In an Israeli study of 58 people prone to canker sores, those who took B12 (1,000 micrograms a day—about 400 times the recommended dietary allowance) had fewer, shorter, and less painful outbreaks after five or six months, compared to those who took a placebo. Moreover, 74% of those taking B12 were free of sores at the end of the study, compared to only 32% of the placebo group. Vitamin B12 treatment “is simple and inexpensive and has no known significant toxic effects,” the researchers said.
