Vitamin D: Bone and Beyond, Rationale and Recommendations for Supplementation
Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Fla, USA. The American journal of medicine
(Impact Factor: 5).
10/2009; 122(9):793-802. DOI: 10.1016/j.amjmed.2009.02.029
Adequate vitamin D status is necessary and beneficial for health, although deficiency plagues much of the world's population. In addition to reducing the risk for bone disease, vitamin D plays a role in reduction of falls, as well as decreases in pain, autoimmune diseases, cancer, heart disease, mortality, and cognitive function. On the basis of this emerging understanding, improving patients' vitamin D status has become an essential aspect of primary care. Although some have suggested increased sun exposure to increase serum vitamin D levels, this has the potential to induce photoaging and skin cancer, especially in patients at risk for these conditions. Vitamin D deficiency and insufficiency can be both corrected and prevented safely through supplementation.
Available from: Eric Descombes
- "Indeed, recent studies have shown that several tissues, in addition to the kidneys, express the enzyme CYP27B1, which catalyzes the 1í µí»¼-hydroxylation of 25(OH)D, and that the vitamin D receptor (VDR) is expressed ubiquitously           . It is now known that a conversion of 25(OH)D to 1í µí»¼,25-dihydroxyvitamin D (calcitriol, the active form of vitamin D) occurs in several extrarenal cells and may be associated with significant biological roles beyond those traditionally attributed to vitamin D           . "
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ABSTRACT: The aim of the present study was to evaluate the dose of postdialysis cholecalciferol needed to maintain the 25-hydroxyvitamin D [25(OH)D] levels in the optimal range of 75-150 nmol/L. Twenty-six patients who had low baseline 25(OH)D levels (mean 27.5 ± 14.9 nmol/L) were studied. The 25(OH)D levels were measured every 2 months for one year. During the first two months, all the patients received 2000 IU of cholecalciferol after each hemodialysis (=6000 IU/wk). Thereafter, the dose was individualized and adapted every 2 months by administering 1 to 6 cholecalciferol tablets (2000 IU each) per week (total weekly dose = 2000-12000 IU/wk). During cholecalciferol supplementation, the 25(OH)D concentrations rapidly increased from baseline to 140.1 ± 28.3 nmol/L at month 6 and 95.6 ± 20.9 nmol/L at month 12. At month twelve, 86% of the patients had 25(OH)D levels within the target range with a mean dose of 5917 ± 4106 IU/wk of cholecalciferol; however, the amount needed to maintain these levels varied widely from 0 (n = 2) to 12000 IU/wk (n = 5). In conclusion, postdialysis cholecalciferol prescription is quite effective in correcting vitamin D deficiency/insufficiency, but the amount of cholecalciferol needed to maintain the 25(OH)D levels within the optimal range over the long-term varies widely among patients and must be individualized.
Available from: Rae Woong Park
- "In addition, increased air pollution in urban centers blocks UV radiation, decreasing vitamin D photosynthesis. There is still no published guideline regarding sunlight exposure for prevention and treatment of vitamin D deficiency, because many factors are associated with photosynthesis of vitamin D. Weather, latitude, altitude, air pollution, age, exposed skin area, and use of sunblock may influence vitamin D synthesis in human skin.27) "
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ABSTRACT: Vitamin D is an important factor in human health. Yet, vitamin D deficiency is very common. We aimed to confirm serum 25-hydroxyvitamin D (25OHD) concentration change after sunlight exposure and to elucidate the relationship between the amount of sunlight exposure and serum 25OHD level change by ambulatory lux meter and sunlight exposure questionnaire.
Twenty healthy young women were enrolled. They were educated to obtain 20 minutes of sunlight exposure during weekdays from October to November, 2010, during which they were to wear an ambulatory lux meter on an arm. All subjects completed a one-week recall sunlight exposure questionnaire at the end of the study. Before and after sunlight exposure, serum 25OHD level was measured.
Mean pre-exposure serum 25OHD concentration was 11.01 ng/mL. The mean change of pre- and post-exposure 25OHD level was -0.62 ng/mL, but it was not statistically significant. The mean personal sunlight exposure recorded by ambulatory lux meter, 292.6 lux/s, showed no significant relationship with average change of 25OHD and average weekly sunlight exposure score, 11.9, calculated by the sunlight exposure questionnaire. However, the mean change of serum 25OHD level and weekly sunlight exposure score showed significant negative correlation (r = -0.469, P = 0.037).
Change of serum 25OHD concentration after four weeks of sunlight exposure was not statistically significant in women with vitamin D deficiency. However, serum 25OHD concentration change was significantly negatively correlated with the sunlight exposure score by the questionnaire.
Available from: Athanasios N Ververidis
- "Inadequate response to BP treatment has also been observed despite vitamin D supplementation. For every 100 IU of supplementation, an elevation of 1 ng/mL of serum 25(OH)D is expected [35, 36]. However, factors such as baseline 25(OH)D serum concentrations, obesity, age, or associated clinical conditions, among others, may influence this response. "
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ABSTRACT: Vitamin D is important for normal development and maintenance of the skeleton. Hypovitaminosis D adversely affects calcium metabolism, osteoblastic activity, matrix ossi�cation, bone remodeling and bone density. It is well known that Vit. D de�ciency in the developing skeleton is related to rickets, while in adults is related to osteomalacia. e causes of rickets include conditions that lead to hypocalcemia and/or hypophosphatemia, either isolated or secondary to vitamin D de�ciency. In osteomalacia, Vit. D de�ciency leads to impairment of the mineralisation phase of bone remodeling and thus an increasing amount of the skeleton being replaced by unmineralized osteoid. e relationship between Vit. D and bone mineral density and osteoporosis are still controversial while new evidence suggests that Vit. D may play a role in other bone conditions such as osteoarthritis and stress fractures. In order to maintain a "good bone health" guidelines concerning the recommended dietary intakes should be followed and screening for Vit. D de�ciency in individuals at risk for de�ciency is re�uired, followed by the appropriate action.
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