J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 10, Number 1, January 2018, pages 13-21

The Effect of Ongoing Vitamin D and Low-Fat Milk Intake on Bone Metabolism in Female High-School Endurance Runners

**Table 1.** Subject Characteristics
	Group	Baseline	3 months	6 months	P
Values are represented as mean ± SD. Differences in time (baseline, 3 months, and 6 months) and group (MKD and CON) were evaluated with repeated two-way ANOVAs for subject characteristics. Because fat mass and fat-free mass (FFM) were measured in before and after the 6-month trial period only, the values in 3 months were not measured (-). MKD: vitamin D supplement + low-fat milk group; CON: control group.
Height (cm)	MKD	158.9 ± 4.2	159.0 ± 4.4	159.3 ± 4.3	< 0.01	n.s	n.s
	CON	158.3 ± 5.0	158.5 ± 5.0	158.9 ± 5.0
Weight (kg)	MKD	47.3 ± 3.3	48.5 ± 2.8	49.3 ± 2.8	< 0.01	n.s	n.s
	CON	45.3 ± 3.2	46.8 ± 3.2	47.6 ± 3.6
BMI (kg/m²)	MKD	18.7 ± 1.5	19.2 ± 1.4	19.5 ± 1.3	< 0.01	n.s	n.s
	CON	18.1 ± 1.1	18.7 ± 1.5	18.9 ± 1.7
Fat mass (%)	MKD	19.6 ± 5.3	-	21.8 ± 5.2	< 0.01	n.s	n.s
	CON	17.9 ± 4.8	-	21.0 ± 5.6
Appendicular FFM (kg)	MKD	16.1 ± 1.3	-	16.6 ± 1.4	< 0.01	n.s	n.s
	CON	15.7 ± 1.3	-	16.1 ± 1.2
Running distance (km/month)	MKD	187.8 ± 88.3	215.5 ± 117.7	179.4 ± 85.2	n.s	0.03	n.s
	CON	124.5 ± 70.7	103.9 ± 73.9	106.7 ± 61.0
Frequency of menses (time/year)	MKD	11.1 ± 2.2	11.8 ± 3.3	12.5 ± 2.9	n.s	0.04	n.s
	CON	6.8 ± 5.3	8.2 ± 5.7	7.7 ± 5.1

Table 1. Subject Characteristics

Group

Baseline

3 months

6 months

Time

Group

Time × group

Values are represented as mean ± SD. Differences in time (baseline, 3 months, and 6 months) and group (MKD and CON) were evaluated with repeated two-way ANOVAs for subject characteristics. Because fat mass and fat-free mass (FFM) were measured in before and after the 6-month trial period only, the values in 3 months were not measured (-). MKD: vitamin D supplement + low-fat milk group; CON: control group.

Height (cm)

MKD

158.9 ± 4.2

159.0 ± 4.4

159.3 ± 4.3

< 0.01

n.s

CON

158.3 ± 5.0

158.5 ± 5.0

158.9 ± 5.0

Weight (kg)

MKD

47.3 ± 3.3

48.5 ± 2.8

49.3 ± 2.8

< 0.01

n.s

CON

45.3 ± 3.2

46.8 ± 3.2

47.6 ± 3.6

BMI (kg/m²)

MKD

18.7 ± 1.5

19.2 ± 1.4

19.5 ± 1.3

< 0.01

n.s

CON

18.1 ± 1.1

18.7 ± 1.5

18.9 ± 1.7

Fat mass (%)

MKD

19.6 ± 5.3

21.8 ± 5.2

< 0.01

n.s

CON

17.9 ± 4.8

21.0 ± 5.6

Appendicular FFM (kg)

MKD

16.1 ± 1.3

16.6 ± 1.4

< 0.01

n.s

CON

15.7 ± 1.3

16.1 ± 1.2

Running distance (km/month)

MKD

187.8 ± 88.3

215.5 ± 117.7

179.4 ± 85.2

n.s

0.03

n.s

CON

124.5 ± 70.7

103.9 ± 73.9

106.7 ± 61.0

Frequency of menses (time/year)

MKD

11.1 ± 2.2

11.8 ± 3.3

12.5 ± 2.9

n.s

0.04

n.s

CON

6.8 ± 5.3

8.2 ± 5.7

7.7 ± 5.1

**Table 2.** Changes in BMD
	Group	Baseline	6 months	P
Values are represented as mean ± SD. Differences in time (baseline, 3 months, and 6 months) and group (MKD and CON) were evaluated with repeated two-way ANOVAs for BMD. TBLH: total bone less head; MKD: vitamin D supplement + low-fat milk group; CON: control group.
Arms BMD (g/cm²)	MKD	0.838 ± 0.063	0.858 ± 0.051	< 0.01	n.s	n.s
	CON	0.818 ± 0.061	0.828 ± 0.051
Legs BMD (g/cm²)	MKD	1.217 ± 0.064	1.230 ± 0.061	< 0.01	n.s	n.s
	CON	1.199 ± 0.077	1.212 ± 0.072
Pelvic BMD (g/cm²)	MKD	1.068 ± 0.082	1.086 ± 0.076	< 0.01	n.s	n.s
	CON	1.051 ± 0.079	1.077 ± 0.075
Spine BMD (g/cm²)	MKD	0.967 ± 0.093	0.999 ± 0.098	< 0.01	n.s	n.s
	CON	0.981 ± 0.073	1.014 ± 0.069
TBLH BMD (g/cm²)	MKD	0.992 ± 0.054	1.002 ± 0.050	< 0.01	n.s	n.s
	CON	0.978 ± 0.059	0.991 ± 0.050

Table 2. Changes in BMD

Group

Baseline

6 months

Time

Group

Time × group

Values are represented as mean ± SD. Differences in time (baseline, 3 months, and 6 months) and group (MKD and CON) were evaluated with repeated two-way ANOVAs for BMD. TBLH: total bone less head; MKD: vitamin D supplement + low-fat milk group; CON: control group.

Arms BMD (g/cm²)

MKD

0.838 ± 0.063

0.858 ± 0.051

< 0.01

n.s

CON

0.818 ± 0.061

0.828 ± 0.051

Legs BMD (g/cm²)

MKD

1.217 ± 0.064

1.230 ± 0.061

< 0.01

n.s

CON

1.199 ± 0.077

1.212 ± 0.072

Pelvic BMD (g/cm²)

MKD

1.068 ± 0.082

1.086 ± 0.076

< 0.01

n.s

CON

1.051 ± 0.079

1.077 ± 0.075

Spine BMD (g/cm²)

MKD

0.967 ± 0.093

0.999 ± 0.098

< 0.01

n.s

CON

0.981 ± 0.073

1.014 ± 0.069

TBLH BMD (g/cm²)

MKD

0.992 ± 0.054

1.002 ± 0.050

< 0.01

n.s

CON

0.978 ± 0.059

0.991 ± 0.050

**Table 3.** Changes in 25(OH)D, PTH, TNF-α, and Bone Metabolism Marker Concentrations
	Group	Baseline	3 months	6 months	P
Values are represented as mean ± SD. Differences in time (baseline, 3 months, and 6 months) and group (MKD and CON) were evaluated with repeated two-way ANOVAs for biomarkers. *P < 0.05 vs. CON, †P < 0.05, ††P < 0.01 vs. Baseline. BAP/CTX: bone formation to resorption ratio; MKD: vitamin D supplement + low-fat milk group; CON: control group.
25(OH)D (ng/mL)	MKD	31.8 ± 6.5	31.8 ± 5.0	30.2 ± 3.8	< 0.01	n.s	< 0.01
	CON	34.7 ± 8.2	28.0 ± 7.1††	27.9 ± 5.3††
PTH (pg/mL)	MKD	33.9 ± 10.0	29.2 ± 7.3	36.9 ± 11.2	< 0.01	n.s	0.06
	CON	30.0 ± 8.5	32.0 ± 6.6	40.5 ± 8.7
TNF-α (pg/mL)	MKD	1.08 ± 0.28*	0.87 ± 0.26	0.83 ± 0.30†	n.s	n.s	0.04
	CON	0.71 ± 0.38	0.85 ± 0.29	0.71 ± 0.34
CTX (ng/mL)	MKD	0.66 ± 0.19	0.54 ± 0.18	0.55 ± 0.18	0.04	n.s	n.s
	CON	0.85 ± 0.23	0.70 ± 0.25	0.76 ± 0.48
BAP (µg/L)	MKD	15.7 ± 5.5	15.3 ± 4.1	16.1 ± 3.3	n.s	n.s	n.s
	CON	17.5 ± 9.5	17.7 ± 11.1	18.2 ± 10.8
BAP/CTX	MKD	24.8 ± 10.4	31.9 ± 17.6	33.5 ± 16.4	< 0.01	n.s	n.s
	CON	20.2 ± 7.3	24.7 ± 7.4	24.8 ± 6.8

Table 3. Changes in 25(OH)D, PTH, TNF-α, and Bone Metabolism Marker Concentrations

Group

Baseline

3 months

6 months

Time

Group

Time × group

Values are represented as mean ± SD. Differences in time (baseline, 3 months, and 6 months) and group (MKD and CON) were evaluated with repeated two-way ANOVAs for biomarkers. *P < 0.05 vs. CON, †P < 0.05, ††P < 0.01 vs. Baseline. BAP/CTX: bone formation to resorption ratio; MKD: vitamin D supplement + low-fat milk group; CON: control group.

25(OH)D (ng/mL)

MKD

31.8 ± 6.5

31.8 ± 5.0

30.2 ± 3.8

< 0.01

n.s

< 0.01

CON

34.7 ± 8.2

28.0 ± 7.1††

27.9 ± 5.3††

PTH (pg/mL)

MKD

33.9 ± 10.0

29.2 ± 7.3

36.9 ± 11.2

< 0.01

n.s

0.06

CON

30.0 ± 8.5

32.0 ± 6.6

40.5 ± 8.7

TNF-α (pg/mL)

MKD

1.08 ± 0.28*

0.87 ± 0.26

0.83 ± 0.30†

n.s

0.04

CON

0.71 ± 0.38

0.85 ± 0.29

0.71 ± 0.34

CTX (ng/mL)

MKD

0.66 ± 0.19

0.54 ± 0.18

0.55 ± 0.18

0.04

n.s

CON

0.85 ± 0.23

0.70 ± 0.25

0.76 ± 0.48

BAP (µg/L)

MKD

15.7 ± 5.5

15.3 ± 4.1

16.1 ± 3.3

n.s

CON

17.5 ± 9.5

17.7 ± 11.1

18.2 ± 10.8

BAP/CTX

MKD

24.8 ± 10.4

31.9 ± 17.6

33.5 ± 16.4

< 0.01

n.s

CON

20.2 ± 7.3

24.7 ± 7.4

24.8 ± 6.8

**Table 4.** Effect of Vitamin D Supplementation and Low-Fat Milk Intake on Each Biomarker
	Baseline to 3 months	Baseline to 6 months
Values are represented as mean ± SE. The change in concentration of each biomarker in both groups was compared after each biomarker was adjusted for Baseline values, frequency of menses, and running distance, respectively. Model 1: baseline value. Model 2: baseline value, frequency of menses (baseline value). Model 3: baseline value, frequency of menses (baseline value), running distance (baseline value). MKD: vitamin D supplement + low-fat milk group; CON: control group.
25(OH)D (ng/mL)
Model 1	-6.33 ± 0.76	-0.32 ± 0.76	< 0.01	-6.12 ± 0.78	-2.21 ± 0.78	< 0.01
Model 2	-6.17 ± 0.83	-0.48 ± 0.83	< 0.01	-5.87 ± 0.85	-2.45 ± 0.85	0.02
Model 3	-6.19 ± 0.96	-0.46 ± 0.96	< 0.01	-5.46 ± 0.95	-2.87 ± 0.95	0.11
PTH (pg/mL)
Model 1	1.17 ± 1.50	-3.87 ± 1.50	0.03	9.91 ± 2.53	3.59 ± 2.53	0.10
Model 2	2.01 ± 1.53	-4.71 ± 1.53	0.01	9.67 ± 2.77	3.83 ± 2.77	0.18
Model 3	1.63 ± 1.65	-4.33 ± 1.65	0.04	7.32 ± 2.43	6.18± 2.43	0.77
TNF-α (pg/mL)
Model 1	0.03 ± 0.08	-0.11 ± 0.08	0.25	-0.07 ± 0.08	-0.19 ± 0.08	0.36
Model 2	0.04 ± 0.10	-0.12 ± 0.10	0.35	-0.10 ± 0.10	-0.16 ± 0.10	0.71
Model 3	-0.03 ± 0.08	-0.05 ± 0.08	0.94	-0.10 ± 0.11	-0.16 ± 0.11	0.77
CTX (ng/mL)
Model 1	-0.13 ± 0.04	-0.13 ± 0.04	0.95	-0.10 ± 0.09	-0.09 ± 0.09	0.92
Model 2	-0.15 ± 0.04	-0.12 ± 0.04	0.60	-0.14 ± 0.09	-0.05 ± 0.09	0.50
Model 3	-0.14 ± 0.04	-0.13 ± 0.04	0.86	-0.15 ± 0.09	-0.04 ± 0.09	0.44
BAP (µg/L)
Model 1	0.31 ± 1.58	-0.53 ± 1.58	0.71	0.85 ± 1.39	0.33 ± 1.39	0.80
Model 2	-0.18 ± 1.72	-0.04 ± 1.72	0.96	0.90 ± 1.54	0.29 ± 1.54	0.80
Model 3	0.25 ± 2.01	-0.47 ± 1.96	0.82	1.05 ± 1.77	0.13 ± 1.77	0.75

Table 4. Effect of Vitamin D Supplementation and Low-Fat Milk Intake on Each Biomarker

Baseline to 3 months

Baseline to 6 months

CON (n = 10)

MKD (n = 10)

CON (n = 10)

MKD (n = 10)

Values are represented as mean ± SE. The change in concentration of each biomarker in both groups was compared after each biomarker was adjusted for Baseline values, frequency of menses, and running distance, respectively. Model 1: baseline value. Model 2: baseline value, frequency of menses (baseline value). Model 3: baseline value, frequency of menses (baseline value), running distance (baseline value). MKD: vitamin D supplement + low-fat milk group; CON: control group.

25(OH)D (ng/mL)

Model 1

-6.33 ± 0.76

-0.32 ± 0.76

< 0.01

-6.12 ± 0.78

-2.21 ± 0.78

< 0.01

Model 2

-6.17 ± 0.83

-0.48 ± 0.83

< 0.01

-5.87 ± 0.85

-2.45 ± 0.85

0.02

Model 3

-6.19 ± 0.96

-0.46 ± 0.96

< 0.01

-5.46 ± 0.95

-2.87 ± 0.95

0.11

PTH (pg/mL)

Model 1

1.17 ± 1.50

-3.87 ± 1.50

0.03

9.91 ± 2.53

3.59 ± 2.53

0.10

Model 2

2.01 ± 1.53

-4.71 ± 1.53

0.01

9.67 ± 2.77

3.83 ± 2.77

0.18

Model 3

1.63 ± 1.65

-4.33 ± 1.65

0.04

7.32 ± 2.43

6.18± 2.43

0.77

TNF-α (pg/mL)

Model 1

0.03 ± 0.08

-0.11 ± 0.08

0.25

-0.07 ± 0.08

-0.19 ± 0.08

0.36

Model 2

0.04 ± 0.10

-0.12 ± 0.10

0.35

-0.10 ± 0.10

-0.16 ± 0.10

0.71

Model 3

-0.03 ± 0.08

-0.05 ± 0.08

0.94

-0.10 ± 0.11

-0.16 ± 0.11

0.77

CTX (ng/mL)

Model 1

-0.13 ± 0.04

0.95

-0.10 ± 0.09

-0.09 ± 0.09

0.92

Model 2

-0.15 ± 0.04

-0.12 ± 0.04

0.60

-0.14 ± 0.09

-0.05 ± 0.09

0.50

Model 3

-0.14 ± 0.04

-0.13 ± 0.04

0.86

-0.15 ± 0.09

-0.04 ± 0.09

0.44

BAP (µg/L)

Model 1

0.31 ± 1.58

-0.53 ± 1.58

0.71

0.85 ± 1.39

0.33 ± 1.39

0.80

Model 2

-0.18 ± 1.72

-0.04 ± 1.72

0.96

0.90 ± 1.54

0.29 ± 1.54

0.80

Model 3

0.25 ± 2.01

-0.47 ± 1.96

0.82

1.05 ± 1.77

0.13 ± 1.77

0.75

**Table 5.** The Correlation Between 25(OH)D or PTH Concentrations and Bone Metabolism Markers With Adjustment for Frequency of Menses
	CTX (ng/mL)	BAP/CTX
Pooled analysis by partial correlation coefficient. Values are r and P values.
25(OH)D (ng/mL)
Baseline	-0.61	< 0.01	-	-	-	-	0.31	0.19	-	-	-	-
3 months	-	-	-0.54	0.02	-	-	-	-	0.59	0.01	-	-
6 months	-	-	-	-	-0.53	0.02	-	-	-	-	0.56	0.01
PTH (pg/mL)
Baseline	0.20	0.42	-	-	-	-	-0.16	0.50	-	-	-	-
3 months	-	-	0.63	< 0.01	-	-	-	-	-0.59	0.01	-	-
6 months	-	-	-	-	0.52	0.02	-	-	-	-	-0.58	< 0.01

Table 5. The Correlation Between 25(OH)D or PTH Concentrations and Bone Metabolism Markers With Adjustment for Frequency of Menses

CTX (ng/mL)

BAP/CTX

Baseline

3 months

6 months

Baseline

3 months

6 months

Pooled analysis by partial correlation coefficient. Values are r and P values.

25(OH)D (ng/mL)

Baseline

-0.61

< 0.01

0.31

0.19

3 months

-0.54

0.02

0.59

0.01

6 months

-0.53

0.02

0.56

0.01

PTH (pg/mL)

Baseline

0.20

0.42

-0.16

0.50

3 months

0.63

< 0.01

-0.59

0.01

6 months

0.52

0.02

-0.58

< 0.01