Does Sugar Cause Tooth Cavities?

When it comes to preventing cavities, it might seem like brushing, flossing, and getting regular dental cleanings are the whole story. But it turns out there’s more you can do to prevent cavities — and it starts with paying attention to what you eat every day. 

Researchers have been digging deep to understand how cavities form, why some people struggle with them more than others, and what can be done to prevent them. As they learn more, we’re starting to understand how our diet can make a difference when it comes to dental health. Read on to understand why.

Sugar consumption and tooth cavities: What does the research say?

We’ve known for half a century that sugar is linked to cavities. Data about people of different ages, diets, cultural habits, levels of education, and access to dental care confirms a clear connection between the sugars we eat and the cavities in our teeth. 

Scientists are still studying exactly how it happens — and what we can do about it — but it’s clear that our risk of sugar-related cavities is affected by:

• How much sugar we eat or drink

• How often we eat or drink sugary foods

• Other foods we eat at the same time as sugary foods

• How quickly sugar is cleaned from the mouth after eating

The connection between sugar and cavities is strongest for people who don’t use fluoride. Fluoride in toothpaste or mouthwash is a powerful way to protect teeth against cavities — but it still isn’t enough to stop the effects of sugar.

What are tooth cavities?

Tooth cavities — which are also called dental caries — are holes and pits in the teeth caused by decay. They make teeth weak and provide shelter for bacteria. These bacteria can cause infections and chronic inflammation and can affect your general health.

What causes tooth cavities?

Cavities happen when the teeth are exposed to an acidic environment for a long period of time. That is, when the saliva around the teeth has a low, or acidic, pH level. This acidic environment is created by bacteria.

How are bacteria linked to cavities?

Certain bacteria in your mouth play a role in causing cavities. When these bacteria take in sugar, they release acid. The acid causes the mineral structure of the teeth to break down, resulting in cavities. 

The natural flow of saliva through your mouth eventually brings the acid level around your teeth back to normal. But it can take a while — up to 40 minutes after eating or drinking anything containing sugar. 

Your oral microbiome matters

It’s normal to have a wide variety of bacteria in your mouth. A healthy mouth contains a balance of thousands of different strains.

Streptococcus mutans and lactobacilli are two strains of bacteria known for causing cavities. They produce acid when they are exposed to sugar, and the acidic environment they create also allows them to thrive and multiply. This pushes out other strains of bacteria and amplifies their cavity-causing effect.

Biofilm, plaque, and tartar: What’s the difference?

Bacteria naturally form a filmy coating on the outside of teeth, known as a biofilm. Biofilms protect bacteria and allow them to multiply. 

Plaque is the thick biofilm you might see or feel when your teeth haven’t been brushed recently. Plaque is soft and sticky, and it can look clear, white, or yellow. Bacteria from many different species live in plaque. While plaque itself doesn’t cause cavities, it provides a home for the bacteria that do. Plaque is easily removed when you brush and floss your teeth.

Tartar is a hard, cement-link substance that forms when plaque is not removed right away. Tartar is a problem because its rough surface provides spaces for bacteria to live and thrive, giving them better access to the outsides of your teeth.

Good nutrition lowers your risk of cavities

As said above, a high-sugar diet makes cavities more likely to occur, because oral bacteria turn those sugars into tooth-damaging acids. So, it’s good to know there are also foods that can help reduce your cavity risk.

What foods stop cavities from forming?

Some nutrients can slow down, or even reverse, some of the effects of acid-producing bacteria. This drives repair of damaged tooth areas and strengthens teeth. 

Calcium-rich foods are especially good for teeth:

• Milk, cheese, yogurt, and other unsweetened dairy products

• Calcium-fortified tofu or soy milk

• Almonds

High-protein foods contain healthy levels of phosphorus, which also protects against dental cavities:

• Fish

• Meat

• Eggs

Fruits and vegetables are a good addition, too. They are high in water, fiber, and vitamins A and C, which encourage a healthy saliva flow to clean teeth naturally. 

Is added sugar different from naturally occurring sugar when it comes to cavities?

Yes. The bacteria that cause cavities prefer added sugar. 

On the other hand, when you eat naturally occurring sugar, you get many other nutrients and minerals at the same time. These help to promote the growth of different populations of bacteria and a healthy oral microbiome.

Can I still get cavities if I don’t eat sugar?

Yes. Although sugar promotes the growth of cavity-forming bacteria, there are other factors involved. Your overall nutrition, dental habits, fluoride use, and genetics all impact your risk of developing dental caries. 

What can I do if I already have cavities?

When small tooth cavities are caught early, they can sometimes repair themselves. You’ll want to talk to a dental professional for advice on how to help early cavities heal.

If you’ve had cavities in the past, it makes sense to take a close look at how you care for your teeth. Dental professionals recommend that you brush your teeth at least twice a day with a fluoride-containing toothpaste, floss between your teeth daily, consult a dentist at least once a year — and make some changes to your diet and eating habits.

How can changing my eating habits help prevent dental caries?

There are a number of things you can do to help reduce your risk of sugar-related dental cares:

• Avoid sweetened drinks, including carbonated soft drinks and sports drinks.

• Stay away from foods with added sugar.

• Try not to eat or drink anything except water between meals.

• Beware of foods that stay in your mouth for a long time, like hard candies.

• Remove sugar and bacteria from your teeth by brushing after you eat.

• If you can’t brush your teeth right away, rinse your mouth with water.

• When you eat sweet foods, include them in a meal with other types of foods.

• If you choose a sweetened beverage, keep it small, and try to drink it quickly instead of sipping slowly over time.

• Clean your teeth regularly with fluoride-containing toothpaste.

Why trust our experts?

Written by:

Kerry R. McGee, MD, FAAP

Kerry McGee, MD, FAAP, has over a decade of experience caring for babies, children, and teenagers as a primary care pediatrician. She has a special interest in adolescent health, particularly in adolescent mental health.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

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