Vitamin B12 is an essential nutrient that is not naturally produced in the body, but must be acquired from different food groups and sometimes through supplementation. The primary role of vitamin B12 is to form red blood cells and DNA. Furthermore, it plays a significant role in developing brain and nerve cells.

from Times of India https://timesofindia.indiatimes.com/life-style/health-fitness/health-news/vitamin-b12-deficiency-beware-of-these-symptoms-that-may-appear-on-your-tongue/photostory/93525772.cms