LAUSR

Vitamin D has long been recognised for its role in maintaining good skeletal health in both adults and children, including the rapid bone mineral accrual in infants, and prevention of rickets in children and osteomalacia in adults [1, 2]. Studies suggest that vitamin D, an essential hormone ingested from the diet (food and supplements) or synthesised in the skin when exposed to UV-B radiation, regulates calcium, phosphorous and bone metabolism, promotes skeletal muscle strength, inhibits cell proliferation, promotes cell differentiation, reduces inflammation, modulates the renin-angiotensin system, and influences glucose metabolism [3, 4]. Vitamin D obtained from the above sources is the biologically inactive and after undergoing first enzymatic hydroxylation reactions in the liver forms 25-hydroxyvitamin D (25(OH)D), an intermediate product which is stored and circulated. Only a small fraction of 25(OH)D is then converted to the physiologically active hormone, calcitriol (1,25-dihydroxyvitamin D) following second reaction in the kidney [5, 6]. Although people living in low latitudes (e.g. large parts of Asia and Africa) are exposed to abundant sunlight and should therefore, in theory, have low risk of vitamin D deficiency and related morbidities, the evidence, however, suggests the contrary; previous studies have reported high prevalence of vitamin D deficiency in these regions, likely to be contributed by other factors including skin complexion, limited outdoor exposure, vegetarian diet, and poorly implemented (or lack of) vitamin D food fortification programmes [7]. Worldwide it is estimated that up to one billion children and adults are vitamin D deficient (plasma 25(OH)D <20 ng·mL−1, with the preferred range of 25(OH)D concentration being 40–60 ng·mL−1) [4]. Many developed countries, including Canada and USA, have been fortifying milk with Vitamin D to maintain the recommended daily intake level of vitamin D [8]. Even so, there is a growing concern in Europe that the high prevalence of low vitamin D intake is causing vitamin D deficiency [9]. Vitamin D deficiency is associated with a number of poor health outcomes but the reported findings on incidence of lung cancer and mortality are inconsistent. The current study does not support a causal link between vitamin D and lung cancer. http://ow.ly/NrAd30k94Oq