When you have a canker sore, the pain may be so intense, it’s impossible to carry on your normal daily activities. Even though it may be just a tiny ulcer in your mouth, it makes you feel like your whole body is out of balance and unhealthy. Since your body functions as a whole system, an eruption of canker sores could mean that your body is indeed out of balance.

Your canker sore is giving you a signal that your body needs some attention and care. A common reason why people get recurrent canker sores is a deficiency of certain micronutrients. The micronutrients listed below have been well-studied and have shown evidence of benefits for canker sores.

Vitamin B-12 (cobalamin)

• Formation of red blood cells
• Cell function and metabolism
• Production of DNA

Food sources rich in Vitamin B-12 include poultry, eggs, meat, fish, and dairy. People who follow a vegan diet are at risk for Vitamin B-12 deficiency because it is not present in plant foods. There are some people who may have a problem absorbing this vitamin due to different factors. In addition, certain medications can interfere with the absorption of Vitamin B-12. If you suspect that your body is not absorbing Vitamin B-12, ask your doctor to order a Vitamin B-12 level test.

Even in healthy people, Vitamin B-12 has poor absorption through the stomach. The recommended daily requirement for Vitamin B-12 is 25 micrograms, which is quite small. However, higher doses of vitamin B-12 supplements have been found to be safe, as your stomach has a maximum capacity for Vitamin B-12 absorption and your body will get rid of the excess.

There are studies that have compared Vitamin B-12 levels in patients with recurrent canker sores and those without. The study found that patients with recurrent canker sores had significantly lower levels of Vitamin B-12 than the control group. In a study published in The Journal of the American Board of Family Medicine, it was found that Vitamin B-12 supplementation has been shown to reduce the frequency of canker sore episodes.

The details of the study are as follows:

• Patients with recurrent aphthous stomatitis were randomly assigned to either two groups. One group was treated nightly doses of sublingual 1,000 mcg of Vitamin B12. The other group was given a placebo.
• Patients were followed for six months.
• The study found that 74% of the treatment group and 32% of the placebo group were free of canker sores at the end of the study.

If your canker sores keep occurring, you may consider supplementing with Vitamin B-12 at a dose of 1,000 mcg daily.

Vitamin B-9 (folate/folic acid)

Folate is used by your body to make DNA and is important for tissue growth and cell function. Folate is found naturally in many foods, including nuts, beans, and green leafy vegetables. Many cereals are fortified with folic acid, which is a more bioavailable form of folate (1mcg of folate from food = 0.6 mcg of folic acid from fortified foods or supplements).

Main causes of folate deficiency:

• A diet low in folate-rich foods.
• Pregnancy or lactation: If you are pregnant or lactating, your body will use up folate more than usual. It’s very important to take folic acid supplements, not just for your own health, but for your baby’s health as well.
• H. Pylori infection: It’s been found that H. pylori infection is associated with poor absorption of vitamin B-12 and folic acid.

Folate has been shown to play an important role in helping people with recurrent canker sores have fewer episodes. In a study of people with recurrent canker sores (at least 3 episodes in the last 12 months), it was found that these people had significantly lower intake of vitamin B-12 and folate.

If you have recurrent canker sores, be sure to choose foods that have a high content of folate or those that have been fortified with folic acid. You may also take a supplement of folic acid to be sure your levels are adequate.

Lysine

Lysine is one of nine essential amino acids, which means it is not made by the body and must be obtained from food sources. Foods that are rich in lysine include those that are high in protein such as fish, beef, chicken, milk, eggs, and peas. There is evidence that lysine supplementation prevents canker sore outbreak as well as shortens their duration when they show up. Lysine becomes more active at the site of damage and helps speed up the healing process by facilitating the formation of collagen.

Some people get canker outbreaks when they have tiny invisible cuts in their mouths. Lysine facilitates the healing of these minor cuts before they have a chance to erupt into a full blown canker sore. This could be the reason why a supplementation of lysine helps these individuals prevent outbreaks. Lysine taken at a dose of 1000 mg daily for a short duration seems effective and safe. Note that there are risks associated with high doses and long-term supplementation of lysine such as kidney damage or abdominal pain.

Zinc

Zinc is an element that is important in the growth of cells, collagen synthesis, wound healing, and promotion of a healthy immune system. Food sources that are rich in zinc include whole grain, dairy, poultry, red meat, and nuts. Its benefits for canker sore treatment were demonstrated in a seminal double-blind placebo-controlled trial published in 2020. 

• The study enrolled patients with recurrent aphthous stomatitis (RAS).
• The treatment group received zinc sulfate 5 mg as a muco-adhesive tablet three times a day.
• The placebo group received a placebo muco-adhesive tablet.
• On the third, fifth, and seventh day of treatment, the intervention group had statistically significant reduction in size and pain of the ulcer.

Zinc levels are not routinely measured and there’s no clear association between zinc levels and RAS, therefore zinc is not recommended to be taken as a prevention. However, once you have an outbreak, you may consider a zinc lozenge or zinc supplementation.

Iron

Iron is an important element for the production of healthy blood cells called hemoglobin that carry oxygen from your lungs throughout your body. Even though iron is an abundant element on earth, deficiency is common. Foods that are good sources of iron include cereals, legumes, fruits, and vegetables. If you have recurrent canker sores, you may want to ask your doctor to order a hematological workup that includes a complete blood count and iron studies.

If it is found that you have iron deficiency, your doctor may suggest iron supplementation. If you are started on iron, it is recommended that you take it with vitamin C as this helps with the absorption of the iron. Also, because iron can cause significant constipation, be sure to have adequate fiber in your diet. Although its role in RAS has not been studied in randomized controlled trials, there is evidence that occurrence of RAS is higher in people with iron deficiency.

A study that reviewed 19 clinical studies found that people with recurrent canker sores have a higher risk of having low levels of iron, vitamin B-12, and folate in their blood. It is important to ensure adequate iron intake if you have regular canker sore outbreaks.

Final Thoughts

Nature has gifted us with nutrients that are available all around us. However, when we don’t take full advantage of these natural nutrients, it’s important to supplement our bodies with vitamins, minerals, and essential amino acids. For many people, simply ensuring that they have adequate levels of these important micronutrients keeps their canker sores away completely.

Sandie Tran, Pharm.D.