The results of a small trial suggest that vitamin B12 is a safe, effective, and inexpensive treatment for repeat canker sores.

"The frequency of (repeat canker sores) is as much as 25 percent in the general population," researcher Dr. Ilia Volkov, from Ben-Gurion University of the Negev, Beer-Sheva, Israel, said in a statement.

The cause of recurrent canker sores is unknown. Over the years a variety of treatments, including adhesive pastes, antiseptics, vitamins, herbs, and steroids have been tested. Although these treatments may reduce pain or the number of lesions in the short term, very few have had any lasting beneficial effect.

Volkov's team had already discovered that treating recurrent canker sores with vitamin B12 produced lasting results. In their most recent study, which involved 58 volunteers, they wanted to confirm the effectiveness of vitamin B12 by comparing results in treated patients to a comparison group that received inactive "placebo."

The results of the study are reported in The Journal of the American Board of Family Medicine.

Compared to placebo, treatment with vitamin B12 significantly reduced pain, the number of ulcers, and the duration of outbreaks at 5 and 6 months. Moreover, the improvements were not affected by what the patients' blood levels of vitamin B12 were at the start of the study.

In the last month of treatment, 74.1 percent of vitamin B12-treated patients were free of canker sores compared with 32 percent of those given placebo.

Exactly how vitamin B12 achieves these beneficial effects is unclear, the authors acknowledge. The fact that the treatment worked equally well regardless of the initial vitamin B12 level suggests that the vitamin may possess some unrecognized functions.

SOURCE: The Journal of the American Board of Family Medicine, January/February 2009.