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The Canker Sore Keto Correlation And How To Fix It

On the surface, it may seem like switching to a ketogenic diet should reduce the recurrence of canker sores due to reduced inflammation and carbohydrates. However, certain individuals may notice that they experience a flare-up after starting a ketogenic diet.

Does keto cause canker sores? There is no conclusive evidence as to what causes canker sores, but a ketogenic diet may cause the recurrence of a canker sore due to increased stress from drastically switching diets. Additionally, a ketogenic diet may cause canker sores through the excretion of acetone, a ketone body, from the breath. 

In this article, I’ll cover reasons thought to cause canker sores, how adopting a ketogenic diet may cause them, and how to help prevent them in the future.

Can keto cause canker sores

What Causes A Canker Sore?

A canker sore is an open and often painful mouth ulcer or sore that can make everyday activities such as eating or talking quite uncomfortable. You can tell a canker sore by its white or yellow appearance surrounded by inflamed soft tissue. 

While not always the case, you may also experience additional symptoms such as hot flashes, swollen lymph nodes or possibly a fever. Either way, a canker sore is a nuance. The good news is most types of canker sores will heal within about a week or two.

 When it comes to what the exact cause of canker sores are, NOBODY knows the exact reason.  

Those with a family history of canker sores are more susceptible. Also, canker sores are more common in young adults and females. 

Some of the most common causes thought to cause canker sores are:

  • A vitamin deficiency, especially B-12, zinc, and iron
  • Stress
  • Certain foods
  • An allergy

Why You May Get Canker Sores After Adopting A Keto Diet


Stress may cause canker sores on keto

A ketogenic diet is often a significant shift in the way most people eat. You may have gone from a high carbohydrate or even moderate carbohydrate diet to a diet that is very low to no carbs.

This shift in diet and metabolic processes can be stressful on the body. While you are adjusting and adapting to a ketogenic diet, you may fall prey to many of the side effects, such as the keto flu, which causes additional stress.

Stress is often one of the major, if not the biggest, factors though to cause canker sores.

Keto breath

If you’re experiencing a metallic taste in your mouth and notice it smells a bit fruity and almost nail polish-like, you have what's commonly called keto breath. Keto is notorious for causing dry eyes, mouth, and lips in addition to changing how your breath smells during the first few weeks. 

The body is inefficient at using ketones for fuel at first, causing ketones to be wasted and excreted. 

While your body is adapting to using ketones for fuel, acetone, one of the ketone bodies you produce, is excreted through the urine and breath. This higher than usual excretion in the first few weeks typically results in keto breath, increased urination, and even more sweat production.

While acetone isn’t highly acidic, it is acidic enough, and acidic foods or drinks are thought to be one of the causes of canker sores.

How A Ketogenic Diet Helps Prevent Canker Sores

While you may be experiencing a canker sore after switching to a ketogenic diet, many people believe a low-carb ketogenic diet can help alleviate or prevent canker sores.

A ketogenic diet helps prevent canker sores by:

Reducing inflammation

A ketogenic diet is highly praised for its ability to reduce inflammation in the body. Chronic inflammation has been linked to a variety of diseases that may also be linked to canker sores:1 

  • Diabetes
  • Cardiovascular disease
  • Arthritis
  • Allergies

Not only can a ketogenic diet help you with your canker sores, but it seems to be better overall for dental health as a whole. Keto’s emphasis on cutting down carbohydrates (sugar) may help stop the inflammation that can cause gingivitis and gum disease.

Minimizes sugar intake

Reduces sugar canker sores keto

Most of us were told as a child to limit or candy intake, or we’d get cavities, and that was for a good cause. Carbohydrates (sugar) is first broken down in the mouth, and bacteria also feed on that very sugar.

Sugar in itself does not cause cavities, but sugar sets off a cascade of events that may lead to them. 

Studies have shown that certain bacteria produce acid in your mouth when they come in contact and break down sugar.2 When you minimize carbohydrate intake, you are reducing the number of bacteria in your mouth.

Germs in your mouth eat the sugar and produce acid. As you may now know, acidic foods and drinks are thought to be one of the causes of canker sores in addition to the weakening of tooth enamel and the formation of cavities.

How To Reduce Canker Sores On A Ketogenic Diet

These are some oral hygiene tips that may help the prevention of canker sores.

Vitamin B-12

Another reason thought to cause canker sores is a vitamin deficiency, but most notably vitamin B-12. Eating foods rich in B vitamins, like nutritional yeast, but most notably B-12, may help prevent or reduce the duration of canker sores.

Keto-friendly foods rich in Vitamins B12 include:

  • Beef, liver, chicken
  • Fish and shellfish 
  • Cheese
  • Eggs

Sodium Lauryl Sulfate (SLS) based toothpastes

Sls dry mouth keto

Sodium lauryl sulfate (SLS) is an ingredient that found in most over the counter toothpaste. The purpose of SLS is to thicken toothpaste and make it lather but does nothing to enhance the effectiveness of the toothpaste. 

SLS is similar to that of alcohol in mouthwash. The alcohol itself doesn’t clean your teeth or gums any better, but it makes you “feel” cleaner or that it’s more effective. 

Using a toothpaste without SLS may help as it's shown to irritate the mucous membranes of the mouth and cause ulcers.3 

Reduce citrus and other acidic foods

Acidic foods canker sores on keto

Certain foods, such as citrus or acidic fruits and vegetables, should be reduced or avoided. 

Some fruits or vegetables that are keto-friendly, but also acidic include:

  • lemon and limes
  • blueberries
  • tomatoes
  • sauerkraut

Additionally, to help prevent the recurrence of canker sores, you should try and avoid foods that may cause allergy symptoms such as:

  • Hives
  • A swollen or tingling tongue
  • Dry eyes

It may be a particular food or foods that triggered the outbreak. Paying attention to what you may have eaten previous to your last canker sore may give you clue on what exactly to avoid.

The Takeaway

While a ketogenic diet, In theory, should help eliminate the recurrence of canker sores, some may experience flare-ups for one reason or another. These flare-ups may be caused by the stress of drastically switching your way of eating or the high levels of ketone excretion from the breath during the keto-adaptation period. 

Other than time, you may try reducing the recurrence of canker sores by:

  • De-stressing
  • Consuming more vitamin B-12 rich foods
  • Cutting foods that may cause allergies
  • Switching to a non-SLS-containing toothpaste

Frequently Asked Questions

What are the worst foods for canker sores?

Generally, when you experience canker sores it's a good idea to avoid chocolate, coffee, spicy, or salty foods. All of these will aggravate the situation.

Do canker sores mean weak immune system?

While there's no conclusive evidence, it's generally suggested that canker sores might be more common among people with weak immune systems.


Founder of The Art Of Keto.

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