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Vitamin D: A D-Lightful Vitamin for Health
Michael F. Holick 대한내분비학회 2012 Endocrinology and metabolism Vol.27 No.4
Vitamin D is a sunshine vitamin that has been produced on this earth for more than 500 million years. Because foods contain so little vitamin D most humans have always depended on sun exposure for their vitamin D requirement. Vitamin D deficiency has been defined as a serum 25-hydroxyvitamin D concentration < 20 ng/mL (50 nmol/L); vitamin D insufficiency as a serum 25-hydroxyvitamin D of 21-29 ng/mL and vitamin D sufficiency as a serum 25-hydroxyvitamin D of 30-100 ng/mL whereas toxicity is usually not seen until blood levels are above 150 ng/mL. Vitamin D deficiency is a global health problem that increases risk for metabolic bone diseases in children and adults as well as many chronic illnesses including autoimmune diseases, type 2 diabetes, cardiovascular disease, infectious disease, and cancer. The major causes of vitamin D deficiency are lack of adequate sensible exposure to sunlight,inadequate dietary intake and obesity. The United States Endocrine Society recommended that to prevent vitamin D deficiency in those at risk, children 1 year and older require 600-1,000 international unit (IU) of vitamin D daily and adults require 1,500-2,000 IU of vitamin D daily. Obese patients require 2-3 times more vitamin D to both treat and prevent vitamin D deficiency.
자외선 조사방법이 육계 병아리의 간장과 골격중 Vitamin $D_{3}$ 및 25-Hydroxyvitamin $D_{3}$ 농도에 미치는 영향
장윤환,이은택,M.F.Holick 한국가금학회 1994 韓國家禽學會誌 Vol.21 No.3
This study was carried out to elucidate the time course variation of vitamin $D_{3}$ (V$D_{3}$) and 25-hydroxyvitamin $D_{3}$ [25(OH)$D_{3}$] contents in the liver and skeleton of 3-wk old broiler chicks when treated with different UV irradiation procedure. Day-old Hubbard chicks were fed vitamin D deficient diet for 3 wk and exposed to medium wave ultraviolet(UVB) light with different irradiation procedures. Procedure I was 30 min continuous irradiation(O.204 mJ /$cm^{2}$) and Procedure II was three seperate 10 min irradiation with 12 h intervals, and Procedure III was three seperate 10 min irradiation with 24 h intervals. The liver and skeleton samples were collected at 10 different times between 0000~2400 h after the last irradiation. The V$D_{3}$ and 25(OH)$D_{3}$ fractions wereseparated by Sep-Pak silica cartridge and the concentrations were determined by normal phase HPLC. The mean content of V$D_{3}$ in the liver of the birds treated by Procedure II was 6.68 ng /g, which was higher than 5.60 and 5.30 ng /g from Procedure I and Ill, respectively(P<.O5). With regard to the effect of elapsed time after UVB irradiation on the V$D_{3}$ concentration of the liver, 96 h treatment showed the highest value(13.08 ng/g)(P<.05). There was a significant(P<O.05) interaction between irradiation procedure and elapsed time. The mean levels of 25(OH)$D_{3}$ were significantly(P<O.05) different among procedures, in which Procedure II showed the highest value(37.41ng /g) followed by Procedure III(29.41) and Procedure I(27.49). With respect to elapsed time after exposure, 12 h treatment showed the highest value(54.71 ng /g) among 10 times tested(P<.05). In regard to the mean content of V$D_{3}$ in the skeleton of tibia and femur, there were no significant differences among Procedure I, II and III, but significant differences were found among those from various elapsed time after irradiation, The highest value was shown at 96 h(O.99 ng /g) treatment, and interaction between irradiation procedure and elapsed time was not significant. With regard to the mean content of 25(OH)$D_{3}$ in bone, the Procedure II(18.79 ng /g) and III(17.73 ng /g) showed higher values than Procedure I did (P<.05), and the 12 h elapsed time showed the highest value(31.17 ng /g) among 10 treatments (P<.05), however, there was no significant interaction between exposing procedure and elapsed time. In conclusion, the Procedure II would he more desirable than Procedure I or III to produce more V$D_{3}$ and 25(OH)$D_{3}$ in the liver and skeleton of birds by exposing to the UVB light. Also, it was verified that 25(OH)$D_{3}$ increases more quickly than V$D_{3}$ in both tissues tested and is utilized more quickly to recover from the rickets of chicks.