There are many types of vitamin B. Lack of vitamin B1 will lead to beriberi; lack of vitamin B2 will lead to mouth ulcers and keratitis; lack of vitamin B6 will lead to decreased sensation and weakness in the limbs; lack of vitamin B12 will lead to anemia. 1. Lack of vitamin B1: it will lead to beriberi, manifesting itself as easy fatigue, easy irritability, indigestion, memory loss and so on. 2. Lack of vitamin B2: keratitis, mouth ulcers, increased dandruff, seborrheic dermatitis due to increased oil secretion of the skin, and so on. 3. Lack of vitamin B6: it can lead to peripheral nerve damage, which can cause loss of sensation in the endings of the limbs, weakness, nausea, vomiting, diarrhea and so on. 4. Lack of vitamin B12: will cause anemia, manifested as dizziness, numbness of hands and feet, weakness, mental instability and so on. It should be noted that the symptoms should be timely consultation, clear causes targeted treatment. In vegetables, fruits contain a large number of vitamin B, can be timely supplementation, to avoid the emergence of the above symptoms.