A METHODOLOGICAL STUDY FOR THE EVALUATION OF THE VITAMIN C STATUS IN HUMAN BODY BY THE RATIO OF REDUCED VITAMIN C TO CREATININE IN A RANDOM URINE SAMPLE / 营养学报

ABSTRACT

One hundred and ten college students, 66 males and 44 females, were studied for the evaluation of vitamin C status by use of the ratio of reduced vitamin C to creatinine in a random urine sample. During the experimental period, the dietary source of creatinine was strictly abstained. After voiding in the morning, the volunteers were weighed and their urine were collected at the end of 1st, 2nd, 4th, 8th, 12th and 24th hr respectively. The contents of reduced vitamin C and creatinine in each collected urine sample were analysed, and then the total amounts in 24 hrs were calculated.The experimental results showed1. The distribution of the creatinine excretion in 24 hrs was nearly constant.2. The percentage of reduced vitamin C excretion per hour to the total 24 hrs excretion was similar in subjects of different vitamin C status and was lowest in 12 hrs of night urine. A curvilinear regression was given for the percentage of reduced vitamin C excretion in relation to the time.3. The ratio of reduced vitamin C (as mg) to creatinine (as gm) and the ratio of reduced vitamin C to creatinine (as mg) per body weight (as kg) were calculated from their contents in 12 hrs urine in those who exc- reted reduced vitamin C in urine less than 80 mg in 24 hrs. The relationship between these two ratios and the excretions of reduced vitamin C in 24 hrs urine was studied and four equations of curvilinear regressions were given.4. According to these equations, the correlated values of vitamin C/ crcatinine and vitamin C/creatinine/body weight in random urine samples in respect of four different grades of vitamin C excretion of 24 hrs urine were recommended.It was shown to be a new simplified method for evaluating the nutritional status of vitamin C in human body. The practical aspect of its application was discussed.