Table of Contents Author Guidelines Submit a Manuscript
BioMed Research International
Volume 2015 (2015), Article ID 953241, 11 pages
http://dx.doi.org/10.1155/2015/953241
Review Article

Vitamin D: A Review on Its Effects on Muscle Strength, the Risk of Fall, and Frailty

Service of Nephrology, Department of Medicine, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland

Received 31 October 2014; Revised 1 March 2015; Accepted 1 March 2015

Academic Editor: Germán Vicente-Rodriguez

Copyright © 2015 Matthieu Halfon et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Linked References

  1. S. J. Marx, U. A. Liberman, and C. Eil, “Calciferols: actions and deficiencies in action,” Vitamins & Hormones, vol. 40, pp. 235–308, 1983. View at Publisher · View at Google Scholar · View at Scopus
  2. E. M. Costa, H. M. Blau, and D. Feldman, “1,25-Dihydroxyvitamin D3 receptors and hormonal responses in cloned human skeletal muscle cells,” Endocrinology, vol. 119, no. 5, pp. 2214–2220, 1986. View at Publisher · View at Google Scholar · View at Scopus
  3. J. Valtueña Santamaría, L. Gracia-Marco, I. Huybrechts et al., “Cardiorespiratory fitness in males, and upper limbs muscular strength in females, are positively related with 25-hydroxyvitamin D plasma concentrations in European adolescents: the HELENA Study,” QJM, vol. 106, no. 9, pp. 809–821, 2013. View at Publisher · View at Google Scholar · View at Scopus
  4. M. F. Holick, “Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease,” The American Journal of Clinical Nutrition, vol. 80, no. 6, supplement, pp. 1678S–1688S, 2004. View at Google Scholar · View at Scopus
  5. C. Annweiler, G. Allali, P. Allain et al., “Vitamin D and cognitive performance in adults: a systematic review,” European Journal of Neurology, vol. 16, no. 10, pp. 1083–1089, 2009. View at Publisher · View at Google Scholar · View at Scopus
  6. S. Cohen, J. A. Nathan, and A. L. Goldberg, “Muscle wasting in disease: molecular mechanisms and promising therapies,” Nature Reviews Drug Discovery, vol. 14, no. 1, pp. 58–74, 2014. View at Google Scholar
  7. S. Yoshikawa, T. Nakamura, H. Tanabe, and T. Imamura, “Osteomalacic myopathy,” Endocrinologia Japonica, vol. 26, supplement, pp. 65–72, 1979. View at Google Scholar · View at Scopus
  8. B. Hamilton, “Vitamin D and human skeletal muscle,” Scandinavian Journal of Medicine and Science in Sports, vol. 20, no. 2, pp. 182–190, 2010. View at Publisher · View at Google Scholar · View at Scopus
  9. L. Y. Matsuoka, L. Ide, J. Wortsman, J. A. MacLaughlin, and M. F. Holick, “Sunscreens suppress cutaneous vitamin D3 synthesis,” The Journal of Clinical Endocrinology & Metabolism, vol. 64, no. 6, pp. 1165–1168, 1987. View at Publisher · View at Google Scholar · View at Scopus
  10. L. Plantalech, P. Knoblovits, E. Cambiazzo et al., “Hypervitaminosis D in institutionalized elderly in Buenos Aires,” Medicina B: Aires, vol. 57, no. 1, pp. 29–35, 1997. View at Google Scholar
  11. T. Songpatanasilp, L.-O. Chailurkit, A. Nichachotsalid, and M. Chantarasorn, “Combination of alfacalcidol with calcium can improve quadriceps muscle strength in elderly ambulatory Thai women who have hypovitaminosis D: a randomized controlled trial,” Journal of the Medical Association of Thailand, vol. 92, supplement 5, pp. S30–S41, 2009. View at Google Scholar · View at Scopus
  12. M. J. McKenna and R. Freaney, “Secondary hyperparathyroidism in the elderly: means to defining hypovitaminosis D,” Osteoporosis International, vol. 8, supplement 2, pp. S3–S6, 1998. View at Google Scholar · View at Scopus
  13. M.-C. Chapuy, P. Preziosi, M. Maamer et al., “Prevalence of vitamin D insufficiency in an adult normal population,” Osteoporosis International, vol. 7, no. 5, pp. 439–443, 1997. View at Publisher · View at Google Scholar · View at Scopus
  14. M. González-Gross, J. Valtueña, C. Breidenassel et al., “Vitamin D status among adolescents in Europe: the healthy lifestyle in Europe by nutrition in adolescence study,” British Journal of Nutrition, vol. 107, no. 5, pp. 755–764, 2012. View at Publisher · View at Google Scholar · View at Scopus
  15. M. F. Holick, N. C. Binkley, H. A. Bischoff-Ferrari et al., “Evaluation, treatment, and prevention of vitamin D deficiency: an endocrine society clinical practice guideline,” Journal of Clinical Endocrinology and Metabolism, vol. 96, no. 7, pp. 1911–1930, 2011. View at Publisher · View at Google Scholar · View at Scopus
  16. H. A. Bischoff-Ferrari, E. Giovannucci, W. C. Willett, T. Dietrich, and B. Dawson-Hughes, “Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes,” The American Journal of Clinical Nutrition, vol. 84, no. 1, pp. 18–28, 2006. View at Google Scholar · View at Scopus
  17. B. Oliveri, L. Plantalech, A. Bagur et al., “High prevalence of vitamin D insufficiency in healthy elderly people living at home in Argentina,” European Journal of Clinical Nutrition, vol. 58, no. 2, pp. 337–342, 2004. View at Publisher · View at Google Scholar · View at Scopus
  18. P. Bettica, M. Bevilacqua, T. Vago, and G. Norbiato, “High prevalence of hypovitaminosis D among free-living postmenopausal women referred to an osteoporosis outpatient clinic in Northern Italy for initial screening,” Osteoporosis International, vol. 9, no. 3, pp. 226–229, 1999. View at Publisher · View at Google Scholar · View at Scopus
  19. H. Reichel, H. P. Koeffler, and A. W. Normal, “The role of the vitamin D endocrine system in health and disease,” The New England Journal of Medicine, vol. 320, no. 15, pp. 980–991, 1989. View at Publisher · View at Google Scholar · View at Scopus
  20. R. U. Simpson, G. A. Thomas, and A. J. Arnold, “Identification of 1,25-dihydroxyvitamin D3 receptors and activities in muscle,” The Journal of Biological Chemistry, vol. 260, no. 15, pp. 8882–8891, 1985. View at Google Scholar · View at Scopus
  21. L. Ceglia and S. S. Harris, “Vitamin D and its role in skeletal muscle,” Calcified Tissue International, vol. 92, no. 2, pp. 151–162, 2013. View at Publisher · View at Google Scholar · View at Scopus
  22. R. Boland, A. R. de Boland, E. Ritz, and W. Hasselbach, “Effect of 1,25-dihydroxycholecalciferol on sarcoplasmic reticulum calcium transport in strontium-fed chicks,” Calcified Tissue International, vol. 35, no. 1, pp. 190–194, 1983. View at Publisher · View at Google Scholar · View at Scopus
  23. D. Lila, Z. Susana, and B. Ricardo, “Induction of a calbindin-D9K-like protein in avian muscle cells by 1,25-dihydroxy-vitamin D3,” Biochemistry and Molecular Biology International, vol. 32, no. 5, pp. 859–867, 1994. View at Google Scholar · View at Scopus
  24. E. R. Barton-Davis, D. I. Shoturma, A. Musaro, N. Rosenthal, and H. Lee Sweeney, “Viral mediated expression of insulin-like growth factor I blocks the aging-related loss of skeletal muscle function,” Proceedings of the National Academy of Sciences of the United States of America, vol. 95, no. 26, pp. 15603–15607, 1998. View at Publisher · View at Google Scholar · View at Scopus
  25. I. Nemere and D. Larsson, “1,25(OH)2-vitamin D3 induces translocation of the vitamin D receptor (VDR) to the plasma membrane in skeletal muscle cells,” Journal of Cellular Biochemistry, vol. 86, no. 1, pp. 128–135, 2002. View at Publisher · View at Google Scholar · View at Scopus
  26. I. Nemere, Z. Schwartz, H. Pedrozo, V. L. Sylvia, D. D. Dean, and B. D. Boyan, “Identification of a membrane receptor for 1,25-dihydroxyvitamin D3 which mediates rapid activation of protein kinase C,” Journal of Bone and Mineral Research, vol. 13, no. 9, pp. 1353–1359, 1998. View at Publisher · View at Google Scholar · View at Scopus
  27. L. Ceglia, S. Niramitmahapanya, M. da Silva Morais et al., “A Randomized study on the effect of vitamin d3 supplementation on skeletal muscle morphology and vitamin d receptor concentration in older women,” Journal of Clinical Endocrinology and Metabolism, vol. 98, no. 12, pp. E1927–E1935, 2013. View at Publisher · View at Google Scholar · View at Scopus
  28. P. Geusens, C. Vandevyver, J. Vanhoof, J.-J. Cassiman, S. Boonen, and J. Raus, “Quadriceps and grip strength are related to vitamin D receptor genotype in elderly nonobese women,” Journal of Bone and Mineral Research, vol. 12, no. 12, pp. 2082–2088, 1997. View at Publisher · View at Google Scholar · View at Scopus
  29. D. K. Houston, M. Cesari, L. Ferrucci et al., “Association between vitamin D status and physical performance: the InCHIANTI study,” Journals of Gerontology Series A: Biological Sciences and Medical Sciences, vol. 62, no. 4, pp. 440–446, 2007. View at Publisher · View at Google Scholar · View at Scopus
  30. S. R. Mastaglia, M. Seijo, D. Muzio, J. Somoza, M. Nuñez, and B. Oliveri, “Effect of vitamin D nutritional status on muscle function and strength in healthy women aged over sixty-five years,” Journal of Nutrition, Health and Aging, vol. 15, no. 5, pp. 349–354, 2011. View at Publisher · View at Google Scholar · View at Scopus
  31. M. Zamboni, E. Zoico, P. Tosoni et al., “Relation between vitamin D, physical performance, and disability in elderly persons,” Journals of Gerontology A—Biological Sciences and Medical Sciences, vol. 57, no. 1, pp. M7–M11, 2002. View at Google Scholar · View at Scopus
  32. I. S. Wicherts, N. M. van Schoor, A. J. P. Boeke et al., “Vitamin D status predicts physical performance and its decline in older persons,” Journal of Clinical Endocrinology and Metabolism, vol. 92, no. 6, pp. 2058–2065, 2007. View at Publisher · View at Google Scholar · View at Scopus
  33. M. Visser, D. J. H. Deeg, P. Lips, and Longitudinal Aging Study, “Low vitamin D and high parathyroid hormone levels as determinants of loss of muscle strength and muscle mass (sarcopenia): the Longitudinal Aging Study Amsterdam,” Journal of Clinical Endocrinology and Metabolism, vol. 88, no. 12, pp. 5766–5772, 2003. View at Publisher · View at Google Scholar · View at Scopus
  34. N. D. A. Boyé, C. Oudshoorn, N. van der Velde et al., “Vitamin D and physical performance in older men and women visiting the emergency department because of a fall: data from the improving medication prescribing to reduce risk of FALLs (IMPROveFALL) study,” Journal of the American Geriatrics Society, vol. 61, no. 11, pp. 1948–1952, 2013. View at Publisher · View at Google Scholar · View at Scopus
  35. E. D. Toffanello, E. Perissinotto, G. Sergi et al., “Vitamin D and physical performance in elderly subjects: the Pro.V.A study,” PLoS ONE, vol. 7, no. 4, Article ID e34950, 2012. View at Publisher · View at Google Scholar · View at Scopus
  36. P. R. von Hurst, C. Conlon, and A. Foskett, “Vitamin D status predicts hand-grip strength in young adult women living in Auckland, New Zealand,” Journal of Steroid Biochemistry and Molecular Biology, vol. 136, no. 1, pp. 330–332, 2013. View at Publisher · View at Google Scholar · View at Scopus
  37. A. S. Grimaldi, B. A. Parker, J. A. Capizzi et al., “25(OH) vitamin D is associated with greater muscle strength in healthy men and women,” Medicine and Science in Sports and Exercise, vol. 45, no. 1, pp. 157–162, 2013. View at Publisher · View at Google Scholar · View at Scopus
  38. P. L. Gordon, J. W. Doyle, and K. L. Johansen, “Association of 1,25-dihydroxyvitamin D levels with physical performance and thigh muscle cross-sectional area in chronic kidney disease stage 3 and 4,” Journal of Renal Nutrition, vol. 22, no. 4, pp. 423–433, 2012. View at Publisher · View at Google Scholar · View at Scopus
  39. H. Taskapan, O. Baysal, D. Karahan, B. Durmus, Z. Altay, and O. Ulutas, “Vitamin D and muscle strength, functional ability and balance in peritoneal dialysis patients with vitamin D deficiency,” Clinical Nephrology, vol. 76, no. 2, pp. 110–116, 2011. View at Publisher · View at Google Scholar · View at Scopus
  40. N. Zahed, S. Chehrazi, and K. Falaknasi, “The evaluation of relationship between vitamin D and muscle power by micro manual muscle tester in end-stage renal disease patients,” Saudi Journal of Kidney Diseases and Transplantation, vol. 25, no. 5, pp. 998–1003, 2014. View at Google Scholar
  41. P. Pramyothin, S. Techasurungkul, J. Lin et al., “Vitamin D status and falls, frailty, and fractures among postmenopausal Japanese women living in Hawaii,” Osteoporosis International, vol. 20, no. 11, pp. 1955–1962, 2009. View at Publisher · View at Google Scholar · View at Scopus
  42. L. Ceglia, G. R. Chiu, S. S. Harris, and A. B. Araujo, “Serum 25-hydroxyvitamin D concentration and physical function in adult men,” Clinical Endocrinology, vol. 74, no. 3, pp. 370–376, 2011. View at Publisher · View at Google Scholar · View at Scopus
  43. C. Matheï, G. van Pottelbergh, B. Vaes, W. Adriaensen, D. Gruson, and J.-M. Degryse, “No relation between vitamin D status and physical performance in the oldest old: results from the belfrail study,” Age and Ageing, vol. 42, no. 2, pp. 186–190, 2013. View at Publisher · View at Google Scholar · View at Scopus
  44. R. Gupta, U. Sharma, N. Gupta et al., “Effect of cholecalciferol and calcium supplementation on muscle strength and energy metabolism in vitamin D-deficient Asian Indians: a randomized, controlled trial,” Clinical Endocrinology, vol. 73, no. 4, pp. 445–451, 2010. View at Publisher · View at Google Scholar · View at Scopus
  45. K. Zhu, N. Austin, A. Devine, D. Bruce, and R. L. Prince, “A randomized controlled trial of the effects of vitamin D on muscle strength and mobility in older women with vitamin d insufficiency,” Journal of the American Geriatrics Society, vol. 58, no. 11, pp. 2063–2068, 2010. View at Publisher · View at Google Scholar · View at Scopus
  46. K. A. Ward, G. Das, S. A. Roberts et al., “A randomized, controlled trial of vitamin D supplementation upon musculoskeletal health in postmenarchal females,” Journal of Clinical Endocrinology and Metabolism, vol. 95, no. 10, pp. 4643–4651, 2010. View at Publisher · View at Google Scholar · View at Scopus
  47. M. A. Wyon, Y. Koutedakis, R. Wolman, A. M. Nevill, and N. Allen, “The influence of winter vitamin D supplementation on muscle function and injury occurrence in elite ballet dancers: a controlled study,” Journal of Science and Medicine in Sport, vol. 17, no. 1, pp. 8–12, 2014. View at Publisher · View at Google Scholar · View at Scopus
  48. A. M. Kenny, B. Biskup, B. Robbins, G. Marcella, and J. A. Burleson, “Effects of vitamin D supplementation on strength, physical function, and health perception in older, community-dwelling men,” Journal of the American Geriatrics Society, vol. 51, no. 12, pp. 1762–1767, 2003. View at Publisher · View at Google Scholar · View at Scopus
  49. P. Lips, N. Binkley, M. Pfeifer et al., “Once-weekly dose of 8400 IU vitamin D3 compared with placebo: effects on neuromuscular function and tolerability in older adults with vitamin D insufficiency,” American Journal of Clinical Nutrition, vol. 91, no. 4, pp. 985–991, 2010. View at Publisher · View at Google Scholar · View at Scopus
  50. K. A. Faulkner, J. A. Cauley, J. M. Zmuda et al., “Higher 1,25-dihydroxyvitamin D3 concentrations associated with lower fall rates in older community-dwelling women,” Osteoporosis International, vol. 17, no. 9, pp. 1318–1328, 2006. View at Publisher · View at Google Scholar · View at Scopus
  51. T. Suzuki, J. Kwon, H. Kim et al., “Low serum 25-hydroxyvitamin D levels associated with falls among Japanese community-dwelling elderly,” Journal of Bone and Mineral Research, vol. 23, no. 8, pp. 1309–1317, 2008. View at Publisher · View at Google Scholar · View at Scopus
  52. P. Glendenning, K. Zhu, C. Inderjeeth, P. Howat, J. R. Lewis, and R. L. Prince, “Effects of three-monthly oral 150,000 IU cholecalciferol supplementation on falls, mobility, and muscle strength in older postmenopausal women: a randomized controlled trial,” Journal of Bone and Mineral Research, vol. 27, no. 1, pp. 170–176, 2012. View at Publisher · View at Google Scholar · View at Scopus
  53. R. Goswami, M. Vatsa, V. Sreenivas et al., “Skeletal muscle strength in young Asian Indian females after vitamin D and calcium supplementation: a double-blind randomized controlled clinical trial,” Journal of Clinical Endocrinology and Metabolism, vol. 97, no. 12, pp. 4709–4716, 2012. View at Publisher · View at Google Scholar · View at Scopus
  54. S. W. Muir and M. Montero-Odasso, “Effect of vitamin D supplementation on muscle strength, gait and balance in older adults: a systematic review and meta-analysis,” Journal of the American Geriatrics Society, vol. 59, no. 12, pp. 2291–2300, 2011. View at Publisher · View at Google Scholar · View at Scopus
  55. K. A. Stockton, K. Mengersen, J. D. Paratz, D. Kandiah, and K. L. Bennell, “Effect of vitamin D supplementation on muscle strength: a systematic review and meta-analysis,” Osteoporosis International, vol. 22, no. 3, pp. 859–871, 2011. View at Publisher · View at Google Scholar · View at Scopus
  56. E. Schacht and J. D. Ringe, “Alfacalcidol improves muscle power, muscle function and balance in elderly patients with reduced bone mass,” Rheumatology International, vol. 32, no. 1, pp. 207–215, 2012. View at Publisher · View at Google Scholar · View at Scopus
  57. P. Gerdhem, K. A. M. Ringsberg, K. J. Obrant, and K. Akesson, “Association between 25- hydroxy vitamin D levels, physical activity, muscle strength and fractures in the prospective population-based OPRA Study of Elderly Women,” Osteoporosis International, vol. 16, no. 11, pp. 1425–1431, 2005. View at Publisher · View at Google Scholar · View at Scopus
  58. M. B. Snijder, N. M. van Schoor, S. M. F. Pluijm, R. M. van Dam, M. Visser, and P. Lips, “Vitamin D status in relation to one-year risk of recurrent falling in older men and women,” The Journal of Clinical Endocrinology & Metabolism, vol. 91, no. 8, pp. 2980–2985, 2006. View at Publisher · View at Google Scholar · View at Scopus
  59. P. Lips, “Vitamin D deficiency and secondary hyperparathyroidism in the elderly: consequences for bone loss and fractures and therapeutic implications,” Endocrine Reviews, vol. 22, no. 4, pp. 477–501, 2001. View at Publisher · View at Google Scholar · View at Scopus
  60. M. Brazier, S. Kamel, M. Maamer et al., “Markers of bone remodeling in the elderly subject: effects of vitamin D insufficiency and its correction,” Journal of Bone and Mineral Research, vol. 10, no. 11, pp. 1753–1761, 1995. View at Google Scholar · View at Scopus
  61. L. D. Gillespie, M. C. Robertson, W. J. Gillespie et al., “Interventions for preventing falls in older people living in the community,” Cochrane Database of Systematic Reviews, vol. 9, Article ID CD007146, 2012. View at Google Scholar · View at Scopus
  62. M. Pfeifer, B. Begerow, H. W. Minne, K. Suppan, A. Fahrleitner-Pammer, and H. Dobnig, “Effects of a long-term vitamin D and calcium supplementation on falls and parameters of muscle function in community-dwelling older individuals,” Osteoporosis International, vol. 20, no. 2, pp. 315–322, 2009. View at Publisher · View at Google Scholar · View at Scopus
  63. H. A. Bischoff, H. B. Stähelin, W. Dick et al., “Effects of vitamin D and calcium supplementation on falls: a randomized controlled trial,” Journal of Bone and Mineral Research, vol. 18, no. 2, pp. 343–351, 2003. View at Publisher · View at Google Scholar · View at Scopus
  64. Y. L. Michael, E. P. Whitlock, J. S. Lin, R. Fu, E. A. O'Connor, and R. Gold, “Primary care-relevant interventions to prevent falling in older adults: a systematic evidence review for the U.S. Preventive Services Task Force,” Annals of Internal Medicine, vol. 153, no. 12, pp. 815–825, 2010. View at Publisher · View at Google Scholar · View at Scopus
  65. M. H. Murad, K. B. Elamin, N. O. Abu Elnour et al., “The effect of vitamin D on falls: a systematic review and meta-analysis,” The Journal of Clinical Endocrinology & Metabolism, vol. 96, no. 10, pp. 2997–3006, 2011. View at Publisher · View at Google Scholar · View at Scopus
  66. H. A. Bischoff-Ferrari, B. Dawson-Hughes, W. C. Willett et al., “Effect of vitamin D on falls: a meta-analysis,” The Journal of the American Medical Association, vol. 291, no. 16, pp. 1999–2006, 2004. View at Publisher · View at Google Scholar · View at Scopus
  67. A. C. Ross, J. E. Manson, S. A. Abrams et al., “The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know,” Journal of Clinical Endocrinology and Metabolism, vol. 96, no. 1, pp. 53–58, 2011. View at Publisher · View at Google Scholar · View at Scopus
  68. L. P. Fried, C. M. Tangen, J. Walston et al., “Frailty in older adults: evidence for a phenotype,” The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, vol. 56, no. 3, pp. M146–M156, 2001. View at Publisher · View at Google Scholar · View at Scopus
  69. V. Hirani, R. G. Cumming, V. Naganathan et al., “Associations between serum 25-hydroxyvitamin D concentrations and multiple health conditions, physical performance measures, disability, and all-cause mortality: the concord health and ageing in men project,” Journal of the American Geriatrics Society, vol. 62, no. 3, pp. 417–425, 2014. View at Publisher · View at Google Scholar · View at Scopus
  70. A. Tajar, D. M. Lee, S. R. Pye et al., “The association of frailty with serum 25-hydroxyvitamin d and parathyroid hormone levels in older european men,” Age and Ageing, vol. 42, no. 3, pp. 352–359, 2013. View at Publisher · View at Google Scholar · View at Scopus
  71. E. R. Wilhelm-Leen, Y. N. Hall, I. H. Deboer, and G. M. Chertow, “Vitamin D deficiency and frailty in older Americans,” Journal of Internal Medicine, vol. 268, no. 2, pp. 171–180, 2010. View at Publisher · View at Google Scholar · View at Scopus
  72. K. E. Ensrud, S. K. Ewing, L. Fredman et al., “Circulating 25-hydroxyvitamin D levels and frailty status in older women,” Journal of Clinical Endocrinology and Metabolism, vol. 95, no. 12, pp. 5266–5273, 2010. View at Publisher · View at Google Scholar · View at Scopus
  73. R. S. Boxer, D. A. Dauser, S. J. Walsh, W. D. Hager, and A. M. Kenny, “The association between vitamin D and inflammation with the 6-minute walk and frailty in patients with heart failure,” Journal of the American Geriatrics Society, vol. 56, no. 3, pp. 454–461, 2008. View at Publisher · View at Google Scholar · View at Scopus
  74. L. Ingle, J. G. Cleland, and A. L. Clark, “The long-term prognostic significance of 6-minute walk test distance in patients with chronic heart failure,” BioMed Research International, vol. 2014, Article ID 505969, 7 pages, 2014. View at Publisher · View at Google Scholar · View at Scopus
  75. E. Smit, C. J. Crespo, Y. Michael et al., “The effect of vitamin D and frailty on mortality among non—institutionalized US older adults,” European Journal of Clinical Nutrition, vol. 66, no. 9, pp. 1024–1028, 2012. View at Publisher · View at Google Scholar · View at Scopus