There are many symptoms caused by vitamin B deficiency: 1. If the human body lacks vitamin B2, it will easily lead to abnormal basal metabolism, which may also affect the human body’s cardiovascular and cerebral nerves, and certain patients will also develop beriberi. 2. If the human body lacks vitamin B2, it will easily lead to a decrease in the human body’s immunity and resistance, making it difficult to resist adverse external invasion, and prone to itchy skin, skin ulcers, 3.If the human body lacks vitamin B6, it will easily lead to seborrheic dermatitis, accompanied by nausea, vomiting, mental discomfort, memory loss and other adverse symptoms. 4.If the human body lacks vitamin B12, it will easily lead to skin pigmentation, tinnitus, numbness of the limbs, trembling of the limbs and other adverse symptoms.