***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 The aim of this population -based matched case-control study was to evaluate the effect of risk factors for hip fracture in Oslo , Norway , which has some of the highest incidence rates ever reported . The study population comprised all non-institutionalized persons 50 years or older living in the catchment area of two Oslo hospitals , and cases were 246 patients admitted for hip fracture during a 1-year period . The controls were r and omly selected from the study population , matched 1:1 for age and sex . Hip fracture was associated with lean body stature , smoking , low grip strength and decreased levels of physical activity , and inversely with length of education . In addition , hip fracture was inversely related to indicators of total food intake ( number of meals per day , frequency of dinners , and slices of bread per day ) . A relation between hip fracture and low vitamin D intake was also suggested , whereas no association with dietary calcium intake was found . Finally , increased risk of fracture was seen in persons reporting two or more hospital admissions in the previous 2 years , and in those reporting weight reduction due to poor appetite during the previous year . In conclusion , the risk factor pattern for hip fracture was much the same in the elderly population of Oslo as previously described in other population s with a lower incidence of fracture . This study also indicates a relation between hip fracture and low food intake Abstract : Low  bone mineral density ( BMD ) is one of the most important elements for the diagnosis of osteoporosis and screening people with higher risk of fractures . To establish the criterion value of BMD for the diagnosis of osteoporosis and to estimate the prevalence rate of  osteoporosis in Japanese women , we performed a Japanese population -based osteoporosis ( JPOS ) study . The subjects were 4550 women aged 15 through 79 years r and omly selected from seven municipalities throughout Japan . The sample size was determined to ensure that the observed mean BMD would remain within 2.5 % from the real value with a probability of 0.95 in each of the 5-year age groups . The study comprised bone mass measurements by dual-energy X-ray absorptiometry at the spine ( L2–4 ) , hip and distal forearm , body size measurements and detailed interviews on medical and gynecologic history . After excluding those subjects with apparent or suggested abnormalities affecting bone mass from 3985 women ( 87.6 % ) who completed the study , 3465 women remained and served as the subjects . We present 5-year age-specific mean values of BMD and cut-off values for the diagnosis of osteoporosis according to World Health Organization ( WHO ) and the Japanese Society of Bone and Mineral Research ( JSBMR ) criteria . The cut-off levels at the spine and the distal radius proposed in this study were similar to those proposed by the JSBMR but the cut-off level at the femoral neck in this study was 4.7 % higher than that of the JSBMR . The prevalence rates of osteoporosis according to WHO criteria in the present subjects aged 50 through 79 years were calculated as 38.0 % at the spine , 11.6 % at the femoral neck and 56.8 % at the distal one-third site of the radius , and those in the Japanese female population of the same age were estimated to be 35.1 % , 9.4 % and 51.2 % , respectively . A fivefold difference was observed among the prevalence rates at different skeletal sites , which suggests that the different definitions of osteoporosis should be established for the different skeletal sites . The prevalence rate diagnosed at the femoral neck seemed to be lower in the present study than those reported for Caucasians . This might account for a lower incidence rate of hip fracture in Japanese women Postmenopausal bone loss is a major factor in the increasing prevalence of osteoporotic fractures . Evidence is abundant that hormonal replacement therapy prevents the bone loss that follows natural or surgical menopause and reduces the prevalence of osteoporotic fractures in later life [ 1 - 4 ] . However , only about 10 % of American women elect to receive replacement therapy because of attitudes of physicians and patients , the undesirability of menstrual bleeding , and unresolved questions about the relation of the use of estrogen to breast cancer [ 5 ] . Moreover , the duration of hormonal therapy may need to be prolonged because bone loss recurs when therapy is discontinued , yet the incidence of some adverse effects increases with the duration of estrogen use . Safer alternatives to estrogen use have been sought . Epidemiologic and cross-sectional studies have suggested that increasing calcium intake might prevent postmenopausal bone loss , and prospect i ve studies have yielded conflicting results [ 6 - 17 ] . Moreover , some investigators have suggested that effects differ on the various skeletal sites used to determine the rate of bone loss [ 18 ] . We compared the efficacy of calcium augmentation in early postmenopause with calcium augmentation plus hormonal replacement therapy and with placebo . The study had a three-arm , r and omized , parallel design . The patients receiving hormonal replacement therapy were obviously not blinded nor were their physicians , whereas the placebo and calcium groups were double blinded . Methods Healthy , white women between 6 months and 6 years after a natural menopause were recruited to participate in the study . The protocol was approved by the Human Investigation Review Committees of Winthrop-University Hospital and Brookhaven National Laboratory ; written informed consent was obtained from each participant . Participants were recruited by announcements in the local press and in hospital and university publications and through a direct mail campaign . All participants had a history and physical examination . Exclusion characteristics included any disorder known to affect bone metabolism such as glucocorticoid use , gastrointestinal disease , or any chronic illness . Previous or current malignancy was an exclusion characteristic as were absolute contraindications to estrogen replacement or calcium supplements . Absolute contraindications to estrogen replacement therapy included estrogen-dependent neoplasm ( breast or uterus ) , undiagnosed vaginal bleeding , thrombophlebitis or thromboembolism , and acute liver disease .  Women with the following problems considered by some investigators to be relative contraindications to estrogen therapy were also excluded : gallbladder disease , history of liver disease , first-degree relatives with breast cancer , and hypertension . Calcium urolithiasis was also an exclusion factor . Women with known osteoporosis or with a vertebral compression fracture were not eligible for the study . One hundred eighteen women entered the study . The women were r and omly assigned to three groups : 1 ) hormonal replacement [ estrogen-progesterone-calcium carbonate ] , 2 ) calcium carbonate , or 3 ) placebo . Assignment to the groups was based on computer-generated r and om numbers provided by the statistician , with stratification for years postmenopause . The women in the hormonal replacement group took conjugated equine estrogens ( Premarin , Wyeth-Ayerst Laboratories , Inc. ; Philadelphia , Pennsylvania ) , 0.625 mg daily for 25 days of the month along with medroxyprogesterone ( Provera , Upjohn ; Kalamazoo , Michigan ) , 10 mg from days 16 to 25 . All women received 400 IU of vitamin D daily in the form of a multivitamin , and calcium supplementation ( as Caltrate , Lederle ; Clifton , New Jersey ) was provided to the two treatment groups . The duration of the study was 2.9 1.1 years ( mean SD ) . A 7-day dietary history was review ed with a nutritionist every 2 months ; calcium was provided as calcium carbonate , 600 mg ( Caltrate ) , and used to supplement the diet to approximate a total daily intake of 1700 mg of elemental calcium ( the mean + 2 SD found by Heaney and colleagues [ 7 ] to result in zero calcium balance in estrogen-deprived women ) . The calcium supplements were taken with meals in divided doses . The placebo appeared identical to the calcium carbonate tablets . No patients took antacids or histamine-2 blockers . All women had a baseline mammogram . Measurements Routine laboratory studies included a complete blood count , urinalysis , and serum fasting calcium , phosphorus , urea nitrogen , creatinine , alkaline phosphatase , cholesterol , and aminotransferase measurements [ 19 , 20 ] . In addition , follicle-stimulating hormone , estradiol , parathyroid hormone , osteocalcin , free thyroxine , and bone alkaline phosphatase were measured , and a urine specimen was collected after an overnight fast for hydroxyproline , calcium , and creatinine determinations , following a 3-day low-hydroxyproline diet [ 21 - 23 ] . Total body calcium was measured annually in the participants , using the delayed neutron activation method at Brookhaven National Laboratory [ 24 , 25 ] . This method uses a whole-body counter to measure the characteristic rays emitted from the neutron capture of Calcium-48 ( natural abundance of 0.187 % ) in the body . The Brookhaven National Laboratory whole-body counter was up grade d in 1987 to use 32 NaI ( T1 ) detectors of 10 cm 10 cm 46 cm positioned symmetrically above and below the patient [ 25 ] . The activated isotope , Calcium-49 , decays with a half-life of 8.72 minutes , emitting a 3.08 MeV characteristic line . More than 99.5 % of the body calcium is contained in the bone [ 26 ] . The method provides total body calcium with a coefficient of variation of about 1.5 % when no substantial change in the body weight occurs during the period of repeated studies . The measurements were made annually . The bone mineral density of the distal radius site was measured using a Lunar Radiation ( Madison , Wisconsin ) single-photon absorptiometer ( SP2 ) .  Bone mineral density of the spine ( L2-L4 ) and femur ( neck , trochanter , and Ward triangle ) was measured using a Lunar Radiation DP4 dual-photon absorptiometer . The software version used for the analysis of scans was DP4 Lunar Corporation Version 1.1 . All scans were analyzed using the same software version , which corrects for source decay . Instruments were calibrated daily , and the radioactive source was changed annually . Each measurement was done every 6 months . The coefficient of variation of these measurements was 2 % , except for the Ward triangle ( 2.5 % ) . Activity was measured using  activity monitors  ( large-scale integrated monitors ) , which were worn about the waist [ 27 ] . The average of 2 weekdays and 1 weekend day was used as an activity score . Activity was measured at baseline and at one other point during the study to ensure that differences among the groups were not due to varied levels of exercise . Statistical Analysis Total body calcium was selected as the primary criterion for efficacy for the following reasons : It measures mass rather than density per unit area ; it measures calcium balance precisely and accurately in the free living state and may be better related to previous studies using the balance technique ; it is more precise than the other measurements ; and it avoids sampling error by measuring the entire skeleton rather than a specific region of the appendicular or axial skeleton . The rate of change in bone mineral was calculated for each woman at each of the sites used in the study . St and ard linear regression procedures were used to estimate the rate of bone min 
    Output:
    
The result of the present systematic review gives the evidence showing that calcium supplementation or optimal dietary calcium intake increases bone density in childhood and adolescence and reduces the risk of fracture due to osteoporosis in the elderly people regardless of the gender .