The broad definition of nutritional metabolic deficiencies should include both undernutrition or deficiency and overnutrition, and only the former will be discussed. Malnutrition is often secondary to a number of medical and surgical causes, such as chronic diarrhea, short bowel syndrome, and malabsorptive disorders. The non-medical causes of malnutrition are poverty food shortage. Lack of nutritional knowledge and parental neglect of scientific feeding methods. In developed countries malnourished patients can usually be treated by treating the primary cause, providing an appropriate diet, parental education and careful follow-up. However, in many third world countries, malnutrition is the leading cause of child mortality. The complex interaction between malnutrition, social habits, environment and acute and chronic infections makes treatment very difficult and cannot be resolved by providing appropriate food alone. Clinical examination of nutrient metabolism deficiency: 1. Vitamin B1 deficiency (thiamine deficiency) with psychiatric symptoms (1) Mental disorders: depressive state; governance disorder; disorders of consciousness can be manifested as hazy state with occasional delirium. (2) Neurological symptoms: neuritis, nystagmus, dyscalculia and occasionally retinal hemorrhage. 2. Niacin deficiency with psychiatric disorders. (1) Mental disorders: ① neurasthenia syndrome: often appear in the early stage of the disease or milder ② depressive state: often accompanied by irritability and anxiety, self-blame and self-guilt attempts to suicide, etc. good to occur in the course of the disease. ③ nervousness syndrome: there is nervousness excitement or nervousness stiffness similar to the performance of schizophrenia nervousness type ④ consciousness disorder: good to occur in the acute onset of the disease in the late stage of the disease patients can appear unconscious drowsiness, delirium, or confusion state can cause coma in serious cases high death rate is called niacin deficiency encephalopathy, when there are often neurological symptoms and features. ⑤ Chronic encephalopathy syndrome: Patients in the chronic phase may have slow reactions, memory, impaired calculating power, clumsy and slow movements, and in the late severe cases, Korsakoff syndrome or dementia may occasionally be seen. (6) A small number of patients may present with encephalopathy: clinical impairment of consciousness with severe neurological symptoms and signs. (2) Neurological symptoms: nystagmus, pupillary changes (pupil enlargement, blunted reflex to light), cone bundle sign positive hypertonia sensory abnormalities peripheral neuritis and epileptiform spasmodic seizures, deep sensory dyskinesia and ataxic dyskinesia may occur if accompanied by subacute joint spinal cord degeneration. (3) Somatic symptoms: tongue inflammation, strawberry tongue; exfoliative dermatitis; gastrointestinal dysfunction. Diarrheal dermatitis is the most pronounced plus dementia is often referred to as a three-principle complication of niacin deficiency. Diagnosis of nutritional metabolic deficiency: 1, there is evidence of nutritional metabolic deficiency disease lesions related to the history of malnutrition such as niacin vitamin B1 and folic acid deficiency. 2, there are signs and symptoms of nutrient metabolism deficiency leading to corresponding functional abnormalities. 3.Psychiatric symptoms change with the development of nutrient metabolism deficiency disease symptoms, i.e., psychiatric symptoms appear after the physical disease, and there is a parallel relationship between the development and physical disease. 4, related nutrition (niacin vitamin B1 and folic acid, etc.) treatment has significant efficacy. 5. It should be distinguished from other hypofunctional psychiatric disorders and other functional psychiatric disorders such as schizophrenia, dysthymia and depression.