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Perspective |
1 Department of Clinical Biochemistry, Royal Infirmary, Glasgow, UK; 2 Department of Clinical Biochemistry, Northwick Park Hospital, Harrow, UK.
aAddress correspondence to this author at: Department of Clinical Biochemistry, Royal Infirmary, Glasgow G4 0SF, United Kingdom. Fax 44-141-5523324; e-mail gbeastall@gri-biochem.org.uk.
| The first 300 words of the full text of this article appear below. |
The role of vitamin D in calcium homeostasis is well established. Recently, there has been growing interest in and evidence for previously unrecognized roles of vitamin D and its metabolites in the physiology of normal health and the pathophysiology of a wide range of clinical disorders. It is an appropriate time to reflect on this recent evidence and the implications for clinical chemists.
the evidence for newly discovered roles for vitamin d
An important clue to roles of vitamin D beyond calcium homeostasis came with the finding that the 1,25-dihydroxyvitamin D nuclear receptor is present in most tissues. A reevaluation of the physiological and pharmacological actions of vitamin D produced evidence that vitamin D can regulate the immune system and thereby is implicated in several immune-mediated diseases. There is also growing evidence that 1,25-dihydroxyvitamin D, the biologically active hormone, may regulate different cellular processes associated with carcinogenesis, including differentiation, proliferation, and apoptosis.
Epidemiological studies have suggested that vitamin D may play a role in protecting against cancer, heart disease, and type 1 diabetes—conditions that account for >60% of all deaths in the western world. In addition the literature contains reports that vitamin D insufficiency may play a role in the development of multiple sclerosis, rheumatoid arthritis, and asthma, and increases the risk of tuberculosis, pneumonia, poor cognitive function, periodontal disease, and reduced muscle tone and lower-extremity function.
The strongest epidemiological evidence for noncalcium-related effects of vitamin D comes from investigations of its role in protection against cancer. For many years common cancers have been known to occur more frequently in northerly populations across the world than in populations close to the equator. As long ago as 1980 Garland and his coworkers suggested that sunlight, and therefore vitamin D, may reduce the likelihood of colon cancer. Subsequent studies suggested that sunlight and vitamin D may have a protective effect on
how much vitamin d do we require?
the implications of new roles for vitamin d for clinical chemistry
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