Br J Nutr. 2013 Aug 9:1-23.
Hilger J, Friedel A, Herr R, Rausch T, Roos F, Wahl DA, Pierroz DD, Weber P, Hoffmann K.
Mannheim Institute of Public Health, Social and Preventive Medicine, Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Strasse 7-11, D-68167 Mannheim, Germany.
Vitamin D deficiency is associated with osteoporosis and is thought to increase the risk of cancer and CVD.
Despite these numerous potential health effects, data on vitamin D status at the population level and within key subgroups are limited. The aims of the present study were to examine patterns of 25-hydroxyvitamin D (25(OH)D) levels worldwide and to assess differences by age, sex and region. In a systematic literature review using the Medline and EMBASE databases, we identified 195 studies conducted in forty-four countries involving more than 168 000 participants.
Mean population-level 25(OH)D values varied considerably across the studies (range 4·9-136·2 nmol/l), with 37·3 % of the studies reporting mean values below 50 nmol/l.
The highest 25(OH)D values were observed in North America.
Although age-related differences were observed in the Asia/Pacific and Middle East/Africa regions, they were not observed elsewhere and sex-related differences were not observed in any region. Substantial heterogeneity between the studies precluded drawing conclusions on overall vitamin D status at the population level.
Exploratory analyses, however, suggested that newborns and institutionalised elderly from several regions worldwide appeared to be at a generally higher risk of exhibiting lower 25(OH)D values. Substantial details on worldwide patterns of vitamin D status at the population level and within key subgroups are needed to inform public health policy development to reduce risk for potential health consequences of an inadequate vitamin D status.
More than one-third of populations worldwide may have low levels of vitamin D, study shows
New review published in the British Journal of Nutrition analyzes close to 200 population-based vitamin D studies from 44 countries; highest vitamin D values found in North America
A new systematic review published in the British Journal of Nutrition*, is one of the first to focus on patterns of vitamin D status worldwide and in key population subgroups, using continuous values for 25(OH)D to improve comparisons.
Principal investigator, Dr. Kristina Hoffmann of the Mannheim Institute of Public Health (MIPH), Medical Faculty Mannheim, Heidelberg University stated, "The strength of our study is that we used strict inclusion criteria to filter and compare data, using consistent values for 25(OH)D. Although we found a high degree of variability between reports of vitamin D status at the population level, more than one-third of the studies reviewed reported mean serum 25(OH)D values below 50 nmol/l."
Low levels of vitamin D have a potentially serious impact on health, particularly on bone and muscle health. In children, vitamin D deficiency is a cause of rickets; while in adults low values are associated with osteomalacia, osteopenia, osteoporosis and risk of fracture. Emerging evidence also points to increased risk for cancer and cardiovascular diseases. Yet despite its importance to public health, data about vitamin D status at the population level are limited and studies are hampered by lack of consensus and consistency.
The study's key findings include:
- 37.3% of the studies reviewed reported mean serum 25(OH)D values below 50 nmol/l, values considered inadequate by health authorities worldwide.
- Only a limited number of studies for Latin America were available.
- Vitamin D values were higher in North America than in Europe or the Middle-East.
- Age-related differences were observed for the Asia-Pacific and Middle East regions, but not elsewhere.
- The substantial heterogeneity between the studies within each region precludes drawing conclusions on overall vitamin D status at the population level.
- There is a need for research designs which minimize potential sources of bias and thus strengthen understanding of vitamin D status in key subgroups worldwide.
International Osteoporosis Foundation (IOF) CEO Judy Stenmark noted, "Given the global increase in the number of seniors and the almost fourfold increase in hip fractures due to osteoporosis since 1990, public health officials must address the impact of inadequate vitamin D status on fracture risk and overall health in their ageing populations as well as on children and adolescents. IOF urges further research as well as public health measures that would help to improve vitamin D status in these high-risk population groups."
40 nanograms is considered by many to be the minimum optimal level of vitamin D