Vitamin B12
People with recurrent mouth sores often have low levels of vitamin B12 in the body. This is because this water-soluble form of B vitamin is essential for many functions, such as retaining nerve cells, producing red blood cells, enhancing immune activities, and generating RNA and DNA. A lack of vitamin B12 leads to many health issues that would trigger mouth sores. Fortunately, you can take in this vitamin in many foods, such as eggs, dairy, fortified cereal, shellfish, fish, chicken, liver, and beef. [7]
