Plasma vitamin C concentrations in patients in a psychiatric hospital.

Plasma vitamin C was measured in 885 patients in a psychiatric hospital and in 110 healthy controls. The average value was lower in the patients (0.51 mg/100 ml) than in the controls (0.87 mg/100 ml). Length of stay in hospital had little effect on plasma vitamin C in the patients, but the values were marginally lower in males, females on iron therapy and in those with senile dementia. In the patients, many of whom had been offered a similar diet for several years, age was not associated with a change in plasma vitamin C and this suggests that changes in vitamin C with age that have been reported reflect differences in intake. Few patients had values as low as those found in clinical scurvy (less than 0.1 mg/100 ml), but many (32 per cent) had concentrations below the threshold (0.35 mg/100 ml) at which some detrimental effects on health have been reported.