A global representation of vitamin D status in healthy populations

ARCHIVES OF OSTEOPOROSIS, 2012, DOI: 10.1007/s11657-012-0093-0
D. A. Wahl, C. Cooper, P. R. Ebeling, M. Eggersdorfer, J. Hilger, K. Hoffmann, R. Josse, J. A. Kanis, A. Mithal and D. D. Pierroz, et al.

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See also Vitamin D Life

• Overview Deficiency of vitamin D
• Vitamin D deficiency is a major global public health problem – Maps Nov 2013
• Percent of population with less than 20 ng of vitamin D has the following graph

• Global Vitamin D levels - Aug 2011 has maps like the following
  A rectangle around the number indicates that it is a population-based study.

Note: to make images LARGER press two keys concurrently: cntrl and '+'
Each time those two keys are pressed the web page gets magnfied
Pressing cntrl and '-' shrinks of the web page

Map

Interactive map by International Osteoporosis Foundation - perhaps from the same data

Children

Adults Countries A-G

Adults Countries G-N

Adults Countries N-S

Adults Countries T-U

Adults Countries U-V

PDF is attached at the bottom of this page

Abstract
Purpose This paper visualizes the available data on vitamin D status on a global map, examines the existing heterogeneities in vitamin D status and identifies research gaps. Methods A graphical illustration of global vitamin D status was developed based on a systematic review of the worldwide literature published between 1990 and 2011. Studies were eligible if they included samples of randomly selected males and females from the general population and assessed circulating 25-hydroxyvitamin D 25(OH)D levels. Two different age categories were selected: children and adolescents (118 years) and adults (>18 years). Studies were chosen to represent a country based on a hierarchical set of criteria.

Results In total, 200 studies from 46 countries met the inclusion criteria, most coming from Europe. Forty-two of these studies (21 %) were classified as representative. In children, gaps in data were identified in large parts of Africa, Central and South America, Europe, and most of the Asia/Pacific region. In adults, there was lack of information in Central America, much of South America and Africa. Large regions were identified for which the mean 25(OH)D levels were below 50 nmol/L.

Conclusions This study provides an overview of 25(OH)D levels around the globe. It reveals large gaps in information in children and adolescents and smaller but important gaps in adults. In view of the importance of vitamin D to musculoskeletal growth, development, and preservation, and of its potential importance in other tissues, we strongly encourage new research to clearly define 25(OH)D status around the world.

B. Dawson-Hughes (*)
U.S. Department of Agriculture Human Nutrition
Research Center on Aging, Tufts University,
711 Washington Street,
Boston, MA 02111, USA
e-mail: bess.dawson-hughes at tufts.edu
J. Hilger • K. Hoffmann
Mannheim Institute of Public Health, Social and Preventive Medicine, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany
D. A. Wahl • D. D. Pierroz : J. Stenmark International Osteoporosis Foundation, Nyon, Switzerland
C. Cooper
MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton and NIHR Musculoskeletal Biomedical Research
Unit, University of Oxford, Oxford, UK P. R. Ebeling
NorthWest Academic Centre, University of Melbourne, Western Health, St. Albans, Victoria, Australia
R. Josse, Division of Endocrinology and Metabolism,
St Michael's Hospital Health Centre, University of Toronto,
Toronto, ON, Canada
A. Mithal, Medanta Medicity, Sector 38, Gurgaon, India
M. Eggersdorfer : E. Stocklin
Nutrition Science & Advocacy and Research & Development Human Nutrition, DSM Nutritional Products, Kaiseraugst, Switzerland
J. A. Kanis, WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Sheffield, UK

Introduction

Vitamin D status in an individual is dependent on numerous genetic, lifestyle and geographical factors that include age, gender, skin pigmentation, sunlight exposure, latitude, the use of sunscreen, dietary habits and supplement intake [1]. It is best measured by the serum concentration of 25-hydroxyvitamin D levels, also known as 25(OH)D levels [2].

Very low levels of 25(OH)D have been documented in different subgroups of the population worldwide [1, 3-6], which have clinical implications. Vitamin D plays an important role in skeletal growth and development, and in bone health throughout life. It promotes calcium absorption [7] and reduces bone loss through the regulation of parathyroid hormone levels [8]. As a consequence, vitamin D deficiency has been linked to reduced bone mineral density [9, 10] and higher risk of osteoporotic fractures [11]. Although further investigation is necessary, vitamin D supplementation may reduce the risk of other diseases, such as colorectal cancer [12], diabetes [13] and infection [14], and it may help decrease fractures and falls [15, 16]. The loss of muscle mass and strength observed in vitamin D-deficient individuals puts them at higher risk of falls and, therefore, fragility fractures.

The International Osteoporosis Foundation took the initiative to describe the vitamin D status in the general population in different countries based on a systematic review and to present the data on a global map. The aims of the study were to provide a general overview of vitamin D status in countries for which data were available, examine the existing heterogeneities in vitamin D status, and identify research gaps.

Methods

The data used in this project are based on a systematic literature review conducted by the Mannheim Institute of Public Health, Germany. The methods used generally follow the PRISMA Statement (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) [17]. Here, we provide a short summary of the methods used in this review. The methods are described in more detail elsewhere [18].

Eligible criteria
A systematic search was conducted in PubMed/Medline and EMBASE to identify articles on vitamin D status in the global population. Eligible studies included samples of randomly selected persons from the general population in countries throughout the world. The outcome of interest was the mean or median 25(OH)D level measured in serum or plasma. There were no limitations based on the type of assay used. Studies were required to have a cross-sectional design or to include a population-based cohort. Other study types like clinical trials, case-control studies, case reports or case series, reviews or qualitative studies were excluded. Articles had to be written in English and published between 1st January 1990 and 28th February 2011.

Abstract and full publication screening
Two thousand five hundred sixty-six articles were identified from both databases. Two independent researchers screened the articles for excluding studies, with a good agreement (kappa coefficient, 0.719). Disagreements were discussed and resolved. After review, 273 articles were eligible and included in a large database which provided, in part, the following information: the mean or median 25(OH)D levels, population characteristics, study location, assay type, number of participants and age groups.

Data filtering
In a second review process, studies on institutionalized elderly only, those on newborn babies and those having an age range that largely overlapped the two age categories (1 -18 and >18 years) were removed. When published repeatedly, the same cohort was not presented more than once. In contrast, studies reporting a sub-analysis of a cohort (number of participants and age range different from the root paper) were retained. Studies originating from England, Northern Ireland and Scotland were grouped as United Kingdom. In the end, our database included 200 studies from 46 countries.

After an examination of the database, two different age categories were selected: children and adolescents (1 -18 years) and adults (>18 years). The mean serum or plasma 25(OH)D levels were extracted and reported as gender-specific means weighted by the sample size, where possible. The median levels of 25(OH)D were included when the mean levels were not reported in a study. When data were classified by specific seasons, winter values were chosen. Values in nanograms per millilitre were converted to nanomoles per litre by a multiple of 2.496.

Four colour codes according to the mean (or median) 25 (OH)D levels were used:
GREEN >75 nmol/L
YELLOW 50-74 nmol/L
ORANGE 25-49 nmol/L
RED <25 nmol/L
For each study, the mean or median vitamin D levels (in nanomoles per litre) were reported from the literature and a study colour code was assigned.

Rationale for the colour coding of countries
For both age categories, the rationale for assigning a colour code to a specific country was based on the following hierarchical selection criteria:
1. Representative of the entire country, population-based and based on a weighted mean of these studies
2. Representative of a region/city of the country, population-based and based on a weighted mean of these studies
3. Based on a weighted mean of multiple studies, non-population-based
4. Based on a single study
Country colour was based on the 25(OH)D level (either the weighted mean or median) of one or more representative studies, if available. If not available, it was based on one or more studies fitting the second criterion cited above, and so forth. A study was considered representative if it represented the entire population for a certain age and sex group in a certain country, region or city. Studies with a selection bias, which excluded individuals for example on the basis of health status, ethnicity, physical abilities, language, smokers and social economic status, were classified as non-representative. However, for some studies, such information was not described in the text.

Design of the figures
The software FlashWorldMap.com was used to produce the maps.

Results

This analysis involves 200 studies from 46 countries. Forty-two of the 200 studies (21 %) were considered representative. Details of these studies for each contributing country are provided in Table 1 (children and adolescents) and Table 2 (adults). The largest number of studies was conducted in Europe (48.0 %), followed by North America (27 %) and the Asia-Pacific region (16.5 %). Of the 46 countries contributing data, 20 (43 %) had at least one study that was classified as representative. Figures 1 and 2 show the vitamin D status in children and adolescents, and adults, respectively, in different countries. The countries are colour-coded according to the serum levels of 25(OH)D reported in Table 1 (children and adolescents) and Table 2 (adults), and the ranges of 25(OH)D represented by each colour are described in the two figures.

Discussion

This project provides a 'snapshot' or summary of the 25 (OH)D levels around the globe, as identified in publications since the year 1990. The maps form a core or platform upon which additional information can and should be added. The number of published papers describing 25(OH)D levels is escalating, and the geographic diversity of incoming data is broadening. As a result, we can anticipate having a more comprehensive picture of global vitamin D status in coming years. Updating of the accompanying tables, in which information from each country is ordered chronologically, will also allow for a qualitative assessment of secular trends in 25(OH)D since 1990, within regions and overall. We can expect to see rises in 25(OH)D levels as awareness and concern about vitamin D deficiency grows and as recommendations for vitamin D supplementation appear in more and more government documents, position statements and clinical practice guidelines for bone health [19-21]. This trend would only be accelerated should vitamin D be proven to modify the risk of non-musculoskeletal diseases, such as diabetes, infection or cancer, as has been suggested by many observational studies [22].

Examination of the current maps enables one to identify regions where information on 25(OH)D levels is lacking. The most striking gap is in children and adolescents. The systematic search did not identify studies in this age range in Central America, the northern and central regions of South America, most of Africa, much of Europe and in Australia. This information gap needs attention in view of the importance of vitamin D in bone and muscle growth and development. In regions where data were available, the predominant colour code for children and adolescents was orange, indicating mean 25(OH)D levels in the 25- to 49-nmol/L range. These values are below those recommended by the Institute of Medicine (50 nmol/L), the International Osteoporosis Foundation and the US Endocrine Society (75 nmol/L) [19-21].

Among adults, most regions offer some data, and their colour codes are approximately evenly split between orange (25-49 nmol/L) and yellow (50-74 nmol/L). Areas where information is not available. An extreme example is that for a few countries, one single small study confined to a limited region of the country and to a narrow age range was used to colour the country (e.g. Argentina). This is of course not a complete picture of the country. Other countries have many studies, representative and non-representative. For example, New Zealand is coloured orange based on the one available representative sample of subjects residing in the city of Auckland. As indicated in the table, other studies from this country involving healthy populations and subjects measured in the summer consistently reported higher 25(OH)D levels in the range of yellow and green. In view of the diversity in the quantity and quality of data used in this study, it is important that the tables be used in conjunction with the maps and that the maps are interpreted with caution.

Several limitations are inherent in the way that the published data were presented. For example, 25(OH)D measurements were sometimes made in specific seasons (i.e. winter or summer) and at other times made without reference to season. When the option was available, we used the winter measurement, representing the worst-case scenario, for the map colouration; however, 25(OH)D levels by season, when available, are provided in the table. There was inconsistency across studies in the age groupings such that we were not always able to break out the levels by our predefined age categories of children and adolescents 118 years and adults >18 years. Another limitation is that some of the studies represented small regions within large countries with diverse latitudes; thus, they did not fairly represent the whole nation with respect to the contribution of sun exposure (skin synthesis) to 25(OH)D levels. Additionally, information on body size, clothing habits and skin pigmentation was not consistently available.

An important limitation of this project and of any inter-study comparison of 25(OH)D levels is the well-described variability in 25(OH)D assays. Since the first 25(OH)D assay was developed 30 years ago [23], the analytical options have expanded from the original competitive protein binding assay to include radioimmunoassay, chemilumines-cent assay, high-performance liquid chromatography and liquid chromatography-mass spectrometry/mass spectrome-try. Unfortunately, the serum 25(OH)D levels vary by up to 20-40 %, depending upon which assay is used [24-27]. Part of the variability can be attributed to the fact that not all of the assays detect 25(OH)D2 as effectively as they detect 25 (OH)D3. As a result, in those regions where vitamin D2 is used in most supplements, the total 25(OH)D levels will tend to be underestimated.

To address the assay problem, many laboratories around the world participate in a quarterly quality assurance and surveillance program, the Vitamin D External Quality Assessment Scheme, which we strongly encourage. Standard reference material consisting of known amounts of 25 (OH)D2 and 25(OH)D3 in human serum is now available through the U.S. National Institute of Standards and Technology (NIST; SRM972, www.NIST.gov/srm). The use of this material should make inter-laboratory comparisons more readily interpreted and allow for the detection of intra-laboratory changes over time. An important initiative, the vitamin D standardization program (VDSP), is currently underway to make the measurement of 25(OH)D accurate and comparable over time, location and laboratory [28]. The first goal of VDSP is to standardize 25(OH)D values currently being measured in national health surveys to the NIST standards. Australia, Canada, Germany, Ireland, Mexico, South Korea, the UK and the USA are participating in this process. A second goal is to design studies to cross-calibrate data from national surveys in which 25(OH)D measurements have already been completed. The longer range goal is to enable the use of standardized 25(OH)D values in individual research laboratories and in clinical care.

Conclusion

In conclusion, this study provides an overview of 25(OH)D status around the globe. It reveals large gaps in information in children and adolescents and smaller but important gaps in adults. In view of the importance of vitamin D to the overall musculoskeletal health and of its potential importance in other tissues, we strongly encourage new research worldwide to define 25(OH)D status. Deficiency must first be identified before it can be appropriately addressed. Knowledge of specific data gaps may help motivate regional policy makers and granting agencies to define the vitamin D status of their population as they decide how to allocate scarce research resources.

Acknowledgments

The authors would like to thank invaluable advice from Professors Noriko Yoshimura, Edith Lau, Jean-Philippe Bonjour, Sunil Wimalawansa, Steven Boonen, Paul Lips and the late Philip Sambrook from the IOF Committee of Scientific Advisors; Professor Peter Weber, Doctors Angelika Friedel and Franz Roos from the DSM Nutrition Science & Advocacy for their intellectual input; and DSM for supporting the work through an unrestricted educational grant.

Conflicts of interest

Drs. Manfred Eggersdorfer and Elisabeth Stocklin are employed by DSM Nutritional Products, Ltd. Professor Cyrus Cooper has received honoraria and consulting fees from Amgen, Eli Lilly, Medtronic, Merck, Novartis and Servier. All the other authors have nothing to disclose.

References

• 1. Mithal A, Wahl DA, Bonjour JP, Burckhardt P, Dawson-Hughes B, Eisman JA, El-Hajj Fuleihan G, Josse RG, Lips P, Morales-Torres J (2009) Global vitamin D status and determinants of hypovitaminosis D. Osteoporos Int 20:1807-1820
• 2. Lips P (2001) Vitamin D deficiency and secondary hyperparathyroidism in the elderly: consequences for bone loss and fractures and therapeutic implications. Endocr Rev 22:477-501
• 3. Lips P (2010) Worldwide status of vitamin D nutrition. J Steroid Biochem Mol Biol 121:297-300
• 4. McKenna MJ (1992) Differences in vitamin D status between countries in young adults and the elderly. Am J Med 93:69-77
• 5. Prentice A (2008) Vitamin D deficiency: a global perspective. NutrRev 66:S153-S164
• 6. van Schoor NM, Lips P (2011) Worldwide vitamin D status. Best Pract Res Clin Endocrinol Metab 25:671-680
• 7. Heaney RP, Dowell MS, Hale CA, Bendich A (2003) Calcium absorption varies within the reference range for serum 25-hydroxyvitamin D. J Am Coll Nutr 22:142-146
• 8. Steingrimsdottir L, Gunnarsson O, Indridason OS, Franzson L, Sigurdsson G (2005) Relationship between serum parathyroid hormone levels, vitamin D sufficiency, and calcium intake. JAMA 294:2336-2341
• 9. Dawson-Hughes B, Dallal GE, Krall EA, Harris S, Sokoll LJ, Falconer G (1991) Effect of vitamin D supplementation on wintertime and overall bone loss in healthy postmenopausal women. Ann Intern Med 115:505-512
• 10. Ooms ME, Roos JC, Bezemer PD, van derVijgh WJ, BouterLM, Lips P (1995) Prevention of bone loss by vitamin D supplementation in elderly women: a randomized double-blind trial. J Clin Endocrinol Metab 80:1052-1058
• 11. Bischoff-Ferrari HA, Kiel DP, Dawson-Hughes B, Orav JE, Li R, Spiegelman D, Dietrich T, Willett WC (2009) Dietary calcium and serum 25-hydroxyvitamin D status in relation to BMD among U.S. adults. J Bone Miner Res 24:935-942
• 12. Gorham ED, Garland CF, Garland FC, Grant WB, Mohr SB, Lipkin M, Newmark HL, Giovannucci E, Wei M, Holick MF (2005) Vitamin D and prevention of colorectal cancer. J Steroid Biochem Mol Biol 97:179-194
• 13. Pittas AG, Harris SS, Stark PC, Dawson-Hughes B (2007) The effects of calcium and vitamin D supplementation on blood glucose and markers of inflammation in nondiabetic adults.
• Diabetes Care 30:980-986
• 14. Urashima M, Segawa T, Okazaki M, Kurihara M, Wada Y, Ida H (2010) Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr 91:1255-1260
• 15. Bischoff-Ferrari HA, Willett WC, Orav EJ et al (2012) A pooled analysis of vitamin D dose requirements for fracture prevention. N Engl J Med 367:40-49
• 16. Bischoff-Ferrari HA, Willett WC, Orav JE, Kiel DP, Dawson-Hughes B (2011) Fall prevention with vitamin D. BMJ 342:d2608
• 17. Moher D, Liberati A, Tetzlaff J, Altman DG (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med 6:e1000097
• 18. Hilger J, Friedel A, Herr R, Ruasch T, Roos F, Wahl DA, Pierroz DD, Weber P, Hoffmann K (2012) A systematic review of vitamin D status in populations worlwide. Br J Nutr (submitted)
• 19. Institute of Medicine (2011) Dietary reference intakes for calcium and vitamin D. National Academies Press, Washington, DC
• 20. Dawson-Hughes B, Mithal A, Bonjour JP, Boonen S, Burckhardt P, Fuleihan GE, Josse RG, Lips P, Morales-Torres J, Yoshimura N (2010) IOF position statement: vitamin D recommendations for older adults. Osteoporos Int 21:1151-1154
• 21. Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM (2011) Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 96:1911-1930
• 22. Rosen CJ, Adams JS, Bikle DD, Black DM, Demay MB, Manson JE, Murad MH, Kovacs CS (2012) The nonskeletal effects of vitamin D: an Endocrine Society scientific statement. Endocr Rev 33:456-492
• 23. Haddad JG, Chyu KJ (1971) Competitive protein-binding radio-assay for 25-hydroxycholecalciferol. J Clin Endocrinol Metab 33:992-995
• 24. Binkley N, Krueger D, Cowgill CS, Plum L, Lake E, Hansen KE, DeLuca HF, Drezner MK (2004) Assay variation confounds the diagnosis of hypovitaminosis D: a call for standardization. J Clin Endocrinol Metab 89:3152-3157
• 25. Binkley N, Krueger D, Gemar D, Drezner MK (2008) Correlation among 25-hydroxy-vitamin D assays. J Clin Endocrinol Metab 93:1804-1808
• 26. Hypponen E, Boucher BJ, Berry DJ, Power C (2008) 25-Hydroxyvitamin D, IGF-1, and metabolic syndrome at 45 years of age: a cross-sectional study in the 1958 British Birth Cohort. Diabetes 57:298-305
• 27. Stepman HC, Vanderroost A, Van Uytfanghe K, Thienpont LM (2011) Candidate reference measurement procedures for serum 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 by using isotope-dilution liquid chromatography-tandem mass spectrometry. Clin Chem 57:441-448
• 28. Sempos CT, Vesper HW, Phinney KW, Thienpont LM, Coates PM (2012) Vitamin D status as an international issue: national surveys and the problem of standardization. Scand J Clin Lab Invest Suppl 243:32-40 PDF is attached at the bottom of this page
• 29. Oliveri MB, Ladizesky M, Mautalen CA, Alonso A, Martinez L (1993) Seasonal variations of 25 hydroxyvitamin D and parathyroid hormone in Ushuaia (Argentina), the southernmost city of the world. Bone Miner 20:99-108
• 30. Koenig J, Elmadfa I (2000) Status of calcium and vitamin D of different population groups in Austria. Int J Vitam Nutr Res 70:214-220
• 31. El Hayek J, Egeland G, Weiler H (2010) Vitamin D status of Inuit preschoolers reflects season and vitamin D intake. J Nutr 140:1839-1845
• 32. Delvin EE, Lambert M, Levy E, O'Loughlin J, Mark S, Gray-Donald K, Paradis G (2010) Vitamin D status is modestly associated with glycemia and indicators of lipid metabolism in French-Canadian children and adolescents. J Nutr 140:987-991
• 33. Du X, Greenfield H, Fraser DR, Ge K, Trube A, Wang Y (2001) Vitamin D deficiency and associated factors in adolescent girls in Beijing. Am J Clin Nutr 74:494-500
• 34. Strand MA, Perry J, Zhao J, Fischer PR, Yang J, Li S (2009) Severe vitamin D-deficiency and the health of North China children. Matern Child Health J 13:144-150
• 35. Andersen R, Molgaard C, Skovgaard LT et al (2005) Teenage girls and elderly women living in Northern Europe have low winter vitamin D status. Eur J Clin Nutr 59:533-541
• 36. Viljakainen HT, Palssa A, Karkkainen M, Jakobsen J, Cashman KD, Molgaard C, Lamberg-Allardt C (2006) A seasonal variation of calcitropic hormones, bone turnover and bone mineral density in early and mid-puberty girls—a cross-sectional study. Br J Nutr 96:124-130
• 37. Kristinsson JO, Valdimarsson O, Sigurdsson G, Franzson L, Olafsson I, Steingrimsdottir L (1998) Serum 25-hydroxyvitamin D levels and bone mineral density in 16-20 years-old girls: lack of association. J Intern Med 243:381-388
• 38. Harinarayan CV, Ramalakshmi T, Prasad UV, Sudhakar D (2008) Vitamin D status in Andhra Pradesh: a population based study. Indian J Med Res 127:211-218
• 39. Rabbani A, Alavian SM, Motlagh ME, Ashtiani MT, Ardalan G, Salavati A, Rabbani B, Shams S, Parvaneh N (2009) Vitamin D
• insufficiency among children and adolescents living in Tehran, Iran. J Trop Pediatr 55:189-191
• 40. Dahifar H, Faraji A, Yassobi S, Ghorbani A (2007) Asymptomatic rickets in adolescent girls. Indian J Pediatr 74:571-575
• 41. Moussavi M, Heidarpour R, Aminorroaya A, Pournaghshband Z, Amini M (2005) Prevalence of vitamin D deficiency in Isfahani high school students in 2004. Horm Res 64:144-148
• 42. McCarthy D, Collins A, O'Brien M, Lamberg-Allardt C, Jakobsen J, Charzewska J, Kiely M, Flynn A, Cashman KD (2006) Vitamin D intake and status in Irish elderly women and adolescent girls. Ir J Med Sci 175:14-20
• 43. Oren Y, Shapira Y, Agmon-Levin N, Kivity S, Zafrir Y, Altman A, Lerner A, Shoenfeld Y (2010) Vitamin D insufficiency in a sunny environment: a demographic and seasonal analysis. Isr Med Assoc J 12:751-756
• 44. Gharaibeh MA, Stoecker BJ (2009) Assessment of serum 25 (OH)D concentration in women of childbearing age and their preschool children in Northern Jordan during summer. Eur J Clin Nutr 63:1320-1326
• 45. Lander RL, Enkhjargal T, Batjargal J, Bailey KB, Diouf S, Green TJ, Skeaff CM, Gibson RS (2008) Multiple micronutrient deficiencies persist during early childhood in Mongolia. Asia Pac J
• Clin Nutr 17:429-440
• 46. van Summeren MJ, van Coeverden SC, Schurgers LJ, Braam LA, Noirt F, Uiterwaal CS, Kuis W, Vermeer C (2008) Vitamin K status is associated with childhood bone mineral content. Br J Nutr 100:852-858
• 47. Rockell JE, Green TJ, Skeaff CM et al (2005) Season and ethnicity are determinants of serum 25-hydroxyvitamin D concentrations in New Zealand children aged 5-14 y. J Nutr 135:2602-2608
• 48. Houghton LA, Szymlek-Gay EA, Gray AR, Ferguson EL, Deng X, Heath AL (2010) Predictors of vitamin D status and its association with parathyroid hormone in young New Zealand children. Am J Clin Nutr 92:69-76
• 49. Grant CC, Wall CR, Crengle S, Scragg R (2009) Vitamin D deficiency in early childhood: prevalent in the sunny South Pacific. Public Health Nutr 12:1893-1901
• 50. Pfitzner MA, Thacher TD, Pettifor JM, Zoakah AI, Lawson JO, Isichei CO, Fischer PR (1998) Absence of vitamin D deficiency in young Nigerian children. J Pediatr 133:740-744
• 51. Davies PS, Bates CJ, Cole TJ, Prentice A, Clarke PC (1999) Vitamin D: seasonal and regional differences in preschool children in Great Britain. Eur J Clin Nutr 53:195-198
• 52. Cashman KD, Hill TR, Cotter AA et al (2008) Low vitamin D status adversely affects bone health parameters in adolescents. Am J Clin Nutr 87:1039-1044
• 53. Hill TR, Cotter AA, Mitchell S et al (2008) Vitamin D status and its determinants in adolescents from the Northern Ireland Young Hearts 2000 cohort. Br J Nutr 99:1061-1067
• 54. Looker AC, Pfeiffer CM, Lacher DA, Schleicher RL, Picciano MF, Yetley EA (2008) Serum 25-hydroxyvitamin D status of the US population: 1988-1994 compared with 2000-2004. Am J Clin Nutr 88:1519-1527
• 55. Mansbach JM, Ginde AA, Camargo CA Jr (2009) Serum 25-hydroxyvitamin D levels among US children aged 1 to 11 years: do children need more vitamin D? Pediatrics 124:1404-1410
• 56. Reis JP, von Muhlen D, Miller ER 3rd, Michos ED, Appel LJ (2009) Vitamin D status and cardiometabolic risk factors in the United States adolescent population. Pediatrics 124:e371-e379
• 57. Weng FL, Shults J, Leonard MB, Stallings VA, Zemel BS (2007) Risk factors for low serum 25-hydroxyvitamin D concentrations in otherwise healthy children and adolescents. Am J Clin Nutr 86:150-158
• 58. Stein EM, Laing EM, Hall DB, Hausman DB, Kimlin MG, Johnson MA, Modlesky CM, Wilson AR, Lewis RD (2006) Serum 25-hydroxyvitamin D concentrations in girls aged 4-8y living in the southeastern United States. Am J Clin Nutr 83:75-81
• 59. Sullivan SS, Rosen CJ, Halteman WA, Chen TC, Holick MF (2005) Adolescent girls in Maine are at risk for vitamin D insufficiency. J Am Diet Assoc 105:971-974
• 60. Hill KM, McCabe GP, McCabe LD, Gordon CM, Abrams SA, Weaver CM (2010) An inflection point of serum 25-hydroxyvitamin D for maximal suppression of parathyroid hormone is not evident from multi-site pooled data in children and adolescents. J Nutr 140:1983-1988
• 61. Breen ME, Laing EM, Hall DB et al (2011) 25-Hydroxyvitamin D, insulin-like growth factor-I, and bone mineral accrual during growth. J Clin Endocrinol Metab 96:E89-E98
• 62. Harkness LS, Cromer BA (2005) Vitamin D deficiency in adolescent females. J Adolesc Health 37:75e71-75e75
• 63. Center JR, Nguyen TV, Sambrook PN, Eisman JA (1999) Hormonal and biochemical parameters in the determination of osteoporosis in elderly men. J Clin Endocrinol Metab 84:36263635
• 64. Pasco JA, Henry MJ, Nicholson GC, Sanders KM, Kotowicz MA (2001) Vitamin D status of women in the Geelong Osteoporosis Study: association with diet and casual exposure to sunlight. Med J Aust 175:401-405
• 65. Ngo DT, Sverdlov AL, McNeil JJ, Horowitz JD (2010) Does vitamin D modulate asymmetric dimethylarginine and C-reactive protein concentrations? Am J Med 123:335-341
• 66. Ding C, Cicuttini F, Parameswaran V, Burgess J, Quinn S, Jones G (2009) Serum levels of vitamin D, sunlight exposure, and knee cartilage loss in older adults: the Tasmanian Older Adult Cohort Study. Arthritis Rheum 60:1381-1389
• 67. Brock K, Wilkinson M, Cook R, Lee S, Bermingham M (2004) Associations with vitamin D deficiency in "at risk" Australians. J Steroid Biochem Mol Biol 89-90:581-588
• 68. Kudlacek S, Schneider B, Peterlik M, Leb G, Klaushofer K, Weber K, Woloszczuk W, Willvonseder R (2003) Assessment of vitamin D and calcium status in healthy adult Austrians. Eur J Clin Invest 33:323-331
• 69. Boonen S, Lesaffre E, Aerssens J, Pelemans W, Dequeker J, Bouillon R (1996) Deficiency of the growth hormone-insulinlike growth factor-I axis potentially involved in age-related alterations in body composition. Gerontology 42:330-338
• 70. Boonen S, Cheng XG, Nijs J, Nicholson PH, Verbeke G, Lesaffre E, Aerssens J, Dequeker J (1997) Factors associated with cortical and trabecular bone loss as quantified by peripheral computed tomography (pQCT) at the ultradistal radius in aging women. Calcif Tissue Int 60:164-170
• 71. Richart T, Thijs L, Nawrot T, Yu J, Kuznetsova T, Balkestein EJ, Struijker-Boudier HA, Staessen JA (2011) The metabolic syndrome and carotid intima-media thickness in relation to the parathyroid hormone to 25-OH-D(3) ratio in a general population. Am J Hypertens 24:102-109
• 72. MacFarlane GD, Sackrison JL Jr, Body JJ, Ersfeld DL, Fenske JS, Miller AB (2004) Hypovitaminosis D in a normal, apparently healthy urban European population. J Steroid Biochem Mol Biol 89-90:621-622
• 73. Moreno-Reyes R, Carpentier YA, Boelaert M, El Moumni K, Dufourny G, Bazelmans C, Leveque A, Gervy C, Goldman S (2009) Vitamin D deficiency and hyperparathyroidism in relation to ethnicity: a cross-sectional survey in healthy adults. Eur J Nutr 48:31-37
• 74. Saraiva GL, Cendoroglo MS, Ramos LR, Araujo LM, Vieira JG, Kunii I, Hayashi LF, Correa MP, Lazaretti-Castro M (2005) Influence of ultraviolet radiation on the production of 25 hydroxyvitamin D in the elderly population in the city of Sao Paulo (23 degrees 34'S), Brazil. Osteoporos Int 16:1649-1654
• 75. Njemini R, Meyers I, Demanet C, Smitz J, Sosso M, Mets T (2002) The prevalence of autoantibodies in an elderly sub-Saharan African population. Clin Exp Immunol 127:99-106
• 76. Langlois K, Greene-Finestone L, Little J, Hidiroglou N, Whiting S (2010) Vitamin D status of Canadians as measured in the 2007 to 2009 Canadian Health Measures Survey. Health Rep 21:47-55
• 77. Rucker D, Allan JA, Fick GH, Hanley DA (2002) Vitamin D insufficiency in a population of healthy western Canadians. CMAJ 166:1517-1524
• 78. Barake R, Weiler H, Payette H, Gray-Donald K (2010) Vitamin D supplement consumption is required to achieve a minimal target 25-hydroxyvitamin D concentration of > or =75 nmol/L in older people. J Nutr 140:551-556
• 79. Sinotte M, Diorio C, Berube S, Pollak M, Brisson J (2009) Genetic polymorphisms of the vitamin D binding protein and plasma concentrations of 25-hydroxyvitamin D in premenopausal women. Am J Clin Nutr 89:634-640
• 80. Chen W, Dawsey SM, Qiao YL, Mark SD, Dong ZW, Taylor PR, Zhao P, Abnet CC (2007) Prospective study of serum 25(OH)-vitamin D concentration and risk of oesophageal and gastric cancers. Br J Cancer 97:123-128
• 81. Abnet CC, Chen W, Dawsey SM, Wei WQ, Roth MJ, Liu B, Lu N, Taylor PR, Qiao YL (2007) Serum 25(OH)-vitamin D concentration and risk of esophageal squamous dysplasia. Cancer Epidemiol Biomarkers Prev 16:1889-1893
• 82. Chan EL, Lau E, Shek CC, MacDonald D, Woo J, Leung PC, Swaminathan R (1992) Age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of bone metabolism in Chinese women. Clin Endocrinol (Oxf) 36:375-381
• 83. Zofkova I, Hill M (2008) Biochemical markers ofbone remodeling correlate negatively with circulating TSH in postmenopausal women. Endocr Regul 42:121 -127
• 84. Rudnicki M, Thode J, Jorgensen T, Heitmann BL, Sorensen OH (1993) Effects of age, sex, season and diet on serum ionized calcium, parathyroid hormone and vitamin D in a random population. J Intern Med 234:195-200
• 85. Rejnmark L, Vestergaard P, Heickendorff L, Mosekilde L (2008) Plasma 1,25(OH)2D levels decrease in postmenopausal women with hypovitaminosis D. Eur J Endocrinol 158:571-576
• 86. Rejnmark L, Vestergaard P, Heickendorff L, Mosekilde L (2011) Determinants of plasma PTH and their implication for defining a reference interval. Clin Endocrinol (Oxf) 74:37-43
• 87. Brot C, Jorgensen N, Madsen OR, Jensen LB, Sorensen OH (1999) Relationships between bone mineral density, serum vitamin D metabolites and calcium:phosphorus intake in healthy perimenopausal women. J Intern Med 245:509-516
• 88. Frost M, Abrahamsen B, Nielsen TL, Hagen C, Andersen M, Brixen K (2010) Vitamin D status and PTH in young men: a cross-sectional study on associations with bone mineral density, body composition and glucose metabolism. Clin Endocrinol (Oxf) 73:573-580
• 89. Dalgard C, Petersen MS, Schmedes AV, Brandslund I, Weihe P, Grandjean P (2010) High latitude and marine diet: vitamin D status in elderly Faroese. Br J Nutr 104:914-918
• 90. Kull M Jr, Kallikorm R, Tamm A, Lember M (2009) Seasonal variance of 25-(OH) vitamin D in the general population of Estonia, a Northern European country. BMC Publ Health 9:22
• 91. Heere C, Skeaff CM, Waqatakirewa L, Vatucawaqa P, Khan AN, Green TJ (2010) Serum 25-hydroxyvitamin D concentration of Indigenous-Fijian and Fijian-Indian women. Asia Pac J Clin Nutr 19:43-48
• 92. Kilkkinen A, Knekt P, Heliovaara M, Rissanen H, Marniemi J, Hakulinen T, Aromaa A (2008) Vitamin D status and the risk of lung cancer: a cohort study in Finland. Cancer Epidemiol Biomarkers Prev 17:3274-3278
• 93. Kilkkinen A, Knekt P, Aro A, Rissanen H, Marniemi J, Heliovaara M, Impivaara O, Reunanen A (2009) Vitamin D status and the risk of cardiovascular disease death. Am J Epidemiol 170:1032-1039
• 94. Kauppi M, Impivaara O, Maki J, Heliovaara M, Marniemi J, Montonen J, Jula A (2009) Vitamin D status and common risk factors for bone fragility as determinants of quantitative ultrasound variables in a nationally representative population sample. Bone 45:119-124
• 95. Partti K, Heliovaara M, Impivaara O, Perala J, Saarni SI, Lonnqvist J, Suvisaari JM (2010) Skeletal status in psychotic disorders: a population-based study. Psychosom Med 72:933-940
• 96. Mattila C, Knekt P, Mannisto S, Rissanen H, Laaksonen MA, Montonen J, Reunanen A (2007) Serum 25-hydroxyvitamin D concentration and subsequent risk of type 2 diabetes. Diabetes Care 30:2569-2570
• 97. Lamberg-Allardt CJ, Outila TA, Karkkainen MU, Rita HJ, Valsta LM (2001) Vitamin D deficiency and bone health in healthy adults in Finland: could this be a concern in other parts of Europe? J Bone Miner Res 16:2066-2073
• 98. Parviainen MT, Kumpusalo E, Halonen P, Neittaanmaki L, Pekkarinen H (1992) Epidemiology of vitamins A, E, D and C in rural villages in Finland: biochemical, nutritional and socioeconomical aspects. Int J Vitam Nutr Res 62:238-243
• 99. Chapuy MC, Preziosi P, Maamer M, Arnaud S, Galan P, Hercberg S, Meunier PJ (1997) Prevalence of vitamin D insufficiency in an adult normal population. Osteoporos Int 7:439-443
• 100. Malvy DJ, Guinot C, Preziosi P, Galan P, Chapuy MC, Maamer M, Arnaud S, Meunier PJ, Hercberg S, Tschachler E (2000)
• Relationship between vitamin D status and skin phototype in general adult population. Photochem Photobiol 71:466-469
• 101. de Carvalho MJ, Guilland JC, Moreau D, Boggio V, Fuchs F (1996) Vitamin status of healthy subjects in Burgundy (France). Ann Nutr Metab 40:24-51
• 102. Blain H, Jaussent A, Thomas E et al (2009) Low sit-to-stand performance is associated with low femoral neck bone mineral density in healthy women. Calcif Tissue Int 84:266-275
• 103. Aspray TJ, Yan L, Prentice A (2005) Parathyroid hormone and rates of bone formation are raised in perimenopausal rural Gambian women. Bone 36:710-720
• 104. Hintzpeter B, Mensink GB, Thierfelder W, Muller MJ, Scheidt-Nave C (2008) Vitamin D status and health correlates among German adults. Eur J Clin Nutr 62:1079-1089
• 105. Scharla SH, Scheidt-Nave C, Leidig G, Woitge H, Wuster C, Seibel MJ, Ziegler R (1996) Lower serum 25-hydroxyvitamin D is associated with increased bone resorption markers and lower bone density at the proximal femur in normal females: a population-based study. Exp Clin Endocrinol Diabetes 104:289292
• 106. Woitge HW, Scheidt-Nave C, Kissling C, Leidig-Bruckner G, Meyer K, Grauer A, Scharla SH, Ziegler R, Seibel MJ (1998) Seasonal variation of biochemical indexes of bone turnover: results of a population-based study. J Clin Endocrinol Metab 83:68-75
• 107. Woitge HW, Knothe A, Witte K, Schmidt-Gayk H, Ziegler R, Lemmer B, Seibel MJ (2000) Circaannual rhythms and interactions of vitamin D metabolites, parathyroid hormone, and biochemical markers of skeletal homeostasis: a prospective study. J Bone Miner Res 15:2443-2450
• 108. Papapetrou PD, Triantaphyllopoulou M, Karga H, Zagarelos P, Aloumanis K, Kostakioti E, Vaiopoulos G (2007) Vitamin D deficiency in the elderly in Athens, Greece. J Bone Miner Metab 25:198-203
• 109. Sigurdsson G, Franzson L, Steingrimsdottir L, Sigvaldason H (2000) The association between parathyroid hormone, vitamin D and bone mineral density in 70-year-old Icelandic women. Osteoporos Int 11:1031-1035
• 110. Goswami R, Kochupillai N, Gupta N, Goswami D, Singh N, Dudha A (2008) Presence of 25(OH)D deficiency in a rural North Indian village despite abundant sunshine. J Assoc Physicians
• India 56:755-757
• 111. Masoompour SM, Sadegholvaad A, Larijani B, Ranjbar-Omrani G (2008) Effects of age and renal function on vitamin D status in
• men. Arch Iran Med 11:377-381
• 112. Hosseinpanah F, Rambod M, Hossein-nejad A, Larijani B, Azizi F (2008) Association between vitamin D and bone mineral density in Iranian postmenopausal women. J Bone Miner Metab 26:86-92
• 113. Omrani GR, Masoompour SM, Sadegholvaad A, Larijani B (2006) Effect of menopause and renal function on vitamin D status in Iranian women. East Mediterr Health J 12:188-195
• 114. Hossein-Nezhad A, Khoshniat Nikoo M, Maghbooli Z, Karimi F, Mirzaei K, Hosseini A, Larijani B (2009) Relationship between serum vitamin D concentration and metabolic syndrome among Iranian adults population. DARU 17(Suppl 1):1-5
• 115. Niafar M, Bahrami A, Aliasgharzadeh A, Aghamohammadzadeh N, Najafipour F, Mobasseri M (2009) Vitamin D status in healthy postmenopausal Iranian women. J Res Med Sci 14:171-177
• 116. Hashemipour S, Larijani B, Adibi H et al (2006) The status of biochemical parameters in varying degrees of vitamin D deficiency. J Bone Miner Metab 24:213-218
• 117. Keane EM, Healy M, O'Moore R, Coakley D, Walsh JB (1995) Hypovitaminosis D in the healthy elderly. Br J Clin Pract 49:301-303
• 118. Hill T, Collins A, O'Brien M, Kiely M, Flynn A, Cashman KD (2005) Vitamin D intake and status in Irish postmenopausal women. Eur J Clin Nutr 59:404-410
• 119. Hill TR, O'Brien MM, Lamberg-Allardt C, Jakobsen J, Kiely M, Flynn A, Cashman KD (2006) Vitamin D status of 51-75-year-old Irish women: its determinants and impact on biochemical indices of bone turnover. Public Health Nutr 9:225-233
• 120. Semba RD, Houston DK, Bandinelli S, Sun K, Cherubini A, Cappola AR, Guralnik JM, Ferrucci L (2010) Relationship of 25-hydroxyvitamin D with all-cause and cardiovascular disease mortality in older community-dwelling adults. Eur J Clin Nutr 64:203-209
• 121. Lauretani F, Bandinelli S, Russo CR et al (2006) Correlates of bone quality in older persons. Bone 39:915-921
• 122. Houston DK, Cesari M, Ferrucci L, Cherubini A, Maggio D, Bartali B, Johnson MA, Schwartz GG, Kritchevsky SB (2007) Association between vitamin D status and physical performance: the InCHIANTI Study. J Gerontol A Biol Sci Med Sci 62:440-446
• 123. Hicks GE, Shardell M, Miller RR, Bandinelli S, Guralnik J, Cherubini A, Lauretani F, Ferrucci L (2008) Associations between vitamin D status and pain in older adults: the Invecchiare in Chianti Study. J Am Geriatr Soc 56:785-791
• 124. Vezzoli G, Soldati L, Arcidiacono T et al (2005) Urinary calcium is a determinant of bone mineral density in elderly men participating in the InCHIANTI Study. Kidney Int 67:2006-2014
• 125. Maggio D, Cherubini A, Lauretani F et al (2005) 25(OH)D Serum levels decline with age earlier in women than in men and less efficiently prevent compensatory hyperparathyroidism in older adults. J Gerontol A Biol Sci Med Sci 60:1414-1419
• 126. Adami S, Viapiana O, Gatti D, Idolazzi L, Rossini M (2008) Relationship between serum parathyroid hormone, vitamin D sufficiency, age, and calcium intake. Bone 42:267-270
• 127. Carnevale V, Modoni S, Pileri M, Di Giorgio A, Chiodini I, Minisola S, Vieth R, Scillitani A (2001) Longitudinal evaluation of vitamin D status in healthy subjects from southern Italy: seasonal and gender differences. Osteoporos Int 12:1026-1030
• 128. Nakamura K, Nashimoto M, Yamamoto M (2001) Are the serum 25-hydroxyvitamin D concentrations in winter associated with forearm bone mineral density in healthy elderly Japanese women? Int J Vitam Nutr Res 71:25-29
• 129. Kwon J, Suzuki T, Yoshida H, Kim H, Yoshida Y, Iwasa H (2007) Concomitant lower serum albumin and vitamin D levels are associated with decreased objective physical performance among Japanese community-dwelling elderly. Gerontology 53:322-328
• 130. Suzuki T, Kwon J, Kim H, Shimada H, Yoshida Y, Iwasa H, Yoshida H (2008) Low serum 25-hydroxyvitamin D levels associated with falls among Japanese community-dwelling elderly. J Bone Miner Res 23:1309-1317
• 131. Nakamura K, Nashimoto M, Hori Y, Yamamoto M (2000) Serum parathyroid hormone in healthy Japanese women in relation to serum 25-hydroxyvitamin D. Int J Vitam Nutr Res 70:287-292
• 132. Kim MK, Il Kang M, Won Oh K, Kwon HS, Lee JH, Lee WC,
• Yoon KH, Son HY (2010) The association of serum vitamin D level with presence of metabolic syndrome and hypertension in middle-aged Korean subjects. Clin Endocrinol (Oxf) 73:330-338
• 133. Arabi A, Baddoura R, El-Rassi R, El-Hajj Fuleihan G (2010) Age but not gender modulates the relationship between PTH and vitamin D. Bone 47:408-412
• 134. Gannage-Yared MH, Chemali R, Yaacoub N, Halaby G (2000) Hypovitaminosis D in a sunny country: relation to lifestyle and bone markers. J Bone Miner Res 15:1856-1862
• 135. Rahman SA, Chee WS, Yassin Z, Chan SP (2004) Vitamin D status among postmenopausal Malaysian women. Asia Pac J Clin Nutr 13:255-260
• 136. Kuchuk NO, Pluijm SM, van Schoor NM, Looman CW, Smit JH, Lips P (2009) Relationships of serum 25-hydroxyvitamin D to bone mineral density and serum parathyroid hormone and markers of bone turnover in older persons. J Clin Endocrinol Metab 94:1244-1250
• 137. van Schoor NM, Visser M, Pluijm SM, Kuchuk N, Smit JH, Lips P (2008) Vitamin D deficiency as a risk factor for osteoporotic fractures. Bone 42:260-266
• 138. Visser M, Deeg DJ, Puts MT, Seidell JC, Lips P (2006) Low serum concentrations of 25-hydroxyvitamin D in older persons and the risk of nursing home admission. Am J Clin Nutr 84:616622, quiz 671-612
• 139. Buizert PJ, van Schoor NM, Lips P, Deeg DJ, Eekhoff EM (2009) Lipid levels: a link between cardiovascular disease and osteoporosis? J Bone Miner Res 24:1103-1109
• 140. de Jongh RT, Lips P, Rijs KJ, van Schoor NM, Kramer MH, Vandenbroucke JP, Dekkers OM (2011) Associations between vitamin D receptor genotypes and mortality in a cohort of older Dutch individuals. Eur J Endocrinol 164:75-82
• 141. Hoogendijk WJ, Lips P, Dik MG, Deeg DJ, Beekman AT, Penninx BW (2008) Depression is associated with decreased 25-hydroxyvitamin D and increased parathyroid hormone levels in older adults. Arch Gen Psychiatry 65:508-512
• 142. Wicherts IS, van Schoor NM, Boeke AJ, Visser M, Deeg DJ, Smit J, Knol DL, Lips P (2007) Vitamin D status predicts physical performance and its decline in older persons. J Clin Endocrinol Metab 92:2058-2065
• 143. Lowik MR, Schrijver J, Odink J, van den Berg H, Wedel M, Hermus RJ (1990) Nutrition and aging: nutritional status of "apparently healthy" elderly (Dutch nutrition surveillance system). JAmCollNutr 9:18-27
• 144. Al-Delaimy WK, Jansen EH, Peeters PH, van der Laan JD, van Noord PA, Boshuizen HC, van der Schouw YT, Jenab M, Ferrari P, Bueno-de-Mesquita HB (2006) Reliability of biomarkers of iron status, blood lipids, oxidative stress, vitamin D, C-reactive protein and fructosamine in two Dutch cohorts. Biomarkers 11:370382
• 145. Pilz S, Dobnig H, Nijpels G, Heine RJ, Stehouwer CD, Snijder MB, van Dam RM, Dekker JM (2009) Vitamin D and mortality in older men and women. Clin Endocrinol (Oxf) 71:666-672
• 146. Scragg R, Holdaway I, Jackson R, Lim T (1992) Plasma 25-hydroxyvitamin D3 and its relation to physical activity and other heart disease risk factors in the general population. Ann Epidemiol 2:697-703
• 147. Bolland MJ, Grey AB, Ames RW, Mason BH, Horne AM, Gamble GD, Reid IR (2007) The effects of seasonal variation of 25-hydroxyvitamin D and fat mass on a diagnosis of vitamin D sufficiency. Am J Clin Nutr 86:959-964
• 148. Bolland MJ, Grey AB, Ames RW, Horne AM, Mason BH, Wattie DJ, Gamble GD, Bouillon R, Reid IR (2007) Age-, gender-, and weight-related effects on levels of 25-hydroxyvitamin D are not mediated by vitamin D binding protein. Clin Endocrinol (Oxf) 67:259-264
• 149. Bolland MJ, Grey AB, Ames RW, Horne AM, Gamble GD, Reid IR (2006) Fat mass is an important predictor of parathyroid hormone levels in postmenopausal women. Bone 38:317-321
• 150. Rockell JE, Skeaff CM, Venn BJ, Williams SM, Green TJ (2008) Vitamin D insufficiency in New Zealanders during the winter is associated with higher parathyroid hormone concentrations: implications for bone health? N Z Med J 121:75-84
• 151. Brustad M, Sandanger T, Aksnes L, Lund E (2004) Vitamin D status in a rural population of northern Norway with high fish liver consumption. Public Health Nutr 7:783-789
• 152. Brustad M, Alsaker E, Engelsen O, Aksnes L, Lund E (2004) Vitamin D status of middle-aged women at 65-71 degrees N in relation to dietary intake and exposure to ultraviolet radiation.
• Public Health Nutr 7:327-335
• 153. Holvik K, Meyer HE, Sogaard AJ, Selmer R, Haug E, Falch JA (2006) Biochemical markers of bone turnover and their relation to forearm bone mineral density in persons of Pakistani and Norwegian background living in Oslo, Norway: The Oslo Health Study. Eur J Endocrinol 155:693-699
• 154. Meyer HE, Falch JA, Sogaard AJ, Haug E (2004) Vitamin D deficiency and secondary hyperparathyroidism and the association with bone mineral density in persons with Pakistani and Norwegian background living in Oslo, Norway, the Oslo Health Study. Bone 35:412-417
• 155. Grimnes G, Almaas B, Eggen AE et al (2010) Effect of smoking on the serum levels of 25-hydroxyvitamin D depends on the assay employed. Eur J Endocrinol 163:339-348
• 156. Jorde R, Sneve M, Hutchinson M, Emaus N, Figenschau Y, Grimnes G (2010) Tracking of serum 25-hydroxyvitamin D levels during 14 years in a population-based study and during 12 months in an intervention study. Am J Epidemiol 171:903-908
• 157. Napiorkowska L, Budlewski T, Jakubas-Kwiatkowska W, Hamzy V, Gozdowski D, Franek E (2009) Prevalence of low serum vitamin D concentration in an urban population ofelderly women in Poland. Pol Arch Med Wewn 119:699-703
• 158. Sapir-Koren R, Livshits G, Kobyliansky E (2003) Genetic effects of estrogen receptor alpha and collagen IA1 genes on the relationships of parathyroid hormone and 25 hydroxyvitamin D with bone mineral density in Caucasian women. Metabolism 52:1129-1135
• 159. Ardawi MS, Maimani AA, Bahksh TA, Rouzi AA, Qari MH, Raddadi RM (2010) Reference intervals of biochemical bone turnover markers for Saudi Arabian women: a cross-sectional study. Bone 47:804-814
• 160. Charlton KE, Labadarios D, Lombard CJ, Louw ME (1996) Vitamin D status of older South Africans. S Afr Med J 86:1406-1410
• 161. Gomez JM, Maravall FJ, Gomez N, Navarro MA, Casamitjana R, Soler J (2004) Relationship between 25-(OH) D3, the IGF-I
• system, leptin, anthropometric and body composition variables in a healthy, randomly selected population. Horm Metab Res 36:48-53
• 162. Almirall J, Vaqueiro M, Bare ML, Anton E (2010) Association of low serum 25-hydroxyvitamin D levels and high arterial blood pressure in the elderly. Nephrol Dial Transplant 25:503-509
• 163. Muray S, Marco MP, Craver L, Rue M, Valdivielso JM, Fernandez E (2006) Influence of mineral metabolism parameters on pulse pressure in healthy subjects. Clin Nephrol 66:411-417
• 164. Gerdhem P, Ringsberg KA, Obrant KJ, Akesson K (2005) Association between 25-hydroxy vitamin D levels, physical activity, muscle strength and fractures in the prospective population-based OPRA Study of Elderly Women. Osteoporos Int 16:1425-1431
• 165. Salminen H, Saaf M, Ringertz H, Strender LE (2008) The role of IGF-I and IGFBP-1 status and secondary hyperparathyroidism in relation to osteoporosis in elderly Swedish women. Osteoporos Int 19:201-209
• 166. Lind L, Hanni A, Lithell H, Hvarfner A, Sorensen OH, Ljunghall S (1995) Vitamin D is related to blood pressure and other cardiovascular risk factors in middle-aged men. Am J Hypertens 8:894-901
• 167. Burgaz A, Akesson A, Oster A, Michaelsson K, Wolk A (2007) Associations of diet, supplement use, and ultraviolet B radiation exposure with vitamin D status in Swedish women during winter. Am J Clin Nutr 86:1399-1404
• 168. Burgaz A, Akesson A, Michaelsson K, Wolk A (2009) 25-Hydroxyvitamin D accumulation during summer in elderly women at latitude 60 degrees N. J Intern Med 266:476-483
• 169. Melhus H, Snellman G, Gedeborg R et al (2010) Plasma 25-hydroxyvitamin D levels and fracture risk in a community-based cohort of elderly men in Sweden. J Clin Endocrinol Metab 95:2637-2645
• 170. Hagstrom E, Hellman P, Larsson TE et al (2009) Plasma parathyroid hormone and the risk of cardiovascular mortality in the community. Circulation 119:2765-2771
• 171. Melin AL, Wilske J, Ringertz H, Saaf M (1999) Vitamin D status, parathyroid function and femoral bone density in an elderly Swedish population living at home. Aging (Milano) 11:200-207
• 172. Burnand B, Sloutskis D, Gianoli F, Cornuz J, Rickenbach M, Paccaud F, Burckhardt P (1992) Serum 25-hydroxyvitamin D: distribution and determinants in the Swiss population. Am J Clin Nutr 56:537-542
• 173. Theiler R, Stahelin HB, Kranzlin M, Tyndall A, Bischoff HA (1999) High bone turnover in the elderly. Arch Phys Med Rehabil 80:485-489
• 174. Tsai KS, Hsu SH, Cheng JP, Yang RS (1997) Vitamin D stores of urban women in Taipei: effect on bone density and bone turnover, and seasonal variation. Bone 20:371-374
• 175. Chailurkit LO, Pongchaiyakul C, Charoenkiatkul S, Kosulwat V, Rojroongwasinkul N, Rajatanavin R (2001) Different mechanism of bone loss in ageing women and men in Khon Kaen Province. J Med Assoc Thai 84:1175-1182
• 176. Chailurkit LO, Piaseu N, Rajatanavin R (2002) Influence of normal ageing on mechanism of bone loss in women and men in Bangkok. J Med Assoc Thai 85:915-921
• 177. Soontrapa S, Boonsiri P, Khampitak T (2009) The prevalence of hypovitaminosis D in the elderly women living in the rural area of Khon Kaen Province, Thailand. J Med Assoc Thai 92(Suppl5): S21-S25
• 178. Chailurkit LO, Kruavit A, Rajatanavin R (2011) Vitamin D status and bone health in healthy Thai elderly women. Nutrition 27:160-164
• 179. Meddeb N, Sahli H, Chahed M et al (2005) Vitamin D deficiency in Tunisia. Osteoporos Int 16:180-183
• 180. Hirani V, Primatesta P (2005) Vitamin D concentrations among people aged 65 years and over living in private households and institutions in England: population survey. Age Ageing 34:485-491
• 181. Hirani V, Tull K, Ali A, Mindell J (2010) Urgent action needed to improve vitamin D status among older people in England! Age Ageing 39:62-68
• 182. Elia M, Stratton RJ (2005) Geographical inequalities in nutrient status and risk of malnutrition among English people aged 65 y and older. Nutrition 21:1100-1106
• 183. Sadideen H, Swaminathan R (2004) Effect of acute oral calcium load on serum PTH and bone resorption in young healthy subjects: an overnight study. Eur J Clin Nutr 58:1661-1665
• 184. Forouhi NG, Luan J, Cooper A, Boucher BJ, Wareham NJ (2008) Baseline serum 25-hydroxy vitamin D is predictive of future glycemic status and insulin resistance: the Medical Research Council Ely Prospective Study 1990-2000. Diabetes 57:26192625
• 185. Wareham NJ, Byrne CD, Carr C, Day NE, Boucher BJ, Hales CN (1997) Glucose intolerance is associated with altered calcium homeostasis: a possible link between increased serum calcium concentration and cardiovascular disease mortality. Metabolism 46:1171-1177
• 186. Hegarty V, Woodhouse P, Khaw KT (1994) Seasonal variation in 25-hydroxyvitamin D and parathyroid hormone concentrations in healthy elderly people. Age Ageing 23:478-482
• 187. Bates CJ, Carter GD, Mishra GD, O'Shea D, Jones J, Prentice A (2003) In a population study, can parathyroid hormone aid the definition of adequate vitamin D status? A study of people aged 65 years and over from the British National Diet and Nutrition Survey. Osteoporos Int 14:152-159
• 188. Macdonald HM, Mavroeidi A, Barr RJ, Black AJ, Fraser WD, Reid DM (2008) Vitamin D status in postmenopausal women living at higher latitudes in the UK in relation to bone health, overweight, sunlight exposure and dietary vitamin D. Bone 42:996-1003
• 189. Mavroeidi A, O'Neill F, Lee PA, Darling AL, Fraser WD, Berry JL, Lee WT, Reid DM, Lanham-New SA, Macdonald HM (2010) Seasonal 25-hydroxyvitamin D changes in British postmenopaus-al women at 57 degrees N and 51 degrees N: a longitudinal study. J Steroid Biochem Mol Biol 121:459-461
• 190. Looker AC, Dawson-Hughes B, Calvo MS, Gunter EW, Sahyoun NR (2002) Serum 25-hydroxyvitamin D status of adolescents and adults in two seasonal subpopulations from NHANES III. Bone 30:771-777
• 191. Reis JP, von Muhlen D, Miller ER 3rd (2008) Relation of 25-hydroxyvitamin D and parathyroid hormone levels with metabolic syndrome among US adults. Eur J Endocrinol 159:41-48
• 192. de Boer IH, Ioannou GN, Kestenbaum B, Brunzell JD, Weiss NS (2007) 25-Hydroxyvitamin D levels and albuminuria in the Third National Health and Nutrition Examination Survey (NHANES III). Am J Kidney Dis 50:69-77
• 193. Dietrich T, Joshipura KJ, Dawson-Hughes B, Bischoff-Ferrari HA (2004) Association between serum concentrations of 25-hydroxyvitamin D3 and periodontal disease in the US population. Am J Clin Nutr 80:108-113 194. Ford ES, Ajani UA, McGuire LC, Liu S (2005) Concentrations of serum vitamin D and the metabolic syndrome among U.S. adults. Diabetes Care 28:1228-1230
• 195. Kant AK, Graubard BI (2008) Ethnic and socioeconomic differences in variability in nutritional biomarkers. Am J Clin Nutr 87:1464-1471
• 196. Scragg R, Sowers M, Bell C (2007) Serum 25-hydroxyvitaminD, ethnicity, and blood pressure in the Third National Health and Nutrition Examination Survey. Am J Hypertens 20:713-719
• 197. SkinnerHG, Schwartz GG (2009) The relationofserumparathy-roid hormone and serum calcium to serum levels of prostate-specific antigen: a population-based study. Cancer Epidemiol Biomarkers Prev 18:2869-2873
• 198. Looker AC, Mussolino ME (2008) Serum 25-hydroxyvitamin D and hip fracture risk in older U.S. white adults. J Bone Miner Res 23:143-150
• 199. Cheng S, Massaro JM, Fox CS et al (2010) Adiposity, cardiome-tabolic risk, and vitamin D status: the Framingham Heart Study.
• Diabetes 59:242-248
• 200. Jacques PF, Felson DT, Tucker KL, Mahnken B, Wilson PW, Rosenberg IH, Rush D (1997) Plasma 25-hydroxyvitamin D and its determinants in an elderly population sample. Am J Clin Nutr 66:929-936
• 201. Liu E, Meigs JB, Pittas AG, McKeown NM, Economos CD, Booth SL, Jacques PF (2009) Plasma 25-hydroxyvitamin D is associated with markers of the insulin resistant phenotype in nondiabetic adults. J Nutr 139:329-334
• 202. Shea MK, Benjamin EJ, Dupuis J et al (2009) Genetic and non-genetic correlates of vitamins K and D. Eur J Clin Nutr 63:458-464
• 203. Hannan MT, Felson DT, Dawson-Hughes B, Tucker KL, Cupples LA, Wilson PW, Kiel DP (2000) Risk factors for longitudinal
• bone loss in elderly men and women: the Framingham Osteoporosis Study. J Bone Miner Res 15:710-720
• 204. Kiel DP, Myers RH, Cupples LA et al (1997) The BsmI vitamin D receptor restriction fragment length polymorphism (bb) influences the effect of calcium intake on bone mineral density. J Bone Miner Res 12:1049-1057
• 205. Johnson MA, Davey A, Park S, Hausman DB, Poon LW (2008) Age, race and season predict vitamin D status in African American and white octogenarians and centenarians. J Nutr Health
• Aging 12:690-695
• 206. Kim DH, Sabour S, Sagar UN, Adams S, Whellan DJ (2008) Prevalence of hypovitaminosis D in cardiovascular diseases (from the National Health and Nutrition Examination Survey 2001 to 2004). Am J Cardiol 102:1540-1544
• 207. Badalian SS, Rosenbaum PF (2010) Vitamin D and pelvic floor disorders in women: results from the National Health and Nutrition Examination Survey. Obstet Gynecol 115:795803
• 208. Forrest KY, Stuhldreher WL (2011) Prevalence and correlates of vitamin D deficiency in US adults. Nutr Res 31:48-54
• 209. Freedman DM, Looker AC, Abnet CC, Linet MS, Graubard BI (2010) Serum 25-hydroxyvitamin D and cancer mortality in the NHANES III Study (1988-2006). Cancer Res 70:85878597
• 210. Chonchol M, Scragg R (2007) 25-Hydroxyvitamin D, insulin resistance, and kidney function in the Third National Health and Nutrition Examination Survey. Kidney Int 71:134-139
• 211. Ginde AA, Scragg R, Schwartz RS, Camargo CA Jr (2009) Prospective study of serum 25-hydroxyvitamin D level, cardiovascular disease mortality, and all-cause mortality in older U.S. adults. J Am Geriatr Soc 57:1595-1603
• 212. Kendrick J, Targher G, Smits G, Chonchol M (2009) 25-Hydroxyvitamin D deficiency is independently associated with cardiovascular disease in the Third National Health and Nutrition Examination Survey. Atherosclerosis 205:255-260
• 213. Martins D, Wolf M, Pan D, Zadshir A, Tareen N, Thadhani R, Felsenfeld A, Levine B, Mehrotra R, Norris K (2007) Prevalence of cardiovascular risk factors and the serum levels of 25-hydroxyvitamin D in the United States: data from the Third National Health and Nutrition Examination Survey. Arch Intern Med 167:1159-1165
• 214. Scragg R, Sowers M, Bell C (2004) Serum 25-hydroxyvitaminD, diabetes, and ethnicity in the Third National Health and Nutrition Examination Survey. Diabetes Care 27:2813-2818
• 215. Zadshir A, Tareen N, Pan D, Norris K, Martins D (2005) The prevalence of hypovitaminosis D among US adults: data from the NHANES III. Ethn Dis 15(S5):97-101
• 216. Reis JP, von Muhlen D, Michos ED, Miller ER 3rd, Appel LJ, Araneta MR, Barrett-Connor E (2009) Serum vitamin D, parathyroid hormone levels, and carotid atherosclerosis. Atherosclerosis 207:585-590
• 217. Jassal SK, Chonchol M, von Muhlen D, Smits G, Barrett-Connor E (2010) Vitamin D, parathyroid hormone, and cardiovascular mortality in older adults: the Rancho Bernardo Study. Am J Med 123:1114-1120
• 218. von Muhlen DG, Greendale GA, Garland CF, Wan L, Barrett-Connor E (2005) Vitamin D, parathyroid hormone levels and bone mineral density in community-dwelling older women: the Rancho Bernardo Study. Osteoporos Int 16:1721 -1726
• 219. Dawson-Hughes B, Harris SS, Dallal GE (1997) Plasma calcidiol, season, and serum parathyroid hormone concentrations in healthy elderly men and women. Am J Clin Nutr 65:67-71
• 220. Avery E, Kleppinger A, Feinn R, Kenny AM (2010) Determinants of living situation in a population of community-dwelling and assisted living-dwelling elders. J Am Med Dir Assoc 11:140-144
• 221. Ilich JZ, Brownbill RA, Tamborini L (2003) Bone and nutrition in elderly women: protein, energy, and calcium as main determinants of bone mineral density. Eur J Clin Nutr 57:554-565
• 222. Lappe JM, Davies KM, Travers-Gustafson D, Heaney RP (2006) Vitamin D status in a rural postmenopausal female population. J Am Coll Nutr 25:395-402
• 223. Mirza FS, Padhi ID, Raisz LG, Lorenzo JA (2010) Serum sclerostin levels negatively correlate with parathyroid hormone levels and free estrogen index in postmenopausal women. J Clin Endocrinol Metab 95:1991-1997
• 224. Sabetta JR, DePetrillo P, Cipriani RJ, Smardin J, Burns LA, Landry ML (2010) Serum 25-hydroxyvitamin d and the incidence of acute viral respiratory tract infections in healthy adults. PLoS One 5:e11088
• 225. Arunabh S, Pollack S, Yeh J, Aloia JF (2003) Body fat content and 25-hydroxyvitamin D levels in healthy women. J Clin Endocrinol Metab 88:157-161
• 226. Khosla S, Atkinson EJ, Melton LJ 3rd, Riggs BL (1997) Effects of age and estrogen status on serum parathyroid hormone levels and biochemical markers of bone turnover in women: a population-based study. J Clin Endocrinol Metab 82:1522-1527
• 227. Iannuzzi-Sucich M, Prestwood KM, Kenny AM (2002) Prevalence of sarcopenia and predictors of skeletal muscle mass in healthy, older men and women. J Gerontol A Biol Sci Med Sci 57:M772-M777
• 228. Alvarez JA, Ashraf AP, Hunter GR, Gower BA (2010) Serum 25-hydroxyvitamin D and parathyroid hormone are independent determinants of whole-body insulin sensitivity in women and may contribute to lower insulin sensitivity in African Americans. Am J Clin Nutr 92:1344-1349
• 229. Chai W, Maskarinec G, Cooney RV (2010) Serum 25-hydroxyvitamin D levels and mammographic density among premenopausal women in a multiethnic population. Eur J Clin Nutr 64:652-654
• 230. Ho-Pham LT, Nguyen ND, Lai TQ, Eisman JA, Nguyen TV (2011) Vitamin D status and parathyroid hormone in a urban population in Vietnam. Osteoporos Int 22:241-248
• 231. Hashemipour S, Larijani B, Adibi H et al (2004) Vitamin D deficiency and causative factors in the population of Tehran.