human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVE To assess the serum level of 25 hydroxyvitamin D 25OHD  among healthy Saudi Arabian women living in the eastern province . METHODS A cross-sectional r and omized study was conducted between February 1st 2008 and May 31st 2008 at the King Fahd University Hospital , Al-Khobar , Kingdom of Saudi Arabia in 200 Saudi women between 25 - 35 years group 1 and women of > or = 50 years group 2 .  Clinical examination , laboratory tests , a complete blood picture , serum calcium , phosphorous , alkaline phosphatase , parathormone , and the serum levels of 25OHD levels were carried out . Data on lifestyle , dietary , and demographic question naires were collected . Vitamin D was defined as deficient with serum level < 50 nmol/L , insufficient between 52 - 72 nmol/L , and normal as 75nmol/L. RESULTS In group 1 , 70 % of women had normal 25OHD , and in women of group 2 , 45 % had normal levels of 25OHD . Alkaline phosphatase and parathormone levels were significantly higher in women with low vitamin D levels . Sun exposure and consumption of dairy products were minimal . CONCLUSION Vitamin D deficiency among healthy young Saudi women of 25 - 35 years was 30 % and 55 % in women of > or = 50 years . This study indicates that hypovitaminosis D is common in young and postmenopausal women . Efforts are require to augment and encouraged women for adequate exposure to sunlight and increased intake of fortified vitamin D products to maintain skeletal health Background : Calcium absorption is generally considered to be impaired under conditions of vitamin D deficiency , but the vitamin D status that fully normalizes absorption is not known for humans . Objective : To quantify calcium absorption at two levels of vitamin D repletion , using pharmacokinetic methods and commercially marketed calcium supplements . Design : Two experiments performed in the spring of the year , one year apart . In the first , in which participants were pretreated with 25-hydroxyvitamin D ( 25OHD )  , mean serum 25OHD concentration was 86.5 nmol/L ; and in the other , with no pretreatment , mean serum concentration was 50.2 nmol/L. Participants received 500 mg oral calcium loads as a part of a st and ard low calcium breakfast . A low calcium lunch was provided at mid-day . Blood was obtained fasting and at frequent intervals for 10 to 12 hours thereafter . Methods : Relative calcium absorption at the two 25OHD concentrations was estimated from the area under the curve ( AUC ) for the load-induced increment in serum total calcium . Results : AUC9 ( ± SEM ) , was 3.63 mg hr/dL ± 0.234 in participants pretreated with 25OHD  and 2.20 ± 0.240 in those not pretreated ( P < 0.001 ) . In brief , absorption was 65 % higher at serum 25OHD levels averaging 86.5 nmol/L than at levels averaging 50 nmol/L ( both values within the nominal reference range for this analyte ) . Conclusions : Despite the fact that the mean serum 25OHD level in the experiment without supplementation was within the current reference ranges , calcium absorptive performance at 50 nmol/L was significantly reduced relative to that at a mean 25OHD level of 86 nmol/L. Thus , individuals with serum 25-hydroxyvitamin D levels at the low end of the current reference ranges may not be getting the full benefit from their calcium intake . We conclude that the lower end of the current reference range is set too low Summary This study aim ed to compare the  vitamin D status  in healthy Moroccan men and women aged 50 years and older . A total of 186 Moroccan women and 68 men , who had no previous diagnosis of osteoporosis , were recruited prospect ively . We found in this study a high prevalence of hypovitaminosis D with no difference between men and women . Purpose The main purpose of this study was to describe and compare the  vitamin D status , parathormone , calcium , and phosphate  of healthy Moroccan men and women aged 50 years and older . Methods We conducted two cross-sectional studies , in postmenopausal women from October 2008 to November 2009 and in men over 50 years old , from December 2009 to August 2010 . A total of 186 Moroccan women and 68 men , who had no previous diagnosis of osteoporosis , were recruited prospect ively . For the definition of hypovitaminosis D , the preferred level for 25-hydroxyvitamin D ( 25(OH)D ) insufficiency , which is now recommended by many experts , is 30 ng/mL ( 75 nmol/L ) , and the levels below 10 ng/ml ( 25 nmol/L ) indicate deficiency . Results The prevalence of vitamin D deficiency in men and women was 4.4 and 8.6 % , respectively , and the prevalence of vitamin D(25(OH ) D ) insufficiency in men and women were 85.2 and 77.4 % , respectively . In men and women , no correlations were found between intact parathormone ( PTHi ) and 25(OH ) D ( r = 0.056 ) . Conclusions Despite a sunny environment , we found in this study a high prevalence of hypovitaminosis D ( insufficiency + deficiency ) in Moroccan men over 50 years old and postmenopausal women INTRODUCTION Vitamin D status is considered as an important determinant of bone health but supplementation trials with vitamin D(3 ) have yielded conflicting results . The aim of this study was to investigate the associations between serum 25-hydroxyvitamin D ( 25-OH D ) , bone turnover markers , bone mineral density ( BMD ) , radius bone loss and incidence of fracture in postmenopausal women . METHODS 669 postmenopausal women ( mean age : 62.2 years ) belonging to a population -based cohort were followed prospect ively for a median of 11.2 years . At baseline , 25-OH D levels , BMD , bone turnover markers and clinical risk factors of osteoporosis were assessed . BMD loss at the radius was estimated by annual measurements of BMD and all incident fractures which occurred in 134 women were confirmed by radiographs . RESULTS 73 % and 35 % of women had serum 25-OH D levels below 75 and 50 nmol/l which correspond respectively to the median and lowest optimal values recently proposed for fracture prevention . 11 % of women had levels below 30 nmol/l . Serum 25-OH D correlated modestly with intact PTH ( r(2)=0.023 , p<0.0001 ) , but not with bone turnover markers or BMD at the hip and radius after adjustment for age . When levels of 25-OH D were considered as a continuous variable , there was no significant association between 25-OH D levels and radius BMD loss or fracture risk . After adjustment for age , there was no significant difference in incidence of fracture , BMD , radius BMD loss , bone turnover markers , grip strength and the percentage of fallers in the previous year between women with 25-OH D levels below or above 75 , 50 or 30 nmol/l . CONCLUSIONS In a population of home-dwelling healthy postmenopausal women with few of them with severe vitamin D deficiency , vitamin D status may not be an important determinant of bone health Objective : The aim of this study was to evaluate serum N-aminoterminal propeptide of type I collagen ( P1NP ) , C-terminal telopeptide of type I collagen ( & bgr;-CTX ) , and vitamin D status in healthy Chinese postmenopausal women . The study was also design ed to investigate their possible relationships with osteoporosis phenotypes . Methods : A community-based population of 1,724 postmenopausal women in Beijing was r and omly selected .  Serum bone turnover markers and 25-hydroxyvitamin D [ 25(OH)D ]  were tested by an automated Roche electrochemiluminescence system . Dual-energy x-ray absorptiometry was used to measure bone mineral density ( BMD ) . Results : The mean ( SD ) values of serum & bgr;-CTX and P1NP were 0.439 ( 0.210 ) and 56.7 ( 27.9 ) ng/mL , respectively . The 25(OH)D level of postmenopausal women in Beijing was remarkably low ( 13.2 ± 5.4 ng/mL ) . Serum & bgr;-CTX and P1NP levels were negatively correlated with BMDs of lumbar spine , femoral neck , and total hip ( all P < 0.01 ) . The cubic regression model better fitted the relationships of BMD and bone turnover markers . Serum & bgr;-CTX levels were significantly higher in women with sustained osteoporotic fracture or vertebral fracture ( P = 0.006 and 0.012 , respectively ) . No association between P1NP and fracture or vertebral fracture was detected . The same situation applied to 25(OH)D. 25(OH)D was negatively correlated with & bgr;-CTX and P1NP ( r = −0.073 and −0.088 , P = 0.002 and < 0.001 , respectively ) . Conclusions : Serum & bgr;-CTX and P1NP levels were negatively correlated with BMD . & bgr;-CTX was significantly higher in postmenopausal women with sustained fracture or vertebral fracture . Vitamin D deficiency was highly prevalent in postmenopausal women in Beijing There is an increase in the incidence of falls with aging and about 10 % of falls lead to fractures . Nearly all hip fractures are due to falls and hip fractures are the most severe of the osteoporotic fractures because they lead to a 20 % mortality rate and a loss of independent living in 50 % of cases . Although there are multiple factors associated with falls , our interest is the role that vitamin D metabolism plays in the pathogenesis of falls . Recent clinical trials show that both vitamin D and the metabolite calcitriol reduce the number of falls by 30 - 40 % in elderly subjects . This should also reduce the number of fractures . In European studies , the decrease in falls could be attributed to an improvement in the muscle weakness that often accompanies vitamin D deficiency . However , in the studies using calcitriol there was no vitamin D deficiency , so the mechanism of its efficacy is less clear . It could be due to increased muscle strength , an improvement in the neurological control of balance or both . Underst and ing these mechanisms would allow us to search for analogs of vitamin D that act more selectively on muscle and on the central nervous system Throughout evolution , exposure to sunlight and the photo synthesis of vitamin D(3 ) in the skin has been critically important for the evolution of l and vertebrates . During exposure to sunlight , the solar UVB photons with energies 290 - 315 nm are absorbed by 7-dehydrocholesterol in the skin and converted to previtamin D(3 ) . Previtamin D(3 ) undergoes a rapid transformation within the plasma membrane to vitamin D(3 ) . Excessive exposure to sunlight will not result in vitamin D intoxication because both previtamin D(3 ) and vitamin D(3 ) are photolyzed to several noncalcemic photoproducts . During the winter at latitudes above approximately 35 degrees , there is minimal , if any , previtamin D(3 ) production in the skin . Altitude also has a significant effect on vitamin D(3 ) production . At 27 degrees N in November , very little ( approximately 0.5 % ) previtamin D(3 ) synthesis was detected in Agra ( 169 m ) and Katm and u ( 1400 m ) . There was an approximately 2- and 4-fold increase in previtamin D(3 ) production at approximately 3400 m and at Everest base camp ( 5300 m ) , respectively . Increased skin pigmentation , application of a sunscreen , aging , and clothing have a dramatic effect on previtamin D(3 ) production in the skin . It is estimated that exposure in a bathing suit to 1 minimal erythemal dose ( MED ) is equivalent to ingesting between 10,000 and 25,000 IU of vitamin D(2 ) . The importance of sunlight for providing most humans with their vitamin D requirement is well documented by the seasonal variation in circulating levels of 25-hydroxyvitamin D [ 25(OH)D ] . Vitamin D deficiency [ i.e. , 25(OH)D < 20 ng/ml ] is common in both children and adults worldwide . Exposure to lamps that produce UVB radiation is an excellent source for producing vitamin D(3 ) in the skin and is especially efficacious in patients with fat malabsorption syndromes . The major cause of vitamin D deficiency globally is an underappreciation of sunlight 's role in providing humans with their vitamin D(3 ) requirement . Very few foods naturally contain vitamin D , and those that do have 
    Output:
    
agent
Neither latitude , region of the world , nor laboratory methodology were found to be associated with the prevalence of hypovitaminosis
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVE To assess the serum level of 25 hydroxyvitamin D 25OHD  among healthy Saudi Arabian women living in the eastern province . METHODS A cross-sectional r and omized study was conducted between February 1st 2008 and May 31st 2008 at the King Fahd University Hospital , Al-Khobar , Kingdom of Saudi Arabia in 200 Saudi women between 25 - 35 years group 1 and women of > or = 50 years group 2 .  Clinical examination , laboratory tests , a complete blood picture , serum calcium , phosphorous , alkaline phosphatase , parathormone , and the serum levels of 25OHD levels were carried out . Data on lifestyle , dietary , and demographic question naires were collected . Vitamin D was defined as deficient with serum level < 50 nmol/L , insufficient between 52 - 72 nmol/L , and normal as 75nmol/L. RESULTS In group 1 , 70 % of women had normal 25OHD , and in women of group 2 , 45 % had normal levels of 25OHD . Alkaline phosphatase and parathormone levels were significantly higher in women with low vitamin D levels . Sun exposure and consumption of dairy products were minimal . CONCLUSION Vitamin D deficiency among healthy young Saudi women of 25 - 35 years was 30 % and 55 % in women of > or = 50 years . This study indicates that hypovitaminosis D is common in young and postmenopausal women . Efforts are require to augment and encouraged women for adequate exposure to sunlight and increased intake of fortified vitamin D products to maintain skeletal health Background : Calcium absorption is generally considered to be impaired under conditions of vitamin D deficiency , but the vitamin D status that fully normalizes absorption is not known for humans . Objective : To quantify calcium absorption at two levels of vitamin D repletion , using pharmacokinetic methods and commercially marketed calcium supplements . Design : Two experiments performed in the spring of the year , one year apart . In the first , in which participants were pretreated with 25-hydroxyvitamin D ( 25OHD )  , mean serum 25OHD concentration was 86.5 nmol/L ; and in the other , with no pretreatment , mean serum concentration was 50.2 nmol/L. Participants received 500 mg oral calcium loads as a part of a st and ard low calcium breakfast . A low calcium lunch was provided at mid-day . Blood was obtained fasting and at frequent intervals for 10 to 12 hours thereafter . Methods : Relative calcium absorption at the two 25OHD concentrations was estimated from the area under the curve ( AUC ) for the load-induced increment in serum total calcium . Results : AUC9 ( ± SEM ) , was 3.63 mg hr/dL ± 0.234 in participants pretreated with 25OHD  and 2.20 ± 0.240 in those not pretreated ( P < 0.001 ) . In brief , absorption was 65 % higher at serum 25OHD levels averaging 86.5 nmol/L than at levels averaging 50 nmol/L ( both values within the nominal reference range for this analyte ) . Conclusions : Despite the fact that the mean serum 25OHD level in the experiment without supplementation was within the current reference ranges , calcium absorptive performance at 50 nmol/L was significantly reduced relative to that at a mean 25OHD level of 86 nmol/L. Thus , individuals with serum 25-hydroxyvitamin D levels at the low end of the current reference ranges may not be getting the full benefit from their calcium intake . We conclude that the lower end of the current reference range is set too low Summary This study aim ed to compare the  vitamin D status  in healthy Moroccan men and women aged 50 years and older . A total of 186 Moroccan women and 68 men , who had no previous diagnosis of osteoporosis , were recruited prospect ively . We found in this study a high prevalence of hypovitaminosis D with no difference between men and women . Purpose The main purpose of this study was to describe and compare the  vitamin D status , parathormone , calcium , and phosphate  of healthy Moroccan men and women aged 50 years and older . Methods We conducted two cross-sectional studies , in postmenopausal women from October 2008 to November 2009 and in men over 50 years old , from December 2009 to August 2010 . A total of 186 Moroccan women and 68 men , who had no previous diagnosis of osteoporosis , were recruited prospect ively . For the definition of hypovitaminosis D , the preferred level for 25-hydroxyvitamin D ( 25(OH)D ) insufficiency , which is now recommended by many experts , is 30 ng/mL ( 75 nmol/L ) , and the levels below 10 ng/ml ( 25 nmol/L ) indicate deficiency . Results The prevalence of vitamin D deficiency in men and women was 4.4 and 8.6 % , respectively , and the prevalence of vitamin D(25(OH ) D ) insufficiency in men and women were 85.2 and 77.4 % , respectively . In men and women , no correlations were found between intact parathormone ( PTHi ) and 25(OH ) D ( r = 0.056 ) . Conclusions Despite a sunny environment , we found in this study a high prevalence of hypovitaminosis D ( insufficiency + deficiency ) in Moroccan men over 50 years old and postmenopausal women INTRODUCTION Vitamin D status is considered as an important determinant of bone health but supplementation trials with vitamin D(3 ) have yielded conflicting results . The aim of this study was to investigate the associations between serum 25-hydroxyvitamin D ( 25-OH D ) , bone turnover markers , bone mineral density ( BMD ) , radius bone loss and incidence of fracture in postmenopausal women . METHODS 669 postmenopausal women ( mean age : 62.2 years ) belonging to a population -based cohort were followed prospect ively for a median of 11.2 years . At baseline , 25-OH D levels , BMD , bone turnover markers and clinical risk factors of osteoporosis were assessed . BMD loss at the radius was estimated by annual measurements of BMD and all incident fractures which occurred in 134 women were confirmed by radiographs . RESULTS 73 % and 35 % of women had serum 25-OH D levels below 75 and 50 nmol/l which correspond respectively to the median and lowest optimal values recently proposed for fracture prevention . 11 % of women had levels below 30 nmol/l . Serum 25-OH D correlated modestly with intact PTH ( r(2)=0.023 , p<0.0001 ) , but not with bone turnover markers or BMD at the hip and radius after adjustment for age . When levels of 25-OH D were considered as a continuous variable , there was no significant association between 25-OH D levels and radius BMD loss or fracture risk . After adjustment for age , there was no significant difference in incidence of fracture , BMD , radius BMD loss , bone turnover markers , grip strength and the percentage of fallers in the previous year between women with 25-OH D levels below or above 75 , 50 or 30 nmol/l . CONCLUSIONS In a population of home-dwelling healthy postmenopausal women with few of them with severe vitamin D deficiency , vitamin D status may not be an important determinant of bone health Objective : The aim of this study was to evaluate serum N-aminoterminal propeptide of type I collagen ( P1NP ) , C-terminal telopeptide of type I collagen ( & bgr;-CTX ) , and vitamin D status in healthy Chinese postmenopausal women . The study was also design ed to investigate their possible relationships with osteoporosis phenotypes . Methods : A community-based population of 1,724 postmenopausal women in Beijing was r and omly selected .  Serum bone turnover markers and 25-hydroxyvitamin D [ 25(OH)D ]  were tested by an automated Roche electrochemiluminescence system . Dual-energy x-ray absorptiometry was used to measure bone mineral density ( BMD ) . Results : The mean ( SD ) values of serum & bgr;-CTX and P1NP were 0.439 ( 0.210 ) and 56.7 ( 27.9 ) ng/mL , respectively . The 25(OH)D level of postmenopausal women in Beijing was remarkably low ( 13.2 ± 5.4 ng/mL ) . Serum & bgr;-CTX and P1NP levels were negatively correlated with BMDs of lumbar spine , femoral neck , and total hip ( all P < 0.01 ) . The cubic regression model better fitted the relationships of BMD and bone turnover markers . Serum & bgr;-CTX levels were significantly higher in women with sustained osteoporotic fracture or vertebral fracture ( P = 0.006 and 0.012 , respectively ) . No association between P1NP and fracture or vertebral fracture was detected . The same situation applied to 25(OH)D. 25(OH)D was negatively correlated with & bgr;-CTX and P1NP ( r = −0.073 and −0.088 , P = 0.002 and < 0.001 , respectively ) . Conclusions : Serum & bgr;-CTX and P1NP levels were negatively correlated with BMD . & bgr;-CTX was significantly higher in postmenopausal women with sustained fracture or vertebral fracture . Vitamin D deficiency was highly prevalent in postmenopausal women in Beijing There is an increase in the incidence of falls with aging and about 10 % of falls lead to fractures . Nearly all hip fractures are due to falls and hip fractures are the most severe of the osteoporotic fractures because they lead to a 20 % mortality rate and a loss of independent living in 50 % of cases . Although there are multiple factors associated with falls , our interest is the role that vitamin D metabolism plays in the pathogenesis of falls . Recent clinical trials show that both vitamin D and the metabolite calcitriol reduce the number of falls by 30 - 40 % in elderly subjects . This should also reduce the number of fractures . In European studies , the decrease in falls could be attributed to an improvement in the muscle weakness that often accompanies vitamin D deficiency . However , in the studies using calcitriol there was no vitamin D deficiency , so the mechanism of its efficacy is less clear . It could be due to increased muscle strength , an improvement in the neurological control of balance or both . Underst and ing these mechanisms would allow us to search for analogs of vitamin D that act more selectively on muscle and on the central nervous system Throughout evolution , exposure to sunlight and the photo synthesis of vitamin D(3 ) in the skin has been critically important for the evolution of l and vertebrates . During exposure to sunlight , the solar UVB photons with energies 290 - 315 nm are absorbed by 7-dehydrocholesterol in the skin and converted to previtamin D(3 ) . Previtamin D(3 ) undergoes a rapid transformation within the plasma membrane to vitamin D(3 ) . Excessive exposure to sunlight will not result in vitamin D intoxication because both previtamin D(3 ) and vitamin D(3 ) are photolyzed to several noncalcemic photoproducts . During the winter at latitudes above approximately 35 degrees , there is minimal , if any , previtamin D(3 ) production in the skin . Altitude also has a significant effect on vitamin D(3 ) production . At 27 degrees N in November , very little ( approximately 0.5 % ) previtamin D(3 ) synthesis was detected in Agra ( 169 m ) and Katm and u ( 1400 m ) . There was an approximately 2- and 4-fold increase in previtamin D(3 ) production at approximately 3400 m and at Everest base camp ( 5300 m ) , respectively . Increased skin pigmentation , application of a sunscreen , aging , and clothing have a dramatic effect on previtamin D(3 ) production in the skin . It is estimated that exposure in a bathing suit to 1 minimal erythemal dose ( MED ) is equivalent to ingesting between 10,000 and 25,000 IU of vitamin D(2 ) . The importance of sunlight for providing most humans with their vitamin D requirement is well documented by the seasonal variation in circulating levels of 25-hydroxyvitamin D [ 25(OH)D ] . Vitamin D deficiency [ i.e. , 25(OH)D < 20 ng/ml ] is common in both children and adults worldwide . Exposure to lamps that produce UVB radiation is an excellent source for producing vitamin D(3 ) in the skin and is especially efficacious in patients with fat malabsorption syndromes . The major cause of vitamin D deficiency globally is an underappreciation of sunlight 's role in providing humans with their vitamin D(3 ) requirement . Very few foods naturally contain vitamin D , and those that do have 
    Output:
    