Urine calcium excretion rates were consistent with osteoporosis development ; however calcium balance studies did not demonstrate loss of whole body calcium with higher net acid excretion .
No study revealed a biologic mechanism functioning at physiological pH. Finally , r and omized studies did not provide evidence for an adverse role of phosphate , milk , and grain foods in osteoporosis .
Conclusions A causal association between dietary acid load and osteoporotic bone disease is not supported by evidence and there is no evidence that an alkaline diet is protective of bone health
Background Modern diets have been suggested to increase systemic acid load and net acid excretion .
In response , alkaline diets and products are marketed to avoid or counteract this acid , help the body regulate its pH to prevent and cure disease .
The objective of this systematic review was to evaluate causal relationships between dietary acid load and osteoporosis using Hill 's criteria .
Protein Supplements Increase Serum Insulin-Like Growth Factor-I Levels and Attenuate Proximal Femur Bone Loss in Patients with Recent Hip Fracture
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 .
Urine calcium excretion rates were consistent with osteoporosis development ; however calcium balance studies did not demonstrate loss of whole body calcium with higher net acid excretion .
No study revealed a biologic mechanism functioning at physiological pH. Finally , r and omized studies did not provide evidence for an adverse role of phosphate , milk , and grain foods in osteoporosis .
Conclusions A causal association between dietary acid load and osteoporotic bone disease is not supported by evidence and there is no evidence that an alkaline diet is protective of bone health
Background Modern diets have been suggested to increase systemic acid load and net acid excretion .
In response , alkaline diets and products are marketed to avoid or counteract this acid , help the body regulate its pH to prevent and cure disease .
The objective of this systematic review was to evaluate causal relationships between dietary acid load and osteoporosis using Hill 's criteria .