The number one food that causes most canker sores and how simple avoidance is all that is needed for most people to banish them for good! 
Chances are, you’ve suffered from a canker sore or two in your life. These painful, open ulcers on the inside of your lips, cheeks, or even your tongue seem to take forever to heal and can really cause some grief!
One young man I know in our community suffers excessively from canker sores. His frequent outbreaks are so bad that ulcers often occur not only in his mouth but also down into his throat. This causes severe pain even when swallowing sips of water.
Canker sores should not be confused with cold sores on your lips or nose that are caused by a virus and are contagious. This cold sore remedy works great for that type of skin issue.
Unlike cold sores, canker sores are not contagious. In most cases, they are the direct result of what you eat.
Even if a canker sore seems to be triggered by something else, like a scrape from a dental appliance like braces or accidentally biting your tongue, the underlying cause is still diet. In other words, the mouth inflammation was already present such that the wound that occurred in the mouth resulted in a canker sore!
That’s right! What you eat GREATLY affects whether or not you suffer from mouth ulcers on a regular or infrequent basis.
The Number One Food That Causes Canker Sores
Guess what frankenfood is the primary cause of canker sores in the Western diet?
That culprit would be high fructose corn syrup or HFCS. Manufacturers sometimes list it as corn sugar on some food labels.
High fructose corn syrup promotes inflammation in the body, which in turn impairs the immune system. An impaired immune system is thought to be the underlying cause of canker sores.
A person on a typical diet of supermarket foods is a prime candidate for frequent mouth ulcers. This is because this stuff is in everything. Plain corn syrup is problematic as well.
This is why eating too much fruit or fruit juice can cause canker sores as well. The sugar in fruit is primarily fructose. Surprisingly, it isn’t the acid in most cases that is causing the problem. Although, acidity may be a contributing factor.
If acid were the primary problem, drinking kombucha tea would also cause canker sores. Most people I know prone to mouth ulcers can drink kombucha regularly without issue.
TOO MUCH FRUCTOSE = CANKER SORES
Even agave nectar, which many consider a health food, contributes to canker sores. The truth is that agave nectar is best avoided. It is highly processed in a manner very similar to HFCS. It is neither healthy nor helpful in any way to the person consuming it. Stay away from it if you want to avoid canker sores!
I used to suffer from canker sores all the time to the point where I had at least one bothering me much of the time.
I haven’t had a canker sore now in over 25 years. Simply cutting out all HFCS from my diet easily accomplished this huge improvement in quality of life! In addition, I watch my intake of regular fructose from other sources like fruit.
If you start checking food labels, you will be shocked. Even commercial peanut butter and ketchup contain it. Simply switching to health food store brands will quickly rid it from your life in most cases.
How Much Fructose is Too Much?
A good idea is to limit your intake of fructose from all sources to no more than 15 grams per day. This is about half the amount of total sugar intake per day that can be tolerated without ill effects.
Dr. Richard Johnson MD in The Sugar Fix describes how important it is to limit your fructose intake for health and weight control.
To give you some idea, in a big, ripe banana, you’d get maybe 10 grams of fructose.
So, if you eliminate HFCS in your diet completely and eat no more than 1-2 pieces of fruit a day, that would be a good way to go.
Be aware also that going over the fructose limit of 15 g per day (25 g at the absolute most) can cause a canker sore very quickly. Sometimes, within a few hours, one or more can appear.
When my kids were younger and attended birthday parties, if they had even ONE Capri Sun juice or a half a can of soda they would invariably have a canker sore within a day or two. I trained them very early to only drink water.
Bottom line is that even if you control your fructose intake 99% of the time, consuming a single food loaded with HFCS can cause one of these baddies very fast.
Imagine what incredible damage a high fructose diet is doing to a person’s insides if it can cause an ulcer in the mouth so quickly!
I realized mine come from extremely salty junk foods????like chips. Every now and again when I have a bag,I get at least three and they hurt like hell! Olive leaf extract helps me a great deal. With consistent use,they usually go away within 3 days.
I could drink a gallon of HFCS and not get a canker sore. I eat an orange, lemon, or other citrus and not only will I have sores within 24 hours but now develop GI issues. HFCS is much easier for me to avoid then citric acid. I have never heard of HFCS ever causing canker sores and I really feel like you just made that info up.
Some people are more sensitive to sources of processed fructose (HFCS) than others. I doubt you could drink a gallon and not get one though! LOL
L lysine vit really helps me. 1000 mg 3x a day for a few days.
ZINC supplements have seriously helped my outbreaks
Unfortunately we were also told not to eat fat for 50 years. You have to make your diet about you. No two people are genetically the same, not even twins. This means that what works for one person won’t necessarily work for the other.
Our ancestors ate fruit in season, not all year round.
hi..i am suffering from canker sore right now..the pain is killing me..it’s all over my mouth..cant eat..im not talking for 4days already..doctor gave me medicines but still ill until now..can u please tell me some home remedy for canker sore..tnx
I have been dieting and taking vitamins for about 3 months strong. I get canker sores religiously now. They trickled in occasionally as a kid, but I’m almost 30 and since 28 to present, I have 1 in my mouth at all times. it’s excruciating, makes me grumpy.. After reading this article I was confused because I don’t eat much on your list, except when I checked my multivitamin. I take the 1 a day for women. I noticed it has Glucose Syrup in it. Is this similar to HFCS?? If so, I bet that’s the cause. Anyone else having this issue?
Glucose syrup can definitely cause similar issues as HFCS. Too much sugar in any form can cause them, but for most people it is too much fruit, fruit juice, or corn syrup in processed foods. Maybe stop taking them for awhile and see if the sore clear up?
Hi, I have just come across your article whilst my tongue is causing me so much pain. I recently thought sugar was causing my problems, I have been suffering since 2012. I have seen the doctor and dentist who didn’t take my site swollen tongue seriously.
I find eating some meats, port for instance makes my tongue break out in sores and if I eat bananas my tongue will swell and I feel the roof of my mouth swell too.
From tomorrow I shall make a real effort to stop eating anything that contains sugar, I have an issue with whey so wonder if this is also contributing to my problem. I drink goats milk and don’t eat dairy products.
I strongly believe there are so many chemicals in our foods today that contribute to the issues I have.
Vicky
Hi Sarah, I stumbled onto this article while fervently searching for (of course) an immediate remedy for my 2nd-within-a-month-excruciating canker sore on the inside of my cheek. Also have a raw tip-of-the-tongue from scraping against my teeth (I assume) and as if that wasn’t enough, I’m apparently biting my lower lip fairly often. I’m 61 and have never had a canker sore in my life and now that I just retired, have high anxiety. So tonight I’m searching for a better mouth guard in another attempt to get some relief. I eat a horrid diet chock full of all kinds of sugar – I’m an addict to sweets. But, I think my stubborn self just now may have made the connection that sugar is causing all this agony and even though I’ve tried a million times to brake away from sugar and failed miserably, this level of pain is making me desparate — enough so that NOW my mind may finally agree to dump the sugar. How an intelligent being can make such poor choices is beyond comprehension some days. Anyway…Thanks so much for writing your article – I’m looking forward to your newsletters. Reading your responses to other comments posted here has been insightful as well.
Keep trying! You will succeed! Here’s an article on how I FINALLY got off sugar for good some years ago. Hope this strategy helps you too 🙂
https://www.thehealthyhomeeconomist.com/slay-the-sugar-monster-in-four-doable-steps/
I get them with regular use of Stevia powder from the grocery. Even 1 packet a day brings them on eventually. Ready to give up Stevia.
Check the ingredients … stevia is often cheapened and blended with artificial sweeteners like xylitol or erythritol which do cause issues for some people.