Effect of amino acid supplementation on muscle mass, strength and physical function in elderly

The Role of Inflammation in Age-Related Sarcopenia

Many physiological changes occur with aging. These changes often, directly or indirectly, result in a deterioration of the quality of life and even in a shortening of life expectancy. Besides increased levels of reactive oxygen species, DNA damage and cell apoptosis, another important factor affecting the aging process involves a systemic chronic low-grade inflammation. This condition has already been shown to be interrelated with several (sub)clinical conditions, such as insulin resistance, atherosclerosis and Alzheimer's disease. Recent evidence, however, shows that chronic low-grade inflammation also contributes to the loss of muscle mass, strength and functionality, referred to as sarcopenia, as it affects both muscle protein breakdown and synthesis through several signaling pathways. Classic interventions to counteract age-related muscle wasting mainly focus on resistance training and/or protein supplementation to overcome the anabolic inflexibility from which elderly suffer. Although the elderly benefit from these classic interventions, the therapeutic potential of anti-inflammatory strategies is of great interest, as these might add up to/support the anabolic effect of resistance exercise and/or protein supplementation. In this review, the molecular interaction between inflammation, anabolic sensitivity and muscle protein metabolism in sarcopenic elderly will be addressed.

Effect of branched-chain amino acid supplements on muscle strength and muscle mass in patients with liver cirrhosis

OBJECTIVE

The aim of this study was to assess the effect of branched-chain amino acid (BCAA) supplements on muscle strength and muscle mass in patients with liver cirrhosis.

PATIENTS AND METHODS

We carried out a single-center, prospective study of adult cirrhotic patients receiving nutrition therapy at Shonan Kamakura General Hospital. A 28-day pretreatment observation period was followed by a 24-week treatment period. Patients who fulfilled the treatment criteria received one package of oral BCAA supplement powder twice a day and the response was evaluated. A responder to BCAA in muscle strength and muscle mass was defined as a patient with an increased skeletal muscle mass index and hand grip assessed 24 weeks after drug treatment commenced.

RESULTS

Eighty-two patients fulfilled our criteria and completed the treatment. In terms of muscle strength, there were 59 (72.0%) responders to BCAA supplementation with a significant increase in hand grip from before treatment (22.2±6.3 kg) to after treatment (23.9±6.4 kg) (P<0.001). In terms of muscle mass, 36 (43.9%) patients responded to BCAA with a slight decrease in skeletal muscle mass index from before treatment (7.40±1.62) to after treatment (7.30±1.49) (P=0.333).

CONCLUSION

BCAA supplementation improved low muscle strength in patients with chronic liver disease, but did not increase muscle mass during the treatment period.

Epidemiology of Sarcopenia: Determinants Throughout the Lifecourse

Sarcopenia is an age-related syndrome characterised by progressive and generalised loss of skeletal muscle mass and strength; it is a major contributor to the risk of physical frailty, functional impairment in older people, poor health-related quality of life and premature death. Many different definitions have been used to describe sarcopenia and have resulted in varying estimates of prevalence of the condition. The most recent attempts of definitions have tried to integrate information on muscle mass, strength and physical function and provide a definition that is useful in both research and clinical settings. This review focuses on the epidemiology of the three distinct physiological components of sarcopenia, and highlights the similarities and differences between their patterns of variation with age, gender, geography and time and the individual risk factors that cluster selectively with muscle mass, strength and physical function. Methods used to measure muscle mass, strength and physical functioning and how differences in these approaches can contribute to the varying prevalence rates will also be described. The evidence for this review was gathered by undertaking a systematic search of the literature. The descriptive characteristics of muscle mass, strength and function described in this review point to the urgent need for a consensual definition of sarcopenia incorporating these parameters.

Special nutrition intervention is required for muscle protective efficacy of physical exercise in elderly people at highest risk of sarcopenia

Progressive loss of muscle mass and strength is a physiological consequence of aging, and without interventions, it usually deteriorates into sarcopenia. In this study, the hypothesis that combined special nutritional-physiotherapeutical intervention to prevent or reverse this biological deterioration in elderly people was tested. The effects of the regular resistance muscle training (PT, n = 17) alone and the combined exercise + special nutrition therapy containing whey protein and vitamin D (PT + NT, n = 17) were monitored for 3 months in 34 elderly patients (12 men and 22 women; mean age: 66.47 years) randomly distributed into two groups at a long-term care facility. Physical exercise alone did not result in significant improvement in skeletal muscle mass or strength, whereas combined intervention significantly increased the muscle strength (22.51 ± 2.35 vs. 24.54 ± 2.65, [Formula: see text] ± SEM, kg, p = 0.027). When therapeutic responses to the intervention were compared, a significant advantage of PT + NT over PT was found. The same trend was found when the non-significant post-therapeutic alterations (χ² test) of the distribution of normal vs. pre-sarcopenic + sarcopenic conditions within the two groups were compared. Combined intervention (PT + NT) is necessary for the efficient protection of the musculature in the high-risk elderly patients.

Epidemiology of sarcopenia and insight into possible therapeutic targets

Musculoskeletal ageing is a major public health concern owing to demographic shifts in the population. Sarcopenia, generally defined as the age-related loss of muscle mass and function, is associated with considerable risk of falls, loss of independence in older adults and hospitalization with poorer health outcomes. This condition is therefore associated with increased morbidity and health care costs. As with bone mass, muscle mass and strength increase during late adolescence and early adulthood, but begin to decline substantially from ∼50 years of age. Sarcopenia is characterized by many features, which include loss of muscle mass, altered muscle composition, infiltration with fat and fibrous tissue and alterations in innervation. A better understanding of these factors might help us to develop strategies that target these effects. To date, however, methodological challenges and controversies regarding how best to define the condition, in addition to uncertainty about what outcome measures to consider, have delayed research into possible therapeutic options. Most pharmacological agents investigated to date are hormonal, although new developments have seen the emergence of agents that target myostatin signalling to increase muscle mass. In this review we consider the current approaching for defining sarcopenia and discuss its epidemiology, pathogenesis, and potential therapeutic opportunities.

Optimizing Protein Intake in Adults: Interpretation and Application of the Recommended Dietary Allowance Compared with the Acceptable Macronutrient Distribution Range

The adult RDA is defined as the average daily level of intake sufficient to meet the nutrient requirements of nearly all healthy people. The RDA for protein for adults ≥18 y of age (0.8 g/kg) has been essentially unchanged for >70 y. In practice, the RDA for protein was derived to estimate the minimum amount of protein that must be eaten to avoid a loss of body nitrogen. The Acceptable Macronutrient Distribution Range (AMDR) (10-35% of calories as protein) was developed to express dietary recommendations in the context of a complete diet. It is noteworthy that the lowest level of protein intake reflected in the AMDR is higher than that of the RDA. Furthermore, recent studies, particularly in older individuals, suggest specific health benefits at levels of protein intake that significantly exceed the RDA. Translation of protein intake recommendations for the general adult population into dietary guidance for individuals requires an understanding of the derivation and intended use of both the protein RDA and AMDR. The following discussion will describe limitations to the derivation and practical application of the RDA compared with the use of the AMDR to help maximize health benefits associated with higher protein intake by using flexible calories inherent in different dietary patterns.

Reduced muscular fatigue after a 12-week leucine-rich amino acid supplementation combined with moderate training in elderly: a randomised, placebo-controlled, double-blind trial

Background

Age-related muscle loss is characterised by a progressing decrease in muscle mass, strength and function. Besides resistance training and physical activity, appropriate nutrition that is rich in protein, especially branched-chain amino acids, is very important to support training effects and positively influence the protein synthesis to degradation ratio.

Aim

The purpose of this study was to evaluate the effect of a 12-week leucine-rich amino acid supplementation in combination with moderate training.

Methods

Forty-eight healthy subjects exercised for 30 min three times per week and received either a leucine-rich amino acid supplementation or a placebo. Before and after supplementation, volunteers performed an exhaustive eccentric exercise protocol. Maximal concentric strength, muscle soreness, creatine kinase (CK), type II collagen collagenase cleavage neoepitope (C2C), C propeptide of type II procollagen (CP2) and safety assessments were performed before exercise and after 3, 24, 48 and 72 hours.

Results

The supplementation with leucine resulted in reduced loss of strength at 0 and 3 hours after downhill walking compared with the placebo (p=0.0439). The reduction of C2C/CP2 ratio deflection was significantly increased (p=0.038) due to leucine compared with the placebo. The same tendency could be observed for the recovery phase. No significant supplement effects for muscle soreness and CK could be observed.

Conclusion

The principle findings show that leucine-rich amino acid supplementation can counteract the negative effects of eccentric exercise. The treatment resulted in a reduction of exercise-induced strength loss.

Protein intake distribution pattern does not affect anabolic response, lean body mass, muscle strength or function over 8 weeks in older adults: A randomized-controlled trial

BACKGROUND & AIMS

In our recent acute metabolic study, we found no differences in the anabolic response to differing patterns of dietary protein intake. To confirm this in a chronic study, we investigated the effects of protein distribution pattern on functional outcomes and protein kinetics in older adults over 8 weeks.

METHODS

To determine chronic effects of protein intake pattern at 1.1 g protein/kg/day in mixed meals on lean body mass (LBM), functional outcomes, whole body protein kinetics and muscle protein fractional synthesis rate (MPS) over 8-week respective dietary intervention, fourteen older subjects were randomly divided into either EVEN or UNVEN group. The UNEVEN group (n = 7) consumed the majority of dietary protein with dinner (UNEVEN, 15/20/65%; breakfast, lunch, dinner), while the EVEN group (n = 7) consumed dietary protein evenly throughout the day (EVEN: 33/33/33%).

RESULTS

We found no significant differences in LBM, muscle strength, and other functional outcomes between EVEN and UNEVEN before and after 8-week intervention. Consistent with these functional outcomes, we did not find significant differences in the 20-h integrated whole body protein kinetics [net protein balance (NB), protein synthesis (PS), and breakdown (PB)] above basal states and MPS between EVEN and UNEVEN intake patterns.

CONCLUSIONS

We conclude that over an 8-week intervention period, the protein intake distribution pattern in mixed meals does not play an important role in determining anabolic response, muscle strength, or functional outcomes. This trial is registered at https://ClinicalTrials.gov as NCT02787889.

L-Lysine suppresses myofibrillar protein degradation and autophagy in skeletal muscles of senescence-accelerated mouse prone 8

Sarcopenia is a condition of the loss of muscle mass that is associated with aging and that increases the risk for bedridden state, thereby warranting studies of interventions that attenuate sarcopenia. Here the effects of 2-month dietary L-lysine (Lys) supplementation (1.5-3.0 %) on myofibrillar protein degradation and major proteolytic systems were investigated in senescence-accelerated mouse prone 8 (SAMP8). At 36 weeks of age, skeletal muscle and lean body mass was reduced in SAMP8 when compared with control senescence-accelerated mouse resistant 1 (SAMR1). The myofibrillar protein degradation, which was evaluated by the release of 3-methylhistidine, was stimulated in SAMP8, and the autophagy activity, which was evaluated by light chain 3-II, was stimulated in the skeletal muscle of SAMP8. The activation of ubiquitin-proteasome system was not observed in the muscles of SAMP8. However, myofibrillar protein degradation and autophagic activity in skeletal muscles of SAMP8 were suppressed by dietary intake of 3.0 % Lys. The present data indicate that myofibrillar protein degradation by bulk autophagy is stimulated in the skeletal muscles of SAMP8 and that dietary Lys supplementation attenuates sarcopenia in SAMP8 by suppressing autophagic proteolysis.

Protein quality as determined by the Digestible Indispensable Amino Acid Score: evaluation of factors underlying the calculation

The Food and Agriculture Organization of the United Nations recently recommended the adoption of a new and improved scoring system (Digestible Indispensable Amino Acid Score [DIAAS]) to quantify dietary protein quality. The DIAAS is based on the relative digestible content of the indispensable amino acids (IAAs) and the amino acid requirement pattern. Factors involved in calculation of the DIAAS include: use of the content and profile of IAAs as the basis for quality; methods for determination of the protein and amino acid content of the protein source; accuracy of individual requirement values for IAAs; normalization of IAA requirements by the estimated average requirement for protein; and basing the DIAAS on the true ileal digestibility of each IAA in the test protein. This review outlines the rationale for including each of these factors in the calculation of the DIAAS and describes associated potential errors.

Japan Society of Hepatology guidelines for sarcopenia in liver disease (1st edition): Recommendation from the working group for creation of sarcopenia assessment criteria

Sarcopenia is defined by muscle loss and muscle dysfunction. Sarcopenia is classified into primary and secondary types, based on the cause. Primary sarcopenia is mainly aging-related sarcopenia, whereas secondary sarcopenia is the reduced muscle mass and strength that accompanies an underlying disease. Given the essential role of the liver in metabolism, secondary sarcopenia due to nutritional disorders or other factors can frequently occur in liver disease. In 2015, the Japan Society of Hepatology (JSH) decided to establish its own assessment criteria for sarcopenia in liver disease because the number of liver disease patients with sarcopenia is expected to increase and there is cumulative evidence to indicate sarcopenic patients have poor clinical outcomes. A working group to create assessment criteria for sarcopenia has thus been established by the JSH. In this article, we summarize the current knowledge with regard to sarcopenia and present the assessment criteria for sarcopenia in liver disease proposed by the JSH (1st edition). To the best of our knowledge, this is globally the first proposed assessment criteria for sarcopenia specializing in liver disease.

Sarcopenia and two types of presarcopenia in Japanese patients with chronic liver disease

BACKGROUND/AIM

The frequency of sarcopenia, defined as loss of both muscle volume and strength, was analyzed in chronic liver disease (CLD).

METHODS AND MATERIALS

From April to September 2015, 807 Japanese CLD patients treated as outpatients were enrolled (67.1±10.0 years, men : women=466 : 341, hepatitis C virus : hepatitis B virus : hepatitis B and C virus : alcohol : other=511 : 134 : 3 : 45 : 114). Sarcopenia was diagnosed when the patient showed muscle volume loss and reduced handgrip strength, whereas those with only muscle volume loss were classified as 'v-presarcopenia' and those with only reduced handgrip strength were classified as 's-presarcopenia'. Muscle volume loss was determined using computed tomography findings and a previously reported index (psoas index), and cut-off values for reduced handgrip strength presented by the Asia Working Group for Sarcopenia (AWGS) (AWGS/grip criteria) and European Working Group on Sarcopenia in Older People (EWGSOP) (EWGSOP/grip criteria) (men; 26 and 30 kg, women; 18 and 20 kg, respectively) were used. Clinical features were analyzed for diagnoses of chronic hepatitis (CH, n=381), liver cirrhosis Child-Pugh A (n=330), and liver cirrhosis Child-Pugh B/C (n=96).

RESULTS

When the AWGS/grip criteria were used, the frequencies of sarcopenia, v-presarcopenia, and s-presarcopenia in CH were 3.9, 7.9, and 19.4%, whereas those in Child-Pugh A were 4.8, 17.6, and 21.8% and those in Child-Pugh B/C were 16.7, 11.5, and 39.6%, respectively. When the EWGSOP/grip criteria were used, these frequencies were 7.1, 4.7, and 33.1%, in CH, 11.8, 10.6, and 32.7%, in Child-Pugh A, and 21.9, 6.3, and 49.0%, in Child-Pugh B/C, respectively. The incidence rates of sarcopenia and both types of presarcopenia increased with progression of CLD.

CONCLUSION

Evaluation of handgrip strength and psoas index is an easy and effective method for the detection of sarcopenia and presarcopenia.

Pork and Chicken Meals Similarly Impact on Cognitive Function and Strength in Community-Living Older Adults: A Pilot Study

A pilot quasi-experimental study investigated whether provision of pork, a rich source of thiamin, as the main protein source in meals four times/week for 12 weeks resulted in improved muscle mass, body strength, and cognitive function in community-living older adults compared to similar meals containing chicken. Retirement villages were randomized to receive pre-prepared frozen meals containing either pork or chicken. Dietary intake was assessed by three-day food records and cognitive domains assessed using validated tests. Hand grip strength was measured and lower extremity performance assessed by the sit-to-stand test, get-up-and-go test and six-minute walk test. Forty-eight volunteers participated (78.2 ± 6.2 y). In linear mixed models, controlling for baseline physical activity and dietary protein and energy intake, no differences were found between pork (n = 19) and chicken (n = 12) groups. The chicken group had improved Rey Auditory Verbal Learning test scores (verbal learning and memory) at six weeks (p < 0.001). Provision of four pork meals a week did not result in improvements in cognitive function, nor measures of strength or physical function, compared to those receiving chicken meals in healthy older adults. This suggests that merely changing the type of dietary protein provided by meat does not impact physical or cognitive function.

Recent developments in understanding protein needs - How much and what kind should we eat?

A novel method has been developed to determine protein requirements, which is called indicator amino acid oxidation (IAAO). This technique has been validated by comparison with the "gold standard" nitrogen balance. Using IAAO we have shown that minimum protein requirements have been underestimated by 30%-50%. The National Academy of Sciences has for macro-nutrients proposed "Acceptable Macronutrient Distribution Ranges", which for protein is 10% to 35% of total energy. In practice, we suggest 1.5-2.2 g/(kg·day) of a variety of high-quality proteins.

Pulsatile delivery of a leucine supplement during long-term continuous enteral feeding enhances lean growth in term neonatal pigs

Neonatal pigs are used as a model to study and optimize the clinical treatment of infants who are unable to maintain oral feeding. Using this model, we have shown previously that pulsatile administration of leucine during continuous feeding over 24 h via orogastric tube enhanced protein synthesis in skeletal muscle compared with continuous feeding alone. To determine the long-term effects of leucine pulses, neonatal piglets (n = 11-12/group) were continuously fed formula via orogastric tube for 21 days, with an additional parenteral infusion of either leucine (CON + LEU; 800 μmol·kg^-1·h^-1) or alanine (CON + ALA) for 1 h every 4 h. The results show that body and muscle weights and lean gain were ∼25% greater, and fat gain was 48% lower in CON + LEU than CON + ALA; weights of other tissues were unaffected by treatment. Fractional protein synthesis rates in longissimus dorsi, gastrocnemius, and soleus muscles were ∼30% higher in CON + LEU compared with CON + ALA and were associated with decreased Deptor abundance and increased mTORC1, mTORC2, 4E-BP1, and S6K1 phosphorylation, SNAT2 abundance, and association of eIF4E with eIF4G and RagC with mTOR. There were no treatment effects on PKB, eIF2α, eEF2, or PRAS40 phosphorylation, Rheb, SLC38A9, v-ATPase, LAMTOR1, LAMTOR2, RagA, RagC, and LAT1 abundance, the proportion of polysomes to nonpolysomes, or the proportion of mRNAs encoding rpS4 or rpS8 associated with polysomes. Our results demonstrate that pulsatile delivery of a leucine supplement during 21 days of continuous enteral feeding enhances lean growth by stimulating the mTORC1-dependent translation initiation pathway, leading to protein synthesis in skeletal muscle of neonates.

Whey protein, amino acids, and vitamin D supplementation with physical activity increases fat-free mass and strength, functionality, and quality of life and decreases inflammation in sarcopenic elderly

BACKGROUND

Interventions to attenuate the adverse effects of age-related loss of skeletal muscle and function include increased physical activity and nutritional supplementation.

OBJECTIVE

This study tested the hypothesis that nutritional supplementation with whey protein (22 g), essential amino acids (10.9 g, including 4 g leucine), and vitamin D [2.5 μg (100 IU)] concurrent with regular, controlled physical activity would increase fat-free mass, strength, physical function, and quality of life, and reduce the risk of malnutrition in sarcopenic elderly persons.

DESIGN

A total of 130 sarcopenic elderly people (53 men and 77 women; mean age: 80.3 y) participated in a 12-wk randomized, double-blind, placebo-controlled supplementation trial. All participants concurrently took part in a controlled physical activity program. We examined body composition with dual-energy X-ray absorptiometry, muscle strength with a handgrip dynamometer, and blood biochemical indexes of nutritional and health status, and evaluated global nutritional status, physical function, and quality of life before and after the 12 wk of intervention.

RESULTS

Compared with physical activity and placebo, supplementation plus physical activity increased fat-free mass (1.7-kg gain, P < 0.001), relative skeletal muscle mass (P = 0.009), android distribution of fat (P = 0.021), handgrip strength (P = 0.001), standardized summary scores for physical components (P = 0.030), activities of daily living (P = 0.001), mini nutritional assessment (P = 0.003), and insulin-like growth factor I (P = 0.002), and lowered C-reactive protein (P = 0.038).

CONCLUSION

Supplementation with whey protein, essential amino acids, and vitamin D, in conjunction with age-appropriate exercise, not only boosts fat-free mass and strength but also enhances other aspects that contribute to well-being in sarcopenic elderly. This trial was registered at clinicaltrials.gov as NCT02402608.

Influence of essential amino acids on muscle mass and muscle strength in patients with cerebral stroke during early rehabilitation: protocol and rationale of a randomized clinical trial (AMINO-Stroke Study)

Background

Patients with stroke are at a high risk for long-term handicap and disability. In the first weeks after stroke muscle wasting is observed frequently. Early post-stroke rehabilitation programs are directed to improve functional independence and physical performance. Supplementation with essential amino acids (EAAs) might prevent muscle wasting and improve rehabilitation outcome by augmenting muscle mass and muscle strength. We aim to examine this in a double blinded, randomized placebo-controlled clinical trial.

Methods

Patients with ischemic or haemorrhagic stroke will be enrolled at begin of the early post-stroke rehabilitation in a parallel group interventional trial. Oral supplementation of EAAs or placebo will be given for 12 weeks in a double blinded manner. Physical and functional performance will be assessed by exercise testing before supplementation of EAAs as well as at discharge from the in-patient rehabilitation, at 12 weeks and 1 year afterwards.

Discussion

This is the first randomized double-blinded placebo-controlled clinical study aiming to assess the effect of the EAAs supplementation on muscle strength, muscle function and physical performance in stroke patients during early post-stroke rehabilitation. Supplementation of EAAs could prevent muscle mass wasting and improve functional independence after stroke.

Trial registration

The study is registered at the German registry for clinical trials as well as at World Health Organization (WHO; number DRKS00005577).

Morphological and Biochemical Effects on the Skeletal Muscle of Ovariectomized Old Female Rats Submitted to the Intake of Diets with Vegetable or Animal Protein and Resistance Training

Introduction. Sarcopenia is a process characterized by reduction in protein mass and muscle strength with increasing age, especially in the postmenopausal period, resulting in functional limitations and with great impact on the physical autonomy of the elderly. Objective. To evaluate the effects of diets with vegetable proteins (VP) or animal proteins (AP) associated with resistance training (RT) on the structural and biochemical parameters of the medial gastrocnemius muscle in Wistar rats with sarcopenia. Methods. An experimental model with ovariectomized rats was used to induce sarcopenia and resistance training. The histochemical technique was used for the typing of muscle fibers, the cross-sectional area of myocytes, and volume densities of myocytes and interstitium; the technique of Picrosirius stain was used to highlight the collagen fibers. Results. The VP diet was not able to minimize the effects of sarcopenia in the medial gastrocnemius of sedentary animals and when associated with RT, it promoted maintenance of the CSA, attenuating the atrophy of type IIB fibers in the medial gastrocnemius. The AP diet in sedentary animals protected the type I fibers. When combined with RT, the AP promoted muscle remodeling, with reduction in volume density of type I and IIA fibers, and increase of IIB fibers, together with an increase in collagen volume density. Conclusion. The data suggest a tendency to better results of hypertrophy in animal groups that consumed the AP diet, even the sedentary animals, although more evident in those trained.

Nutrition for Sarcopenia

Aging-related sarcopenia means that muscle mass, strength, and physical performance tend to decline with age, and malnutrition is associated with sarcopenia. Therefore, nutritional interventions may make an important contribution to prevent the development of sarcopenia. Here I reviewed published articles about the effects of nutritional factors on sarcopenia in elderly people. A growing body of evidence suggests that metabolic factors associated with obesity and diabetes induce the progression of sarcopenia. However, the effectiveness and safety of caloric restriction for sarcopenia remained unclear. Protein intake and physical activity are the main anabolic stimuli for muscle protein synthesis. As optimal dietary protein intake, 1.0 - 1.2 g/kg (body weight)/day with an optimal repartition over each daily meal or 25 - 30 g of high quality protein per meal were recommended to prevent sarcopenia, which was supported by some observational studies. Protein supplementation using cheese and milk protein, essential amino acids, leucine, beta-hydroxy-beta-methylbutyrate and vitamin D has been investigated as a potential supplement to improve muscle quality in sarcopenic elderly people.

Essential amino acid ingestion as an efficient nutritional strategy for the preservation of muscle mass following gastric bypass surgery

Loss of skeletal muscle in patients who have undergone gastric bypass is a consistent observation. Skeletal muscle constitutes the largest protein/amino acid pool in the body, and loss of skeletal muscle has important implications in health and disease. Sustaining a given level of muscle protein requires a balance between the rates of muscle protein synthesis and breakdown. Current evidence suggests that reduced rate of protein synthesis is implicated in the loss of muscle after gastric bypass. This is not surprising given a less than optimal dietary protein intake after the procedure and because, unlike other macronutrients, protein/amino acids are not stored in the body. Ingesting essential amino acids (EAAs), which cannot be synthesized de novo and have the primary role in the regulation of muscle protein synthesis, can potentially ameliorate loss of muscle protein after gastric bypass. At the same time, ingestion of EAAs provides a more efficient nutritional approach (i.e., greater stimulation of protein synthesis relative to the amount of amino acids ingested) to enhance muscle protein synthesis compared with the ingestion of intact protein. Changing current dietary practices toward increasing ingestion of EAAs provides an approach that can potentially prevent loss of lean body tissue and ultimately achieve a more sustained level of health in patients who have undergone gastric bypass.

Update on protein intake: importance of milk proteins for health status of the elderly

Loss of lean body mass that occurs with aging is the primary endpoint with which sarcopenia is defined. Furthermore, loss of muscle mass is central to the development of many adverse health issues in the elderly. Consequently, the response of lean body mass to nutritional interventions, particularly to dietary protein, has been a commonly measured endpoint. However, increased protein intake has been associated with improved markers for cardiovascular health, improved bone health, management of weight and metabolic diseases, and reduced all-cause mortality. Strength, rather than lean body mass, may be a more accurate indicator of health, especially in the elderly. The recommended dietary allowance for protein has been set at 0.8 g/kg/day. Because the average protein intake in the United States is approximately 1.2 g/kg/day, it appears that the average protein intake is above the recommended dietary allowance but below the low end of the acceptable macronutrient distribution range recommended by expert committees of the National Academy of Sciences and below the dietary intake levels suggested by the US Department of Agriculture in the Dietary Guidelines.

Bone Mineral Density and Protein-Derived Food Clusters from the Framingham Offspring Study

BACKGROUND

Dietary protein is beneficial to bone health; however, dietary patterns of protein intake and their relationship with bone mineral density (BMD) have not been evaluated.

OBJECTIVE

To examine the relationship of dietary protein food clusters with BMD at the femoral neck, trochanter, total femur, and lumbar spine among middle-aged and older men and women.

DESIGN

Cross-sectional study.

PARTICIPANTS AND SETTING

Two thousand seven hundred fifty-eight community-dwelling individuals from the Framingham Offspring Study.

METHODS

BMD was measured by Lunar DPX-L (Lunar Radiation Corporation) in 1996-2001. Dietary intakes were estimated using the Willett food frequency questionnaire in either 1995-1998 or 1998-2001, and the exam closest to a participant's BMD measurement was used. Cluster analysis (FASTCLUS procedure, k-means method) was used to classify participants into groups, determined by major sources of protein. Generalized linear regression was used to compare adjusted least-squares mean BMD across protein food clusters for all pairwise comparisons.

RESULTS

From 2,758 participants (44% men; mean age 61±9 years, range=29 to 86 years), five protein food clusters were identified (chicken, fish, processed foods, red meat, and low-fat milk). Three of these food clusters showed associations with BMD. The red meat protein food cluster presented with significantly lower femoral neck BMD compared with the low-fat milk cluster (red meat 0.898±0.005 g/cm(2) vs low-fat milk 0.919±0.007 g/cm(2); P=0.04). Further, the processed foods protein cluster presented with significantly lower femoral neck BMD compared with the low-fat milk cluster (processed foods 0.897±0.004 g/cm(2) vs low-fat milk 0.919±0.007 g/cm(2); P=0.02). A similar, yet nonsignificant, trend was observed for other BMD sites examined.

CONCLUSIONS

Diets with the greatest proportion of protein intake from red meat and processed foods may not be as beneficial to the skeleton compared with dietary patterns where the highest proportion of protein is derived from low-fat milk.

Improving rehabilitation after critical illness through outpatient physiotherapy classes and essential amino acid supplement: A randomized controlled trial

PURPOSE

Patients recovering from critical illness may be left with significant muscle mass loss. This study aimed to evaluate whether a 6-week program of enhanced physiotherapy and structured exercise (PEPSE) and an essential amino acid supplement drink (glutamine and essential amino acid mixture [GEAA]) improves physical and psychological recovery.

MATERIALS AND METHODS

Intensive care patients aged 45 years or older, with a combined intensive care unit stay/pre-intensive care unit stay of 5 days or more were recruited to a randomized controlled trial examining the effect of PEPSE and GEAA on recovery. The 2 factors were tested in a 2 × 2 factorial design: (1) GEAA drink twice daily for 3 months and (2) 6-week PEPSE in first 3 months. Primary efficacy outcome was an improvement in the 6-minute walking test at 3 months.

RESULTS

A total of 93 patients were randomized to the study. Patients receiving the PEPSE and GEA had the biggest gains in distance walked in 6-minute walking test (P < .0001). There were also significant reductions in rates of anxiety in study groups control supplement/PEPSE (P = .047) and GEAA supplement/PEPSE (P = .036) and for GEAA supplement/PEPSE in depression (P = .0009).

CONCLUSION

Enhanced rehabilitation combined with GEAA supplement may enhance physical recovery and reduce anxiety and depression.

Nutritional Supplementation with Essential Amino Acids and Phytosterols May Reduce Risk for Metabolic Syndrome and Cardiovascular Disease in Overweight Individuals with Mild Hyperlipidemia

BACKGROUND

Hyperlipidemia and insulin resistance are risk factors for the development of metabolic syndrome and cardiovascular disease. We have previously observed that supplementation with essential amino acids (EAA) could lower plasma triglycerides, and may improve glucose metabolism.

OBJECTIVE

We sought to determine whether EAA's combined with whey protein and phytosterols would facilitate improvements in plasma lipids and insulin sensitivity in adults with mild hypertriglyceridemia.

DESIGN

We enrolled nine subjects who were 50 years or older, had a documented plasma TG >150 mg/dl, and had not recently taken statin medications (within 6 weeks). Each subject served as his or her own control. These individuals underwent an oral glucose tolerance test (OGTT) before and after four weeks consumption of the oral nutritional supplement without dietary counseling or recommendations for physical activity.

RESULTS

Plasma total cholesterol and LDL levels decreased in all nine volunteers (P<0.005 for cholesterol and P<0.02 for LDL). In six of these individuals, plasma triglycerides (TG) fell by 95±13 mg/dl (P=0.007); while the other three showed no TG reduction. Genotyping revealed that in two of the three individuals that did not have TG reduction in response to the nutritional supplementation. Insulin sensitivity (ISI) and the total AUC_ins/glucose were significantly reduced by leucine/EAAs and phytosterol supplementation (P=0.008).

CONCLUSIONS

These findings suggest that a dietary supplementation of EAAs and phytosterols may promote favorable reductions of blood lipids as well as insulin resistance in individuals with hypertriglyceridemia. Future larger studies of SNPs and TG response to dietary supplements will be of interest.

Effects of leucine-rich protein supplements on anthropometric parameter and muscle strength in the elderly: a systematic review and meta-analysis

OBJECTIVE

The primary objective of the present systematic review and meta-analysis was to synthesize the available literature relating to leucine supplementation in the elderly with respect to its effects on anthropometrical parameters and muscle strength. The secondary aim was to perform a selective subgroup analysis when possible differentiating between healthy and sarcopenic subjects.

METHODS

Literature search was performed using the electronic databases MEDLINE, EMBASE, SportDiscus, and the Cochrane Central Register of trials with restrictions to randomized controlled trials or studies following a cross-over design. Parameters taken into account were body weight, body mass index, lean body mass, fat mass, percentage of body fat, hand grip strength, and knee extension strength. Moreover, biomarkers of glucose metabolism (fasting glucose, fasting insulin, albumin, and HOMA index) were extracted when possible. For each outcome measure of interest, a meta-analysis was performed in order to determine the pooled effect of the intervention in terms of weighted mean differences between the post-intervention (or differences in means) values of the leucine and the respective control groups. Data analysis was performed using the Review Manager 5.2.4. software.

RESULTS

A total of 16 studies enrolling 999 subjects met the inclusion criteria. Compared with control groups, leucine supplementation significantly increased gain in body weight [mean differences 1.02 kg, 95%-CI (0.19, 1.85), p=0.02], lean body mass [mean differences 0.99 kg, 95%-CI (0.43, 1.55), p=0.0005], and body mass index [mean differences 0.33 kg/m2, 95%-CI (0.13, 0.53), p=0.001], when compared to the respective control groups. With respect to body weight and lean body mass, leucine supplementation turned out to be more effective in the subgroup of study participants with manifested sarcopenia. All other parameters under investigation were not affected by leucine supplementation in a fashion significantly different from controls.

CONCLUSIONS

It is concluded that leucine supplementation was found to exert beneficial effects on body weight, body mass index, and lean body mass in older persons in those subjects already prone to sarcopenia, but not muscle strength. However, due to the heterogeneity between the trials included in this systematic review, further studies adopting a homogenous design with respect to participant characteristics duration as well as the kind and amount of daily supplement in use are required.

Dietary protein intake is associated with maximal and explosive strength of the leg flexors in young and older blue collar workers

The aim of this study was to investigate the association between dietary protein (PRO) intake and maximal and rapid strength of the leg flexors in blue collar (BC) working men. Twenty-four young (age, 23.2 ± 2.1 years) and 19 older (age, 52.8 ± 5.2 years) men employed in BC occupations completed a 3-day dietary record and isometric strength testing of the leg flexors. Food logs were analyzed for total PRO (TPRO) and essential amino acid (EAA) intake. Rapid and maximal strength capacities were examined from the rate of torque development at 50 milliseconds and peak torque of the torque-time curves, respectively. Pearson correlations and partial correlations were used to examine the relationships between TPRO and EAA intake on strength variables. Peak torque was positively correlated to TPRO and EAA intake in the young (r = 0.439 and r = 0.431; P < .05) and older (r = 0.636 and r = 0.605; P < .01) men, and rate of torque development at 50 milliseconds was correlated to TPRO and EAA intake in the young (r = 0.512 and r = 0.310; P = .01) and older (r = 0.662 and r = 0.665; P < .01) men, respectively. There were no relationships (P > .05) between TPRO and strength variables when controlling for EAA intake. Total PRO intake explained 20 to 44% of the variance in rapid and maximal strength for both age groups. Essential amino acid intake was largely responsible for the positive relationship between PRO intake and strength. Across young and older BC working male populations, PRO consumption was associated with both maximal and explosive strength capacities of the leg flexors muscle group.

Interaction between bone and muscle in older persons with mobility limitations

Aging is associated with a progressive loss of bone-muscle mass and strength. When the decline in mass and strength reaches critical thresholds associated with adverse health outcomes, they are operationally considered geriatric conditions and named, respectively, osteoporosis and sarcopenia. Osteoporosis and sarcopenia share many of the same risk factors and both directly or indirectly cause higher risk of mobility limitations, falls, fractures and disability in activities of daily living. This is not surprising since bones adapt their morphology and strength to the long-term loads exerted by muscle during anti-gravitational and physical activities. Non-mechanical systemic and local factors also modulate the mechanostat effect of muscle on bone by affecting the bidirectional osteocyte-muscle crosstalk, but the specific pathways that regulate these homeostatic mechanisms are not fully understood. More research is required to reach a consensus on cut points in bone and muscle parameters that identify individuals at high risk for adverse health outcomes, including falls, fractures and disability. A better understanding of the muscle-bone physiological interaction may help to develop preventive strategies that reduce the burden of musculoskeletal diseases, the consequent disability in older persons and to limit the financial burden associated with such conditions. In this review, we summarize age-related bone-muscle changes focusing on the biomechanical and homeostatic mechanisms that explain bone-muscle interaction and we speculate about possible pathological events that occur when these mechanisms become impaired. We also report some recent definitions of osteoporosis and sarcopenia that have emerged in the literature and their implications in clinical practice. Finally, we outline the current evidence for the efficacy of available anti-osteoporotic and proposed antisarcopenic interventions in older persons.

Association of vegetables and fruits consumption with sarcopenia in older adults: the Fourth Korea National Health and Nutrition Examination Survey

BACKGROUND

several studies have found nutrients, including antioxidants, to be associated with sarcopenia. However, whether specific foods, such as vegetables and fruits, are associated with sarcopenia has not been studied.

OBJECTIVE

to examine the association of the frequency of vegetables and fruits consumption with sarcopenia in older people.

METHODS

this study used cross-sectional data from the Fourth Korea National Health and Nutrition Examination Survey in 2008-09. Subjects were community-dwelling 823 men and 1,089 women aged ≥65 years. Frequency of food group consumption was obtained by using the food frequency questionnaire. Body composition was measured with the dual-energy X-ray absorptiometry and sarcopenia was defined as appendicular lean mass adjusted for height and fat mass. Logistic regression was used to assess the association of the frequency of food group consumption with sarcopenia, controlling for sociodemographics and health-related variables.

RESULTS

dietary intake of vegetables, fruits and both vegetables and fruits was associated with a significantly reduced risk of sarcopenia after controlling for covariates in men (P = 0.026 for trend, P = 0.012 for trend, P = 0.003 for trend, respectively). Men in the highest quintile, compared with those in the lowest quintile, of vegetables [odds ratio (OR) = 0.48; 95% confidence interval (CI): 0.24-0.95], fruits (OR = 0.30; 95% CI: 0.13-0.70) and vegetables and fruits consumption (OR = 0.32; 95% CI: 0.16-0.67) demonstrated a lower risk of sarcopenia. In women, high consumption of fruits demonstrated a lower risk of sarcopenia (OR = 0.39; 95% CI: 0.18-0.83).

CONCLUSION

frequent vegetables and fruits consumption was inversely associated with sarcopenia in older adults.

Protein is an important but undervalued macronutrient in the nutritional care of patients with cystic fibrosis

PURPOSE OF REVIEW

Achieving an optimal nutritional status in patients with cystic fibrosis (CF) is important to maintain better pulmonary function, physical performance, and to prolong survival. So far, nutrition care in CF has mainly focused on fat intake and achieving energy balance, but there is increasing information on the clinical importance of muscle maintenance and protein intake in CF.

RECENT FINDINGS

Low muscle mass is consistently associated with pulmonary decline, bone mineral loss, and poor survival in CF. High energy and fat intake contributes to an increased prevalence of overweight and obesity in CF. Obesity per se is not related to better lung function in CF and has negative metabolic and clinical consequences, particularly when muscle wasting is present. Protein digestion capacity is severely impaired in CF, but high protein intake is needed and essential amino acid mixtures appear highly anabolic even in those with severe muscle loss.

SUMMARY

Body composition assessment and achieving protein balance in the routine care in CF is important to prevent muscle loss and further improve the clinical and overall outcome of these patients. New approaches are needed to optimize the interaction between high essential amino-acid-rich protein intake and pancreatic enzyme regimen in CF. The optimal level of protein intake needs to be assessed in clinically stable CF patients as well as in those recovering from an acute exacerbation.

High whey protein intake delayed the loss of lean body mass in healthy old rats, whereas protein type and polyphenol/antioxidant supplementation had no effects

Our aim was to compare and combine 3 nutritional strategies to slow down the age-related loss of muscle mass in healthy old rats: 1) increase protein intake, which is likely to stimulate muscle protein anabolism; 2) use leucine rich, rapidly digested whey proteins as protein source (whey proteins are recognized as the most effective proteins to stimulate muscle protein anabolism). 3) Supplement animals with a mixture of chamomile extract, vitamin E, vitamin D (reducing inflammation and oxidative stress is also effective to improve muscle anabolism). Such comparisons and combinations were never tested before. Nutritional groups were: casein 12% protein, whey 12% protein, whey 18% protein and each of these groups were supplemented or not with polyphenols/antioxidants. During 6 months, we followed changes of weight, food intake, inflammation (plasma fibrinogen and alpha-2-macroglobulin) and body composition (DXA). After 6 months, we measured muscle mass, in vivo and ex-vivo fed and post-absorptive muscle protein synthesis, ex-vivo muscle proteolysis, and oxidative stress parameters (liver and muscle glutathione, SOD and total antioxidant activities, muscle carbonyls and TBARS). We showed that although micronutrient supplementation reduced inflammation and oxidative stress, the only factor that significantly reduced the loss of lean body mass was the increase in whey protein intake, with no detectable effect on muscle protein synthesis, and a tendency to reduce muscle proteolysis. We conclude that in healthy rats, increasing protein intake is an effective way to delay sarcopenia.

Clinical effectiveness of protein and amino acid supplementation on building muscle mass in elderly people: a meta-analysis

OBJECTIVE

A major reason for the loss of mobility in elderly people is the gradual loss of lean body mass known as sarcopenia. Sarcopenia is associated with a lower quality of life and higher healthcare costs. The benefit of strategies that include nutritional intervention, timing of intervention, and physical exercise to improve muscle loss unclear as finding from studies investigating this issue have been inconsistent. We have performed a systematic review and meta-analysis to assess the ability of protein or amino acid supplementation to augment lean body mass or strength of leg muscles in elderly patients.

METHODS

Nine studies met the inclusion criteria of being a prospective comparative study or randomized controlled trial (RCT) that compared the efficacy of an amino acid or protein supplement intervention with that of a placebo in elderly people (≥ 65 years) for the improvement of lean body mass (LBM), leg muscle strength or reduction associated with sarcopenia.

RESULTS

The overall difference in mean change from baseline to the end of study in LBM between the treatment and placebo groups was 0.34 kg which was not significant (P = 0.386). The overall differences in mean change from baseline in double leg press and leg extension were 2.14 kg (P = 0.748) and 2.28 kg (P = 0.265), respectively, between the treatment group and the placebo group.

CONCLUSIONS

These results indicate that amino acid/protein supplements did not increase lean body mass gain and muscle strength significantly more than placebo in a diverse elderly population.

Nutrient-rich dairy proteins improve appendicular skeletal muscle mass and physical performance, and attenuate the loss of muscle strength in older men and women subjects: a single-blind randomized clinical trial

Background

At present, it is unknown whether the use of nutrient-rich dairy proteins improves the markers of sarcopenia syndrome. Therefore, our proposal was to investigate whether adding 210 g of ricotta cheese daily would improve skeletal muscle mass, handgrip strength, and physical performance in non-sarcopenic older subjects.

Subjects and methods

This was a single-blind randomized clinical trial that included two homogeneous, randomized groups of men and women over 60 years of age. Participants in the intervention group were asked to consume their habitual diet but add 210 g of ricotta cheese (IG/HD + RCH), while the control group was instructed to consume only their habitual diet (CG/HD). Basal and 12-week follow-up measurements included appendicular skeletal muscle mass (ASMM) by dual-energy X-ray absorptiometry, handgrip strength by a handheld dynamometer, and physical performance using the short physical performance battery (SPPB) and the stair-climb power test (SCPT). The main outcomes were relative changes in ASMM, strength, SPPB, and SCPT.

Results

ASMM increased in the IG/HD + RCH (0.6±3.5 kg), but decreased in the CG/HD (−1.0±2.6). The relative change between groups was statistically significant (P=0.009). The relative change in strength in both groups was negative, but the loss of muscle strength was more pronounced in CG/HD, though in this regard statistical analysis found only a tendency (P=0.07). The relative change in the balance-test scores was positive for the IG/HD + RCH, while in the CG/HD it was negative, as those individuals had poorer balance. In this case, the relative change between groups did reach statistical significance.

Conclusion

The addition of 210 g of ricotta cheese improves ASMM and balance-test scores, while attenuating the loss of muscle strength. These results suggest that adding ricotta cheese to the habitual diet is a promising dietetic strategy that may improve the markers of sarcopenia in subjects without a pronounced loss of ASMM or sarcopenia.

Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group

The aging process is associated with gradual and progressive loss of muscle mass along with lowered strength and physical endurance. This condition, sarcopenia, has been widely observed with aging in sedentary adults. Regular aerobic and resistance exercise programs have been shown to counteract most aspects of sarcopenia. In addition, good nutrition, especially adequate protein and energy intake, can help limit and treat age-related declines in muscle mass, strength, and functional abilities. Protein nutrition in combination with exercise is considered optimal for maintaining muscle function. With the goal of providing recommendations for health care professionals to help older adults sustain muscle strength and function into older age, the European Society for Clinical Nutrition and Metabolism (ESPEN) hosted a Workshop on Protein Requirements in the Elderly, held in Dubrovnik on November 24 and 25, 2013. Based on the evidence presented and discussed, the following recommendations are made (a) for healthy older people, the diet should provide at least 1.0-1.2 g protein/kg body weight/day, (b) for older people who are malnourished or at risk of malnutrition because they have acute or chronic illness, the diet should provide 1.2-1.5 g protein/kg body weight/day, with even higher intake for individuals with severe illness or injury, and (c) daily physical activity or exercise (resistance training, aerobic exercise) should be undertaken by all older people, for as long as possible.

Dietary protein is beneficial to bone health under conditions of adequate calcium intake: an update on clinical research

PURPOSE OF REVIEW

To underscore recent clinical studies, which evaluate the association between dietary protein and bone health.

RECENT FINDINGS

Epidemiologic studies show greater protein intake to be beneficial to bone health in adults. In addition, randomized controlled trials show that protein's positive effect on bone health is augmented by increased calcium intake. The relation between dietary protein and fracture risk is unclear. Dietary protein may positively impact bone health by increasing muscle mass, increasing calcium absorption, suppressing parathyroid hormone, and augmenting insulin-like growth factor 1 production; but the effects of other factors that contribute to this association, such as dietary protein dose and timing response, require further research.

SUMMARY

The positive effects of protein intake on bone health may only be beneficial under conditions of adequate calcium intake. Dietary protein's relation with fracture risk requires further investigation.

Adequate dietary protein is associated with better physical performance among post-menopausal women 60-90 years

OBJECTIVES

Sarcopenia, the involuntary loss of skeletal muscle with age, affects up to one-quarter of older adults. Evidence indicates a positive association between dietary protein intake and lean muscle mass and strength among older persons, but information on dietary protein's effect on physical performance in older adults has received less attention.

DESIGN

Cross-sectional observational analysis of the relationship of dietary protein on body composition and physical performance.

SETTING

Clinical research center.

PARTICIPANTS

387 healthy women aged 60 - 90 years (mean 72.7 ± 7.0 y).

MEASUREMENTS

Measures included body composition (fat-free mass, appendicular skeletal mass and fat mass) via dual x-ray absorptiometry (DXA), physical performance (Physical Performance Test [PPT] and Short Physical Performance Battery [SPPB]), handgrip strength, Physical Activity Scale in the Elderly (PASE), quality of life measure (SF-8), falls, fractures, nutrient and macromolecule intake (four-day food record). Independent samples t-tests determined mean differences between the above or below RDA protein groups.

STATISTICAL ANALYSIS

Analysis of covariance was used to control for body mass index (BMI) between groups when assessing physical performance, physical activity and health-related quality of life.

RESULTS

The subjects consumed an average of 72.2 g protein/day representing 1.1 g protein/kg body weight/day. Subjects were categorized as below the recommended daily allowance (RDA) for protein (defined as less than 0.8 g protein/kg) or at or above the RDA (equal to or higher than 0.8 g protein/kg). Ninety-seven subjects (25%) were in the low protein group, and 290 (75%) were in the higher protein group. Women in the higher protein group had lower body mass, including fat and lean mass, and fat-to-lean ratio than those in the lower-protein group (p <0.001). Composite scores of upper and lower extremity strength were impaired in the group with low protein intake; SPPB score was 9.9±1.9 compared to 10.6±1.6 in those with higher protein intake and PPT was 19.8± 2.9 compared to 20.9± 2.1 in the low and higher protein groups, respectively. The results were attenuated by correction for BMI, but remained significant. The physical component of the SF-8 was also lower in the low protein group but did not remain significant when controlling for BMI. No significant differences were found in hand grip strength or reported physical activity.

CONCLUSION

Healthy, older postmenopausal women consumed, on average, 1.1 g/kg/d protein, although 25% consumed less than the RDA. Those in the low protein group had higher body fat and fat-to-lean ratio than those who consumed the higher protein diet. Upper and lower extremity function was impaired in those who consumed a low protein diet compared to those with a higher protein intake. Protein intake should be considered when evaluating the multi-factorial loss of physical function in older women.

Effect of resistance-type exercise training with or without protein supplementation on cognitive functioning in frail and pre-frail elderly: secondary analysis of a randomized, double-blind, placebo-controlled trial

Physical activity has been proposed as one of the most effective strategies to prevent cognitive decline. Protein supplementation may exert an additive effect. The effect of resistance-type exercise training with or without protein supplementation on cognitive functioning in frail and pre-frail elderly people was assessed in a secondary analysis. Two 24-week, double-blind, randomized, placebo-controlled intervention studies were carried out in parallel. Subjects performed a resistance-type exercise program of two sessions per week (n=62) or no exercise program (n=65). In both studies, subjects were randomly allocated to either a protein (2×15 g daily) or a placebo drink. Cognitive functioning was assessed with a neuropsychological test battery focusing on the cognitive domains episodic memory, attention and working memory, information processing speed, and executive functioning. In frail and pre-frail elderly, resistance-type exercise training in combination with protein supplementation improved information processing speed (changes in domain score 0.08±0.51 versus -0.23±0.19 in the non-exercise group, p=0.04). Exercise training without protein supplementation was beneficial for attention and working memory (changes in domain scores 0.35±0.70 versus -0.12±0.69 in the non-exercise group, p=0.02). There were no significant differences among the intervention groups on the other cognitive tests or domain scores.

Nutritional influences on age-related skeletal muscle loss

Age-related muscle loss impacts on whole-body metabolism and leads to frailty and sarcopenia, which are risk factors for fractures and mortality. Although nutrients are integral to muscle metabolism the relationship between nutrition and muscle loss has only been extensively investigated for protein and amino acids. The objective of the present paper is to describe other aspects of nutrition and their association with skeletal muscle mass. Mechanisms for muscle loss relate to imbalance in protein turnover with a number of anabolic pathways of which the mechanistic TOR pathway and the IGF-1–Akt–FoxO pathways are the most characterised. In terms of catabolism the ubiquitin proteasome system, apoptosis, autophagy, inflammation, oxidation and insulin resistance are among the major mechanisms proposed. The limited research associating vitamin D, alcohol, dietary acid–base load, dietary fat and anti-oxidant nutrients with age-related muscle loss is described. Vitamin D may be protective for muscle loss; a more alkalinogenic diet and diets higher in the anti-oxidant nutrients vitamin C and vitamin E may also prevent muscle loss. Although present recommendations for prevention of sarcopenia focus on protein, and to some extent on vitamin D, other aspects of the diet including fruits and vegetables should be considered. Clearly, more research into other aspects of nutrition and their role in prevention of muscle loss is required.

Effectiveness of exercise and protein supplementation intervention on body composition, functional fitness, and oxidative stress among elderly Malays with sarcopenia

Sarcopenia, characterized as muscle loss that occurs with aging, is a major health problem in an aging population, due to its implications on mobility, quality of life, and fall risk. Protein supplementation could improve the physical fitness by increasing protein anabolism, and exercise has a documented evidence of positive effect on functional status among the elderly. However, the combined effect of both protein supplementation and exercise has not been investigated among sarcopenic elderly in the Asian population. Thus, this study aimed to determine the effectiveness of exercise intervention and protein supplementation either alone or in combination for 12 weeks, on body composition, functional fitness, and oxidative stress among elderly Malays with sarcopenia. Sixty five sarcopenic elderly Malays aged 60–74 years were assigned to the control group, exercise group (ExG), protein supplementation group (PrG), or the combination of exercise and protein supplementation group. A significant interaction effect between body weight and body mass index (BMI) was observed, with the PrG (−2.1% body weight, −1.8% BMI) showing the highest reductions. Further, there was a decrease in % body fat (−4.5%) and an increase in fat-free mass (kg) (+5.7%) in the ExG after 12 weeks (P < 0.05). The highest increments in lower and upper body strength were observed in the PrG (73.2%) and ExG (47.6%), respectively. In addition, the ExG showed a reduction in superoxide dismutase (SOD) levels, and both interventions did not alter either lipid or protein oxidation. In conclusion, the exercise program was found to improve muscle strength and body composition, while protein supplementation reduced body weight and increased upper body strength, among sarcopenic elderly in Malaysia.

Insufficient amounts and inadequate distribution of dietary protein intake in apparently healthy older adults in a developing country: implications for dietary strategies to prevent sarcopenia

BACKGROUND

Both low dietary protein intake and inadequate distribution of protein over the three mealtimes have been reported in older Caucasian adults, but the association between protein intake at each meal and muscle mass has not been studied. The purpose of this study was to evaluate dietary protein intake and distribution by mealtimes, and to explore their association with appendicular skeletal muscle mass in apparently healthy older adults.

METHODS

This was a cross-sectional pilot study that included 78 people over the age of 60 years. Caloric and protein intake were estimated on the basis of three nonconsecutive 24-hour diet recalls and appendicular skeletal muscle mass by dual-energy X-ray absorptiometry.

RESULTS

Men consumed 13.4 g of protein/day more than women (P < 0.05). The estimated value of dietary protein intake was 0.9 g/kg/day. In this sample, 28% of subjects did not cover 100% of the dietary reference intake for protein. Lower consumption of dietary protein was found at breakfast and dinnertime compared with the recommended amount of 25-30 g (P < 0.05). Also, the study observed that appendicular skeletal muscle mass in men and women who consumed <25 g of protein at each mealtime was different from that found in the group that consumed >25 g of protein at one, two, or three mealtimes.

CONCLUSION

While protein intake was higher than current recommendations, it failed to achieve the values reported as necessary to prevent sarcopenia. In addition, there was under-consumption of protein per mealtime, especially at breakfast and dinner.

Dietary protein in relation to bone stiffness index and fat-free mass in a population consuming relatively low protein diets

Dietary protein has a mixed effect on skeletal health and the effect may differ by amount or source of protein. The purpose of this study was to investigate dietary protein in relation to bone density and fat-free mass in rural Korean residents consuming relatively low protein diets. Between 2008 and 2010, 3,330 participants were recruited for a baseline examination of a community-based study in Kangwha. Of those, 1,182 men and 1,393 postmenopausal women were eligible for the present study. Diet was assessed using a food-frequency questionnaire developed for Korean adults. Calcaneal bone density measured by ultrasound was expressed as the stiffness index (SI). Fat-free mass index (FFMI) was defined as fat-free mass in kilograms divided by the height in meters squared. The mean ages of men and women were 59.5 and 60.0 years, respectively. The median daily intakes of total and meat protein were 52.3 and 6.7 g in men and 45.0 and 3.0 g in women, respectively. After controlling for potential confounders, SI and FFMI showed an increasing trend with a higher meat protein intake in men (P for trend = 0.017 and 0.033, respectively), but not in women. No positive association was observed for other food sources of protein. In conclusion, our findings suggest that meat protein contributes to skeletal health in men consuming relatively low protein diets.