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Vitamin D and vitamin D analogues for preventing fractures associated with involutional and post-menopausal osteoporosis. Avenell A, Gillespie WJ, Gillespie LD, O'Connell D. Cochrane Database Syst Rev. 2009 Apr 15;(2):CD000227. Review. PMID: 19370554 DOI: 10.1002/14651858.CD000227.pub3 AUTHORS' CONCLUSIONS: Frail older people confined to institutions may sustain fewer hip fractures if given vitamin D with calcium. Vitamin D alone is unlikely to prevent fracture. Overall there is a small but significant increase in gastrointestinal symptoms and renal disease associated with vitamin D or its analogues. Calcitriol is associated with an increased incidence of hypercalcaemia.

Gonzalez G, Alvarado JN, Rojas A, Navarrete C, Velasquez CG, Arteaga E. High prevalence of vitamin D deficiency in Chilean healthy postmenopausal women with normal sun exposure: additional evidence for a worldwide concern. Menopause. 2007 May-Jun;14(3

Current impediments to acceptance of the ultraviolet-B-vitamin D-cancer hypothesis. Grant WB, Boucher BJ. Anticancer Res. 2009 Sep;29(9):3597-604. PMID: 19667154 The ultraviolet-B (UVB)-vitamin D-cancer hypothesis was proposed in 1980. There have been numerous ecological, observational and other studies of the hypothesis. There are about 14 types of cancer for which it seems to apply: bladder, breast, colon, endometrial, esophageal, gallbladder, gastric, ovarian, pancreatic, rectal, renal and vulvar cancer and both Hodgkin's and non-Hodgkin's lymphoma. Nonetheless, the hypothesis has not yet been accepted by public health agencies. Some of the reasons for this include a distrust of ecological studies, some mistrust of observational studies, and the existence of just one positive randomized controlled trial, an analysis of a vitamin D and calcium supplementation study involving post-menopausal women in Nebraska. Paradigm shifts such as this generally take time, in part due to opposition from those content with the status quo. In this paper, results of ecological studies in the United States using summertime solar UVB as the index of vitamin D production, which is highly asymmetrical with respect to latitude, and indices for other cancer risk-modifying factors (air pollution, alcohol consumption, dietary iron and zinc, ethnic background, socioeconomic status, smoking and urban/rural residence) are discussed in terms of supporting the hypothesis. These studies were not considered while other ecological studies were examined in recent critiques of the hypothesis. While additional randomized controlled trials would, of course, be helpful, the current evidence seems to satisfy the criteria for causality as outlined by A. Bradford Hill.

Vitamin D and breast cancer. Bertone-Johnson ER. Ann Epidemiol. 2009 Jul;19(7):462-7. Epub 2009 Feb 20. Review. PMID: 19230714 Though the relationship between vitamin D and breast cancer remains unclear, a growing body of evidence suggests that vitamin D may modestly reduce risk. A large number of in vitro studies indicate that vitamin D can inhibit cell proliferation and promote apoptosis and cell differentiation in breast tumor tissue. Results from analytic studies of sunlight exposure and dietary intake have been inconsistent but together generally support a modestly protective role of vitamin D, at least in some population subgroups. Studies using blood vitamin D metabolites to assess vitamin D status may be less prone to misclassification than those of diet and sunlight exposure. Overall, the two prospective and four case-control studies of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D tend to support a protective effect in older women. The relationship between common vitamin D receptor polymorphisms and risk remains unclear. Many questions about this relationship clearly remain, including the utility of assessing vitamin D through diet and sunlight exposure, the relationship between plasma metabolites, and the potential modifying effects of age, menopausal status and tumor characteristics. Given that vitamin D status is modifiable, additional prospective studies are necessary to determine if vitamin D may have important potential for breast cancer prevention.

A New Zealand study has found that South Asian women with insulin resistance improved markedly after taking vitamin D supplements Nutrition researcher Pamela von Hurst of the Institute of Food, Nutrition and Human Health at Albany, said while diet and exercise played a major part in the onset of type-2 diabetes, her findings reinforced the importance of vitamin D from the sun and supplements to prevent type-2 diabetes. Initial screening of 235 Auckland women from India, Pakistan and Sri Lanka aged 20 and older, revealed 47 per cent were insulin deficient and 84 per cent were vitamin D deficient. The 81 recruited for the study were split into two groups for a randomised controlled trial and given a vitamin D supplement or placebo. As well as an improvement in insulin resistance among those who took vitamin D for six months, Ms Von Hurst said post-menopausal women in the study also showed a reduced rate of bone breakdown.