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: however , vitamin d deficiency is not only a risk factor for osteoporosis ; there is also evidence that it is responsible for decreased muscle functions and falls1 ,2,3,4,5 . recently , there has been a growing field of research concerned with the association between vitamin d deficiency and a wide range of diseases other than osteoporosis in the elderly . it has been found that the capacity for synthesizing vitamin d decreases with age due to the changes in the skin seen with aging2 . decreases in oral intake and absorption of vitamin d in the intestines as well as low 1 alpha hydroxylase enzyme activity in the kidneys , frequently lead to the development of vitamin d deficiency in the elderly2 . considering the theory that vitamin d regulates skeletal muscle physiology , as suggested by various clinical observations and experimental studies , the muscular weakness seen in older patients with low - serum 25 - oh - vitamin d ( 25 ( oh ) d ) concentrations may lead to falls6 , 7 . indeed , cholecalciferol - calcium supplementation reduces falls by 46 % to 65 % in community - dwelling older women5 . on the other hand , there are many factors affecting fall - risk in the older population . in an overview of the literature by annweiler et al. 8 , it was asserted that age - related changes in postural reactions may be related to vitamin d status , mediated through either central nervous system integration or antigravity muscles as the effectors in postural responses . some studies showed that people with vision and balance disorders had lower levels of vitamin d compared to those without . although no evidence has reported that lower levels of vitamin d result in neurobehavioral impairment , it seems that vitamin d plays an important role in neurobehavioral functions9 . this suggests that muscular weakness can not be considered as the only mechanism of fall - risk related to vitamin d deficiency . on the other hand , there is no clear consensus regarding the relationship between falls and vitamin d. karlsson et al. 10 in their review reported that vitamin d supplementation , with or without calcium , in the community - living elderly did not reduce the number of falls or number of fallers . in that study , the authors recommended the administration of vitamin d supplements in those with low levels of vitamin d. there has been confusion about which form of vitamin d is effective in reducing the risk of falls . no fall - reductive effect in community - dwellers has been reported with alfacalcidol , whereas those with calcitriol had a 36 % reduction in the number of falls11 . according to previous data showing that impaired balance is an established risk factor for falls in older persons12 , 13although clinical studies indicated a significant impairment of postural balance in vitamin d deficiency , there are few studies in which the effect of vitamin d on falls and balance were assessed by the posturographic method14 ,15,16 . for this reason , our study intends to explore whether there is an association between vitamin d and risk of falling , balance , and lower extremity neuromuscular function in women aged 60 and above by using tetrax posturography . a total 200 women aged 60 and above who applied to our outpatient clinic were enrolled into the study between december 2010 and june 2012 . a history of intake of medications that affect the central nervous system and / or bone metabolism ; the presence of a disease that affects postural stability and gait such as parkinson s disease , stroke , dementia and vitamin b12 deficiency ; the presence of any neurological motor deficit such as paresis or orthopedic problems such as previous arthroplasty , amputation or severe osteoarthritis in the lower extremities , were exclusion criteria . in addition , patients who had severe liver disease , cardiac failure , other severe metabolic diseases , and mental disorders were also excluded . the patients cognitive status was measured by the mini mental state test ( mmst ) 17 . if the patient had had a score 24 in the mmst , they were excluded . the study was approved by the institutional review board , and all participants provided written informed consent . after the socio - demographic characteristics were recorded , a detailed medical history was taken . for osteoporosis and vitamin d , duration of exposure to sun , number of births , duration of nursing , diet , and history of falls were recorded . vitamin d supplement use was coded as yes if participants reported currently taking supplements . the medical history related to other diseases such as diabetes mellitus , hypertension , use of loop and / or thiazide diuretics , and the taking of psychotropic medications were also recorded . in the assessment of balance , a tetrax posturography device ( sunlight medical ltd . , israel ) was used , taking into consideration the oscillation rates from the postugraphic software . this device is comprised of four independent platforms which measure the vertical pressure changes from both toe tips and from both soles , and a computer which collects and processes the digital data from the platform . the system can digitally save the data from the four different measurement platforms simultaneously and document them as visual and numerical values . pressure detectors placed on a platform on which the person stands straight detect the patterns of displacement at the center of pressure . the subject s risk of falling was calculated by the device from the oscillation angle between the center of pressure and the center of gravity . the patients were asked to look forward with eyes open and closed ( no and nc ) . next , they were asked to turn their head to the left and right ( hl and hr ) more than 45 . next , they were asked to extend their head upward and downward ( hf and hb ) . finally , the patients were asked to stand on a foam - rubber pillow with their eyes open and closed ( po and pc ) . falling risk , stability index ( si ) , and weight distribution index ( wdi ) were calculated for each patient , with high values indicating a worse postural performance . as a clinical balance test , the sppb is a valid and reliable test which is comprised of three tasks : standing balance , usual gait , and chair stand performance . scores of 14 for each task were computed according to the time spent for the activity . summing the three individual categorical scores , a summary performance score was created for each participant ( range : 012 ) , with higher scores indicating better lower body function . in addition , physical activity levels were evaluated by a short form of the international physical activity questionnaire ( ipaq ) 19 . this self - reported questionnaire is based on estimations of time spent per week on different physical activities , in order to classify individuals as sedentary , irregularly active ( a or b ) , active , or very active . total weekly physical activity was estimated by converting the activity items into multiples of the basal resting energy expenditure ( metabolic equivalent of task , met ) for each domain alone ( walking activity , moderate physical activity , and vigorous physical activity ) and in combination ( sum of all physical activity ) . grip strength was measured in the dominant hand using a jamar plus digital handheld dynamometer . three attempts at maximal squeeze were recorded , and the best of the three measurements was used . serum 25 ( oh ) d levels were measured using manual radioimmunoassay using single - batch reagents ( ids , england ) . blood sampling was divided into two seasonal groups as winter ( october march ) and summer ( aprilparticipants were classified based in their 25 ( oh ) d values using previously published cut - offs : hypo - vitaminosis group ( less than 50.0 nmol / l ) and normal group ( 50.0 and greater ) 20 . statistical analyses were performed with the statistical package for the social sciences ( spss ) 15.0 . crosstabs were created on variants from nominal and ordinal scales , and chi - square analysis was conducted . shapiro wilk test was used to assess the distribution of the variables . for variables with normal distribution , comparison analyses of the other variables were carried out by the mann whitney u test . in their results , the demographic and clinical characteristics are reported in table 1table 1.socio - demographic characteristicstotaln = 200hypo - vitaminosis group ( 50.0 nmol / l ) n = 77normal group ( 50.0 nmol / l ) n = 123age ( years , meansd ) 67.36.067.76.167.05.9 bmi ( kg / m , meansd ) 29.44.829.64.829.24.9 education level ( n , % ) * 5 schooling years139 ( 69.5 ) 58 ( 75.4 ) 81 ( 65.9 ) 5 to 12 schooling years32 ( 16.0 ) 13 ( 16.9 ) 19 ( 15.4 ) 12 schooling years29 ( 14.5 ) 6 ( 7.8 ) 23 ( 18.7 ) vitamin d supplementation ( n , % ) * 63 ( 31.5 ) 13 ( 16.9 ) 50 ( 40.7 ) * history of falls ( n , % ) * 1 fall36 ( 18.0 ) 14 ( 18.2 ) 22 ( 11.5 ) 1 fall18 ( 9.0 ) 9 ( 11.7 ) 9 ( 9.6 ) season of blood collectionwinter ( n , % ) * 123 ( 61.5 ) 48 ( 62.5 ) 75 ( 61.0 ) summer ( n , % ) * 77 ( 38.5 ) 29 ( 37.7 ) 48 ( 39.0 ) using of loop and / or thiazide diuretics ( n , % ) * 38 ( 19.0 ) 14 ( 18.2 ) 24 ( 19.5 ) using of psychotropic medications ( n , % ) * 34 ( 17 ) 9 ( 11.7 ) 25 ( 20.3 ) number of births ( meansd ) 3.31.93.52.03.11.8 ocular problems ( n , % ) 179 ( 89.5 ) 68 ( 88.3 ) 111 ( 90.2 ) 25 - oh - vitamin d ( nmol / l , meansd ) 68.738.734.09.490.433.9 * student t test , test . * p 0.05 . there was no significant difference between the groups except vitamin d supplementation ( 13 subjects - 16.9 % vs. 50 subjects - 40.7 % , p 0.05 ) . * p 0.05 a comparison of the serum 25 ( oh ) d level groups ( hypo - vitaminosis group and normal group ) for the clinical assessment parameters is presented in table 2table 2 . comparison of the groups for clinical testshypo - vitaminosis group ( 50.0 nmol / l ) n = 77normal group ( 50.0 nmol / l ) n = 123standing balance , median ( min / max ) 3 ( 04 ) 4 ( 14 ) * gait , median ( min / max ) 3 ( 14 ) 3 ( 14 ) * chair stand performance , median ( min / max ) 2 ( 04 ) 3 ( 04 ) * sppb total , median ( min / max ) 8 ( 112 ) 10 ( 212 ) * ipaqsedentary ( n , % ) 59 ( 76.6 ) 78 ( 63.4 ) * low physical activity ( n , % ) 18 ( 23.4 ) 45 ( 36.6 ) * hand grip , jamar ( kg , meansd ) 18.34.919.54.6 tetrax - falling risk , ( meansd ) 55.725.841.125.0 * tetrax - si , median ( min / max ) no19 .6 ( 7.748.5 ) 15.8 ( 6.454.0 ) * nc21 .2 ( 8.397.5 ) 18.3 ( 7.865.8 ) * po20 .2 ( 8.778.6 ) 19.6 ( 8.856.2 ) pc28 .3 ( 12.776.3 ) 21.1 ( 8.990.4 ) * hr23 .3 ( 13.298.2 ) 22.3 ( 8.387.7 ) hl24 .5 ( 10.289.3 ) 22.0 ( 7.888.4 ) * hb24 .9 ( 12.271.4 ) 20.2 ( 8.3124.6 ) * hf22 .5 ( 10.5113.6 ) 21.18 ( 9.1389.33 ) total 190.9 ( 115.0607.0 ) 167.7 ( 80.3614.2 ) * tetrax - wdi . median ( min - max ) no5 .9 ( 1.020.0 ) 6.0 ( 1.2518.9 ) nc5 .6 ( 019.1 ) 5.5 ( 0. - 19.1 ) po8 .4 ( 2.020.9 ) 9.1 ( 0.929.1 ) pc9 .1 ( 1.821.3 ) 9.0 ( 2.027.8 ) hr7 .2 ( 1.321.3 ) 5.9 ( 1.618.1 ) hl7 .3 ( 0.717.8 ) 6.2 ( 0.619.5 ) hb7 .3 ( 1.019.1 ) 7.0 ( 1.018.4 ) hf6 .5 ( 0.618.2 ) 5.0 ( 0.516.9 ) total57 .0 ( 17.3156.0 ) 52.7 ( 22.4146.8 ) sppb : short physical performance battery , ipaq : international physical activity questionnaire , si : stability index , wdi : weight distribution index , no : neutral position with eyes open , nc : neutral position with eyes closed , po : eyes open on pillows , pc : eyes closed on pillows , hr : head turned right and eyes closed , hl : head turned left and eyes closed , hb : eyes closed raising head backward 30 , hf : eyes closed with head forward approximately 30 . mann whitney u test . test . sppb scores , si and wdi results on posturography were given as median values because normal distribution could not be obtained . standing balance , gait , and chair stand performance scores were significantly better in patients with serum 25 ( oh ) d levels higher than 50.0 nmol / l ( p 0.05 ) . total sppb scores were also different between the groups , indicating that the group with serum 25 ( oh ) d levels higher than 50.0 nmol / l had significantly better lower extremity functions ( p 0.05 ) . similarly , falling risk andsi values in the most of the postures were significantly higher in the hypovitaminosis group ( p 0.05 ) . sppb : short physical performance battery , ipaq : international physical activity questionnaire , si : stability index , wdi : weight distribution index , no : neutral position with eyes open , nc : neutral position with eyes closed , po : eyes open on pillows , pc : eyes closed on pillows , hr : head turned right and eyes closed , hl : head turned left and eyes closed , hb : eyes closed raising head backward 30 , hf : eyes closed with head forward approximately 30 . mann whitney u test . this study showed that serum 25 ( oh ) d levels were significantly associated with clinical balance test results , falling risk and si values on tetrax posturography . this finding was confirmed with comparison analyses showing better balance control , lower extremity function , and less falling risk in the patients with serum 25 ( oh ) d levels higher than 50.0 falling is a significant concern in elderly individuals , resulting in complex problems related to the personal and societal impact of aging . recently , there has been a growing field of research concerned with reducing the risk of falls and increasing muscle strength in at - risk subjects . for this purpose , major institutions such as the international osteoporosis foundation , endocrine society and us preventive services task force recommend giving vitamin d to elderly people in order to reduce the risk of falling . muscle weakness , muscle pain ( especially in the proximal muscles ) , and gait disorders are commonly seen in vitamin d deficiency3 ,4,5,6 . from previous data , it has been demonstrated that the lower extremity functions were better with higher 25 ( oh ) d levels in older people21 ,22,23,24 . our findings , in accordance with these reports , support the importance of vitamin d in lower extremity functions . an accurate evaluation of balance control in elderly patients is necessary before effective treatment can be recommended or developed . sppb , which is comprised of standing balance , usual gait , and chair stand performance , is a widely - used test for this purpose18 . although such clinical tests may allow for interference of subjective factors , it is easy to use and is reported to have high validity and reliability . in our study , we found significant differences between the two groups for all subtests , and the total score of sppb indicated better performance in the patients with serum 25 ( oh ) d levels higher than 50.0 posturography is a balance - status measurement that is used to quantitatively assess human postural stability and postural responses25 . it is based on computerized elaboration of electronic signals emitted by four footplates , one for each heel and toe25 . in this way , it provides the investigation of visual , somatosensory , motor and central nervous processes and their effect on stability . st , which quantitatively measures the postural sway according to changes in the pivoting center with high values indicating worse postural performance , was higher in most of the postures of hypovitaminosis group compared to those of the other group . on tetrax posturography , falling risk is a comprehensive result based on all results in all positions , with higher values indicating that the patient is at risk of falling . falling risk was significantly higher in the hypovitaminosis group in our study . in the regression analysis , serum 25 ( oh ) d concentrations were also associated with falling risk , supporting this result , even with adjustment for confounding variables and potential mediators of fall risk . on the other hand , wdi was not different between the groups . wdi is a discrepancy from equal weight distribution ( 25 % of weight on each plate ) . considering its role on balance , with high values indicating orthopedic problems , this result may be explained . according to our findings , the anti - fall effect of vitamin d is supported by the results of the clinical balance test and tetrax posturography are inconsistent with previous observations . in many studies on elderly people , a clear relation between vitamin d deficiency and postural instability has been demonstrated5 , 14 , 26 . however , most of these studies used sppb as a balance test in evaluating this relationship . among the studies which used posturography , a similar study investigating the effects of vitamin d on postural balance was conducted by boersma d et al14 . in that study , it was concluded that posture was impaired in vitamin d deficiency ( 30nmol / l ) in comparison to patients with vitamin d levels between 30 to 50 nmol / l and higher than 50 nmol / l . when compared with our study , it seems that their results are of a similar nature , but are not completely comparable due to the variability in vitamin d boundaries , parameters , and method used . indeed , the absence of standardization of method particularly regarding the range of vitamin d levels - in such studies leads to incompatible results . there is no clear consensus on what is the optimal range of vitamin d in the prevention of deterioration of balance and neuromuscular functions . the american endocrine society defines levels of 50 nmol / l or below as deficiency20 . thus , we grouped our patients according to serum 25 ( oh ) d levels below or above 50 nmol / l . recent research has provided an increasing number of arguments in favor of an action of vitamin d on muscles and the central nervous system . it is well known that 1.25 - dihydroxy vitamin d , the active vitamin d metabolite , binds to a vitamin - d - specific nuclear receptor ( vdr ) in muscle tissue27 ,28,29 , leading to de novo protein synthesis30 and muscle cell growth29 . vitamin d may improve muscle strength and function , as well as balance due to the improved strength . on the other hand , vdrs have been demonstrated in some parts of the brain , especially in the cortical , subcortical and spinal motor zones31 , 32 . according to this evidence , it seems that vitamin d plays a role in the cerebral processes of postural balance . since only women aged 60 and above were enrolled into the study , we can not apply our results to all older people in this age population . secondly , since tetrax usually evaluates stability in the static condition , it is difficult to assess the problems of balance control in the dynamic state . another limitation could be addressed through a pilot study to investigate whether the tetrax balance control index is confounded by age , weight , or height , which is currently lacking . because a difference regarding these parameters could not be found between the two groups in our study , any confounding effects of age , weight , or height may be limited . in summary , this study showed better balance control , better lower extremity function , and less falling risk in patients with serum 25 ( oh ) d levels higher than 50.0 this finding was supported using both clinical tests of postural balance and tetrax posturography . nevertheless , our results should be confirmed by further studies on wider populations to establish definitive effectiveness .
output:

agent
[ purpose ] to evaluate the association between vitamin d and risk of falling , balance , and lower extremity neuromuscular function in women aged 60 and above by using tetrax posturography . [ subjects and methods ] a total 200 women were classified based on their 25 - oh - vitamin d ( 25 ( oh ) d ) values : hypo - vitaminosis group ( less than 50.0 nmol / l ) and normal group ( 50.0 more ) . balance was measured using a tetrax posturography device ( sunlight medical ltd , israel ) . falling risk , stability index ( si ) , and weight distribution index ( wdi ) were calculated . short physical performance battery ( sppb ) and international physical activity questionnaire ( ipaq ) were used as the clinical tests . [ results ] standing balance , gait , chair stand performance and total sppb scores were significantly better in the patients with serum 25 ( oh ) d levels higher than 50.0 nmol / l . similarly , falling risk and si values in the most of the postures were significantly higher in the hypovitaminosis group . there were significant associations between serum 25 ( oh ) d levels with sppb total score and tetrax - measured falling risk . [ conclusion ] this study showed better balance control , lower extremity function , and reduced falling risk in patients with serum 25 ( oh ) d levels higher than 50.0 nmol / l in women aged 60 and above .
***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: however , vitamin d deficiency is not only a risk factor for osteoporosis ; there is also evidence that it is responsible for decreased muscle functions and falls1 ,2,3,4,5 . recently , there has been a growing field of research concerned with the association between vitamin d deficiency and a wide range of diseases other than osteoporosis in the elderly . it has been found that the capacity for synthesizing vitamin d decreases with age due to the changes in the skin seen with aging2 . decreases in oral intake and absorption of vitamin d in the intestines as well as low 1 alpha hydroxylase enzyme activity in the kidneys , frequently lead to the development of vitamin d deficiency in the elderly2 . considering the theory that vitamin d regulates skeletal muscle physiology , as suggested by various clinical observations and experimental studies , the muscular weakness seen in older patients with low - serum 25 - oh - vitamin d ( 25 ( oh ) d ) concentrations may lead to falls6 , 7 . indeed , cholecalciferol - calcium supplementation reduces falls by 46 % to 65 % in community - dwelling older women5 . on the other hand , there are many factors affecting fall - risk in the older population . in an overview of the literature by annweiler et al. 8 , it was asserted that age - related changes in postural reactions may be related to vitamin d status , mediated through either central nervous system integration or antigravity muscles as the effectors in postural responses . some studies showed that people with vision and balance disorders had lower levels of vitamin d compared to those without . although no evidence has reported that lower levels of vitamin d result in neurobehavioral impairment , it seems that vitamin d plays an important role in neurobehavioral functions9 . this suggests that muscular weakness can not be considered as the only mechanism of fall - risk related to vitamin d deficiency . on the other hand , there is no clear consensus regarding the relationship between falls and vitamin d. karlsson et al. 10 in their review reported that vitamin d supplementation , with or without calcium , in the community - living elderly did not reduce the number of falls or number of fallers . in that study , the authors recommended the administration of vitamin d supplements in those with low levels of vitamin d. there has been confusion about which form of vitamin d is effective in reducing the risk of falls . no fall - reductive effect in community - dwellers has been reported with alfacalcidol , whereas those with calcitriol had a 36 % reduction in the number of falls11 . according to previous data showing that impaired balance is an established risk factor for falls in older persons12 , 13although clinical studies indicated a significant impairment of postural balance in vitamin d deficiency , there are few studies in which the effect of vitamin d on falls and balance were assessed by the posturographic method14 ,15,16 . for this reason , our study intends to explore whether there is an association between vitamin d and risk of falling , balance , and lower extremity neuromuscular function in women aged 60 and above by using tetrax posturography . a total 200 women aged 60 and above who applied to our outpatient clinic were enrolled into the study between december 2010 and june 2012 . a history of intake of medications that affect the central nervous system and / or bone metabolism ; the presence of a disease that affects postural stability and gait such as parkinson s disease , stroke , dementia and vitamin b12 deficiency ; the presence of any neurological motor deficit such as paresis or orthopedic problems such as previous arthroplasty , amputation or severe osteoarthritis in the lower extremities , were exclusion criteria . in addition , patients who had severe liver disease , cardiac failure , other severe metabolic diseases , and mental disorders were also excluded . the patients cognitive status was measured by the mini mental state test ( mmst ) 17 . if the patient had had a score 24 in the mmst , they were excluded . the study was approved by the institutional review board , and all participants provided written informed consent . after the socio - demographic characteristics were recorded , a detailed medical history was taken . for osteoporosis and vitamin d , duration of exposure to sun , number of births , duration of nursing , diet , and history of falls were recorded . vitamin d supplement use was coded as yes if participants reported currently taking supplements . the medical history related to other diseases such as diabetes mellitus , hypertension , use of loop and / or thiazide diuretics , and the taking of psychotropic medications were also recorded . in the assessment of balance , a tetrax posturography device ( sunlight medical ltd . , israel ) was used , taking into consideration the oscillation rates from the postugraphic software . this device is comprised of four independent platforms which measure the vertical pressure changes from both toe tips and from both soles , and a computer which collects and processes the digital data from the platform . the system can digitally save the data from the four different measurement platforms simultaneously and document them as visual and numerical values . pressure detectors placed on a platform on which the person stands straight detect the patterns of displacement at the center of pressure . the subject s risk of falling was calculated by the device from the oscillation angle between the center of pressure and the center of gravity . the patients were asked to look forward with eyes open and closed ( no and nc ) . next , they were asked to turn their head to the left and right ( hl and hr ) more than 45 . next , they were asked to extend their head upward and downward ( hf and hb ) . finally , the patients were asked to stand on a foam - rubber pillow with their eyes open and closed ( po and pc ) . falling risk , stability index ( si ) , and weight distribution index ( wdi ) were calculated for each patient , with high values indicating a worse postural performance . as a clinical balance test , the sppb is a valid and reliable test which is comprised of three tasks : standing balance , usual gait , and chair stand performance . scores of 14 for each task were computed according to the time spent for the activity . summing the three individual categorical scores , a summary performance score was created for each participant ( range : 012 ) , with higher scores indicating better lower body function . in addition , physical activity levels were evaluated by a short form of the international physical activity questionnaire ( ipaq ) 19 . this self - reported questionnaire is based on estimations of time spent per week on different physical activities , in order to classify individuals as sedentary , irregularly active ( a or b ) , active , or very active . total weekly physical activity was estimated by converting the activity items into multiples of the basal resting energy expenditure ( metabolic equivalent of task , met ) for each domain alone ( walking activity , moderate physical activity , and vigorous physical activity ) and in combination ( sum of all physical activity ) . grip strength was measured in the dominant hand using a jamar plus digital handheld dynamometer . three attempts at maximal squeeze were recorded , and the best of the three measurements was used . serum 25 ( oh ) d levels were measured using manual radioimmunoassay using single - batch reagents ( ids , england ) . blood sampling was divided into two seasonal groups as winter ( october march ) and summer ( aprilparticipants were classified based in their 25 ( oh ) d values using previously published cut - offs : hypo - vitaminosis group ( less than 50.0 nmol / l ) and normal group ( 50.0 and greater ) 20 . statistical analyses were performed with the statistical package for the social sciences ( spss ) 15.0 . crosstabs were created on variants from nominal and ordinal scales , and chi - square analysis was conducted . shapiro wilk test was used to assess the distribution of the variables . for variables with normal distribution , comparison analyses of the other variables were carried out by the mann whitney u test . in their results , the demographic and clinical characteristics are reported in table 1table 1.socio - demographic characteristicstotaln = 200hypo - vitaminosis group ( 50.0 nmol / l ) n = 77normal group ( 50.0 nmol / l ) n = 123age ( years , meansd ) 67.36.067.76.167.05.9 bmi ( kg / m , meansd ) 29.44.829.64.829.24.9 education level ( n , % ) * 5 schooling years139 ( 69.5 ) 58 ( 75.4 ) 81 ( 65.9 ) 5 to 12 schooling years32 ( 16.0 ) 13 ( 16.9 ) 19 ( 15.4 ) 12 schooling years29 ( 14.5 ) 6 ( 7.8 ) 23 ( 18.7 ) vitamin d supplementation ( n , % ) * 63 ( 31.5 ) 13 ( 16.9 ) 50 ( 40.7 ) * history of falls ( n , % ) * 1 fall36 ( 18.0 ) 14 ( 18.2 ) 22 ( 11.5 ) 1 fall18 ( 9.0 ) 9 ( 11.7 ) 9 ( 9.6 ) season of blood collectionwinter ( n , % ) * 123 ( 61.5 ) 48 ( 62.5 ) 75 ( 61.0 ) summer ( n , % ) * 77 ( 38.5 ) 29 ( 37.7 ) 48 ( 39.0 ) using of loop and / or thiazide diuretics ( n , % ) * 38 ( 19.0 ) 14 ( 18.2 ) 24 ( 19.5 ) using of psychotropic medications ( n , % ) * 34 ( 17 ) 9 ( 11.7 ) 25 ( 20.3 ) number of births ( meansd ) 3.31.93.52.03.11.8 ocular problems ( n , % ) 179 ( 89.5 ) 68 ( 88.3 ) 111 ( 90.2 ) 25 - oh - vitamin d ( nmol / l , meansd ) 68.738.734.09.490.433.9 * student t test , test . * p 0.05 . there was no significant difference between the groups except vitamin d supplementation ( 13 subjects - 16.9 % vs. 50 subjects - 40.7 % , p 0.05 ) . * p 0.05 a comparison of the serum 25 ( oh ) d level groups ( hypo - vitaminosis group and normal group ) for the clinical assessment parameters is presented in table 2table 2 . comparison of the groups for clinical testshypo - vitaminosis group ( 50.0 nmol / l ) n = 77normal group ( 50.0 nmol / l ) n = 123standing balance , median ( min / max ) 3 ( 04 ) 4 ( 14 ) * gait , median ( min / max ) 3 ( 14 ) 3 ( 14 ) * chair stand performance , median ( min / max ) 2 ( 04 ) 3 ( 04 ) * sppb total , median ( min / max ) 8 ( 112 ) 10 ( 212 ) * ipaqsedentary ( n , % ) 59 ( 76.6 ) 78 ( 63.4 ) * low physical activity ( n , % ) 18 ( 23.4 ) 45 ( 36.6 ) * hand grip , jamar ( kg , meansd ) 18.34.919.54.6 tetrax - falling risk , ( meansd ) 55.725.841.125.0 * tetrax - si , median ( min / max ) no19 .6 ( 7.748.5 ) 15.8 ( 6.454.0 ) * nc21 .2 ( 8.397.5 ) 18.3 ( 7.865.8 ) * po20 .2 ( 8.778.6 ) 19.6 ( 8.856.2 ) pc28 .3 ( 12.776.3 ) 21.1 ( 8.990.4 ) * hr23 .3 ( 13.298.2 ) 22.3 ( 8.387.7 ) hl24 .5 ( 10.289.3 ) 22.0 ( 7.888.4 ) * hb24 .9 ( 12.271.4 ) 20.2 ( 8.3124.6 ) * hf22 .5 ( 10.5113.6 ) 21.18 ( 9.1389.33 ) total 190.9 ( 115.0607.0 ) 167.7 ( 80.3614.2 ) * tetrax - wdi . median ( min - max ) no5 .9 ( 1.020.0 ) 6.0 ( 1.2518.9 ) nc5 .6 ( 019.1 ) 5.5 ( 0. - 19.1 ) po8 .4 ( 2.020.9 ) 9.1 ( 0.929.1 ) pc9 .1 ( 1.821.3 ) 9.0 ( 2.027.8 ) hr7 .2 ( 1.321.3 ) 5.9 ( 1.618.1 ) hl7 .3 ( 0.717.8 ) 6.2 ( 0.619.5 ) hb7 .3 ( 1.019.1 ) 7.0 ( 1.018.4 ) hf6 .5 ( 0.618.2 ) 5.0 ( 0.516.9 ) total57 .0 ( 17.3156.0 ) 52.7 ( 22.4146.8 ) sppb : short physical performance battery , ipaq : international physical activity questionnaire , si : stability index , wdi : weight distribution index , no : neutral position with eyes open , nc : neutral position with eyes closed , po : eyes open on pillows , pc : eyes closed on pillows , hr : head turned right and eyes closed , hl : head turned left and eyes closed , hb : eyes closed raising head backward 30 , hf : eyes closed with head forward approximately 30 . mann whitney u test . test . sppb scores , si and wdi results on posturography were given as median values because normal distribution could not be obtained . standing balance , gait , and chair stand performance scores were significantly better in patients with serum 25 ( oh ) d levels higher than 50.0 nmol / l ( p 0.05 ) . total sppb scores were also different between the groups , indicating that the group with serum 25 ( oh ) d levels higher than 50.0 nmol / l had significantly better lower extremity functions ( p 0.05 ) . similarly , falling risk andsi values in the most of the postures were significantly higher in the hypovitaminosis group ( p 0.05 ) . sppb : short physical performance battery , ipaq : international physical activity questionnaire , si : stability index , wdi : weight distribution index , no : neutral position with eyes open , nc : neutral position with eyes closed , po : eyes open on pillows , pc : eyes closed on pillows , hr : head turned right and eyes closed , hl : head turned left and eyes closed , hb : eyes closed raising head backward 30 , hf : eyes closed with head forward approximately 30 . mann whitney u test . this study showed that serum 25 ( oh ) d levels were significantly associated with clinical balance test results , falling risk and si values on tetrax posturography . this finding was confirmed with comparison analyses showing better balance control , lower extremity function , and less falling risk in the patients with serum 25 ( oh ) d levels higher than 50.0 falling is a significant concern in elderly individuals , resulting in complex problems related to the personal and societal impact of aging . recently , there has been a growing field of research concerned with reducing the risk of falls and increasing muscle strength in at - risk subjects . for this purpose , major institutions such as the international osteoporosis foundation , endocrine society and us preventive services task force recommend giving vitamin d to elderly people in order to reduce the risk of falling . muscle weakness , muscle pain ( especially in the proximal muscles ) , and gait disorders are commonly seen in vitamin d deficiency3 ,4,5,6 . from previous data , it has been demonstrated that the lower extremity functions were better with higher 25 ( oh ) d levels in older people21 ,22,23,24 . our findings , in accordance with these reports , support the importance of vitamin d in lower extremity functions . an accurate evaluation of balance control in elderly patients is necessary before effective treatment can be recommended or developed . sppb , which is comprised of standing balance , usual gait , and chair stand performance , is a widely - used test for this purpose18 . although such clinical tests may allow for interference of subjective factors , it is easy to use and is reported to have high validity and reliability . in our study , we found significant differences between the two groups for all subtests , and the total score of sppb indicated better performance in the patients with serum 25 ( oh ) d levels higher than 50.0 posturography is a balance - status measurement that is used to quantitatively assess human postural stability and postural responses25 . it is based on computerized elaboration of electronic signals emitted by four footplates , one for each heel and toe25 . in this way , it provides the investigation of visual , somatosensory , motor and central nervous processes and their effect on stability . st , which quantitatively measures the postural sway according to changes in the pivoting center with high values indicating worse postural performance , was higher in most of the postures of hypovitaminosis group compared to those of the other group . on tetrax posturography , falling risk is a comprehensive result based on all results in all positions , with higher values indicating that the patient is at risk of falling . falling risk was significantly higher in the hypovitaminosis group in our study . in the regression analysis , serum 25 ( oh ) d concentrations were also associated with falling risk , supporting this result , even with adjustment for confounding variables and potential mediators of fall risk . on the other hand , wdi was not different between the groups . wdi is a discrepancy from equal weight distribution ( 25 % of weight on each plate ) . considering its role on balance , with high values indicating orthopedic problems , this result may be explained . according to our findings , the anti - fall effect of vitamin d is supported by the results of the clinical balance test and tetrax posturography are inconsistent with previous observations . in many studies on elderly people , a clear relation between vitamin d deficiency and postural instability has been demonstrated5 , 14 , 26 . however , most of these studies used sppb as a balance test in evaluating this relationship . among the studies which used posturography , a similar study investigating the effects of vitamin d on postural balance was conducted by boersma d et al14 . in that study , it was concluded that posture was impaired in vitamin d deficiency ( 30nmol / l ) in comparison to patients with vitamin d levels between 30 to 50 nmol / l and higher than 50 nmol / l . when compared with our study , it seems that their results are of a similar nature , but are not completely comparable due to the variability in vitamin d boundaries , parameters , and method used . indeed , the absence of standardization of method particularly regarding the range of vitamin d levels - in such studies leads to incompatible results . there is no clear consensus on what is the optimal range of vitamin d in the prevention of deterioration of balance and neuromuscular functions . the american endocrine society defines levels of 50 nmol / l or below as deficiency20 . thus , we grouped our patients according to serum 25 ( oh ) d levels below or above 50 nmol / l . recent research has provided an increasing number of arguments in favor of an action of vitamin d on muscles and the central nervous system . it is well known that 1.25 - dihydroxy vitamin d , the active vitamin d metabolite , binds to a vitamin - d - specific nuclear receptor ( vdr ) in muscle tissue27 ,28,29 , leading to de novo protein synthesis30 and muscle cell growth29 . vitamin d may improve muscle strength and function , as well as balance due to the improved strength . on the other hand , vdrs have been demonstrated in some parts of the brain , especially in the cortical , subcortical and spinal motor zones31 , 32 . according to this evidence , it seems that vitamin d plays a role in the cerebral processes of postural balance . since only women aged 60 and above were enrolled into the study , we can not apply our results to all older people in this age population . secondly , since tetrax usually evaluates stability in the static condition , it is difficult to assess the problems of balance control in the dynamic state . another limitation could be addressed through a pilot study to investigate whether the tetrax balance control index is confounded by age , weight , or height , which is currently lacking . because a difference regarding these parameters could not be found between the two groups in our study , any confounding effects of age , weight , or height may be limited . in summary , this study showed better balance control , better lower extremity function , and less falling risk in patients with serum 25 ( oh ) d levels higher than 50.0 this finding was supported using both clinical tests of postural balance and tetrax posturography . nevertheless , our results should be confirmed by further studies on wider populations to establish definitive effectiveness .
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