1. Liu, X, Baylin, A & Levy, PD (2018) Vitamin D deficiency and insufficiency among US adults: prevalence, predictors and clinical implications. Br J Nutr 119, 928–936.
2. Rockell, JE, Skeaff, CM, Williams, SM, et al. (2006) Serum 25-hydroxyvitamin D concentrations of New Zealanders aged 15 years and older. Osteoporos Int 17, 1382–1389.
3. Sarafin, K, Durazo-Arvizu, R, Tian, L, et al. (2015) Standardizing 25-hydroxyvitamin D values from the Canadian Health Measures Survey. Am J Clin Nutr 102, 1044–1050.
4. Cashman, KD, Dowling, KG, Škrabáková, Z, et al. (2016) Vitamin D deficiency in Europe: pandemic? Am J Clin Nutr 103, 1033–1044.
5. Black, LJ, Walton, J, Flynn, A, et al. (2015) Small increments in vitamin D intake by Irish adults over a decade show that strategic initiatives to fortify the food supply are needed. J Nutr 145, 969–976.
6. Vatanparast, H, Calvo, MS, Green, TJ, et al. (2010) Despite mandatory fortification of staple foods, vitamin D intakes of Canadian children and adults are inadequate. J Steroid Biochem Mol Biol 121, 301–303.
7. Bailey, RL, Dodd, KW, Goldman, JA, et al. (2010) Estimation of total usual calcium and vitamin D intakes in the United States. J Nutr 140, 817–822.
9. Daly, RM, Gagnon, C, ZX, Lu, et al. (2012) Prevalence of vitamin D deficiency and its determinants in Australian adults aged 25 years and older: a national, population-based study. Clin Endocrinol 77, 26–35.
10. Sempos, CT, Vesper, HW, Phinney, KW, et al. (2012) Vitamin D status as an international issue: national surveys and the problem of standardization. Scand J Clin Lab Invest 243, 32–40.
11. Mineva, EM, Schleicher, RL, Chaudhary-Webb, M, et al. (2015) A candidate reference measurement procedure for quantifying serum concentrations of 25-hydroxyvitamin D(3) and 25-hydroxyvitamin D(2) using isotope-dilution liquid chromatography-tandem mass spectrometry. Anal Bioanal Chem 407, 5615–5624.
12. Lai, JKC, Lucas, RM, Banks, E, et al. (2012) Variability in vitamin D assays impairs clinical assessment of vitamin D status. Intern Med J 42, 43–50.
13. Black, LJ, Anderson, D, Clarke, MW, et al. (2015) Analytical bias in the measurement of serum 25-hydroxyvitamin D concentrations impairs assessment of vitamin D status in clinical and research settings. PLOS ONE 10, e0135478.
14. Binkley, N, Krueger, DC, Morgan, S, et al. (2010) Current status of clinical 25-hydroxyvitamin D measurement: an assessment of between-laboratory agreement. Clin Chim Acta 411, 1976–1982.
15. Lucas, R & Neale, R (2014) What is the optimal level of vitamin D?: Separating the evidence from the rhetoric. Aust Fam Physician 43, 119–122.
18. Australian Bureau of Statistics (2013) Australian Health Survey, National Health Survey, 2011–13, expanded confidentialised unit record file (CURF): ABS DataLab. Findings based on use of ABS microdata. http://www.abs.gov.au/ausstats/abs@.nsf/mf/4363.0.55.001 (accessed March 2018).
19. Holick, MF, Binkley, NC, Bischoff-Ferrari, HA, et al. (2011) Evaluation, treatment, and prevention of vitamin D deficiency: an endocrine society clinical practice guideline. J Clin Endocrinol Metab 96, 1911–1930.
23. Looker, AC, Pfeiffer, CM, Lacher, DA, et al. (2008) Serum 25-hydroxyvitamin D status of the US population: 1988–1994 compared with 2000–2004. Am J Clin Nutr 88, 1519–1527.
24. Schleicher, RL, Sternberg, MR, Lacher, DA, et al. (2016) The vitamin D status of the US population from 1988 to 2010 using standardized serum concentrations of 25-hydroxyvitamin D shows recent modest increases. Am J Clin Nutr 104, 454–461.
25. Cashman, KD, Kiely, M, Kinsella, M, et al. (2013) Evaluation of vitamin D standardization program protocols for standardizing serum 25-hydroxyvitamin D data: a case study of the program’s potential for national nutrition and health surveys. Am J Clin Nutr 97, 1235–1242.
26. Holick, MF (2004) Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Am J Clin Nutr 80, Suppl., 1678S–1688S.
27. Drincic, AT, Armas, LA, Van Diest, EE, et al. (2012) Volumetric dilution, rather than sequestration best explains the low vitamin D status of obesity. Obesity (Silver Spring) 20, 1444–1448.
28. Holick, MF (2004) Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin Nutr 79, 362–371.
29. Kimlin, MG (2008) Geographic location and vitamin D synthesis. Mol Aspects Med 29, 453–461.
30. Munns, CF, Simm, PJ, Rodda, CP, et al. (2012) Incidence of vitamin D deficiency rickets among Australian children: an Australian Paediatric Surveillance Unit Study. Med J Aust 196, 466–468.
34. Black, L, Jacoby, P, Nowson, C, et al. (2016) Predictors of vitamin D-containing supplement use in the Australian population and associations between dose and serum 25-hydroxyvitamin D concentrations. Nutrients 8, E356.
35. Kantor, ED, Rehm, CD, Du, M, et al. (2016) Trends in dietary supplement use among US adults from 1999–2012. JAMA 316, 1464–1474.
36. Koch, S, Pettigrew, S, Minto, C, et al. (2017) Trends in sun-protection behaviour in Australian adults 2007–2012. Australas J Dermatol
37. Mealing, NM, Banks, E, Jorm, LR, et al. (2010) Investigation of relative risk estimates from studies of the same population with contrasting response rates and designs. BMC Med Res Methodol 10, 26.