Dietary protein and beef consumption predict for markers of muscle mass and nutrition status in older adults

Common questions and misconceptions about protein supplementation: what does the scientific evidence really show?

Protein supplementation often refers to increasing the intake of this particular macronutrient through dietary supplements in the form of powders, ready-to-drink shakes, and bars. The primary purpose of protein supplementation is to augment dietary protein intake, aiding individuals in meeting their protein requirements, especially when it may be challenging to do so through regular food (i.e. chicken, beef, fish, pork, etc.) sources alone. A large body of evidence shows that protein has an important role in exercising and sedentary individuals. A PubMed search of "protein and exercise performance" reveals thousands of publications. Despite the considerable volume of evidence, it is somewhat surprising that several persistent questions and misconceptions about protein exist. The following are addressed: 1) Is protein harmful to your kidneys? 2) Does consuming "excess" protein increase fat mass? 3) Can dietary protein have a harmful effect on bone health? 4) Can vegans and vegetarians consume enough protein to support training adaptations? 5) Is cheese or peanut butter a good protein source? 6) Does consuming meat (i.e., animal protein) cause unfavorable health outcomes? 7) Do you need protein if you are not physically active? 8) Do you need to consume protein ≤ 1 hour following resistance training sessions to create an anabolic environment in skeletal muscle? 9) Do endurance athletes need additional protein? 10) Does one need protein supplements to meet the daily requirements of exercise-trained individuals? 11) Is there a limit to how much protein one can consume in a single meal? To address these questions, we have conducted a thorough scientific assessment of the literature concerning protein supplementation.

Growth, physiological responses, and meat quality of feedlot-finished Bonsmara steers offered unprocessed Mucuna pruriens utilis seed meal with or without conventional and green zinc oxide nanoparticles

Feedlot finishing of beef cattle on commercial nutrient-dense diets based on expensive corn (maize), soybean meal (SBM) and other commonly used protein-rich ingredients is economically unsustainable, especially for smallholder farmers. Rich in energy and proteins, Mucuna pruriens utilis seed meal (MSM) could replace corn and protein-rich ingredients in beef cattle diets provided its problems of antinutritional factors (ANFs) and high fiber content that compromise animal growth performance are resolved. The objective of this study was, therefore, to investigate the effects of incorporation of conventional (C-Nano-ZnO) versus green (G-Nano-ZnO) zinc oxide (ZnO) nanoparticles in the diets of feedlot-finished Bonsmara steers supplemented with 20% MSM (dry matter basis). In a completely randomized design, 28 Bonsmara steers were randomly allocated to 4 experimental diets [i.e., Control diet without MSM (C); C with 20% MSM replacing corn (partially) and the common protein-rich ingredients (CM); CM with 25 mg/kg C-Nano-ZnO (CM-C); and CM with 25 mg/kg G-Nano-ZnO (CM-G)] each with seven replicates for 98 days. Performance variables, carcass traits, hemato-biochemistry, and meat quality were then measured. All data were analyzed with SAS using one-way ANOVA applying the GLM procedure, with diet as the independent variable, except for growth performance data that were analyzed as repeated measures. Results showed that while dietary MSM did not affect (P > 0.05) meat quality and serum biochemistry, it decreased body weight gain (BWG; P < 0.01), feed intake (FI; P = 0.001), feed conversion efficiency (FCE; P < 0.01), carcass fatness (P = 0.05), hot carcass weight (HCW; P < 0.05), cold carcass weight (CCW; P = 0.05), blood MCV (P < 0.05), MCH (P < 0.01), and neutrophils (P < 0.01) as it increased blood lymphocytes (P < 0.001). Interestingly, the harmful effects of MSM were attenuated by C-Nano-ZnO and worsened by G-Nano-ZnO. In conclusion, feeding of high dietary unprocessed MSM did not affect Bonsmara beef meat quality and serum biochemistry but compromised their growth performance, carcass traits, and some hematology responses, and these were alleviated by C-Nano-ZnO and deteriorated by G-Nano-ZnO incorporation. We recommend feeding commercial diets supplemented with 20% MSM, replacing corn and commonly used protein-rich ingredients, plus 25 mg/kg of C-Nano-ZnO to feedlot-finishing beef cattle.

The Modification of Dietary Protein with Ammonium Hydroxide Enhancement Improves Longevity and Metabolic Outcomes in a Sex-Dependent Manner

(1) Background: Dietary protein is a key component of all dietary patterns. It has been demonstrated that there are subtle differences in health implications associated with the source of dietary protein consumed. This study examined dietary protein sources (DPSs) in a long-term study of diet-induced obesity ± ammonium hydroxide enhancement (AHE) and its role in improving long-term health outcomes. (2) Methods: Over 18 months, 272 C3H/HeJ mice (136 male and 136 female) were monitored on high-fat diets with varying DPSs ± AHE. Mice were monitored for weekly change in total mass, as well as 6-month assessments of lean and fat mass. At each assessment, a cohort (~8 mice per diet per sex) was censored for a cross-sectional examination of organ function. (3) Results: Longevity was improved in females fed AHE diets, regardless of DPSs. Females' measures of fat and lean mass were markedly elevated with casein protein diets compared to beef protein diets regardless of AHE. Females fed a beef protein diet + AHE demonstrated reduced fat mass and increased lean mass with aging. In males, AHE beef protein diet-fed mice showed marked improvement to longevity and increased lean mass at 6 months. (4) Conclusions: This study demonstrates that dietary protein modification by AHE attenuates the negative impacts of HF diets in both males and females in a sex-dependent manner. Furthermore, the results from this study emphasize the importance of identifying the differences in the utilization of dietary proteins in both a sex- and age-related manner and demonstrate the potential of DPS modification by AHE as a dietary intervention.

Impact of Quantity and Type of Dietary Protein on Cardiovascular Disease Risk Factors Using Standard and Network Meta-analyses of Randomized Controlled Trials

CONTEXT

Higher protein diets (HPDs) have shown favorable outcomes on weight maintenance and body-composition management; however, their protective effects against cardiovascular diseases (CVDs) remain uncertain and contentious. Furthermore, it is important to consider the influence of other macronutrients in the diet and type of dietary protein when studying HPDs, because this aspect has been overlooked in previous studies.

OBJECTIVE

We assessed the impacts of quantity and type of dietary protein on CVD risk factors.

DATA SOURCES

A database search was conducted in PubMed, Embase, CINAHL, Web of Science, and Cochrane Library and a total of 100 articles met the eligibility criteria.

DATA EXTRACTION

Extracted data from 100 articles were analyzed using standard meta-analysis, and 41 articles were also analyzed using network meta-analysis.

DATA ANALYSIS

In the standard meta-analysis, an HPD had significant favorable effects on systolic blood pressure (SBP) (mean difference [MD] = -1.51 mmHg; 95% CI: -2.77, -0.25), diastolic blood pressure (DBP) (MD = -1.08 mmHg; 95% CI: -1.81, -0.35), and flow-mediated dilation (MD = 0.78%; 95% CI: 0.09, 1.47) compared with lower protein diets. The further network meta-analysis supported that the high-protein, high-carbohydrate, low-fat diet was the most recommended diet to ensure a maximum decrease in SBP, DBP, total cholesterol (TC), and low-density-lipoprotein cholesterol (LDL-C). In comparison to animal-protein-rich diets, plant-protein-rich diets (PPRs) exhibited a significant favorable effects on improving TC (MD = -0.12 mmol/L; 95% CI: -0.19, -0.05), triglyceride (MD = -0.05 mmol/L; 95% CI: -0.09, -0.01), LDL-C (MD = -0.11 mmol/L; 95% CI: -0.18, -0.04), and high-density-lipoprotein cholesterol (MD = 0.03 mmol/L; 95% CI: 0.02, 0.04) levels.

CONCLUSION

Consumption of HPDs and PPRs supports improvements in vascular health and lipid-lipoprotein profiles, respectively. Furthermore, macronutrient composition should be carefully designed in the dietary approach to maximize the effectiveness of HPDs in improving CVD risk factors.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022369931.

Beef Consumption Is Associated with Higher Intakes and Adequacy of Key Nutrients in Older Adults Age 60+ Years: National Health and Nutrition Examination Survey 2011-2018 Analysis

Beef is an important source of high-quality protein and several micronutrients, including iron, zinc, and B vitamins. We determined beef intake and its relationship with intakes of nutrients and their adequacy using 24 h dietary recall data from 5868 older adults. Usual intakes from foods were determined using the National Cancer Institute method, and the percent of the population below the estimated average requirement or above adequate intake was estimated. A high percentage of older adults did not meet nutrient recommendations for vitamin D (96%), choline (96%), vitamin E (84%), potassium (70%), calcium (63%), magnesium (60%), vitamin C (46%), vitamin A (39%), zinc (21%), vitamin B6 (19%), and folate (15%). About 68% of older adults were beef consumers with a mean intake of 56 g/day. Beef consumers had higher (p < 0.05) intakes of energy, protein, calcium, iron, phosphorus, selenium, sodium, zinc, thiamin, riboflavin, niacin, vitamin B12, and choline, and a higher (p < 0.05) proportion met nutrient recommendations for protein, calcium, copper, zinc, thiamin, folate, and vitamin B12 than non-consumers. Consumers of fresh, ground, and processed beef also had generally higher intakes and lower inadequacies of many nutrients depending on the beef type. In conclusion, older adults generally had poor nutrient adequacy from their diets, while beef consumers had higher nutrient intakes and adequacy for certain key nutrients, which are inherently generally available from beef or from foods consumed with beef.

Dietary protein and amino acid intakes for mitigating sarcopenia in humans

Adult humans generally experience a 0.5-1%/year loss in whole-body skeletal muscle mass and a reduction of muscle strength by 1.5-5%/year beginning at the age of 50 years. This results in sarcopenia (aging-related progressive losses of skeletal muscle mass and strength) that affects 10-16% of adults aged ≥ 60 years worldwide. Concentrations of some amino acids (AAs) such as branched-chain AAs, arginine, glutamine, glycine, and serine are reduced in the plasma of older than young adults likely due to insufficient protein intake, reduced protein digestibility, and increased AA catabolism by the portal-drained viscera. Acute, short-term, or long-term administration of some of these AAs or a mixture of proteinogenic AAs can enhance blood flow to skeletal muscle, activate the mechanistic target of rapamycin cell signaling pathway for the initiation of muscle protein synthesis, and modulate the metabolic activity of the muscle. In addition, some AA metabolites such as taurine, β-alanine, carnosine, and creatine have similar physiological effects on improving muscle mass and function in older adults. Long-term adequate intakes of protein and the AA metabolites can aid in mitigating sarcopenia in elderly adults. Appropriate combinations of animal- and plant-sourced foods are most desirable to maintain proper dietary AA balance.

Associations of plasma retinol and α-tocopherol levels with skeletal muscle health in Chinese children

Childhood is a critical period for muscle accumulation. Studies in elders have reported that antioxidant vitamins could improve muscle health. However, limited studies have assessed such associations in children. This study included 243 boys and 183 girls. A seventy-nine-item FFQ was used to investigate dietary nutrients intake. Plasma levels of retinol and α-tocopherol were measured using high-performance liquid chromatography with MS. Dual X-ray absorptiometry was used to assess appendicular skeletal muscle mass (ASM) and total body fat. The ASM index (ASMI) and ASMI Z-score were then calculated. Hand grip strength was measured using a Jamar® Plus+ Hand Dynamometer. Fully adjusted multiple linear regression models showed that for each unit increase in plasma retinol content, ASM, ASMI, left HGS and ASMI Z-score increased by 2·43 × 10-3 kg, 1·33 × 10-3 kg/m2, 3·72 × 10-3 kg and 2·45 × 10-3 in girls, respectively (P < 0·001-0·050). ANCOVA revealed a dose-response relationship between tertiles of plasma retinol level and muscle indicators (Ptrend: 0·001-0·007). The percentage differences between the top and bottom tertiles were 8·38 %, 6·26 %, 13·2 %, 12·1 % and 116 % for ASM, ASMI, left HGS, right HGS and ASMI Z-score in girls, respectively (Pdiff: 0·005-0·020). No such associations were observed in boys. Plasma α-tocopherol levels were not correlated with muscle indicators in either sex. In conclusion, high circulating retinol levels are positively associated with muscle mass and strength in school-age girls.

Dietary protein recommendations to support healthy muscle ageing in the 21st century and beyond: considerations and future directions

This review explores the evolution of dietary protein intake requirements and recommendations, with a focus on skeletal muscle remodelling to support healthy ageing based on presentations at the 2023 Nutrition Society summer conference. In this review, we describe the role of dietary protein for metabolic health and ageing muscle, explain the origins of protein and amino acid (AA) requirements and discuss current recommendations for dietary protein intake, which currently sits at about 0⋅8 g/kg/d. We also critique existing (e.g. nitrogen balance) and contemporary (e.g. indicator AA oxidation) methods to determine protein/AA intake requirements and suggest that existing methods may underestimate requirements, with more contemporary assessments indicating protein recommendations may need to be increased to >1⋅0 g/kg/d. One example of evolution in dietary protein guidance is the transition from protein requirements to recommendations. Hence, we discuss the refinement of protein/AA requirements for skeletal muscle maintenance with advanced age beyond simply the dose (e.g. source, type, quality, timing, pattern, nutrient co-ingestion) and explore the efficacy and sustainability of alternative protein sources beyond animal-based proteins to facilitate skeletal muscle remodelling in older age. We conclude that, whilst a growing body of research has demonstrated that animal-free protein sources can effectively stimulate and support muscle remodelling in a manner that is comparable to animal-based proteins, food systems need to sustainably provide a diversity of both plant and animal source foods, not least for their protein content but other vital nutrients. Finally, we propose some priority research directions for the field of protein nutrition and healthy ageing.

Combined Aerobic Training and Mediterranean Diet Is Not Associated with a Lower Prevalence of Sarcopenia in Italian Older Adults

Previous studies found a lower prevalence of sarcopenia in older adults engaged in regular aerobic training (AT) or with greater adherence to a Mediterranean (MED) diet. However, the effect of their combination on sarcopenia indices is unknown. The present study tested the association between AT plus a MED diet and the presence of sarcopenia and its defining elements in a sample of Italian older adults enrolled in the Longevity Check-up 7+ (Lookup 7+) project. Analyses were conducted in participants 65+ years, with a body mass index of at least 18.5 kg/m2, engaged in regular AT, and without missing information for the variables of interest. MED diet adherence was evaluated via a modified version of the MEDI-LITE score and categorized as low, moderate, or high. The presence of sarcopenia was established by handgrip strength and appendicular skeletal muscle mass (ASM) values below sex-specific cut-points recommended by the European Working Group on Sarcopenia in Older People 2. Data from 491 older adults were analyzed for the present study. The mean age was 72.7 ± 5.7 years, and 185 (37.7%) were women. MED diet adherence was low in 59 (12.0%) participants, moderate in 283 (57.6%), and high in 149 (30.3%). Sarcopenia was identified in 26 participants (5.3%), with no differences across MED diet adherence groups. The results of binary logistic regression showed no significant associations between AT plus adherence to a MED diet and dynapenia, low ASM, or sarcopenia. The findings of the present study indicate that the combination of AT with a MED diet is not associated with a lower probability of sarcopenia or its defining elements in Italian older adults enrolled in Lookup 7+. Further research is warranted to establish whether exercise frequency, volume, intensity, and length of engagement in AT impact the association between MED diet and sarcopenia.

Dietary protein requirements and recommendations for healthy older adults: a critical narrative review of the scientific evidence

Adequate protein intake is essential for the maintenance of whole-body protein mass. Different methodological approaches are used to substantiate the evidence for the current protein recommendations, and it is continuously debated whether older adults require more protein to counteract the age-dependent loss of muscle mass, sarcopenia. Thus, the purpose of this critical narrative review is to outline and discuss differences in the approaches and methodologies assessing the protein requirements and, hence, resulting in controversies in current protein recommendations for healthy older adults. Through a literature search, this narrative review first summarises the historical development of the Food and Agriculture Organization/World Health Organization/United Nations University setting of protein requirements and recommendations for healthy older adults. Hereafter, we describe the various types of studies (epidemiological studies and protein turnover kinetic measurements) and applied methodological approaches founding the basis and the different recommendations with focus on healthy older adults. Finally, we discuss important factors to be considered in future studies to obtain evidence for international agreement on protein requirements and recommendations for healthy older adults. We conclude by proposing future directions to determine 'true' protein requirements and recommendations for healthy older adults.

Early cognitive dysfunction after stroke and related risk factors in the high-altitude and multi-ethnic region of Qinghai, China: A multi-center cross-sectional study

OBJECTIVE

Cognitive impairment is a common outcome of stroke, but there is limited evidence regarding its prevalence at high altitude, especially within the context of specific ethnic groups or lifestyle habits. This prospective exploratory study investigated early cognitive impairment after stroke in Qinghai Province, 3000 m above sea level.

METHODS

Patients with acute stroke (n = 1047) were enrolled from 3 hospitals in Qinghai Province. Cognitive performance was measured by Montreal Cognitive Assessment (MoCA) scores within 5 days of stroke symptom onset; MoCA < 26 defined impairment. Patient data included demographics, education, vascular risk factors, diet, and activities of daily living rated by Barthel index.

RESULTS

Cognitive impairment within 5 days of stroke symptom onset affected 77.65% of these patients. The factors independently associated with early cognitive impairment were: older age (mean difference [MD]: -4.857, 95% confidence interval [CI]: 6.685-3.030, P < 0.001); female gender (odds ratio [OR]: 1.674, 95% CI: 1.212-2.313, P = 0.002); and a diet containing yak butter (OR: 1.587, 95% CI: 1.247-2.021, P < 0.001). Progressively lesser odds were accounted to beef (Yak) and mutton consumption (OR: 0.804, 95% CI: 0.655-0.987, P = 0.037); fruit (OR: 0.792, 95% CI: 0.672-0.933, P = 0.005); status as an immigrant (OR: 0.666, 95% CI: 0.445-0.996, P = 0.048); education (OR: 0.514, 95% CI: 0.400-0.660, P < 0.001); and multiple daily leisure activities (OR: 0.999, 95% CI: 0.999-0.999, P < 0.001).

CONCLUSION

Persons in Qinghai province who experience stroke are likely to show signs of early cognitive dysfunction. Preventive modifiable features include diet and daily activities.

The Health Benefits of Egg Protein

Once the general public accepts that dietary cholesterol is not a concern for cardiovascular disease risk, foods that have been labeled as high-cholesterol sources, including eggs, may be appreciated for their various other dietary components. One of the nutrients in eggs that deserves further discussion is egg protein. Egg protein has been recognized to be highly digestible and an excellent source of essential amino acids, with the highest attainable protein digestibility-corrected amino acid score. Egg protein has been shown to decrease malnutrition in underdeveloped countries, possibly increase height in children, and protect against kwashiorkor. Egg protein has been demonstrated to be important to skeletal muscle health and protective against sarcopenia. Egg protein also can decrease appetite, resulting in a reduction in the caloric intake from the next meal and weight reduction. Other protective effects of egg protein addressed in this review include protection against infection as well as hypotensive and anti-cancer effects.

The potential role of beef and nutrients found in beef on outcomes of wellbeing in healthy adults 50 years of age and older: A systematic review of randomized controlled trials

Shifts in wellbeing and health occur as we age. As life expectancy increases, maintenance of wellbeing and health becomes increasingly important. Nutrients found in beef are associated with outcomes of wellbeing such as physical and cognitive function, lean body mass, and mood in older adults and individuals with chronic disease. However, it is unclear how beef and nutrients found in beef impact wellbeing in healthy adults ≥50 years of age. This study systematically reviewed evidence linking the intake of beef and nutrients found in beef to markers of wellbeing in healthy adults. PubMed, CINAHL, and Web of Science were searched up to August 31, 2021 for eligible randomized controlled trials (RCTs). Nutrients included in the analysis were beef, red meat, dietary protein, essential amino acids, branched chain amino acids, tryptophan, arginine, cysteine, glycine, glutamate, vitamin B6, vitamin B12, choline, zinc, and iron. We identified nine RCTs with results from 55 measurements of markers of wellbeing. An overall positive effect was found of beef and beef's nutrients on wellbeing. There was an overall positive effect of amino acids and protein on wellbeing, with no effect of arginine, vitamin B-12, leucine, and zinc. Physical function was also influenced by beef and nutrients found in beef. Eight of the studies found focused on specific nutrients found in beef, and not beef itself in older adults with one or more chronic diseases. This study identified a need for further research regarding the effect of beef and nutrients found in beef on defined functional outcomes of wellbeing in healthy adults ≥50 years of age.

Influences of Vitamin D and Iron Status on Skeletal Muscle Health: A Narrative Review

There is conflicting evidence of the roles vitamin D and iron have in isolation and combined in relation to muscle health. The purpose of this narrative review was to examine the current literature on the roles that vitamin D and iron have on skeletal muscle mass, strength, and function and how these nutrients are associated with skeletal muscle health in specific populations. Secondary purposes include exploring if low vitamin D and iron status are interrelated with skeletal muscle health and chronic inflammation and reviewing the influence of animal-source foods rich in these nutrients on health and performance. PubMed, Scopus, SPORT Discus, EMBAE, MEDLINE, and Google Scholar databases were searched to determine eligible studies. There was a positive effect of vitamin D on muscle mass, particularly in older adults. There was a positive effect of iron on aerobic and anaerobic performance. Studies reported mixed results for both vitamin D and iron on muscle strength and function. While vitamin D and iron deficiency commonly occur in combination, few studies examined effects on skeletal muscle health and inflammation. Isolated nutrients such as iron and vitamin D may have positive outcomes; however, nutrients within food sources may be most effective in improving skeletal muscle health.

The Molecular Effects of Dietary Acid Load on Metabolic Disease (The Cellular PasaDoble: The Fast-Paced Dance of pH Regulation)

Metabolic diseases are becoming more common and more severe in populations adhering to western lifestyle. Since metabolic conditions are highly diet and lifestyle dependent, it is suggested that certain diets are the cause for a wide range of metabolic dysfunctions. Oxidative stress, excess calcium excretion, inflammation, and metabolic acidosis are common features in the origins of most metabolic disease. These primary manifestations of "metabolic syndrome" can lead to insulin resistance, diabetes, obesity, and hypertension. Further complications of the conditions involve kidney disease, cardiovascular disease, osteoporosis, and cancers. Dietary analysis shows that a modern "Western-style" diet may facilitate a disruption in pH homeostasis and drive disease progression through high consumption of exogenous acids. Because so many physiological and cellular functions rely on acid-base reactions and pH equilibrium, prolonged exposure of the body to more acids than can effectively be buffered, by chronic adherence to poor diet, may result in metabolic stress followed by disease. This review addresses relevant molecular pathways in mammalian cells discovered to be sensitive to acid - base equilibria, their cellular effects, and how they can cascade into an organism-level manifestation of Metabolic Syndromes. We will also discuss potential ways to help mitigate this digestive disruption of pH and metabolic homeostasis through dietary change.

Influence of maintenance technology in arid conditions on efficiency of marbled beef production

In recent years, Russia has been developing domestic single-purpose meat cattle breeding. Some livestock farms have focused on the production of high-quality grades of raw meat, i.e. ‘marbled’ beef. Meat of that kind is in great demand in the premium meat market. At the same time, production of beef without using steroids and hormonal drugs increases the competitiveness of this product on the world market in countries of the West and the Middle East. Within the framework of our study, an experiment was conducted on Kalmyk cattle in the arid conditions of OAO Kirovskij in the Republic of Kalmykia. Standardized methods of analysis were used. For the experiment, 10-month-old steers were selected and divided into two groups (Control and Test), 30 heads each. They were kept and fed according to different technologies until the age of 19 months. The Test group steers were kept tied up and fed with a diet developed by the Volga Region Research Institute of Manufacture and Processing of Meat-and-Milk Production; the Control group steers were kept according to conventional beef cattle production technology. The wide expansion range and popularity of this cattle breed are caused by the high productivity of steers whether kept tied up or allowed to graze free. The compared qualities of beef obtained from Kalmyk steers proved that keeping them tied up allows increased production efficiency of raw meat which is an important factor for meat production, being intensified in an unstable situation in agriculture

Myoprotective Whole Foods, Muscle Health and Sarcopenia: A Systematic Review of Observational and Intervention Studies in Older Adults

Decline in skeletal muscle strength and mass (sarcopenia) accelerates with age, leading to adverse health outcomes and poor quality of life. Diet plays a crucial role in muscle ageing being an important element of a healthy lifestyle. However, unlike single nutrients, such as dietary protein, or dietary patterns, such as the Mediterranean diet, the relationship between individual whole foods and muscle health has not been systematically evaluated. We aimed to investigate which whole foods (meat, fish, eggs, fruit and vegetables, and non-liquid dairy) may be beneficial (myoprotective) for ageing muscle and sarcopenia in adults aged ≥ 50 years. Nineteen observational and nine intervention studies were identified through systematic searches of the four electronic databases (last search: March 2020). The synthesis of findings showed strong and consistent evidence for a beneficial effect of lean red meat on muscle mass or lean tissue mass in both observational and intervention studies. Higher intake of fruit and vegetables was associated with better muscle function in observational studies, but the evidence from intervention studies was scarce. Non-liquid dairy foods were beneficial for muscle mass in both observational and intervention studies. There was moderate evidence for the role of these foods in muscle strength and sarcopenia, and limited or inconclusive evidence for the benefits of other whole foods (e.g., fish, eggs) for muscle health in older adults. Although current nutritional recommendations are often based on a single nutrient approach, further research about the role of protein-rich and other foods in muscle health will allow for the development of guidelines that are based on whole foods, also highlighting the potential importance of non-protein nutrients within these foods for myoprotection in older adults.

Producing high-oleic acid beef and the impact of ground beef consumption on risk factors for cardiovascular disease: A review

This review summarizes the effects of high-oleic acid oil and high-oleic acid ground beef interventions on risk factors for cardiovascular disease (CVD) in human trials, and also summarizes studies designed to increase the amount of oleic acid (18:1n-9) in beef. In three human trials, high-oleic acid oils and high-oleic acid ground beef increased plasma high-density lipoprotein cholesterol over baseline values or over high-carbohydrate diets. Neither low-oleic acid nor high-oleic acid ground beef increased risk factors for CVD, confirming earlier studies that used high-oleic acid oils. High-oleic acid beef can be obtained from cattle fed a corn-based finishing diet to USDA Grade of USDA Choice or greater; from beef from cattle with Japanese genetics; and from the brisket. Beef from grass-fed cattle contains more n-3 fatty acids than beef from conventionally-fed cattle, but also contains greater amounts of saturated and trans-fatty acids.

Diet and Genetics Influence Beef Cattle Performance and Meat Quality Characteristics

A comprehensive review of the impact of tropical pasture grazing, nutritional supplementation during feedlot finishing and fat metabolism-related genes on beef cattle performance and meat-eating traits is presented. Grazing beef cattle on low quality tropical forages with less than 5.6% crude protein, 10% soluble starches and 55% digestibility experience liveweight loss. However, backgrounding beef cattle on high quality leguminous forages and feedlot finishing on high-energy diets increase meat flavour, tenderness and juiciness due to improved intramuscular fat deposition and enhanced mono- and polyunsaturated fatty acids. This paper also reviews the roles of stearoyl-CoA desaturase, fatty acid binding protein 4 and fatty acid synthase genes and correlations with meat traits. The review argues that backgrounding of beef cattle on Desmanthus, an environmentally well-adapted and vigorous tropical legume that can persistently survive under harsh tropical and subtropical conditions, has the potential to improve animal performance. It also identifies existing knowledge gaps and research opportunities in nutrition-genetics interactions aimed at a greater understanding of grazing nutrition, feedlot finishing performance, and carcass traits of northern Australian tropical beef cattle to enable red meat industry players to work on marbling, juiciness, tenderness and overall meat-eating characteristics.

Association Between Sarcopenia and Nutritional Status in Older Adults: A Systematic Literature Review

HOW TO OBTAIN CONTACT HOURS BY READING THIS ARTICLE INSTRUCTIONS 1.2 contact hours will be awarded by Villanova University College of Nursing upon successful completion of this activity. A contact hour is a unit of measurement that denotes 60 minutes of an organized learning activity. This is a learner-based activity. Villanova University College of Nursing does not require submission of your answers to the quiz. A contact hour certificate will be awarded once you register, pay the registration fee, and complete the evaluation form online at http://goo.gl/gMfXaf. To obtain contact hours you must: 1. Read the article, "Association Between Sarcopenia and Nutritional Status in Older Adults: A Systematic Literature Review" found on pages 33-41, carefully noting any tables and other illustrative materials that are included to enhance your knowledge and understanding of the content. Be sure to keep track of the amount of time (number of minutes) you spend reading the article and completing the quiz. 2. Read and answer each question on the quiz. After completing all of the questions, compare your answers to those provided within this issue. If you have incorrect answers, return to the article for further study. 3. Go to the Villanova website listed above to register for contact hour credit. You will be asked to provide your name; contact information; and a VISA, MasterCard, or Discover card number for payment of the $20.00 fee. Once you complete the online evaluation, a certificate will be automatically generated. This activity is valid for continuing education credit until June 30, 2019. CONTACT HOURS This activity is co-provided by Villanova University College of Nursing and SLACK Incorporated. Villanova University College of Nursing is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's Commission on Accreditation. ACTIVITY OBJECTIVES 1. Describe the geriatric syndrome of sarcopenia. 2. Identify the outcome of the sarcopenia studies. DISCLOSURE STATEMENT Neither the planners nor the authors have any conflicts of interest to disclose. Sarcopenia is an important geriatric syndrome with high prevalence rates and one of the most common causes of reductions in mobility, quality of life, and increasing dependency on care. The current study examined the relationship between sarcopenia and nutritional status in adults 60 and older. A systematic literature search was conducted, and data from 33 publications were included. The currently available literature indicates that sarcopenia is correlated with poor nutritional status (e.g., low body mass index, unfavorable nutritional risk screening results, decreased nutritional laboratory parameters, anorexia). Comparison of the studies' results were complicated by the lack of a generally accepted definition for sarcopenia, as well as the use of many different instruments to detect sarcopenia. The co-occurrence of malnutrition and sarcopenia is of great relevance. Future scientific work should focus on the formation of consistent definitions and instruments for the detection of sarcopenia to improve data comparisons. [Journal of Gerontological Nursing, 42(7), 33-41.].

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.

Animal-Derived Protein Consumption Is Associated with Muscle Mass and Strength in Community-Dwellers: Results from the Milan EXPO Survey

OBJECTIVES

Behavioral factors, including protein intake, influence the quantity and quality of skeletal muscle. The aim of this study was to explore the relationship between animal-derived protein intake and muscle mass and function in a large sample of unselected community-dwellers.

MATERIAL AND METHODS

The VIP (Very Important Protein) study, conducted during Expo 2015 in Milan, was a population survey aimed at assessing major health metrics in a population outside of the research setting, with a special focus on the relation between animal-derived protein intake and muscle mass and function. A brief questionnaire exploring lifestyle habits, dietary preferences and the consumption of selected foods was administered. Muscle mass was estimated by calf circumference (CC) and mid-arm muscle circumference (MAMC) of the dominant side. Muscle strength of upper and lower extremities was assessed through handgrip strength testing and repeated chair stand test, respectively.

RESULTS

The mean age of the 1,853 participants was 50.3 years (standard deviation: 15.7; range: 18-98 years), of whom 959 (51.7%) were women. Participants in the highest tertile of protein consumption showed better performance at both the handgrip strength (p <0.001) and chair stand tests than those in the lowest tertile (p <0.01). The same results were found for CC (p <0.001) and MAMC (p <0.001). Participants with high protein intake and engaged in regular physical activity showed the higher scores in all the assessed domains.

CONCLUSIONS

The results of the VIP survey suggest an association between animal-derived protein intake and muscle mass and strength across ages. Our findings also indicate a synergistic effect of animal-derived protein intake and physical activity on muscle-related parameters.

Associations between body composition, nutrition, and physical activity in young adults

OBJECTIVE

The aim of the present study is to investigate the associations between total energy, macronutrient intakes, and physical activity (PA) and body composition by assessing body fat mass, fat-free mass, and BMI in a population of young adults.

METHODS

The study population consisted of 605 young Spanish adults (median age 20.38 ± 2.67). Body composition, including fat mass and fat-free mass, was calculated with body composition analyzer. Daily energy and macronutrient intakes were measured using a 72-h recall method. The International PA Questionnaire was used to assess PA and sedentary time. Linear regression analyses were performed to test the possible associations between nutrition, PA factors, and body composition.

RESULTS

Linear regression analyses revealed that BMI has a significant positive association with protein intake (P = .004, B = 0.088, 95% CI 0.028-0.149) and an inverse association with carbohydrate intake (P = 0.034, B = -0.027, 95% CI -0.053 - -0.002). Protein intake also demonstrated a significant association with fat-free mass, but the size of the effect was smaller (P = .027, B = 96.965, 95% CI 11.250-182.679). There was evidence of a positive association between total PA and moderate-to-vigorous PA (P < .001, B = 15.630, 95% CI 6.989 -24.270) and fat-free mass (P < .001, B = 20.208, 95% CI 9.694 -30.723). When fat mass was used as the outcome variable, there was no evidence of any association with the PA, total energy, and macronutrient intakes variables analyzed.

CONCLUSIONS

Our findings suggest that PA variables were consistently associated with body composition, specifically fat-free mass. Dietary factors also have influence over body composition; we showed that protein intake is significantly associated with fat-free mass and BMI.

Two-Year Whey Protein Supplementation Did Not Enhance Muscle Mass and Physical Function in Well-Nourished Healthy Older Postmenopausal Women

BACKGROUND

Protein may play a role in preventing muscle loss with aging. To our knowledge, there have been no long-term randomized controlled trials to examine the effects of increased dietary protein intake on muscle health in community-dwelling older women.

OBJECTIVE

In this study, we evaluated the effects of whey protein supplementation on muscle mass and physical function in community-dwelling older Australian women.

METHODS

In this 2 y randomized, double-blind, placebo-controlled trial, women aged 70-80 y (mean 74.3 ± 2.7 y) were randomly assigned to either a high protein drink containing 30 g of whey protein (n = 109) or a placebo drink containing 2.1 g protein (n = 110) daily. Dual-energy X-ray absorptiometry appendicular skeletal muscle mass, upper arm and calf (38% tibia) muscle cross-sectional area, physical function including hand grip strength, lower limb muscle strength and Timed Up and Go test, and 24 h urinary nitrogen were measured at baseline, 1 y, and 2 y.

RESULTS

A total of 196 women with at least one follow-up measurement were included in this analysis. Baseline mean BMI was 26.7 ± 3.9 kg/m(2) and protein intake was 76 ± 17 g/d (1.1 ± 0.3 g · kg body weight(-1) · d(-1)). A mean increase in protein intake of ∼ 20 g/d in the protein group was confirmed by the estimates from 24 h urinary nitrogen. Over the 2 y in both groups there was a significant decrease in the upper arm (mean ± SE: -5.59 ± 0.75 cm(2)) and calf (-0.77 ± 0.11 cm(2)) muscle area, as well as hand grip strength (-1.30 ± 0.3 kg) (all P < 0.05), but appendicular skeletal muscle mass did not change significantly. There were no significant effects of the protein intervention on any of the muscle mass or physical function measures (all P > 0.05) at 1 and 2 y.

CONCLUSION

This study showed that in protein-replete, healthy, ambulant, postmenopausal older women, 30 g/d of extra protein did not improve the maintenance of muscle mass or physical function despite evidence of deterioration in muscle measurements in the upper limb. This trial was registered at the Australian New Zealand Clinical Trials Registry as ACTRN012607000163404.

Protein and healthy aging

Our understanding of the potential benefits and challenges of optimizing dietary protein intake in older adults continues to evolve. An overarching hypothesis generated during Protein Summit 2.0 was that consuming an adequate amount of high-quality protein at each meal, in combination with physical activity, may delay the onset of sarcopenia, slow its progression, reduce the magnitude of its functional consequences, or all of these. The potential benefits of young and middle-aged adults adopting a diet pattern whereby adequate protein is consumed at each meal as a countermeasure to sarcopenia are presented and discussed. For example, meeting a protein threshold (∼25-30 g/meal) represents a promising, yet still largely unexplored dietary strategy to help maintain muscle mass and function. For many older adults, breakfast is a carbohydrate-dominated lower-protein meal and represents an opportunity to improve and more evenly distribute daily protein intake. Although both animal and plant-based proteins can provide the required essential amino acids for health, animal proteins generally have a higher proportion of the amino acid leucine. Leucine plays a key role in stimulating translation initiation and muscle protein anabolism and is the focus of ongoing research. Protein requirements should be assessed in the light of habitual physical activity. An evenly distributed protein diet provides a framework that allows older adults to benefit from the synergistic anabolic effect of protein and physical activity. To fully understand the role of dietary protein intake in healthy aging, greater efforts are needed to coordinate and integrate research design and data acquisition and interpretation from a variety of disciplines.

Inclusion of red meat in healthful dietary patterns

Dietary patterns are an important concept in dietary recommendations. The Western pattern is most commonly defined as a diet characterized by high intakes of refined grains, sugar and red meat, and has been shown to be associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity. However, isolating the independent effects of individual foods on health outcomes is central to helping individuals choose foods to build healthier dietary patterns to which they can adhere. Red meat is a popular source of high quality protein and provides a variety of essential nutrients that improve overall diet quality. It is also a source of saturated fatty acids, which observational evidence suggests are associated with heart disease, although recent data challenge this. Several studies have shown that lean red meat can be successfully included in recommended heart-healthy dietary patterns without detriment to blood lipids. Furthermore, increased dietary protein has been shown to promote healthy body weight and composition, in part by increasing satiety, and to improve vitality and stamina.