The vitamin B-complex are essential water-soluble vitamins, including vitamin B1(thiamine), vitamin B2 (riboflavin ), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine), biotin, folic acid and vitamin B12 (cobalamins). A. Vitamin B1 (Thiamine) Severe lactic acidosis and Vitamin B1 deficiency There was a report of a leukemic child treated with chemotherapy and parenteral …