Global vitamin D levels in relation to age, gender, skin pigmentation and latitude: An ecologic meta-regression analysis

Department of Endocrinology and Metabolism C, Aarhus Amtssygehus, Aarhus University Hospital, Aarhus, Denmark.
Osteoporosis International (Impact Factor: 4.17). 05/2008; 20(1):133-40. DOI: 10.1007/s00198-008-0626-y
Source: PubMed


We performed a meta-analysis of cross-sectional studies on serum 25(OH)D status globally. Serum 25(OH)D levels on average were 54 nmol/l, were higher in women than men, and higher in Caucasians than in non-Caucasians. There was no trend in serum 25(OH)D level with latitude. Vitamin D deficiency was widespread.
We studied vitamin D status (expressed as serum 25-hydroxy-vitamin D [25(OH)D]) in native subjects worldwide.
Meta-analysis and meta-regression of studies reporting on 25(OH)D in healthy subjects retrieved from Pubmed, Embase and Web of Science using the terms "serum", "25-hydroxy-vitamin D", "cholecalciferol", and "human". A total of 394 studies were included.
The mean 25(OH)D level was 54 nmol/l (95% CI: 52-57 nmol/l). Women had borderline significantly higher 25(OH)D levels than men, and Caucasians had higher levels than non-Caucasians. 25(OH)D levels were higher in subjects aged >15 years than in younger subjects. Unadjusted there was no significant decrease in 25(OH)D with latitude (slope of curve -0.03 +/- 0.12 nmol/l per degree latitude north or south of equator, p = 0.8). There was a significant decline with latitude for Caucasians (-0.69 +/- 0.30 nmol/l per degree, p = 0.02), but not for non-Caucasians (0.03 +/- 0.39 nmol/l per degree, p = 0.14). After adjustment for age, gender, and ethnicity, no overall correlation was present between 25(OH)D and latitude (-0.29 +/- 0.24 nmol/l per degree, p = 0.23).
There was no overall influence of latitude on 25(OH)D. However, in separate analyses 25(OH)D decreased with latitude in Caucasians but not in non-Caucasians. A widespread global vitamin D insufficiency was present compared with proposed threshold levels.

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    • "Furthermore, 25(OH)D3 and total 25(OH)D concentrations were usually similar but not identical, so we analyzed results from studies irrespective of type of vitamin D determination. A review of 394 studies of unadjusted serum 25(OH)D concentrations from around the world found a mean value of 22 ± 1 ng/mL, with no effect of latitude for nonwhites [63]. However, the regression fit to the data for white people went from approximately 40 ng/mL near the equator to approximately 16 ng/mL at the poles. "
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    ABSTRACT: Little published information is available regarding epidemiological data on vitamin D status in the large geographical region of Central Europe (CE). We searched the journal literature with regard to 25(OH)D concentrations among community-dwelling or healthy people living in CE. 25(OH)D concentrations varied by age, season, study sample size, and methodological approach [i.e., 25(OH)D assay used]. Concentrations of 25(OH)D in CE appeared lower than 30 ng/mL, and the magnitude of hypovitaminosis D was similar to that reported in Western Europe. While most of the studies reviewed were cross-sectional studies, a longitudinal study was also included to obtain information on seasonal variability. The longitudinal study reported wintertime 25(OH)D values close to 21-23 ng/mL for all studied age groups, with a significant increase of 25(OH)D in August reaching 42 ng/mL for those aged 0-9 years, but only 21 ng/mL for the elderly aged 80-89 years. The decrease in 25(OH)D with respect to age was attributed to decreased time spent in the sun and decreased vitamin D production efficiency. Based on the literature review on vitamin D status in the CE populations, it can be concluded that 25(OH)vitamin D levels are on average below the 30 ng/mL level.
    International Journal of Endocrinology 03/2014; 2014(1):589587. DOI:10.1155/2014/589587 · 1.95 Impact Factor
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    • "The effect of latitude and season on vitamin D concentrations is well documented in humans, where people living closer to the equator have higher vitamin D concentrations due to longer periods of sunlight (Hagenau et al., 2009; Mithal et al., 2009). Of interest and supporting the importance of sunlight exposure, the highest rates of hypovitaminosis D and rickets in the world are reported in the Middle East and Africa (Hagenau et al., 2009; Mithal et al., 2009). This is explained by ethnicity, cultural and religious practices (body covering, veils), prolonged breastfeeding, and inhabitants with darker skin color. "
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    ABSTRACT: Vitamin D is essential in calcium and phosphorus regulation, bone physiology, cell proliferation and epithelial integrity. Literature on vitamin D in growing horses is sparse, and the effect of age on vitamin D has not been evaluated in equids in the United States or in tropical countries. The goal of this study was to determine if there was an effect of age on serum 25(OH)D3 concentrations in equids in the US (Ohio/Kentucky) and Thailand (Chiang Rai and Kanchanaburi) during the same time of the year. Blood samples were collected from healthy ponies (n=21) and Thoroughbred foals (n=13), yearlings (n=10), and horses (n=20) in Thailand and from Thoroughbred foals (n=10) and horses (n=17) in the US. Serum concentrations of 25(OH)D3, calcium and phosphorus were measured. In both countries, serum 25(OH)D3 concentrations were lower in foals than in yearlings and adult horses. Serum 25(OH)D3 concentrations were higher in horses than in ponies in Thailand, but were not different between horses from either country. Calcium concentrations were not different between groups or location. In both countries, phosphorus concentrations were higher in foals than in older groups; however, were not different between ponies and horses. This study shows that independent of geography there are age-related differences in 25(OH)D3 concentrations in horses and further confirms that 25(OH)D3 concentrations are lower in horses compared to other species. The information will serve as the basis for future clinical studies and to help understand better the pathophysiology of equine disorders associated with calcium and phosphorus dysregulation.
    The Veterinary Journal 03/2014; 199(3). DOI:10.1016/j.tvjl.2014.01.002 · 1.76 Impact Factor
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    • "In heavier, larger infants, increased vitamin D levels with lower estrogen levels should demonstrate a lower incidence of DDH, but the opposite occurs [119–121]. Vitamin D levels in Caucasians which decrease with increasing latitude [122] and less sun exposure are also modulated by genetic factors. The genetic variability for vitamin D levels ranges from 14 % to 70 % [112, 113, 123–125]. "
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    ABSTRACT: It has been postulated that developmental dysplasia of the hip (DDH) is more frequent in infants born in the winter months. It was the purpose of this study to ascertain if there was any seasonal variation in DDH at the author's institution and compare/contrast our results with those in the literature using rigorous mathematical fitting. All children with DDH treated at the author's institution from 1993 to 2012 were identified. The month of birth was recorded and temporal variation was analyzed using cosinor analysis. Similar data from the literature was analyzed. There were 424 children (363 girls, 61 boys). An additional 22,936 children were added from the literature for a total of 23,360. Pearson's Chi-square test demonstrated a non-uniform distribution in the month of birth for both our 424 children as well as the combined literature series in both the Northern and Southern hemispheres. Cosinor analysis of the 424 children demonstrated double peaks in mid-March and mid-October. For the entire 23,360 children, no seasonal variation was observed in 2,205 (9.4 %), a single winter peak in 16,425 (70.3 %), a single summer peak in 1,280 (5.5 %), and double peaks in the spring and autumn in 3,450 (14.8 %). This study partly supports the hypothesis of tight clothing/cold temperature as one factor in the etiology of DDH with the tighter clothing/swaddling increasing the risk of DDH. However ~20 % of the DDH births demonstrated a non-winter peak. The single summer and double spring/autumn peaks, as well as in those series where no seasonal variation was noted, refutes the cold winter clothing hypothesis. Perhaps these different patterns in seasonal variation represent the heterogeneity of the genetic factors in DDH interacting with external factors (temperature and clothing) and internal factors (metabolic). Further study will be required to understand these different patterns in DDH seasonal variation. IV-case series.
    Journal of Children s Orthopaedics 02/2014; 8(1). DOI:10.1007/s11832-014-0558-3
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