1. Adams JS, Clemens TL, Parrish JA, Holick MF. Vitamin-D synthesis and metabolism after ultraviolet irradiation of normal and vitamin-D-deficient subjects. N Engl J Med. 1982; 306(12):722–725.
2. Baker MR, Peacock M, Nordin BE. The decline in vitamin D status with age. Age Ageing. 1980; 9(4):249–252.
3. Binkley N, Krueger D, Drezner MK. Low vitamin D status: time to recognize and correct a Wisconsin epidemic. WMJ. 2007; 106(8):466–472.
4. Buchanan JR, Santen R, Cauffman S, Cavaliere A, Greer RB, Demers LM. The effect of endogenous estrogen fluctuation on metabolism of 25-hydroxyvitamin D. Calcif Tissue Int. 1986; 39(3):139–144.
5. Cinar N, Harmanci A, Yildiz BO, Bayraktar M. Vitamin D status and seasonal changes in plasma concentrations of 25-hydroxyvitamin D in office workers in Ankara, Turkey. Eur J Intern Med. 2014; 25(2):197–201.
6. Chapuy MC, Preziosi P, Maamer M, Arnaud S, Galan P, Hercberg S, Meunier PJ. Prevalence of vitamin D insufficiency in an adult normal population. Osteoporos Int. 1997; 7(5):439–443.
7. Choi EY. 25(OH)D status and demographic and lifestyle determinants of 25(OH)D among Korean adults. Asia Pac J Clin Nutr. 2012; 21(4):526–535.
8. Choi SH, Lee DJ, Kim KM, Kim BT. Association between seasonal changes in vitamin D and Bone mineral density. J Korean Soc Menopause. 2011; 17(2):88–93.
9. Darling AL, Hart KH, Gibbs MA, Gossiel F, Kantermann T, Horton K, Johnsen S, Berry JL, Skene DJ, Eastell R, Vieth R, Lanham-New SA. Greater seasonal cycling of 25-hydroxyvitamin D is associated with increased parathyroid hormone and bone resorption. Osteoporos Int. 2014; 25(3):933–941.
10. Dattani JT, Exton-Smith AN, Stephen JM. Vitamin D status of the elderly in relation to age and exposure to sunlight. Hum Nutr Clin Nutr. 1984; 38(2):131–137.
11. Dawson-Hughes B. Racial/ethnic considerations in making recommendations for vitamin D for adult and elderly men and women. Am J Clin Nutr. 2004; 80(6):1763S–1766S.
12. Devgun MS, Paterson CR, Johnson BE, Cohen C. Vitamin D nutrition in relation to season and occupation. Am J Clin Nutr. 1981; 34(8):1501–1504.
13. Holick MF. Mccollum award lecture, 1994: vitamin D-new horizons for the 21st century. Am J Clin Nutr. 1994; 60(4):619–630.
14. Holick MF. Vitamin D deficiency. N Engl J Med. 2007; 357(3):266–281.
15. Kim HB, Park JG. A study on the solar UVA and UVB doses at Kongju. Korean J Dermatol. 1987; 25(1):16–24.
16. Kluczynski MA, Lamonte MJ, Mares JA, Wactawski-Wende J, Smith AW, Engelman CD, Andrews CA, Snetselaar LG, Sarto GE, Millen AE. Duration of physical activity and serum 25-hydroxyvitamin D status of postmenopausal women. Ann Epidemiol. 2011; 21(6):440–449.
17. Korean Nutrition Society. Dietary reference intakes for
Koreans. Seoul, Korea: 2010. p. 590–592.
18. Lamberg-Allardt C. Vitamin D intake, sunlight exposure and 25-hydroxyvitamin D levels in the elderly during one year. Ann Nutr Metab. 1984; 28(3):144–150.
19. Lee MK, Yoon BK, Chung HY, Park HM. The serum vitamin D nutritional status and its relationship with skeletal status in Korean postmenopausal women. Korean J Obstet Gynecol. 2011; 54(5):241–246.
20. Lim HJ, Kim JI. Serum 25-hydroxyvitamin D status in wintertime in premenopausal working women. Korean J Nutr. 2006; 39(7):649–660.
21. Lim HJ. Serum 25-hydroxyvitamin D status and associated factors in premenopausal working women. Korean J Community Nutr. 2005; 10(1):79–90.
22. Lips P, Chapuy MC, Dawson-Hughes B, Pols HAP, Holick MF. An international comparison of serum 25-hydroxyvitamin D measurements. Osteoporos Int. 1999; 9(5):394–397.
23. Lund B, Sørensen OH. Measurement of 25-hydroxyvitamin D in serum and its relation to sunshine, age and vitamin D intake in the Danish population. Scand J Clin Lab Invest. 1979; 39(1):23–30.
24. MacLaughlin J, Holick MF. Aging decreases the capacity of human skin to produce vitamin D3. J Clin Invest. 1985; 76(4):1536–1538.
25. Matsuoka LY, Wortsman J, Dannenberg MJ, Hollis BW, Lu Z, Holick MF. Clothing prevents ultraviolet-B radiationdependent photosynthesis of vitamin D3. J Clin Endocrinol Metab. 1992; 75(4):1099–1103.
26. Matsuoka LY, Wortsman J, Hollis BW. Use of topical sunscreen for the evaluation of regional synthesis of vitamin D3. J Am Acad Dermatol. 1990; 22(5 Pt 1):772–775.
27. Ministy of Health and Welfare & Korea Center for Disease Control and Prevention. Korea health statistics 2010: Korea National Health and Nutrition Examination Survey (KNHANES V-1). Seoul: Korea Center for Disease Control and Prevention;2012. p. 341–434.
28. Moon SJ, Kim JH. The effects of vitamin D status on bone mineral density of Korean adults. Korean J Nutr. 1998; 31(1):46–61.
29. Park HM, Kim JG, Choi WH, Lim SK, Kim GS. The vitamin D nutritional status of postmenopausal women in Korea. Korean J Bone Metab. 2003; 10(1):47–55.
30. Park SY, Yim CH, Kim SH, Han KO, Yoon HK. Changes of serum parathyroid hormone and bone turnover status according to serum vitamin D levels in Korean postmenopausal women. Korean J Bone Metab. 2008; 15(1):17–24.
31. Scragg R, Camargo CA. Frequency of leisure-time physical activity and serum 25-hydroxyvitamin D levels in the US population: results from the Third National Health and Nutrition Examination Survey. Am J Epidemiol. 2008; 168(6):577–586.
32. Thuesen B, Husemoen L, Fenger M, Jakobsen J, Schwarz P, Toft U, Ovesen L, Jørgensen T, Linneberg A. Determinants of vitamin D status in a general population of Danish adults. Bone. 2012; 50(3):605–610.
33. Van Dam RM, Snijder MB, Dekker JM, Stehouwer CD, Bouter LM, Heine RJ, Lips P. Potentially modifiable determinants of vitamin D status in an older population in the Netherlands: the Hoorn Study. Am J Clin Nutr. 2007; 85(3):755–761.
34. Webb AR, Kline L, Holick MF. Influence of season and latitude on the cutaneous synthesis of vitamin D3: Exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin. J Clin Endocrinol Metab. 1988; 67(2):373–378.
35. Webb AR, Pilbeam C, Hanafin N, Holick MF. An evaluation of the relative contributions of exposure to sunlight and of diet to the circulating concentrations of 25-hydroxyvitamin D in an elderly nursing home population in Boston. Am J Clin Nutr. 1990; 51(6):1075–1081.
36. World Health Organization. Assessment of fracture risk and its application to screening for postmenopausal osteoporosis (WHO Technical Report Series 843). Geneva, Switzerland: 1994. p. 5–6.
37. Yoon JS, Song MK. Seasonal differences in outdoor activity time and serum 25-(OH) vitamin D status of Korean young women. Korean J Community Nutr. 2014; 19(3):231–240.