International Osteoporosis Foundation (IOF) and DSM Nutritional Products (DSM) have jointly developed an interactive worldwide map on vitamin D status.
Two global maps illustrating vitamin D status - one for children and one for adults - have been developed. The data is derived from a systematic review of the worldwide literature published between 1990 and 2011, according to standardized criteria and guidelines. 200 single studies from 46 different countries all over the world met the inclusion criteria and were evaluated to develop the global maps.
The systematic review has been conducted in collaboration with the Mannheim Institute for Public Health, Germany.
Vitamin D status in adults (> 18 years) around the world
Key findings for adults > 18 years
Vitamin D status in children and adolescents (1 – 18 years) worldwide
Key findings for children and adolescents:
Development of the worldwide maps
Rationale for the colouring of countries
For both age categories, the rationale for assigning a colour to a specific country was based on the following hierarchical selection criteria:
1. Available data from several studies for the entire country, based on a weighted average of these studies.
2. Available data from several studies for a region/city of the country, based on a weighted average of these studies.
3. Available data based on a single study for the entire country.
4. Available data based on a single study for a region/city within the country.
Limitations of the maps
Despite using data from a systematic literature review the maps have limitations. The study base is quite heterogeneous and adequate information is not available for some countries. As an extreme example, one single study confined to a limited region was used to colour countries such as Argentina or Mongolia for children; thus they did not fairly represent the whole country. Furthermore there was inconsistency for thresholds for age groups. In view of the diversity of quality and quantity of data the maps have to be interpreted with caution. One further limitation is the variability in vitamin D assays described and the inter-study comparison of the 25(OH)D levels.
New recommendations for higher vitamin D intake
As a concern to the widespread vitamin D deficiency and the beneficial effect of vitamin D on bone health government documents, position statements and clinical practical guidelines have recently been published with higher recommendations for daily vitamin D intake.