Urinary metabolic profiles after vitamin D versus vitamin D supplementation in prediabetes.

AIM

To assess the potential biological differences between vitamin D and D using urinary metabolite profiles in response to vitamin D or D supplementation.

METHOD

Subjects consisted of 29 subjects with impaired fasting glucose and/or impaired glucose tolerance. Subjects were randomized into two groups, vitamin D (20,000 IU weekly, n = 14) or vitamin D (15,000 IU weekly, n = 15). Urine and serum samples were taken at two different time points for each subject (at baseline and at 12 weeks). Urinary metabolite profiling was performed by liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS). Serum calcium was analyzed on an automated biochemical analyzer and serum intact parathyroid hormone was determined by electrochemiluminescence immunoassay.

RESULTS

At baseline, there was no statistically significant difference in clinical characteristics including age, gender, body mass index, waist circumference and 25-hydroxyvitamin D (25(OH)D) levels between the 2 groups. Weekly administration of 20,000 U D for 12 weeks resulted in comparable 25(OH)D concentrations as compared to weekly 15,000 U D supplementation (97.8 ± 305 vs. 96.8 ± 3.4 nmol/L,  = 0.84). No difference in serum calcium (2.3 ± 0.03 vs. 2.2 ± 0.03 nmol/L,  = 0.52) or intact parathyroid hormone (5.3 ± 0.3 vs. 4.9 ± 0.5 pmol/L,  = 0.54) at 12 weeks was found. Principle component analysis did not reveal apparent segregation of metabolites according to D or D supplementation. Moreover, using partial least square regression, no apparent separation between the D and the D group was found. No important metabolite influencing the separation of the D from the D group was found using variables importance on projection analysis.

CONCLUSIONS

At comparable circulating 25(OH)D concentrations, vitamin D or D supplementation does not appear to result in different urinary metabolite profiles. Our finding does not support a biological difference between vitamin D and D.