Dietary protein intake and risk of osteoporotic hip fracture in elderly residents of Utah. Protein consumption and bone fractures in women. Does dietary protein reduce hip fracture risk in elders? The Framingham osteoporosis study Proteins, dietary acid load, and calcium and risk of postmenopausal fractures in the E3N French women prospective study. Benefits of oral protein supplementation in elderly patients with fracture of the proximal femur. Calcium intake influences the association of protein intake with rates of bone loss in elderly men and women. Protein intake: effects on bone mineral density and the rate of bone loss in elderly women. Association of protein intake with bone mineral density and bone mineral content among elderly women: The OSTPRE fracture prevention study Protein Supplements Increase Serum Insulin-Like Growth Factor-I Levels and Attenuate Proximal Femur Bone Loss in Patients with Recent Hip Fracture Biomarker-calibrated protein intake and bone health in the Women's Health Initiative clinical trials and observational study. A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women. Study of Osteoporotic Fractures Research Group. Is dietary counselling effective in increasing dietary calcium, protein and energy intake in patients with osteoporotic fractures? A randomized controlled clinical trial. The Effect of a Whey Protein Supplement on Bone Mass in Older Caucasian Adults. The effects of a two-year randomized, controlled trial of whey protein supplementation on bone structure, IGF-1, and urinary calcium excretion in older postmenopausal women. One year soy protein supplementation has positive effects on bone formation markers but not bone density in postmenopausal women Nutritional factors that influence change in bone density and stress fracture risk among young female cross-country runners. A diet high in protein, dairy, and calcium attenuates bone loss over twelve months of weight loss and maintenance relative to a conventional high-carbohydrate diet in adults.
UNLABELLED The role of protein intake in osteoporosis is unclear . In a case-control study in Utah ( n = 2501 ) , increasing level of protein intake was associated with a decreased risk of hip fracture in men and women 50 - 69 years of age but not in those 70 - 89 years of age . Protein intake may be important for optimal bone health . INTRODUCTION Protein is an important component of bone , but the role of dietary protein intake in osteoporosis and fracture risk remains controversial . MATERIAL AND METHODS The role of dietary protein intake in osteoporotic hip fracture was evaluated in a statewide case-control study in Utah . Patients , 50 - 89 years of age , with hip fracture ( cases ) were ascertained through surveillance of 18 Utah hospitals during 1997 - 2001 . Age- and gender-matched controls were r and omly selected . Participants were interviewed in their place of residence , and diet was assessed using a picture-sort food frequency question naire previously reported to give a useful measure of usual dietary intake in the elderly Utah population . The association between  protein intake  and risk of hip fracture was examined across quartiles of protein intake and stratified by age group for 1167 cases ( 831 women , 336 men ) and 1334 controls ( 885 women , 449 men ) . RESULTS In logistic regression analyses that controlled for gender , body mass index , smoking status , alcohol use , calcium , vitamin D , potassium , physical activity , and estrogen use in women , the odds ratios ( OR ) of hip fracture decreased across increasing quartiles of total protein intake for participants 50 - 69 years of age ( OR : 1.0 [ reference ] ; 0.51 [ 95 % CI : 0.30 - 0.87 ] ; 0.53 [ 0.31 - 0.89 ] ; 0.35 [ 0.21 - 0.59 ] ; p < 0.001 ) . No similar associations were observed among participants 70 - 89 years of age . Results from analyses stratified by low and high calcium and potassium intake did not differ appreciably from the results presented above . CONCLUSION Higher total protein intake was associated with a reduced risk of hip fracture in men and women 50 - 69 years of age but not in men and women 70 - 89 years of age . The association between  dietary protein intake  and risk of hip fracture may be modified by age . Our study supports the hypothesis that adequate dietary protein is important for optimal bone health in the elderly 50 - 69 years of age Dietary protein increases urinary calcium losses and has been associated with higher rates of hip fracture in cross-cultural studies . However , the relation between protein and risk of  osteoporotic bone fractures among individuals has not been examined in detail . In this prospect i ve study , usual dietary intake was measured in 1980 in a cohort of 85,900 women , aged 35 - 59 years , who were participants in the Nurses ' Health Study . A mailed food frequency question naire was used and incident hip ( n = 234 ) and distal forearm ( n = 1,628 ) fractures were identified by self-report during the following 12 years . Information on other factors related to osteoporosis , including obesity , use of postmenopausal estrogen , smoking , and physical activity , was collected on biennial question naires . Dietary measures were up date d in 1984 and 1986 . Protein was associated with an increased risk of forearm fracture ( relative risk ( RR ) = 1.22 , 95 % confidence interval ( Cl ) 1.04 - 1.43 , p for trend = 0.01 ) for women who consumed more than 95 g per day compared with those who consumed less than 68 g per day . A similar increase in risk was observed for animal protein , but no association was found for consumption of vegetable protein . Women who consumed five or more servings of red meat per week also had a significantly increased risk of forearm fracture ( RR = 1.23 , 95 % Cl 1.01 - 1.50 ) compared with women who ate red meat less than once per week . Recall of teenage diet did not reveal any increased risk of forearm fracture for women with higher consumption of animal protein or red meat during this earlier period of life . No association was observed between  adult protein intake  and the incidence of hip fractures , though power to assess this association was low Summary Association between dietary protein and fracture risk is unclear . We examined association between energy-adjusted protein intake  and  hip fracture risk in elders . The risk of hip fracture was reduced in upper quartiles of protein intake when compared with lowest quartile . Introduction Studies of the association between dietary protein intake and hip fracture risk are conflicting . Therefore , we examined protein intake and hip fracture risk in a population -based group of elderly men and women . Methods Five hundred seventy-six women and 370 men from the Framingham Osteoporosis Study with no previous history of hip fracture completed Food Frequency Question naires .  Energy-adjusted protein intake  was evaluated as a continuous variable and as quartiles . Incidence rates and hazard ratios were calculated , adjusting for age , BMI , sex , and energy intake . Results Among 946 participants ( mean age 75 years ) , mean protein intake  was found to be 68 gm/d . Increased protein intake was associated with a decreased risk of hip fracture compared to those in the lowest quartile of protein intake ( Q2 HR = 0.70 , Q3 HR = 0.56 , and Q4 HR = 0.63 ; all p values ≥ 0.044 ) , p for trend was 0.07 . When a threshold effect was considered ( Q2–4 vs Q1 ) , intakes in the higher quartiles combined were associated with a significantly lower risk for hip fracture ( HR = 0.63 ; p = 0.04 ) . Conclusion Our results are consistent with reduced risk of hip fracture with higher dietary protein intake . Larger prospect i ve studies are needed to confirm and extend this finding in elderly men and women Excess dietary proteins and " acid ash " diets have been suspected to increase the risk of osteoporosis , but experimental and epidemiological evidence is mixed . We aim ed to determine whether the association between protein intake and the overall acid-base equilibrium of the diet ( as renal net acid excretion [ RNAE ] estimate ) and fracture risk vary according to calcium intake . During an average of 8.37 + /- 1.73 yr of follow-up , 2408 women reported a fracture ( excluding high-impact trauma ) among 36,217 postmenopausal women from the E3N prospect i ve study . We used Cox regression models to study the interaction between calcium and , respectively , proteins and RNAE , from the 1993 dietary question naire for fracture risk determination , adjusting for potential confounders . There was no overall association between fracture risk and total protein or RNAE . However , in the lowest quartile of calcium ( < 400 mg/1000 kcal ) , high protein intake was associated with a significant increased fracture risk ( RR = 1.51 for highest versus lowest quartile ; 95 % CI , 1.17 - 1.94 ) . An increasing fracture risk with increasing animal protein intake was also observed ( trend , p < 0.0001 ) . A similar pattern of interaction for fracture risk was observed between RNAE and calcium . In this Western population of postmenopausal women with normal to high protein intake and fairly high calcium intake , there was no overall association between total protein or RNAE and fracture risk . However , there was some evidence that high protein-high acid ash diets were associated with an increased risk of fracture when calcium intake was low ( < 400 mg/1000 kcal ) Malnutrition has been often suggested as contributing to both the high incidence of hip fracture in elderly people and its complications . In a recent prospect i ve controlled r and omized study , the clinical outcome of elderly patients with osteoporotic fracture of the proximal femur ( hip fracture ) improved by giving a simple oral dietary supplement . This study , however , did not prove that protein was responsible for the clinical improvement since the supplement also contained vitamins and minerals . We addressed this question by comparing the clinical outcome and bone mineral density ( BMD ) changes in elderly patients with hip fracture , receiving two different dietary supplements with different protein contents . Sixty-two patients ( mean age 82 ) admitted into the orthopedic ward for fracture of the proximal femur were r and omized into two groups . One group ( n = 33 ) received 250 ml/day of an oral nutritional supplement containing protein ( 20.4 g ) , mineral salts ( Ca : 0.525 g ) and vitamins A = 750 IU ; D3 = 25 IU ) for a mean of 38 days . A control group ( n = 29 ) received the same supplement dose , but with no protein , for the same period of time . The clinical course was significantly better in the group receiving protein , with 79 % having a favorable course as compared to 36 % ( p less than 0.02 ) in the control group during the stay in the recovery hospital . The rate of complications and deaths was also significantly lower in the protein-supplemented vs the control group ( 52 vs 80 % , p less than 0.05 ) 7 months after hip fracture . The median hospital stay was significantly lower in the protein-supplemented group ( 69 vs 102 days , p less than 0.05 ) . ( ABSTRACT TRUNCATED AT 250 WORDS BACKGROUND There is currently no consensus on the effect of dietary protein intake on the skeleton , but there is some indication that low calcium intakes adversely influence the effect of dietary protein on fracture risk . OBJECTIVE The objective of the present study was to determine whether supplemental calcium citrate malate and vitamin D influence any associations between  protein intake and change in bone mineral density ( BMD ) . DESIGN Associations between protein intake and change in BMD were examined in 342 healthy men and women ( aged > or = 65 y ) who had completed a 3-y , r and omized , placebo-controlled trial of calcium and vitamin D supplementation . Protein intake was assessed at the midpoint of the study with the use of a food-frequency question naire and  BMD  was assessed every 6 mo by dual-energy X-ray absorptiometry . RESULTS The mean ( + /-SD ) protein intake of all subjects was 79.1 + /- 25.6 g/d and the mean total calcium intakes of the supplemented and placebo groups were 1346 + /- 358 and 871 + /- 413 mg/d , respectively . Higher protein intake was significantly associated with a favorable 3-y change in total-body BMD in the supplemented group ( in a model containing terms for age , sex , weight , total energy intake , and dietary calcium intake ) but not in the placebo group . The pattern of change in femoral neck BMD with increasing protein intake in the supplemented group was similar to that for the total body . CONCLUSION Increasing protein intake may have a favorable effect on change in BMD in elderly subjects supplemented with calcium citrate malate and vitamin BACKGROUND The role of dietary protein in bone metabolism is controversial . OBJECTIVE We investigated the associations of dietary protein intake with baseline bone mineral density ( BMD ) and the rate of bone loss over 3 y in postmenopausal elderly women . DESIGN Women aged 65 - 77 y ( n = 489 ) were enrolled in an osteoporosis intervention trial . We studied the associations of protein intake as a percentage of energy with baseline BMD and the rate of bone loss in 96 women in the placebo group ( n = 96 ) . We also examined the effect of the interaction of dietary  calcium  intake with protein intake on BMD . RESULTS In the cross-sectional study , a higher intake of protein was associated with higher BMD . BMD was significantly higher ( P < 0.05 ) in the spine ( 7 % ) , midradius ( 6 % ) , and total body ( 5 % ) in subjects in the highest quartile of protein intake than in those in the lower 2 quartiles . This positive association was seen in women with calcium intakes > 408 mg/d . There was no significant effect of protein intake on hip BMD . In the longitudinal study of the placebo group , there was no association between protein intake and the rate of bone loss . CONCLUSIONS The highest quartile of protein intake (: 72 g/d ) was associated with higher BMD  in elderly women at baseline only when the calcium intake exceeded 408 mg/d . In the longitudinal study , no association was seen between protein intake and the rate of bone loss , perhaps because the sample size was too small or the follow-up period of 3 y was not long enough to detect changes Abstract It has been hypothesized that high protein intakes are associated with lower bone mineral content ( BMC ) . Previous studies yield conflicting results and thus far no studies have undertaken the interaction of body mass index ( BMI ) and physical activity with protein intakes in relation to BMC and bone mineral density ( BMD ) . Objective To evaluate the associations of dietary total protein ( TP ) , animal protein ( AP ) and plant protein ( PP ) intakes with BMC and BMD and their changes . We tested also the interactions of protein intake with , obesity ( BMI ≤30 vs. > 30 kg/m2 ) and physical activity level ( passive vs. active ) . Design / Setting Prospect i ve cohort study ( Osteoporosis Risk-Factor and Fracture-Prevention Study ) . Participants / measures At the baseline , 554 women aged 65 - 72 years filled out a 3-day food record and a question naire covering data on lifestyle , physical activity , diseases , and medications . Intervention group received calcium 1000 mg/d and cholecalciferol 800 IU for 3 years . Control group received neither supplementation nor placebo . Bone density was measured at baseline and year 3 , using dual energy x-ray absorptiometry . Multivariable regression analyses were conducted to examine the associations between protein intake and BMD and BMC . Results In cross-sectional analyses energy-adjusted TP ( P≤0·029 ) and AP ( P≤0·045 ) but not PP ( g/d ) were negatively associated with femoral neck ( FN ) BMD and BMC . Women with TP≥1·2 g/kg/body weight ( BW ) ( Ptrend≤0·009 ) had lower FN , lumbar spine ( LS ) and total BMD and BMC . In follow-up analysis , TP ( g/kg/BW ) was inversely associated with LS BMD and LS BMC . The detrimental associations were stronger in women with BMI < 30 kg/m2 . In active women , TP ( g/kg/BW ) was positively associated with LS BMD and FN BMC changes . Conclusions This study suggests detrimental associations between protein intake and bone health . However , these negative associations maybe counteracted by BMI > 30 kg/m2 and physical activity Fracture of the proximal femur is the most dramatic clinical sequela of osteoporosis [ 1 , 2 ] . It is associated with a high mortality rate , need for long-term medical care , and prolonged disability [ 3 - 5 ] . Protein malnutrition is often seen in elderly persons and is more severe in patients with hip fracture [ 6 - 11 ] . Protein deficiency may contribute to the occurrence of hip fracture by reducing muscle strength , impairing movement coordination , and diminishing the protective layer of soft tissue padding [ 9 , 10 , 12 - 14 ] It may also be associated with lower bone mineral density at the proximal femur [ 15 ] . Furthermore , malnutrition in general and protein deficiency in particular at admission and during recovery may adversely influence clinical outcome after hip fracture [ 7 , 9 , 10 , 16 - 18 ] . Protein restriction has been shown to reduce plasma levels of insulin-like growth factor-I ( IGF-I ) by inducing resistance to the action of growth hormone in the liver and increasing the metabolic clearance rate of the growth factor [ 19 - 23 ] . Furthermore , evidence shows that protein depletion may blunt the effect of IGF-I on target organs [ 20 ] . Thus , low protein intake in elderly persons may be detrimental to skeletal integrity , muscle strength , and immune response [ 11 , 24 - 27 ] because of decreased production and action of IGF-I , which favorably influences these systems [ 28 - 33 ] . Previous studies [ 16 , 17 ] have shown that a 5-week course of protein supplements can reduce the medical complication rate and duration of hospital stay in patients with recent hip fracture . These findings were independent of energy , calcium , and vitamin D intake [ 17 ] . Whether these observations were related to the restoration of decreased IGF-I levels and whether bone may benefit from long-term protein supplementation are not known . We investigated whether protein supplements in vitamin D-replete patients with a recent hip fracture who were receiving calcium supplements could increase circulating IGF-I levels and favorably influence bone mineral density . Methods Patients Patients were recruited in the orthopedic ward of Geneva University Hospital , the referral center that receives 94.6 % of all patients with hip fracture from an area with a population of approximately 400 000 persons [ 5 ] . The protocol was approved by the ethical committee of the Geneva University Hospital Department of Surgery . Inclusion criteria were age greater than 60 years ; recent hip fracture ( within 2 weeks ) attributable to osteoporosis ( that is , a fracture after a minor trauma , such as a fall from st and ing height ) ; and the ability to give written , informed consent . Exclusion criteria were pathologic fracture ; fracture caused by severe trauma ; history of contralateral hip fracture ; severe mental impairment ; active metabolic bone disease ; renal failure ( plasma creatinine concentration 200 mol/L ) ; acute illness that could interfere with the study protocol ; severe malnutrition ( serum albumin level < 15 g/L ) ; consumption of drugs known to alter bone metabolism , such as calcitonin , fluoride , sex hormones , corticosteroids , or bisphosphonates ; and life expectancy of less than 1 year . Using a r and om number table , we assigned patients to receive an oral protein supplement composed of 90 % milk proteins or a placebo made isocaloric by the addition of maltodextrins . Patients took the assigned intervention 5 days a week for 6 months in addition to their regular diet . All patients received one oral dose of vitamin D3 , 200 000 IU ( vitamine D3B.O.N. , Doms-Adrian , Courbevoie , France ) , to correct any possible vitamin D deficiency [ 34 ] . The daily protein supplement ( Meritene , S and oz Nutrition Ltd. , Berne , Switzerl and ) provided 1050 kJ ( 250 kcal ) of energy in the form of 20 g of proteins , 3.1 g of lipids , and 35.7 g of carbohydrates ( 54.4 g in placebo ) . The other constituents of the 65 g powder supplement were vitamin A ( 1000 IU ) , vitamin K1 ( 30 g ) , vitamin C ( 20 mg ) , calcium ( 550 mg ) , magnesium ( 91 mg ) , phosphorus ( 429 mg ) , and sodium ( 228 mg ) . The supplement is design ed to normalize but not overcompensate for the insufficient dietary intake of protein of elderly persons with a recent fracture of the proximal femur [ 16 ] . Compliance was verified by weekly phone calls and by counting the remaining nutritional supplement bags , which were forwarded monthly by mail . Clinical Data Medical history , clinical characteristics , anthropometric data , and performance status according to an Activities of Daily Living score [ 35 ] were evaluated . Dietary intakes were recorded by using a food-frequency question naire [ 36 ] about the week before the fracture . Food intakes were analyzed by using a nutrient software system ( Fruitdor , Astra-Calve , Paris , France ) . Dietary intake of calcium , phosphorus , and protein was calculated from intake of dairy products , meat , fish , and vegetables . Because many patients were unable to st and a few days after hip fracture , their height was determined with a fathom measure while they were recumbent . Body weight was determined with a scale that correlated highly with that provided by measurement of whole body bone , fat , and lean mass as assessed by dual x-ray absorptiometry [ 37 ] . Mid-arm circumference was measured with a tape measure ( coefficient of variation , 2 % ) . Isometric muscle strength of the biceps of the dominant arm was evaluated with a dynamometer ( Lido , Lidoactive Isokinetic System , Loredan Biomedical Inc. , West Sacramento , California ) , which measures the peak torque ( coefficient of variation < 5 % ) . The grip strength of the same arm was measured with a dynamometer ( Vigorimeter , Martin Medizin-Technik , Tuttlingen , Germany ) [ 38 ] . The mean of three measurements was used for calculation . Biochemical Data Within 120 hours after surgery , we used st and ard methods to analyze venous blood sample s for protein-corrected plasma levels of calcium , phosphate , creatinine , total proteins , albumin , and prealbumin . We also measured levels of IGF-I ( Nichols Institute , San Juan Capistrano , California ) after acid-ethanol extraction and cryoprecipitation [ 39 ] , intact parathyroid hormone ( Immulite , Diagnostic Products , Los Angeles , California ) , calcitriol , calcidiol ( Incstar , Stillwater , Minnesota ) , and osteocalcin ( CIS-BIO International , Gif-sur-Yvette , France ) . Biochemical measurements were repeated 6 and 12 months after the fracture . Serum IGF-I binding proteins were measured by Western lig and blot analysis [ 40 ] . Briefly , 3 L of serum was boiled and separated onto 15 % sodium dodecylsulfate polyacrilamide gel electrophoresis under nonreducing conditions . Proteins were electrically blotted onto a nitrocellulose membrane , and IGF-I binding proteins were detected after incubating the membranes with radioiodinated IGF-I at 4C for 24 hours . Insulin-like growth factor binding proteins were quantified by phosphorimaging ( Molecular Dynamics , Sunnyvale , California ) . The intensity of the b and s corresponding to the appropriate molecular weights [ 40 ] was expressed as the percentage of total bound radioactive IGF-I. Measurements of calcium , phosphate , and creatinine were obtained from the second fasting morning urine . The ratio of hydroxyproline to creatinine in the same sample was taken as a reflection of bone resorption . Markers of bone resorption ( pyridinoline and deoxypyridinoline ) in the first morning spot urine were measured by detecting fluorescence emission after acid hydrolysis and separation with isocratic reverse-phase high-performance liquid chromatography ( BioRad System , Munich , Germany ) , and the values were adjusted to the creatinine concentration . Immunologic Data Concentrations of IgA , IgG , IgM , and isohemagglutinins were measured by using st and ard methods . Cell-mediated immunity was assessed by using a skin-test antigens for cellular hypersensitivity system ( STACH , Institut Merieux , Lyon , France ) , which evaluates the size of the skin reaction to various antigens injected intradermally [ 41 ] . Bone Mass Assessment We measured areal bone mineral density at the lumbar spine ( anteroposterior and lateral views ) , the contralateral proximal femur ( femoral neck and trochanter ) , and the contralateral mid-femoral shaft . We also measured whole-body bone mineral content , fat , and lean mass by using dual x-ray absorptiometry ( Hologic QDR-2000 , Waltham , Massachusetts ) . The coefficients of variation of these measurements are reported elsewhere [ 37 , 42 ] . Vertebral Deformity Two series of lateral radiography of the thoracic and lumbar spine were taken at the start of the study and at 12 months . The films were examined by a single investigator ( who was unaware of treatment group assignment ) according to a 6-point analysis procedure for each vertebral body from T4 to L4 [ 43 , 44 ] ( intra-observer coefficient of variation , 1.8 % to 3.1 % ) . At baseline , fracture was defined by a decrease of 20 % in the ratio of anterior or middle height to posterior height . Patients were considered to have a new vertebral deformity if the anterior , middle , or posterior height decreased by more than 20 % between the two examinations . Statistical Analysis All values are given as the mean SD for baseline measurement and the mean SE for comparisons of outcome results . All analyses were performed by using the SAS procedure ( Cary , North Carolina ) . One-way analysis of variance was used . A two-tailed P value less than 0.05 was considered significant . Role of the Funding Sources This study was supported by grants from S and oz Nutrition Ltd. , Berne , Switzerl and , and the Swiss National Research Science Foundation . The skin-test antigens for cellular hypersensitivity system was supplied by Rhone-Poulenc , Thalwil , Switzerl and . No organization influenced the design , conduct , or reporting of the study . Results Of 842 patients evaluated from April 1992 to February 1994 , 82 were recruited into the r and omized , double-blind , placebo-controlled trial . This low enrollment rate was due to patients ' poor medical or cognitive conditions and reluctance to give informed consent . BACKGROUND The effects of dietary protein on bone health are controversial . OBJECTIVE We examined the relation between protein intake with fracture and  bone mineral density ( BMD )  within the Women 's Health Initiative ( WHI ) . DESIGN This prospect i ve analysis included 144,580 women aged 50 - 79 y at baseline in the WHI clinical trials ( CTs ) and observational study ( OS ) that recruited participants in 1993 - 1998 with follow-up through 2011 . Self-reported clinical fractures were collected semiannually through the original end of the trials ( WHI CTs ) and annually ( WHI OS ) by question naires . Hip fracture was adjudicated by a central review of radiology reports . BMDs for total body , hip , and spine were measured at baseline and 3 and 6 y in 9062 women at 3 WHI clinics by using dual-energy X-ray absorptiometry .  Protein intake was assessed via food-frequency question naire and calibrated by using biomarkers of energy and protein intakes . Associations between protein intake and fracture were estimated by using Cox proportional hazards regression , and the relation between protein intake and BMD was estimated by using linear regression . RESULTS Median biomarker-calibrated protein intake was 15 % of energy intake . Per 20 % increase in calibrated protein intake ( percentage of energy ) , there was no significant association with total fracture ( HR : 0.99 ; 95 % CI : 0.97 , 1.02 ) or hip fracture ( HR : 0.91 ; 95 % CI : 0.84 , 1.00 ) , but there was an inverse association with forearm fracture ( HR : 0.93 ; 95 % CI : 0.88 , 0.98 ) . Each 20 % increase in calibrated protein intake was associated with a significantly higher BMD for total body ( mean 3-y change : 0.003 g/cm² ; 95 % CI : 0.001 , 0.005 g/cm² ) and hip ( mean 3-y change : 0.002 g/cm² ; 95 % CI : 0.001 , 0.004 g/cm² ) . CONCLUSIONS Higher biomarker-calibrated protein intake within the range of usual intake was inversely associated with forearm fracture and was associated with better maintenance of total and hip BMDs . These data suggest higher protein intake is not detrimental to bone health in postmenopausal women BACKGROUND Different sources of dietary protein may have different effects on bone metabolism . Animal foods provide predominantly acid precursors , whereas protein in vegetable foods is accompanied by base precursors not found in animal foods . Imbalance between dietary acid and base precursors leads to a chronic net dietary acid load that may have adverse consequences on bone . OBJECTIVE We wanted to test the hypothesis that a high dietary ratio of animal to vegetable foods , quantified by protein content , increases bone loss and the risk of fracture . DESIGN This was a prospect i ve cohort study with a mean ( + /-SD ) of 7.0+/-1.5 y of follow-up of 1035 community-dwelling white women aged > 65 y.  Protein intake  was measured by using a food-frequency question naire and  bone mineral density was measured by dual-energy X-ray absorptiometry . RESULTS Bone mineral density was not significantly associated with the ratio of animal to vegetable protein intake . Women with a high ratio had a higher rate of bone loss at the femoral neck than did those with a low ratio ( P = 0.02 ) and a greater risk of hip fracture ( relative risk = 3.7 , P = 0.04 ) . These associations were unaffected by adjustment for age , weight , estrogen use , tobacco use , exercise , total calcium intake , and total protein intake . CONCLUSIONS Elderly women with a high dietary ratio of animal to vegetable protein intake  have more rapid femoral neck bone loss and a greater risk of hip fracture than do those with a low ratio . This suggests that an increase in vegetable protein intake and a decrease in animal protein intake may decrease bone loss and the risk of hip fracture . This possibility should be confirmed in other prospect i ve studies and tested in a r and omized trial To determine the feasibility of increasing the calcium , protein and calorie intake of osteoporotic fracture patients by repeated dietary counselling delivered by a dietitian , a r and omized controlled trial was conducted . Among 189 patients presenting with osteoporotic fractures to an Orthopaedics and Traumatology Department of a large regional hospital , 98 patients were r and omized to the intervention group and 91 were r and omized to the control group ( with usual care ) . Intervention group received three sessions of dietary counselling with tailored made recommendations over a period of 4 months , while the control group only received dietary assessment and pamphlets on the prevention of osteoporosis . Almost all subjects in both intervention and control groups had calcium intake below the recommended level of 1000 mg at baseline . Half and 60 % of subjects in both groups had total energy and protein intake below recommended levels respectively . The mean weights of control and intervention groups at baseline were 51.5 and 50.9 kg respectively , while the body mass index ( BMI ) were 22.6 ( kg m(-2 ) ) and 22.6 ( kg m(-2 ) ) respectively . After dietary intervention , significant increase of intake was seen in calcium intake ( P = 0.0095 by t-test ) in the intervention group . No significant increase was seen in protein or calorie intake . No significant change was observed in the body weight or BMI although there was a positive trend in the intervention group for all these parameters . We concluded that there was general malnutrition in Chinese elderly who presented with osteoporotic fractures . Dietary calcium could be increased by repeated professional dietary counselling . Future studies with longer duration and more objective clinical outcomes will be helpful to further demonstrate the long-term effects of dietary intervention on osteoporosis and other chronic diseases CONTEXT It has been assumed that the increase in urine calcium ( Ca ) that accompanies an increase in dietary protein was due to increased bone resorption . However , studies using stable Ca isotopes have found that dietary protein increases Ca absorption without increasing bone resorption . OBJECTIVE The objective of the study was to investigate the impact of a moderately high protein diet on bone mineral density ( BMD ) . DESIGN This was a r and omized , double-blind , placebo-controlled trial of protein supplementation daily for 18 months . SETTING The study was conducted at two institutional research centers . PARTICIPANTS Two hundred eight older women and men with a body mass index between 19 and 32 kg/m(2 ) and a self-reported protein intake between 0.6 and 1.0 g/kg participated in the study . INTERVENTION Subjects were asked to incorporate either a 45-g whey protein or isocaloric maltodextrin supplement into their usual diet for 18 months . MAIN OUTCOME MEASURE BMD by dual-energy x-ray absorptiometry , body composition , and markers of skeletal and mineral metabolism were measured at baseline and at 9 and 18 months . RESULTS There were no significant differences between groups for changes in L-spine BMD ( primary outcome ) or the other skeletal sites of interest . Truncal lean mass was significantly higher in the protein group at 18 months ( P = .048 ) . C-terminal telopeptide ( P = .0414 ) , IGF-1 ( P = .0054 ) , and urinary urea ( P < .001 ) were also higher in the protein group at the end of the study period . There was no difference in estimated glomerular filtration rate at 18 months . CONCLUSION Our data suggest that protein supplementation above the recommended dietary allowance ( 0.8 g/kg ) may preserve fat-free mass without adversely affecting skeletal health or renal function in healthy older adults The effects of dietary protein on bone structure and metabolism have been controversial , with evidence for and against beneficial effects . Because no long-term r and omized , controlled studies have been performed , a two-year study of protein supplementation in 219 healthy ambulant women aged 70 to 80 years was undertaken . Participants were r and omized to either a high-protein drink containing 30 g of whey protein ( n = 109 ) or a placebo drink identical in energy content , appearance , and taste containing 2.1 g of protein ( n = 110 ) . Both drinks provided 600 mg of calcium . Dual-energy X-ray absorptiometric ( DXA ) hip areal bone mineral density ( aBMD ) , 24-hour urinary calcium excretion , and serum insulin-like growth factor 1 ( IGF-1 ) were measured at baseline and at 1 and 2 years . Quantitative computed tomographic ( QCT ) hip volumetric bone mineral density ( vBMD ) and a femoral neck engineering strength analysis were undertaken at baseline and at 2 years . Baseline average protein intake was 1.1 g/kg of body weight per day . There was a significant decrease in hip DXA aBMD and QCT vBMD over 2 years with no between-group differences . Femoral neck strength was unchanged in either group over time . The 24-hour urinary calcium excretion increased significantly from baseline in both groups at 1 year but returned to baseline in the placebo group at 2 years , at which time the protein group had a marginally higher value . Compared with the placebo group , the protein group had significantly higher serum IGF-1 level at 1 and 2 years ( 7.3 % to 8.0 % , p < .05 ) . Our study showed that in protein-replete healthy ambulant women , 30 g of extra protein increased IGF-1 but did not have beneficial or deleterious effects on bone mass or strength . The effect of protein supplementation in population s with low dietary protein intake requires urgent attention Background Although soy protein and its isoflavones have been reported to reduce the risk of osteoporosis in peri- and post-menopausal women , most of these studies are of short duration ( i.e. six months ) . The objective of this study was to examine if one year consumption of soy-containing foods ( providing 25 g protein and 60 mg isoflavones ) exerts beneficial effects on bone in postmenopausal women . Methods Eighty-seven eligible postmenopausal women were r and omly assigned to consume soy or control foods daily for one year . Bone mineral density ( BMD ) and bone mineral content ( BMC ) of the whole body , lumbar ( L1-L4 ) , and total hip were measured using dual energy x-ray absorptiometry at baseline and after one year . Blood and urine markers of bone metabolism were also assessed . Results and Discussion Sixty-two subjects completed the one-year long study . Whole body and lumbar BMD and BMC were significantly decreased in both the soy and control groups . However , there were no significant changes in total hip BMD and BMC irrespective of treatment . Both treatments positively affected markers of bone formation as indicated by increased serum bone-specific alkaline phosphatase ( BSAP ) activity , insulin-like growth factor-I ( IGF-I ) , and osteocalcin ( BSAP : 27.8 and 25.8 % , IGF-I : 12.8 and 26.3 % , osteocalcin : 95.2 and 103.4 % for control and soy groups , respectively ) . Neither of the protein supplements had any effect on urinary deoxypyridinoline excretion , a marker of bone resorption . Conclusion Our findings suggest that although one year supplementation of 25 g protein per se positively modulated markers of bone formation , this amount of protein was unable to prevent lumbar and whole body bone loss in postmenopausal women OBJECTIVE To identify nutrients , foods , and dietary patterns associated with stress fracture risk and changes in bone density among young female distance runners . DESIGN AND SETTING Two-year , prospect i ve cohort study . Observational data were collected in the course of a multicenter r and omized trial of the effect of oral contraceptives on bone health . PARTICIPANTS One hundred and twenty-five female competitive distance runners ages 18 - 26 years . ASSESSMENT OF RISK FACTORS Dietary variables were assessed with a food frequency question naire . MAIN OUTCOME MEASUREMENTS Bone mineral density and content ( BMD/ BMC ) of the spine , hip , and total body were measured annually by dual x-ray absorptiometry ( DEXA ) .  Stress fractures were recorded on monthly calendars , and had to be confirmed by radiograph , bone scan , or magnetic resonance imaging . RESULTS Seventeen participants had at least one stress fracture during follow-up . Higher intakes of calcium , skim milk , and dairy products were associated with lower rates of stress fracture . Each additional cup of skim milk consumed per day was associated with a 62 % reduction in stress fracture incidence ( P < .05 ) ; and a dietary pattern of high dairy and low fat intake was associated with a 68 % reduction ( P < .05 ) . Higher intakes of skim milk , dairy foods , calcium , animal protein , and potassium were associated with significant ( P < .05 ) gains in whole-body BMD and BMC . Higher intakes of calcium , vitamin D , skim milk , dairy foods , potassium , and a dietary pattern of high dairy and low fat were associated with significant gains in hip BMD . CONCLUSIONS In young female runners , low-fat dairy products and the major nutrients in milk ( calcium , vitamin D , and protein ) were associated with greater bone gains and a lower stress fracture rate . Potassium intake was also associated with greater gains in hip and whole-body BMD Weight loss causes  bone mineral loss .  Higher protein diets continue to be criticized for further potential harmful bone effects , including elevated urinary calcium , but may promote bone health if protein sources include dairy . Overweight middle-aged subjects ( n = 130 , 59 males ) were r and omized to a diet providing 1.4 g.kg(-1).d(-1 ) protein and 3 daily servings of dairy ( PRO ) or 0.8 g.kg(-1).d(-1 ) protein and 2 daily servings of dairy ( CARB ) for 4 mo of weight loss plus 8 mo of weight maintenance . Diets prescribed 6276 kJ/d for females and 7113 kJ/d for males . Bone mineral content and density ( BMD ) for whole body ( WB ) , lumbar spine ( LS ) and total hip ( TH ) were measured using dual X-ray absorptiometry , and dietary intake using 3-d weighed food records . Urinary calcium was measured using 24-h collection at 0 and 8 mo for a sub sample ( n = 42 ) . Participants lost body weight ( mean , 95 % CI ) of 8.2 % ( 7.5 - 8.9 % ) at 4 mo , 10.6 % ( 9.5 - 11.8 % ) at 8 mo , and 10.5 % ( 8.9 - 12.0 % ) at 12 mo without differences between groups at any time ( P = 0.64 ) . At 12 mo , PRO BMD was higher by 1.6 % ( 0.3 - 3.0 % ) at WB , 2.1 % ( 0.6 - 3.7 % ) at LS , and 1.4 % ( 0.2 - 2.5 % ) at TH compared with  CARB  .  PRO calcium intake was higher ( PRO : 1140 + /- 58 mg/d , CARB : 766 + /- 46 ; P < 0.01 ) , as was urinary calcium ( PRO : 163 + /- 15 mg/d , CARB : 100 + /- 9.2 ; P < 0.01 ) . A reduced-energy diet supplying 1.4 g.kg(-1).d(-1 ) protein and 3 dairy servings increased urinary calcium excretion but provided improved calcium intake and attenuated bone loss over 4 mo of weight loss and 8 additional mo of weight maintenance
In older people with osteoporosis , higher protein intake ( ≥ 0.8-g/kg body weight/day , i.e. , above the current RDA ) is associated with higher BMD , a slower rate of bone loss , and reduced risk of hip fracture , provided that dietary calcium intakes are adequate .
Intervention with dietary protein supplements attenuate age-related BMD decrease and reduce bone turnover marker levels , together with an increase in IGF-I and a decrease in PTH .
There is no evidence that diet-derived acid load is deleterious for bone health .
Thus , insufficient dietary protein intakes may be a more severe problem than protein excess in the elderly .
A summary of systematic review s and meta-analyses addressing the benefits and risks of dietary protein intakes  for  bone health in adults suggests that dietary protein levels even above the current RDA may be beneficial in reducing bone loss and hip fracture risk , provided calcium intakes are adequate .
Several systematic review s and meta-analyses have addressed the benefits and risks of dietary protein intakes for bone health in adults .
Adequate supplies of dietary protein are required for optimal bone growth and maintenance of healthy bone .
Variation in protein intakes within the “ normal ” range accounts for 2–4 % of BMD variance in adults .