Reactive Oxygen Species (ROS) can cause oxidative damage, resulting in oxidation of lipids, proteins and DNA. In fatigue patients, there are some evidences of oxidative damage to DNA. Ascorbic acid was known to protect mitochondrial injury against oxidative stress by depolarizing the mitochondrial membrane. The copy number of mitochondrial DNA(mtDNA) was suggested mitochondrial gene stability and biogenesis and reflected mitochondrial function. There is no evidence ascorbic acid would decrease the mtDNA damage in fatigue patients. The investigators hypothesized that decreasing in mtDNA copy number in salivary and blood sample may be reversed by high-dose vitamin C intravenous injection in fatigue patients. The investigators will compare the mtDNA copy number and fatigue scale between moderate-severe fatigue patients and control group that had not malignant and chronic illness by a randomized controlled trial.

Inclusion Criteria:

1. Adults with above 18 years old and 6 month fatigue duration
2. Moderate to severe fatigue scale (Brief fatigue inventory-Korean version scale ≥ 4)
3. Normal limit values in the screening test (White blood cell count, Hemoglobin, Creatinine, SGOT/SGPT, Thyroid stimulating hormone, Urinalysis)
4. Normal limit values in glucose 6 phosphate dehydrogenase level
5. Agree the subjects explanation

Exclusion Criteria:

1. pregnancy and lactation
2. acute common cold, acute gastroenteritis, uncontrolled diabetes, uncontrolled hypertension, liver disease or renal disease
3. previous medical history, affectable by high-dose ascorbic acid (gout, renal calculi and glucose 6 phosphate dehydrogenase deficiency)
4. hypersensitivity from ascorbic acid
5. vitamin supplement intake until 2 days ago
6. drug interactions with ascorbic acid ( aspirin, Fe, phenytoin, estrogen, tetracycline, coumarin, corticosteroid)
7. Do not read a consent fom