Vitamin D deficiency occurs when the body doesn't get enough of this essential nutrient from sunlight or diet. This can lead to a range of health issues, including bone density loss, osteoporosis, and fractures. Primary Care Doctor Mindy Lacey, MD, evaluates this condition in patients struggling with fatigue, depressive symptoms, and bone problems. Recent advances in biochemical evaluation have revived interest in this hormone, and it's become more common in recent years.
Vitamin D deficiency may not cause any symptoms initially, but it can increase the risk of long-term health problems. Vitamin D is sometimes called a sun vitamin because the body produces it from cholesterol when the skin is exposed to sunlight. The total level of 25 (OH), D allows diagnosis and monitoring of vitamin D deficiency, while quantifying fractions 25 (OH), D2 and 25 (OH), D3 can facilitate treatment monitoring. Vitamin D3 (D), also known as cholecalciferol, is mainly obtained from skin exposure to ultraviolet B (UVB) radiation from sunlight, ingesting food sources such as oily fish, and variably fortified foods (milk, juices, margarines, yogurts, cereals and soy), and oral supplements.
Renal 24-hydroxylase activity further limits calcitriol availability by creating inert metabolites of both calcitriol (1,24,25-trihydroxyvitamin D) and calcidiol (24,25-dihydroxyvitamin D). Do not take higher than recommended doses of vitamin D without first talking to your healthcare provider. Unfortunately, the commonly recommended daily intake of vitamin D is known to be insufficient if exposure to sunlight is limited. Hypervitaminosis D in the absence of hypercalcemia may lead to further research to assess the etiology of increased vitamin D levels; however, unlike hypercalcemia, it is not a medical emergency.
Vitamin D ingested and produced by the skin rapidly converts to 25 (OH), D, but in serum only a fraction of 25 (OH), D is converted to its active metabolite 1,25 (OH), 2D. The Office of Dietary Supplements (ODS) recommends that people who use a lot of sunscreen or wear clothing that covers the body include sources of vitamin D in their diet. Latitude, cultural dress habits, season, sun avoidance, and sunscreen protection can limit vitamin D production. Standard multivitamin preparations for intravenous parenteral nutrition provide only 200 IU, a dose that helps maintain normal levels of 25 (OH), D in the short term.
but that may not correct vitamin D deficiency. Researchers are investigating whether other symptoms or conditions such as depression, bone pain and weakness may result from low levels of vitamin D. Vitamin D also seems to play a role in insulin production and immune function and how this relates to the prevention of chronic diseases and cancer but research is still under way. In addition to rich sources such as oily fish, the vitamin D content of most foods is between 50 and 200 IU per serving.