Those most likely to be affected by<unk>  are people with little exposure to sunlight. Certain climates, dress habits, the avoidance of sun exposure and the use of too much sunscreen protection can all limit the production of vitamin D. Age Elderly people have a higher risk of having a<unk>  due to a combination of several risk factors, including decreased sunlight exposure, decreased intake of vitamin D in the diet, and decreased skin thickness, which leads to further decreased absorption of vitamin D from sunlight. Fat percentage Since vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol) are fat-soluble, humans and other animals with a skeleton need to store some fat. Without fat, the animal will have a hard time absorbing vitamin D2 and vitamin D3, and the lower the fat percentage, the greater the risk of vitamin deficiency, which is true in some athletes who strive to get as lean as possible. Malnutrition Although rickets and osteomalacia are now rare in Britain, osteomalacia outbreaks in some immigrant communities included women with seemingly adequate daylight outdoor exposure wearing typical Western clothing. Having darker skin and reduced exposure to sunshine did not produce rickets unless the diet deviated from a Western omnivore pattern characterized by high intakes of meat, fish, and eggs and low intakes of high-extraction cereals. In sunny countries where rickets occurs among older toddlers and children, the rickets has been attributed to low dietary calcium intakes. This is characteristic of cereal-based diets with limited access to dairy products. Rickets was formerly a major public health problem among the US population; in Denver, almost two-thirds of 500 children had mild rickets in the late 1920s. An increase in the proportion of animal protein in the 20th-century American diet coupled with increased consumption of milk fortified with relatively small quantities of vitamin D coincided with a dramatic decline in the number of rickets cases. One study of children in a hospital in Uganda, however, showed no significant difference in vitamin D levels of malnourished children compared to non-malnourished children. Because both groups were at risk due to darker skin pigmentation, both groups had<unk> . Nutritional status did not appear to play a role in this study. Obesity There is an increased risk of<unk>  in people who are considered overweight or obese based on their body mass index (BMI) measurement. The relationship between these conditions is not well understood. There are different factors that could contribute to this relationship, particularly diet and sunlight exposure. Alternatively, vitamin D is fat-soluble, so excess amounts can be stored in fat tissue and used during winter, when sun exposure is limited. Sun exposure The use of sunscreen with a sun protection factor of 8 can theoretically inhibit more than 95% of vitamin D production in the skin. In practice, however, sunscreen is applied so as to have a negligible effect on vitamin D status. The vitamin D status of those in Australia and New Zealand is unlikely to have been affected by campaigns advocating sunscreen. Instead, wearing clothing is more effective at reducing the amount of skin exposed to UVB and reducing natural vitamin D synthesis. Clothing that covers a large portion of the skin, when worn on a consistent and regular basis, such as the burqa, is correlated with lower vitamin D levels and an increased prevalence of<unk> . Regions far from the equator have a high seasonal variation of the amount and intensity of sunlight. In the UK, the prevalence of low vitamin D status in children and adolescents is found to be higher in winter than in summer. Lifestyle factors such as indoor versus outdoor work and time spent in outdoor recreation play an important role. Additionally,<unk>  has been associated with urbanisation in terms of both air pollution, which blocks UV light, and an increase in the number of people working indoors. The elderly are generally exposed to less UV light due to hospitalisation, immobility, institutionalisation, and being housebound, leading to decreased levels of vitamin D. Darker skin color Because of melanin which enables natural sun protection, dark-skinned people are susceptible to<unk> . Three to five times greater sun exposure is necessary for naturally darker skinned people to produce the same amount of vitamin D as those with white skin. Malabsorption Rates of<unk>  are higher among people with untreated celiac disease, inflammatory bowel disease, exocrine pancreatic insufficiency from cystic fibrosis, and short bowel syndrome, which can all produce problems of malabsorption.<unk>  is also more common after surgical procedures that reduce absorption from the intestine, including weight loss procedures. Critical illness<unk>  is associated with increased mortality in critical illness. People who take vitamin D supplements before being admitted for intensive care are less likely to die than those who do not take vitamin D supplements. Additionally, vitamin D levels decline during stays in intensive care. Vitamin D3 (cholecalciferol) or calcitriol given orally may reduce the mortality rate without significant adverse effects. Breastfeeding Infants who exclusively breastfeed need a vitamin D supplement, especially if they have dark skin or have minimal sun exposure. The American Academy of Pediatrics recommends that all breastfed infants receive 400 international units (IU) per day of oral vitamin D.
Vitamin D deficiency
Vitamin D toxicity
Endocrine bone disease
Metabolic bone disease
Disorders of calcium metabolism
Steroid-induced osteoporosis
Molybdenum deficiency
Mineral deficiency