This systematic review highlights the effects of dairy products on muscle mass , muscle strength and body performance in the elderly population in the perspective of Ca , P , vitamin D and protein
The risk of sarcopenia increases with aging .
Malnutrition in the elderly population is an important risk factor for sarcopenia .
Calcium ( Ca ) , phosphate ( P ) , vitamin D and protein are key nutrients for the human body and affect muscle mass and quality .
Dairy products are rich in these nutrients , which implicates that dairy products might be ideal for elderly population .
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 .
This systematic review highlights the effects of dairy products on muscle mass , muscle strength and body performance in the elderly population in the perspective of Ca , P , vitamin D and protein
The risk of sarcopenia increases with aging .
Malnutrition in the elderly population is an important risk factor for sarcopenia .
Calcium ( Ca ) , phosphate ( P ) , vitamin D and protein are key nutrients for the human body and affect muscle mass and quality .
Dairy products are rich in these nutrients , which implicates that dairy products might be ideal for elderly population .