There are more types of vitamin B, such as vitamin B1, vitamin B2, vitamin B12, vitamin B6, vitamin B9, etc. When deficient, it can produce corresponding symptoms, such as beriberi, xerostomia, fatigue, anemia and so on. 1. Vitamin B1: When deficient in vitamin B1, nerve or heart conduction abnormalities can occur, causing athlete’s foot, such as easy fatigue, irritability, anorexia, muscle aches and pains. 2. Vitamin B2: when lacking, it can cause stomatitis, mouth ulcers, lingual inflammation, necrotizing periodontitis and so on. 3. Vitamin B6: when deficient, it can cause fatigue, irritability, lack of concentration, numbness of limbs, cold hands and feet, etc. 4. Vitamin B12: when lacking, it can cause megaloblastic anemia, peripheral neuropathy, hyperpigmentation, nausea, vomiting and other symptoms. 5. Vitamin B9: also known as folic acid, when deficient, it can cause megaloblastic anemia, stomatitis and so on. Symptoms such as mental depression, developmental delay, loss of appetite, pallor, etc. appear. Folic acid deficiency in women of childbearing age can also lead to anencephaly, fetal neural tube malformations, and so on. In addition, the lack of vitamin B can also cause dementia, dizziness, dermatitis and other symptoms, usually eat more vegetables and fruits, eat more coarse grains of food, lack of which can be under the guidance of the doctor oral B vitamin supplementation therapy.