Foods Which Cause Mouth Ulcers

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woman suffering from mouth ulcers

Mouth ulcers are common and mostly harmless sores that occur inside the mouth. However, anyone who’s had one knows how unpleasant they are.

Many things cause these painful sores. Anxiety, stress, biting the inside of your cheek, and smoking are typical reasons you develop canker sores. What you eat is a huge contributor as well.

If you experience frequent mouth sores that are not going away, this may have to do with your diet. It’s important to visit our dentist in NW Calgary, that knows how to identify the source of your canker sore problem and offer immediate treatment. This way, you can get professional advice that is also personalized.

In the meantime, read on to discover what major foods can cause mouth ulcers.

Acidic fruits

Fruits that are acidic, or particularly citrusy, can cause your mouth to break out in ulcers. Pineapples, oranges, lemons, and limes are examples of high-acidity fruits. Strawberries, in particular, tend to cause mouth irritation.

These fruits cause mouth tissue stress and can aggravate your gums. It is especially true if you already have a sensitive mouth. Any juices made with these fruits will also have the same effect.
Bananas, watermelon, and apples are good fruits to eat – you will avoid abrasion.


As nutritious as nuts are, they are surprisingly bad for your teeth. Nuts such as walnuts, peanuts, cashews, and almonds are dangerous territory for your gnashers. The amino acid L-Arginine in these nuts contributes to canker sores.

Salted nuts are especially bad, as the sodium dries your mouth out and causes the lining to become slightly inflamed.


Deal breaker! Chocolate, unfortunately, is a top food that causes mouth ulcers. It is mainly because of an alkaloid in chocolate called bromide. The mouth is quite sensitive to this ingredient, and it can lead to something similar to an allergic reaction. Some people with this mild allergy will develop canker sores on their tongue and inner cheeks.

You don’t have to cut out chocolate completely, but if it causes pain, consider cutting down on the cocoa.

Spicy Foods

Spicy foods can disrupt the lining inside your mouth, causing an ulcer. Like acidic fruits, spicy foods have high acidity and are more likely to distress the skin.

You’ll want to avoid foods like curries, hot sauce, jalapenos, and spicy chips to save yourself from oral pain. Most of these are a double whammy, as they also tend to have high salt content.

Hard Foods

It is quite a broad range of foods. Yet, it is foods classified as “hard” that are abrasive, sharp, and sore-forming:

  • Raw vegetables
  • Toast
  • Potato chips
  • Pretzels

It’s best to avoid these when you can if you’re prone to canker sores.

Alternatively, eat these in smaller-sized mouthfuls. You could also combine the foods with something that removes the dryness and hardness. Applying extra butter to toast and having raw vegetables or potato chips with dip may help your mouth cope better.

Foods You Are Allergic To

We briefly mentioned chocolate allergies. You may be allergic if a certain food gives you mouth ulcers repeatedly.
Try and note down what foods trigger your mouth ulcers. Experiment with the foods you eat each week, cutting back on certain items and increasing your dosage of others. This way, you can figure out what ingredients are the most harmful.

If you’re in pain from eating a small quantity of a certain food, see a doctor for allergy testing.


Dairy products like milk, cheese, and yogurt commonly contribute to canker sores. Some doctors think an ingredient in cow milk proteins links to mouth ulcers. A flare-up could be due to an adverse immune reaction to cow’s milk.

If your mouth sores are recurring, cutting out dairy products, especially those containing animal milk, are worth cutting out. Opt for soy and oat milk-based products and vegan cheese and see if these changes make a difference.

Coffee and Alcohol

There are certain drinks that, if consumed, bring a risk of oral ulcers. Coffee and alcohol (preferably not together!) are both very acidic. We often take these drinks in large quantities and are least likely to give these up. It might be necessary to decrease your dose if you’re experiencing chronic mouth pain.

The Food You’re Not Eating

Now, let’s shift the focus away from the foods you should avoid to foods you should pay attention to!

People get mouth ulcers if they lack certain vitamins and minerals in their diet. If your body is low on zinc, iron, B12 and folate, then there’s a high chance you will get recurring sores.

To boost your levels of these, get more of these foods in your diet:

  • Zinc: oysters, whole grains and legumes
  • B12: meat, nutritional yeast, yeast extract, and fortified cereals
  • Iron: dried fruit, green vegetables, red meat, beans and lentils
  • Folate: bread, rice, chickpeas, beans, and fresh fruit and vegetables


As you can see, many items cause mouth ulcers and irritate the tissue. It’s best to eat these foods in moderation. Cut down on the foods contributing to canker sores; you don’t have to ban them entirely.

However, if you find an underlying allergy, it is best to eliminate those foods. Make sure you’re getting all the nutrients you need too. As we said, it’s not always about what you eat, but what you’re not eating that causes problems.

If you have altered your diet to eradicate your mouth ulcers, which are still recurring, schedule an appointment with your dentist in NW Calgary today.

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