Table 1.

Summary of included studies.

Author, year	Postmenopausal women’s characteristics/Randomization/Study quality testing	Study design/Vitamin D3 regimen	Mean baseline and post-treatment 25(OH)D, ng/ml	Conclusions
Hansen, 2015	N: 230 Age: 61 ±6 years Block randomization was performed Intent to treat was performed	Randomized clinical trial Loading dose of oral 50,000 IU/day for 15 days followed by maintenance dose of oral 50,000 IU every 2 weeks for 11.5 months	Baseline: 21 ±3 Post-treatment: 30 days: 80 60 days: 59 120 days: 46 240 days: 45 365 days: 42	Oral loading dose of 50,000 IU/day for 2 weeks followed by 50,000 IU/2 weeks for a year was effective for raising 25(OH)D level above normala and was maintained up to 1 year Maintenance oral dose of 800 IU/day was not sufficient to raise serum 25(OH)D level to normal, p < 0.001b
		Randomized clinical trial Maintenance dose of oral 800 IU/day for 12 months	Baseline: 21 ±3 Post-treatment: 30 days: 26 60 days: 27 120 days: 29 240 days: 28 365 days: 27
Romagnoli, 2008	N: 32 Age range: 66-97 years No information on randomization was stated No study quality testing was reported	Prospective randomized intervention study Loading oral dose of 300,000 IU	Baseline: 13.3 ±9.9 Post-treatment: 30 days: 47.8 ±7.3 60 days: 28.06 ±8.33	A single oral dose of 300,000 IU had a faster onset and was more effective than equal intramuscular dose in elevating 25(OH)D to normal levels but after 60 days, neither doses were effective in keeping 25(OH)D level cbove normal, (p < 0.001c)
		Prospective randomized intervention study Loading intramuscular dose of 300,000 IU	Baseline: 8.3 ±3.6 Post-treatment: 30 days: 15.91 ±11.3 60 days: 26.16 ±12.1
Aloia, 2014	N: 76 Age: 58 ±4.9 Computer randomization was Performed No study quality testing was reported	Randomized clinical trial Maintenance oral doses of 800, 2000, or 4000 IU/day for 2 months	Baseline: 25.2 ±5.6 Post-treatment: Mean at 800: 26 Mean at 2000: 32 Mean at 4000: 40	Maintenance oral dose of 800 IU/day was not effective. Maintenance oral dose of 2000 IU/day successfully raised 25(OH)D to normal. Maintenance oral dose of 4000 IU/day produced the highest response (p = 0.002b)
Ceglia, 2016	N: 21 Age: 78 ±5 No information on randomization was stated No study quality testing was reported	Randomized clinical trial Maintenance oral doses of 4000 IU/day for 4 months	Baseline: 17.6 ±4 Post-treatment: 32 ±4.8	Maintenance oral dose of 4000 IU/day was effective for raising serum 25(OH)D above normal (p < 0.01d)
Golombick, 2008	N: 23 Age: 61.2 ±3.2 No study quality testing was reported	Prospective open-label study Maintenance oral dose of 1000 IU/day for 1 month then 500 IU/day for 2 months	Baseline: 14.4 ±0.4 Post-treatment: 36 ±2.4	Loading dose of oral 1000/day for one month followed by maintenance oral dose of 500 IU/day for one month raised serum 25(OH)D to normal in 86% of women (p = 0.0001d)
Cangussu, 2015	N: 160 Age: 58.8 ±6.6 Computer randomization was performed Intent to treat was performed	Randomized clinical trial Oral 1000 IU/day for 9 months	Baseline: 15 ±7.5 Post-treatment: 27.5 ±10.4	Maintenance oral dose of 1000 IU/day for 9 months was not sufficient to raise serum 25(OH)D to normal (p < 0.001d)
Thomas, 2010	N: 22 Mean age: 66 Computer randomization was Performed No study quality testing was reported	Randomized clinical trial Oral 1000 IU/day for 7 weeks	Baseline: 19.6 Post-treatment: 30.8 ±7.2	Maintenance oral dose of 1000 IU/day for 7-8 weeks was sufficient to raise serum 25(OH)D to normal (p < 0.001d)
		Randomized clinical trial Oral 1000 IU/day for 8 weeks	Baseline: 19.6 Post-treatment: 36 ±10
Gallagher, 2012	N: 163 Age: 67 ±7.3 Computer randomization was performed No study quality testing was reported	Randomized clinical trial Oral 4800 IU/day for 12 months	Baseline: 15.3 ±3.7 Post-treatment: 46.5	Maintenance oral dose of 4800 IU/day for 12 months was effective to raise serum 25(OH)D above normal
Mason, 2016	N: 218 Age: 59.6 ±5.9 Block randomization was performed Intent to treat was performed	Randomized clinical trial Oral 2000 IU/day for 12 months	Baseline: 21.4 ±5.1 Post-treatment: 35	Maintenance oral dose of 2000 IU/day for 12 months was sufficient to raise serum 25(OH)D above normal (p = 0.02d)
Talwar, 2007	N: 208 Age: 59.9 ±6.2 Computer randomization was performed Intent to treat was performed	Randomized clinical trial Oral 800 IU/day for 24 months followed by oral 2000 IU/day for another 12 months	Baseline: 18.8 ±8.4 Post-treatment: 3 months: 28.4 ±8.8 24 months: 26.4 ±8.8 27 months: 34.8 ±10.8 36 months: 29.6 ±10.8	Maintenance oral dose of 800 IU/day for 24 months was not sufficient to raise serum 25(OH)D to normal. Maintenance oral dose of 2000 IU/day for 12 months was effective to raise serum 25(OH)D above normal in 50% of women (p < 0.0001d)
Viljakainen, 2006	N: 49 Age: 65-85 No information on randomization was stated No study quality testing was reported	Randomized clinical trial Oral 200, 400, or 800 IU/day for 3 months	Baseline: 18.8 ±6 Post-treatment: 200 IU/day: 23.2 ±3.6 400 IU/day: 24 ±3.6 At 800: 28.4 ±3.6	Maintenance oral dose of 800 IU/day for 3 months failed to raise serum 25(OH)D above normal
Apaydin, 2018	N: 60 Age range: 50-68 No information on randomization was stated No study quality testing was reported	Randomized clinical trial A single oral dose of 300,000 IU	Baseline: 9.7 ±4.4 Post-treatment: 1 month: 35.9 ±9.6 3 months: 23.1 ±4.7	Maintenance oral dose of 800 IU/day for 3 months was not sufficient to raise serum 25(OH)D above normal (3.2% of treated women had repletion).A single oral dose of 300,000 IU was more effective (63.3% of women were repleted, p = 0.049c) but did not maintain 25(OH)D level above normal after 3 months of follow-up
		Randomized clinical trial Oral 800 IU/day for 3 months	Baseline: 10.2 ±4.4 Post-treatment: 1 month: 16.9 ±5.8 3 months: 19.8 ±7.2

IU – international unit, 25(OH)D – 25-hydroxyvitamin D

^aNormal 25(OH)D level is 30 ng/ml

^bamong all groups

^cbetween the two treatment groups

^dpre- and post-treatment