['Appropriateness of the vitamin doses in Japanese commercial multi-vitamin preparations for parenteral nutrition therapy was investigated in patients with gastrointestinal tract disorder by evaluating the vitamin status (blood concentrations and urinary excretions of vitamins B1, B2, B6, and C) of them.', 'Commercial multivitamin preparations were administered continuously with a commercial PN solution over 5 days to 10 patients with gastrointestinal tract disorder. Blood concentrations of vitamins B1, B2, B6, and C were measured on the mornings of day 1, day 4, and day 6. Urinary excretions were measured in 24-h urine collections collected after day 3 and after day 5.', 'Blood concentrations of vitamins B1, B2, and B6 increased but remained within or slightly above the normal throughout the study, and urinary excretion values were normal in all patients. However, blood vitamin C concentration surpassed the lower limit of normal (5.5 microg/mL) only on day 6. Urinary vitamin C excretion was below normal (20.0 mg/day) in all and 7 patients on days 3 and 5, respectively.'] Do patients with gastrointestinal tract disorders receiving parenteral nutrition need a higher dose of vitamin C?