- Haakon E Meyer, professor, senior medical officer12,
- Kristin Holvik, researcher1,
- Paul Lips, professor3
- 1Norwegian Institute of Public Health, Division of Epidemiology, Box 4404, Nydalen, 0403 Oslo, Norway
- 2University of Oslo, Department of Community Medicine, Oslo, Norway
- 3Endocrine Section, Department of Internal Medicine, VU University Medical Centre, Amsterdam, Netherlands
- Correspondence to: H E Meyer
The bottom line
Do not recommend vitamin D supplements to prevent chronic disease because clear evidence of benefit does not currently exist and adverse effects cannot be excluded
Vitamin D supplements in doses of 600-800 IU (15-20 µg) per day combined with calcium (0-1000 mg/day, depending on current dairy intake) may be recommended to prevent fractures in elderly people
Vitamin D has gained much attention in research and clinical practice as a possible preventive factor for a wide array of chronic diseases, including cardiovascular disease, various cancers, type 2 diabetes, autoimmune diseases, and chronic obstructive pulmonary disease. Vitamin D3 (cholecalciferol) is a steroid hormone precursor and is synthesised when skin is exposed to ultraviolet B radiation. It is also found in a limited number of foods, especially oily fish. The other form of the vitamin, vitamin D2 (ergocalciferol), is found in dietary plant sterols exposed to ultraviolet B radiation and is somewhat less effective than vitamin D3.1 Vitamin D has well known effects on calcium metabolism and is traditionally linked to the prevention of rickets in children. It is also now clear that vitamin D deficiency causes bone loss through secondary hyperparathyroidism.2
Because vitamin D receptors are present in many organs and tissues, vitamin D may have extraskeletal effects.2 In addition, many observational studies have shown associations between 25-hydroxyvitamin D3 (25(OH)D3), the major circulating form of vitamin D, and the risk of chronic diseases.3 As a consequence of increased popularity, measurement of 25(OH)D3 to determine vitamin D status has become common, and vitamin D supplements, at doses far exceeding the recommended daily allowances or dietary reference values,4 5 6 are often given, despite limited evidence of an effect.
What is the evidence of the uncertainty?
What are the possible benefits?
On the basis of the existing evidence, we can conclude that vitamin D …