Isotopic values of control subject's blood plasma.

a.The 11 human blood plasma samples (CS-1 to CS-11) were collected from the control subjects with healthy kidney.b.All control subjects are inside the country without traveling three months prior to sample.c.The blood urea nitrogen (BUN) test is to evaluate the renal function by measuring the amount of nitrogen in the form of urea in blood. The normal level of urea in blood is 7–20 mg/dL.d.The creatinine is the metabolite of creatine. The creatinine test is used as an indicator of renal function. The normal level of creatinine in blood is 0.7–1.2 mg/dL for male, and 0.5–1.9 mg/dL for female [48].e.The estimation of Glomerular filtration rate, an index of renal function. The eGFR value is calculated based on the MDRD (Modification of Diet in Renal Disease) formula, eGFR = 186×serium creatinine−1.154×age−0.203×(1.212 if black)×(0.742 if female) [49].f.The ratio is reported as the δ-notation (‰) relative to the international V-SMOW (Vienna Standard Mean Ocean Water) standard and normalized on the scale that the δ 18O and δ2H of SLAP (Standard Light Antarctic Precipitation) are −55.5‰ and −428‰, respectively [47].g.CSR's are human blood plasma samples collected from the control subjects (CS-1 to CS-6) at random. These subjects didn't take the BUN, Creat, and eGFR test.h.CSF's are human blood plasma samples collected from the control subjects (CS-7 to CS-11) fasting for 8 hours.i.The numbers in the parenthesis are the standard deviations taken all numbers of each group.