Table 3.

Comparing the serum levels of vitamin D, vitamin A, PB and PTH in the study groups before and after intervention.

Variable		The Study Groups		MMD	p-Value **
		Placebo (n = 37)	Vitamin D (n = 34)
Vitamin D (ng/mL)	Before	22.15 ± 12.33	24.16 ± 10.16	17.08	<0.001
	After	23.45 ± 10.10	41.65 ± 6.82
	PC	16.51	97.66
	p-value *	0.275	<0.001
Vitamin A (mg/l)	Before	0.485 ± 0.099	0.464 ± 0.072	−0.006	0.731
	After	0.484 ± 0.069	0.470 ± 0.081
	PC	2.78	2.45
	p-value *	0.913	0.677
PB (µg/dL)	Before	1.54 ± 1.77	1.25 ± 1.24	0.012	0.953
	After	1.17 ± 0.746	1.13 ± 0.995
	PC	90.25	114.52
	p-value *	0.133	0.661
PTH (pg/mL)	Before	25.44 ± 7.42	26.80 ± 7.94	−5.47	0.003
	After	28.59 ± 9.53	23.43 ± 4.91
	PC	20.70	−8.37
	p-value *	0.111	0.004
Calcium(mg/dl)	Before	10.80 ± 0.380	10.74 ± 0.400	−0.021	0.788
	After	10.63 ± 0.358	10.59 ± 0.314
	PC	−1.47	−1.26
	p-value *	0.017	0.054
Albumin (g/dl) ***	Before	5.15 ± 0.308	5.22 ± 0.322	−0.001	0.992
	After	5.26 ± 0.314	5.29 ± 0.297
	PC	2.17	1.40
	p-value *	0.071	0.265

* p-value was reported based on Paired sample t test. ** p-value was reported based on ANCOVA after adjustment of baseline values. MMD: Marginal Mean Difference; PC: Percent Change; PB: Lead; PTH: Parathyroid hormone. *** In order to have an accurate analysis on impacts of supplementation on serum calcium, the serum albumin was also measured and analyzed. The result has shown no significant difference in serum levels of Albumin between the two study groups (p = 0.992).