How to Treat Canker Sores

Vitamin C, turmeric, beta-glucan fiber, and vitamin B12 are put to the test for recurring canker sores (aphthous ulcers).

Canker sores can be “a painful and often recurrent inflammatory process of the oral mucosa,” the lining of our mouths. Similar to other chronic inflammatory conditions, DNA damage due to oxidative stress caused by free radicals is thought to play a role.

Normally, free radical production is balanced with antioxidants, but if the concentration of free radicals gets too high and our antioxidant enzymes and the antioxidants we get in our diet “cannot compensate for these radicals, the balance changes in favor of the oxidants”—that is, in a pro-oxidant direction. This can lead to oxidative damage within our body. Does that mean that people who experience recurring canker sores—also known as recurrent aphthous stomatitis (RAS)—have fewer antioxidants, more oxidation, and more DNA damage? Yes, yes, and yes. As you can see in the graph below and at 0:51 in my video Best Supplement for Canker Sores, they exhibit more pro-oxidants and more oxidative stress in their bloodstream, lower antioxidant status, and more DNA damage. This suggests it might be possible for antioxidants to help improve the DNA damage caused by recurring canker sores, but you don’t know until you put it to the test.

Sixteen boys and girls around age 12 with recurring canker sores were given a whopping 2,000 mg (2 g) of vitamin C a day. That’s considered the tolerable upper daily limit for adults before you start getting diarrhea, and 1,200 mg may have that effect on a 12-year-old, but it’s all about risks versus benefits. How did they do? As you can see in the graph below and at 1:33 in my video, 15 out of the 16 kids cut the number of canker sores they were getting at least in half. In the three months before they started the vitamin C, they had averaged four canker sores each, but in the three months they were on it, they each had less than one on average. When they stopped the vitamin C for another three months, the ulcers started coming back. Then, when they once again added the vitamin C, the canker sore rate dropped again.

What about directly applying antioxidants, like a turmeric gel? Let’s find out. A turmeric gel containing 2 percent curcumin, the yellow pigment in the spice turmeric, was swabbed directly onto canker sores twice a day and “significantly reduced pain intensity and size of the aphthous ulcer [canker sore] compared to placebo,” which was a gel containing no active ingredient. Okay, but wouldn’t it be nice to see a comparison to an active treatment from an independent research group, rather than this study without an active treatment that was funded by the curcumin gel manufacturer?

Yes, and here we go. This randomized clinical trial compared a generic 2 percent curcumin gel to a prescription steroid gel and found that the curcumin worked just as well. This provides “strong evidence that [topical] curcumin gel can be used as an effective and safer alternative to steroids in treatment of RAS.” You may remember I’ve previously discussed that topical honey beat out the same steroid for both ulcer healing and pain reduction, as you can see in the graph and at 2:46 in my video. So, if you’re going to use something topically, honey seems better, but what if, instead of a topical application, you just want to swallow something like vitamin C but want something that doesn’t give you diarrhea?

Thirty-one patients with recurring canker sores were split into two groups and received either 20 mg a day of placebo or yeast beta-glucan fiber, which is the amount found in just an eighth of a teaspoon of brewer’s yeast or nutritional yeast. As you can see below and at 3:17 in my video, the placebo group experienced no significant change, whereas ulcer severity in the yeast group was cut nearly in half. So, now you have another useful alternative.

If it’s all about antioxidants, can’t you just treat recurring canker sores by eating a plant-based diet high in fruits and vegetables? That hasn’t been put to the test, but keep in mind a plant-based diet could also make things worse if one is not ensuring a regular reliable source of vitamin B12 through supplements or fortified foods. For example, a 30-year-old women had recurring canker sores for four years. She ate few animal products and didn’t supplement with vitamin B12, so she became B12-deficient and began experiencing weakness, tiredness, numbness, and tingling. She was immediately started on vitamin B12, and her deficiency symptoms got better. Her canker sores also improved and she experienced “a rapid and complete recovery” within weeks of starting vitamin B12 after years of suffering.

We’ve known since the 1970s that vitamin B12 deficiency can lead to canker sores—so much so that it’s recommended to consider B12 deficiency any time a patient has with recurring canker sores. In fact, a number of nutrient deficiencies may contribute. A study compared the lab tests of those with recurrent canker sores to those without and found that more than half of the canker sore group showed evidence of hematinic deficiencies—that is, blood-forming nutrient deficiencies. In contrast, less than one in ten in the non-canker sore group exhibited these deficiencies. In this case, we’re talking about iron and folate deficiency in addition to vitamin B12 deficiency. When the study participants were given supplements, their canker sores improved and this was more pronounced among those who had no family history of canker sore problems.

You can see how vitamin and mineral supplements might help people who are deficient, but might a supplement like vitamin B12 help people who are not vitamin B12 deficient? Apparently so. As the title of the study states, “cyanocobalamin”—the most common form of supplemental B12—“may be beneficial in the treatment of recurrent aphthous ulcers [canker sores] even when vitamin B12 levels are normal.” The researchers took a group of 72 patients with frequent canker sores and gave them vitamin B12, regardless of what their levels were. Ninety-six percent of the participants got better regardless of whether they started out vitamin B12–deficient or with normal vitamin B12 levels in their blood, as you can see below and at 5:37 in my video. In this case, there was no control group, though, so we don’t know how many would have gotten better without the vitamin B12 supplement. In addition, the researchers injected the vitamin B12, and injections can have an even greater placebo effect than pills—especially with something like a syringe of vitamin B12, which has a striking mad-scientist-looking ruby red color, as you can see below and at 5:57 in my video.

If only there were a randomized, double-blind, placebo-controlled trial of oral vitamin B12 for canker sores. And, here we go. In this case, 1,000 micrograms of sublingual vitamin B12 were taken every day for six months. It took five months, but, eventually, the duration of canker outbreaks, the number of ulcers, and the level of pain were significantly reduced, “regardless of initial vitamin B12 levels in the blood.” So, whether you are vitamin B12–deficient or not, B12 supplements seem to help. By the end of the study, twice as many in the vitamin B12 group appeared to have been cured. The researchers concluded that “vitamin B12 treatment, which is simple, inexpensive, and low-risk, seems to be effective,” but don’t forget that it appeared to take months before it started working. In another randomized, double-blind, placebo-controlled trial of a vitamin B12 ointment applied directly to the canker sores, a significant reduction in pain was demonstrated within only two days compared to placebo, regardless of whether the participant was vitamin B12–deficient or not.

Here’s a link to the video on the remarkable honey results I mentioned: Flashback Friday: Topical Honey for Canker Sores.