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 In observational studies , low serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations have been associated with insulin resistance and other risk factors for cardiovascular disease . RESEARCH DESIGN AND METHODS We present 1-year data from an ongoing 5-year trial in 511 individuals with impaired fasting glucose ( IFG ) and /or impaired glucose tolerance ( IGT ) r and omly assigned to 20,000 IU/week vitamin D3 or placebo .  An oral glucose tolerance test was performed at baseline and after 1 year . RESULTS Mean baseline serum 25(OH)D was 59.9 nmol/L and 61.1 nmol/L in the vitamin D and placebo groups , respectively , and increased by 45.8 nmol/L and 3.4 nmol/L , respectively . With adjustment for baseline concentrations , no differences in measures of glucose metabolism , insulin secretion or sensitivity , blood pressure , or hs-CRP were found after 1 year . There was a slight , but significant decrease in total and LDL cholesterol in the vitamin D group compared with the placebo group , but as there was also a decrease in HDL cholesterol , the change in the total/HDL cholesterol ratio did not differ significantly . Only analyzing subjects with 25(OH)D < 50 nmol/L did not change the results . CONCLUSIONS This study shows that vitamin D supplementation does not improve glycemic indices , blood pressure , or lipid status in subjects with IFG and /or IGT BACKGROUND Studies suggest that vitamin D deficiency is a risk factor for cardiovascular disease and diabetes . Vitamin D deficiency is prevalent in HIV patients but the effect of vitamin D supplementation on cardiovascular risk in this population is unknown . METHODS We conducted a r and omized , double-blind , placebo-controlled trial among 45 HIV-infected adults in Clevel and ( OH , USA ) on stable antiretroviral therapy with durable virological suppression and a baseline serum 25-hydroxyvitamin D level of ≤20 ng/ml . Participants were r and omized 2:1 to vitamin D3 4,000 IU daily or placebo  for 12 weeks . The primary outcome was a change in flow-mediated brachial artery dilation ( FMD ) . RESULTS Baseline demographics were similar except for age ( vitamin D versus placebo , mean ±sd 47 ±8 versus 40 ±10 years ; P=0.009 ) . Both groups had reduced FMD at baseline ( median values 2.9 % [ IQR 1.6 - 4.8 ] for vitamin D versus 2.5 % [ IQR 1.7 - 6.4 ] for placebo ; P=0.819 ) . Despite an increase in the concentration of serum 25-hydroxyvitamin D from baseline to 12 weeks ( 5.0 ng/ml [ IQR -0.9 - 7.4 ] versus -1.9 ng/ml [ IQR -4.0 - 0.1 ] for vitamin D versus placebo , respectively ; P=0.003 ) , there was no difference in FMD change ( 0.55 % [ IQR -1.05 - 2.13 ] versus 0.29 % [ IQR -1.61 - 1.77 ] ; P=0.748 ) . Vitamin D supplementation was associated with a decrease in total and non-high-density lipoprotein cholesterol , and an increase in indices of insulin resistance . CONCLUSIONS Among HIV-infected individuals with vitamin D deficiency , supplementation with 4,000 IU vitamin D3 daily for 12 weeks modestly improved vitamin D status and cholesterol but worsened insulin resistance without change in endothelial function . The mechanisms of resistance to st and ard doses of vitamin D and the complex role of vitamin D in glucose metabolism in this population require further investigation OBJECTIVE Low vitamin D levels and risk factors for vascular disease are both common in South Asian women . This trial evaluated whether vitamin D supplementation could improve markers of vascular health in South Asian women with low 25-hydroxyvitamin D levels . METHODS Parallel-group , double-blind , r and omised placebo-controlled trial . Healthy South Asian women with baseline serum 25-hydroxyvitamin D levels of < 75 nmol/L were r and omised to receive a single dose of 100,000 units oral vitamin D3 or matching placebo . Outcomes were measured at baseline , 4 and 8 weeks . The primary outcome was change in endothelial function measured using brachial artery flow-mediated dilatation . Secondary outcomes included blood pressure , arterial stiffness , microvascular function measured using laser Doppler iontophoresis , insulin resistance , serum lipids , circulating markers of inflammation , thrombosis and adipokines . RESULTS 50 women were r and omised , 25 to each group . Mean age was 41 years ; mean baseline 25-hydroxyvitamin D level was 27 nmol/L.  25-Hydroxyvitamin D levels rose in the vitamin D group relative to the placebo group by 4 weeks ( 16 nmol/L , 95 % CI 11 to 21 , p < 0.001 ) . There was no improvement in flow-mediated dilatation in the vitamin D group relative to placebo at 4 weeks ( 0.1 % , 95 % CI -0.9 to 1.1 , p = 0.84 ) or 8 weeks ( 0.0 % , 95 % CI -1.4 to 1.4 , p = 0.98 ) . There was no improvement in cholesterol , insulin resistance or markers of inflammation . Both platelet activation inhibitor-1 and tissue plasminogen activator levels fell significantly in the vitamin D group relative to placebo at 8 weeks . CONCLUSION A single large dose of vitamin D3 did not improve blood pressure or endothelial function in South Asian women with low baseline 25-hydroxyvitamin D levels . TRIAL REGISTRATION IS RCT N75081811 BACKGROUND Low 25-hydroxy-vitamin D ( 25(OH)D ) levels are inversely related to blood pressure ( BP ) and have been associated with incident hypertension . In people living at northern latitudes diminished cholecalciferol synthesis in the winter increases the risk of vitamin D deficiency . We wanted to test the hypothesis that daily cholecalciferol supplementation in the winter lowers BP in patients with hypertension . METHODS We investigated the effect of 75 µg ( 3,000 IU ) cholecalciferol per day in a r and omized , placebo-controlled , double-blind study in 130 hypertensive patients residing in Denmark ( 56º N ) . Ambulatory BP ( 24-h BP ) and arterial stiffness were measured before and after 20 weeks of treatment , that took place between October and March . RESULTS A total of 112 patients ( mean age 61 ± 10 ) with a baseline p-25(OH)D of 23 ± 10 ng/ml completed the study . Compared with placebo , a nonsignificant 3/1 mm Hg ( P = 0.26/0.18 ) reduction was found in 24-h BP . In patients with vitamin D insufficiency ( < 32 ng/ml ) at baseline ( n =  92 ) , 24-h BP decreased by 4/3 mm Hg ( P = 0.05/0.01 ) . Central BP ( CBP ) estimated by applanation tonometry and calibrated with a st and ardized office BP was reduced by 7/2 mm Hg ( P = 0.007/0.15 ) vs. placebo . No differences in carotid-femoral pulse wave velocity ( PWV ) or central augmentation index ( AIx ) were found between treatment arms . CONCLUSIONS Cholecalciferol supplementation , by a dose that effectively increased vitamin D levels , did not reduce 24-h BP , although central systolic BP decreased significantly . In a post-hoc subgroup analysis of 92 subjects with baseline p-25(OH)D levels < 32 ng/ml , significant decreases in 24-h systolic and diastolic BP occurred during cholecalciferol supplementation OBJECTIVE The purpose of this study was to prospect ively examine the association between vitamin D and calcium intake and risk of type 2 diabetes .  RESEARCH DESIGN AND METHODS In the Nurses ' Health Study , we followed 83,779 women who had no history of diabetes , cardiovascular disease , or cancer at baseline for the development of type 2 diabetes .  Vitamin D and calcium intake from diet and supplements was assessed every 2 - 4 years . During 20 years of follow-up , we documented 4,843 incident cases of type 2 diabetes . RESULTS After adjusting for multiple potential confounders , there was no association between total vitamin D intake and type 2 diabetes . However , the relative risk ( RR ) of type 2 diabetes was 0.87 ( 95 % CI 0.75 - 1.00 ; P for trend = 0.04 ) comparing the highest with the lowest category of vitamin D intake from supplements . The multivariate RRs of type 2 diabetes were 0.79 ( 0.70 - 0.90 ; P for trend < 0.001 ) comparing the highest with the lowest category of calcium intake from all sources and 0.82 ( 0.72 - 0.92 ; P for trend < 0.001 ) comparing the highest with the lowest category of calcium intake from supplements . A combined daily intake of > 1,200 mg calcium and > 800 IU vitamin D was associated with a 33 % lower risk of type 2 diabetes with RR of 0.67 ( 0.49 - 0.90 ) compared with an intake of < 600 mg and 400 IU calcium and vitamin D , respectively . CONCLUSIONS The results of this large prospect i ve study suggest a potential beneficial role for both vitamin D and calcium intake in reducing the risk of type 2 diabetes BACKGROUND Vitamin D and calcium metabolism are involved in vascular smooth muscle cell proliferation , endothelial function and blood pressure ( BP ) regulation . Their physiopathology has been a matter of intensive clinical investigation with variable and sometimes contradictory results . Vitamin D insufficiency is highly prevalent in the general population , particularly among the elderly . We evaluated the association between serum 25(OH)-D levels and arterial BP in this population . METHODS An epidemiological cross-sectional study was design ed to analyse the prevalence of hypovitaminosis D ( ' D'AVIS ' study ) in our reference area . The study was performed on a representative r and om sample of the population over 64 years of age obtained from five primary health care areas . A medical record , arterial BP and biological analysis : serum 25(OH)-D , iPTH , creatinine , urea , calcium , albumin were obtained . RESULTS A total of 237 subjects ( 53 % women ) , aged between 64 and 93 ( mean 71.7 + /- 5.3 ) , were evaluated . The mean serum 25(OH)-D levels were 17.21 + /- 7.57 ng/ml ( interval 5 - 54 ; 86 % had < 25 ng/ml ) . The mean BP was 138.8 + /- 14/80 + /- 7.4 mmHg , and 46 % were on antihypertensive treatment . A significant negative association was observed between serum 25(OH)-D levels and systolic ( r = -0.153 , P = 0.018 ) and diastolic BP ( r = -0.152 , P = 0.019 ) . This association persisted after controlling for possible confounders in the multivariate analyses . CONCLUSIONS Low serum 25(OH)-D levels were inversely and independently associated with BP . Supplemental measures to prevent hypovitaminosis D in this population would be important , not only to protect the skeletal system but also for the possible beneficial effects on the cardiovascular system and the BP regulation BACKGROUND AND AIMS Low vitamin D levels are associated with increased incidence of future cardiovascular events and are common in stroke patients . We tested whether vitamin D supplementation could reduce blood pressure and improve markers of vascular health in patients who had previously suffered a stroke . METHODS AND RESULTS R and omised , placebo-controlled , double-blind trial . Community-dwelling patients with a history of stroke and baseline 25-hydroxyvitamin D levels < 75 nmol/L received 100,000 units of oral vitamin D2 or placebo at baseline . Office and 24 h blood pressure , endothelial function measured by flow-mediated dilatation of the brachial artery , cholesterol , oxidised low density lipoprotein , B-type natriuretic peptide and heart rate turbulence were measured at baseline , 8 weeks and 16 weeks . 58 patients were r and omised . Mean age was  
    Output:
    
agent
Conclusions Vitamin D supplementation did not improve EF .
The significant effect of vitamin D in diabetics and a tendency for an association with BMI may indicate a role of excess adiposity and insulin resistance in modulating the effects of vitamin D on vascular function .
***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 In observational studies , low serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations have been associated with insulin resistance and other risk factors for cardiovascular disease . RESEARCH DESIGN AND METHODS We present 1-year data from an ongoing 5-year trial in 511 individuals with impaired fasting glucose ( IFG ) and /or impaired glucose tolerance ( IGT ) r and omly assigned to 20,000 IU/week vitamin D3 or placebo .  An oral glucose tolerance test was performed at baseline and after 1 year . RESULTS Mean baseline serum 25(OH)D was 59.9 nmol/L and 61.1 nmol/L in the vitamin D and placebo groups , respectively , and increased by 45.8 nmol/L and 3.4 nmol/L , respectively . With adjustment for baseline concentrations , no differences in measures of glucose metabolism , insulin secretion or sensitivity , blood pressure , or hs-CRP were found after 1 year . There was a slight , but significant decrease in total and LDL cholesterol in the vitamin D group compared with the placebo group , but as there was also a decrease in HDL cholesterol , the change in the total/HDL cholesterol ratio did not differ significantly . Only analyzing subjects with 25(OH)D < 50 nmol/L did not change the results . CONCLUSIONS This study shows that vitamin D supplementation does not improve glycemic indices , blood pressure , or lipid status in subjects with IFG and /or IGT BACKGROUND Studies suggest that vitamin D deficiency is a risk factor for cardiovascular disease and diabetes . Vitamin D deficiency is prevalent in HIV patients but the effect of vitamin D supplementation on cardiovascular risk in this population is unknown . METHODS We conducted a r and omized , double-blind , placebo-controlled trial among 45 HIV-infected adults in Clevel and ( OH , USA ) on stable antiretroviral therapy with durable virological suppression and a baseline serum 25-hydroxyvitamin D level of ≤20 ng/ml . Participants were r and omized 2:1 to vitamin D3 4,000 IU daily or placebo  for 12 weeks . The primary outcome was a change in flow-mediated brachial artery dilation ( FMD ) . RESULTS Baseline demographics were similar except for age ( vitamin D versus placebo , mean ±sd 47 ±8 versus 40 ±10 years ; P=0.009 ) . Both groups had reduced FMD at baseline ( median values 2.9 % [ IQR 1.6 - 4.8 ] for vitamin D versus 2.5 % [ IQR 1.7 - 6.4 ] for placebo ; P=0.819 ) . Despite an increase in the concentration of serum 25-hydroxyvitamin D from baseline to 12 weeks ( 5.0 ng/ml [ IQR -0.9 - 7.4 ] versus -1.9 ng/ml [ IQR -4.0 - 0.1 ] for vitamin D versus placebo , respectively ; P=0.003 ) , there was no difference in FMD change ( 0.55 % [ IQR -1.05 - 2.13 ] versus 0.29 % [ IQR -1.61 - 1.77 ] ; P=0.748 ) . Vitamin D supplementation was associated with a decrease in total and non-high-density lipoprotein cholesterol , and an increase in indices of insulin resistance . CONCLUSIONS Among HIV-infected individuals with vitamin D deficiency , supplementation with 4,000 IU vitamin D3 daily for 12 weeks modestly improved vitamin D status and cholesterol but worsened insulin resistance without change in endothelial function . The mechanisms of resistance to st and ard doses of vitamin D and the complex role of vitamin D in glucose metabolism in this population require further investigation OBJECTIVE Low vitamin D levels and risk factors for vascular disease are both common in South Asian women . This trial evaluated whether vitamin D supplementation could improve markers of vascular health in South Asian women with low 25-hydroxyvitamin D levels . METHODS Parallel-group , double-blind , r and omised placebo-controlled trial . Healthy South Asian women with baseline serum 25-hydroxyvitamin D levels of < 75 nmol/L were r and omised to receive a single dose of 100,000 units oral vitamin D3 or matching placebo . Outcomes were measured at baseline , 4 and 8 weeks . The primary outcome was change in endothelial function measured using brachial artery flow-mediated dilatation . Secondary outcomes included blood pressure , arterial stiffness , microvascular function measured using laser Doppler iontophoresis , insulin resistance , serum lipids , circulating markers of inflammation , thrombosis and adipokines . RESULTS 50 women were r and omised , 25 to each group . Mean age was 41 years ; mean baseline 25-hydroxyvitamin D level was 27 nmol/L.  25-Hydroxyvitamin D levels rose in the vitamin D group relative to the placebo group by 4 weeks ( 16 nmol/L , 95 % CI 11 to 21 , p < 0.001 ) . There was no improvement in flow-mediated dilatation in the vitamin D group relative to placebo at 4 weeks ( 0.1 % , 95 % CI -0.9 to 1.1 , p = 0.84 ) or 8 weeks ( 0.0 % , 95 % CI -1.4 to 1.4 , p = 0.98 ) . There was no improvement in cholesterol , insulin resistance or markers of inflammation . Both platelet activation inhibitor-1 and tissue plasminogen activator levels fell significantly in the vitamin D group relative to placebo at 8 weeks . CONCLUSION A single large dose of vitamin D3 did not improve blood pressure or endothelial function in South Asian women with low baseline 25-hydroxyvitamin D levels . TRIAL REGISTRATION IS RCT N75081811 BACKGROUND Low 25-hydroxy-vitamin D ( 25(OH)D ) levels are inversely related to blood pressure ( BP ) and have been associated with incident hypertension . In people living at northern latitudes diminished cholecalciferol synthesis in the winter increases the risk of vitamin D deficiency . We wanted to test the hypothesis that daily cholecalciferol supplementation in the winter lowers BP in patients with hypertension . METHODS We investigated the effect of 75 µg ( 3,000 IU ) cholecalciferol per day in a r and omized , placebo-controlled , double-blind study in 130 hypertensive patients residing in Denmark ( 56º N ) . Ambulatory BP ( 24-h BP ) and arterial stiffness were measured before and after 20 weeks of treatment , that took place between October and March . RESULTS A total of 112 patients ( mean age 61 ± 10 ) with a baseline p-25(OH)D of 23 ± 10 ng/ml completed the study . Compared with placebo , a nonsignificant 3/1 mm Hg ( P = 0.26/0.18 ) reduction was found in 24-h BP . In patients with vitamin D insufficiency ( < 32 ng/ml ) at baseline ( n =  92 ) , 24-h BP decreased by 4/3 mm Hg ( P = 0.05/0.01 ) . Central BP ( CBP ) estimated by applanation tonometry and calibrated with a st and ardized office BP was reduced by 7/2 mm Hg ( P = 0.007/0.15 ) vs. placebo . No differences in carotid-femoral pulse wave velocity ( PWV ) or central augmentation index ( AIx ) were found between treatment arms . CONCLUSIONS Cholecalciferol supplementation , by a dose that effectively increased vitamin D levels , did not reduce 24-h BP , although central systolic BP decreased significantly . In a post-hoc subgroup analysis of 92 subjects with baseline p-25(OH)D levels < 32 ng/ml , significant decreases in 24-h systolic and diastolic BP occurred during cholecalciferol supplementation OBJECTIVE The purpose of this study was to prospect ively examine the association between vitamin D and calcium intake and risk of type 2 diabetes .  RESEARCH DESIGN AND METHODS In the Nurses ' Health Study , we followed 83,779 women who had no history of diabetes , cardiovascular disease , or cancer at baseline for the development of type 2 diabetes .  Vitamin D and calcium intake from diet and supplements was assessed every 2 - 4 years . During 20 years of follow-up , we documented 4,843 incident cases of type 2 diabetes . RESULTS After adjusting for multiple potential confounders , there was no association between total vitamin D intake and type 2 diabetes . However , the relative risk ( RR ) of type 2 diabetes was 0.87 ( 95 % CI 0.75 - 1.00 ; P for trend = 0.04 ) comparing the highest with the lowest category of vitamin D intake from supplements . The multivariate RRs of type 2 diabetes were 0.79 ( 0.70 - 0.90 ; P for trend < 0.001 ) comparing the highest with the lowest category of calcium intake from all sources and 0.82 ( 0.72 - 0.92 ; P for trend < 0.001 ) comparing the highest with the lowest category of calcium intake from supplements . A combined daily intake of > 1,200 mg calcium and > 800 IU vitamin D was associated with a 33 % lower risk of type 2 diabetes with RR of 0.67 ( 0.49 - 0.90 ) compared with an intake of < 600 mg and 400 IU calcium and vitamin D , respectively . CONCLUSIONS The results of this large prospect i ve study suggest a potential beneficial role for both vitamin D and calcium intake in reducing the risk of type 2 diabetes BACKGROUND Vitamin D and calcium metabolism are involved in vascular smooth muscle cell proliferation , endothelial function and blood pressure ( BP ) regulation . Their physiopathology has been a matter of intensive clinical investigation with variable and sometimes contradictory results . Vitamin D insufficiency is highly prevalent in the general population , particularly among the elderly . We evaluated the association between serum 25(OH)-D levels and arterial BP in this population . METHODS An epidemiological cross-sectional study was design ed to analyse the prevalence of hypovitaminosis D ( ' D'AVIS ' study ) in our reference area . The study was performed on a representative r and om sample of the population over 64 years of age obtained from five primary health care areas . A medical record , arterial BP and biological analysis : serum 25(OH)-D , iPTH , creatinine , urea , calcium , albumin were obtained . RESULTS A total of 237 subjects ( 53 % women ) , aged between 64 and 93 ( mean 71.7 + /- 5.3 ) , were evaluated . The mean serum 25(OH)-D levels were 17.21 + /- 7.57 ng/ml ( interval 5 - 54 ; 86 % had < 25 ng/ml ) . The mean BP was 138.8 + /- 14/80 + /- 7.4 mmHg , and 46 % were on antihypertensive treatment . A significant negative association was observed between serum 25(OH)-D levels and systolic ( r = -0.153 , P = 0.018 ) and diastolic BP ( r = -0.152 , P = 0.019 ) . This association persisted after controlling for possible confounders in the multivariate analyses . CONCLUSIONS Low serum 25(OH)-D levels were inversely and independently associated with BP . Supplemental measures to prevent hypovitaminosis D in this population would be important , not only to protect the skeletal system but also for the possible beneficial effects on the cardiovascular system and the BP regulation BACKGROUND AND AIMS Low vitamin D levels are associated with increased incidence of future cardiovascular events and are common in stroke patients . We tested whether vitamin D supplementation could reduce blood pressure and improve markers of vascular health in patients who had previously suffered a stroke . METHODS AND RESULTS R and omised , placebo-controlled , double-blind trial . Community-dwelling patients with a history of stroke and baseline 25-hydroxyvitamin D levels < 75 nmol/L received 100,000 units of oral vitamin D2 or placebo at baseline . Office and 24 h blood pressure , endothelial function measured by flow-mediated dilatation of the brachial artery , cholesterol , oxidised low density lipoprotein , B-type natriuretic peptide and heart rate turbulence were measured at baseline , 8 weeks and 16 weeks . 58 patients were r and omised . Mean age was  
    Output:
    