***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: Vitamin D insufficiency and low calcium intake contribute to increase parathyroid function and bone fragility in elderly people .  Calcium and vitamin D supplements can reverse secondary hyperparathyroidism thus preventing hip fractures , as proved by Decalyos I. Decalyos II is a 2-year , multicenter , r and omized , double-masked , placebo-controlled confirmatory study . The intention-to-treat population consisted of 583 ambulatory institutionalized women ( mean age 85.2 years , SD = 7.1 ) r and omized to the  calcium – vitamin D3  fixed combination group ( n= 199 ) ; the calcium plus vitamin D3 separate combination group ( n= 190 ) and the placebo group ( n= 194 ) . Fixed and separate combination groups received the same daily amount of calcium ( 1200 mg ) and vitamin D3 ( 800 IU ) , which had similar pharmacodynamic effects . Both types of calcium-vitamin D3 regimens increased serum 25-hydroxyvitamin D and decreased serum intact parathyroid hormone to a similar extent , with levels returning within the normal range after 6 months . In a subgroup of 114 patients  , femoral neck bone mineral density ( BMD ) decreased in the placebo group ( mean = –2.36 % per year , SD = 4.92 ) , while remaining unchanged in women treated with calcium-vitamin D3 ( mean = 0.29 % per year , SD = 8.63 ) . The difference between the two groups was 2.65 % ( 95 % CI = –0.44 , 5.75 % ) with a trend in favor of the active treatment group . No significant difference between groups was found for changes in distal radius BMD and quantitative ultrasonic parameters at the os calcis . The relative risk ( RR ) of HF in the placebo group compared with the active treatment group was 1.69 ( 95 % CI = 0.96 , 3.0 ) , which is similar to that found in Decalyos I ( RR = 1.7 ; 95 % CI = 1.0 , 2.8 ) . Thus , these data are in agreement with those of Decalyos I and indicate that calcium and vitamin D3 in combination reverse senile secondary hyperparathyroidism and reduce both hip bone loss and the risk of hip fracture  in elderly institutionalized women An unexplained loss of muscle strength occurs with aging . Vitamin D deficiency can cause myopathy and administration of 1,25-dihydroxyvitamin D3 [ 1,25-(OH2)D3 ] to persons with low serum concentrations can improve strength . To test the hypothesis that the weakness associated with aging is in part due to inadequate serum concentrations of [ 1,25-(OH2)D3 ] , we conducted a r and omized , controlled , double blinded trial in 98 men and women volunteers over 69 yr old . Treatment consisted of 0.25 micrograms 1,25-(OH)2D3 , orally , twice per day or identical placebo for 6 months .  Leg muscle strength of the quadriceps was measured with an isokinetic dynamometer . There was no difference between the two groups at 1 week , 1 month , or 6 months of treatment in any of the measures of muscle strength . We conclude that oral administration of 0.5 micrograms 1,25-(OH)2D3/day does not improve muscle strength in older persons . Further research is needed to determine the etiology of the decline in muscle strength associated with aging Objectives : To assess the effectiveness of a multivitamin ( MV ) tablet on nutritional status , quantitative heel ultrasound ( QUS ) , mobility , muscle strength and falls . The design comprised two groups matched on mobility levels , r and omized to receive a daily MV or placebo ( P ) tablet for 6 months . The setting was an Australian residential care facility . Subjects : A total of 92 aged care residents . Serum micronutrients , body weight , QUS , rate of falls , h and grip strength , and the timed up and go test were assessed at baseline and 6 months . Results : A total of 49 participants consumed a MV and 43 , a matched P for 6 months . There was a greater increase in the MV vs P group for serum 25(OH)D ( mean difference±st and ard error , 33.4±2.6 nmol l−1 ) , folate ( 13.4±2.8 nmol l−1 ) , and vitamin B12 ( 178.0±40.3 pmol l−1 ) ( all P<0.001 ) . Adequate 25(OH)D concentrations ( ⩾50 nmol l−1 ) were found among 77 % of participants in the MV group vs 10 % taking P ( P<0.001 ) . Adjusting for baseline levels , the increase in QUS was greater in the MV vs P group ( 3.0±2.0 dB MHz−1 vs −2.9±2.1 dB MHz−1 , respectively , P=0.041 ) . There was a trend towards a 63 % lower mean number of falls in the MV vs P group ( 0.3±0.1 falls vs 0.8±0.3 falls , P=0.078 ) . Conclusions : MV  supplementation raised serum vitamin B12 and folate concentrations and increased serum 25(OH)D , which was accompanied by an apparent positive effect on bone density . We also found a trend towards a reduction in falls and this could contribute to a reduction in fractures Estrogen deficiency and declining calcium absorption due to reduced calcitriol levels or intestinal resistance to calcitriol , are important factors in the pathogenesis of age-related bone loss . The main objective of this study was to examine the effect of estrogen and 1,25-dihydroxyvitamin D therapy given individually or in combination on  bone loss in elderly women . Four hundred eighty-nine elderly women with normal bone density for their age , aged 65 - 77 yr , were entered into a r and omized double blind , placebo-controlled trial . Women were r and omized to one of four groups : conjugated estrogens ( 0.625 mg , daily ) to women without a uterus ( estrogen replacement therapy ) plus medroxyprogesterone acetate ( 2.5 mg , daily ) to women with a uterus ( hormone replacement therapy ) , calcitriol ( 0.25 microg twice daily ) , a combination of hormone replacement therapy/estrogen replacement therapy plus calcitriol , or placebos for 3 yr . The primary outcome was the change in bone mineral density of the femoral neck and spine . In the intent to treat analysis , hormone therapy ( hormone replacement therapy/estrogen replacement therapy ) produced a mean ( + /-1 SD ) increase in bone mineral density of 2.98 % ( + /-5.45 % ) at the femoral neck ( P < 0.0001 ) and 4.36 % ( + /-6.42 % ) at the spine ( P < 0.0001 ) . There were parallel increases in total hip and trochanter bone mineral density . Calcitriol increased bone mineral density 0.10 % ( + /- 4.27 % ) at the femoral neck ( P = 0.57 ) and 1.65 % ( + /- 4.83 % ) at the spine ( P < 0.0124 ) . The combination of hormone replacement therapy/estrogen replacement therapy + calcitriol  increased bone mineral density 3.80 % ( + /-4.95 % ) at the femoral neck ( P < 0.001 ) , 4.91 % ( + /-6.0 % ) at the spine ( P < 0.0001 ) , and parallel changes at the total hip and trochanter . All three treatment groups differed significantly from placebo at the spine and for the hormone replacement therapy/estrogen replacement therapy groups at the femoral neck , spine , total hip and trochanter . There were no significant differences between combination therapy and hormone replacement therapy/estrogen replacement therapy alone on bone mineral density at any site in the intent to treat analysis . In a secondary analysis of the effect in women who were adherent to treatment , calcitriol had a more significant effect on spine ( P = 0.003 ) and total hip ( P = 0.004 ) . The increase in bone mineral density in the adherent groups of women was always higher compared with the intent to treat groups . Combination therapy compared with hormone replacement therapy/estrogen replacement therapy alone produced a significantly greater response in trochanter ( P = 0.007 ) and total hip bone mineral density ( P = 0.0017 ) . In summary , hormone replacement therapy/estrogen replacement therapy alone and in combination with calcitriol therapy was highly effective in reducing bone resorption and increasing bone mineral density at the hip and other clinical ly relevant sites in a group of elderly women , with normal bone density for their age . Calcitriol was effective in increasing spine bone mineral density . In the adherent women , combination therapy with hormone replacement therapy/estrogen replacement therapy and calcitriol increased bone mineral density significantly more in the total hip and trochanter than did hormone replacement therapy/estrogen replacement therapy alone The necessity and safety of an oral calcium ( Ca ) and vitamin D regimen was evaluated in a population of 66 independently living and 73 institutionalized elderly women over an 11-week winter period . The members of both groups were r and omly assigned into trial and control groups . Serum Ca , creatinine , and calcidiol levels were measured before and after the trial . The regimen consisted of 1.558 g of Ca and 45 micrograms ( equal to 1,800 IU ) of vitamin D administered daily in addition to the normal diet . The controls received no treatment . A majority of the elderly subjects living independently had ensured their Ca , and a quarter of them also their vitamin D intake on their own initiative . The mean serum calcidiol concentration before the trial was 24.1 nmol/L in the institutionalized and 38.5 nmol/L in the elderly subjects living independently ( P less than .001 ) . After the trial , serum calcidiol was 10.4 nmol/L in the institutionalized control subjects and had decreased ( P less than .001 ) in both control groups , but increased ( P less than .001 ) in both treatment groups . The safety indicators , serum Ca , creatinine , and calcidiol , did not indicate any group or individual side effect CONTEXT Decreased calcitriol production due to impaired renal function may be a significant risk factor for falls in normal aging population . OBJECTIVE The objective of the study was to examine the association between creatinine clearance ( CrCl ) and the incidence of falls and fallers in groups treated with placebo , calcitriol , estrogen therapy (ET)/estrogen + progestin therapy ( HT ) , and calcitriol + ET/HT . DESIGN This was a 3-yr , double-blind , placebo-controlled study design ed to test the efficacy of calcitriol and ET/HT on bone loss and falls with analysis by intention to treat and post hoc . SETTING The study was conducted at an academic outpatient center . PARTICIPANTS Four hundred eighty-nine normal elderly women aged 65 - 77 yr ; 415 women completed the study . INTERVENTION Subjects were r and omized to placebo , calcitriol 0.25 mug twice a day , ET daily ( conjugated equine estrogens 0.625 mg ) , HT ( conjugated equine estrogen 0.625 mg + medroxyprogesterone acetate 2.5 mg ) and calcitriol + ET/HT . MAIN OUTCOME MEASURES Cumulative number of falls and fallers were compared between groups with 24-h urine CrCl less than 60 and 60 ml/min or greater . RESULTS Calcitriol treatment decreased the number of fallers and falls . Low CrCl less than 60 ml/min was a predictor of the number of falls per person but not fallers in the placebo group ( P = 0.007 ) . In the low CrCl group ( < 60 ml/min ) , the rate of falls decreased on calcitriol by 53 % [ 95 % confidence interval ( CI ) -71 % to -22 % ; P = 0.003 ] , calcitriol + ET/HT by 61 % ( 95 % CI -76 % to -37 % ; P = 0.001 ) , and ET/HT by 25 % ( 95 % CI : -55 % to + 24 % ; not significant ) . Calcitriol reduced the rate of falls by 30 % ( 95 % CI -49 % to -4 % ; P = 0.027 ) in the CrCl 60 ml/min or greater group . CONCLUSION Calcitriol treatment decreases falls in all subjects but especially in elderly women with decreased renal function ( < 60 ml/min ) and frequent fallers Aims : To investigate the effects of a 6-month supplementation with calcium and cholecalciferol on biochemical parameters and muscle strength of institutionalized elderly . Methods : This prospect i ve , double-blind , placebo-controlled , r and omized trial included Brazilian institutionalized people ≥60 years of age receiving a 6-month supplementation ( December to May ) of daily calcium plus monthly placebo ( calcium/placebo group ) or daily calcium plus oral cholecalciferol ( 150,000 IU once a month during the first  
    Output:
    
All studies with daily doses of 800 IU or more demonstrated beneficial effects on balance and muscle strength .
CONCLUSION Supplemental vitamin D with daily doses of 800 to 1,000 IU consistently demonstrated beneficial effects on strength and balance .