Curr Drug Targets. 2010 Aug 27.
Department of Medicine, Section of Endocrinology, Nutrition, and Diabetes, Vitamin D, Skin and Bone Research Laboratory, Boston University Medical Center, Boston, MA, USA. mfholick at bu.edu.
Vitamin D, the sunshine vitamin, has been important not only for the evolution of a healthy calcified vertebrate skeleton but it also evolved into a hormone that has a wide diversity of biologic effects. During exposure to sunlight the ultraviolet B radiation converts 7-dehydrocholesterol to previtamin D(3) which in turn rapidly isomerizes to vitamin D(3). Once formed, vitamin D(3) is metabolized in the liver to 25-hydroxyvitamin D(3) and in the kidneys to its active form 1,25-dihydroxyvitamin D(3). 1,25-dihydroxyvitamin D(3) interacts with its vitamin D receptor in calcium regulating tissues to regulate calcium metabolism and bone health. It is now recognized that most cells in the body have a vitamin D receptor and they also have the capability of producing 1,25-dihydroxyvitamin D(3) which in turn is capable of regulating a wide variety of genes that have important functions in regulating cell growth, modulating immune function and cardiovascular health.
Epidemiologic evidence and prospective studies have linked vitamin D deficiency with increased risk of many chronic diseases including autoimmune diseases, cardiovascular disease, deadly cancers, type II diabetes and infectious diseases. Vitamin D deficiency and insufficiency have been defined as a 25-hydroxyvitamin D <20 ng/ml and 21-29 ng/ml respectively.
For every 100 IU of vitamin D ingested the blood level of 25-hydroxyvitamin D, the measure vitamin D status, increases by 1 ng/ml. It is estimated that children need at least 400-1000 IU of vitamin D a day while teenagers and adults need at least 2000 IU of vitamin D a day to satisfy their body's vitamin D requirement. It is estimated that 1 billion people worldwide are vitamin D deficient or insufficient. Correcting and preventing this deficiency could have an enormous impact on reducing health costs worldwide. PMID: 20795941
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It appears that 100 IU per ng would be a horizontal line at 10 on the vertical axis of the following graph