Dietary Protein and Muscle Mass: Translating Science to Application and Health Benefit

Adequate consumption of dietary protein is critical for the maintenance of optimal health during normal growth and aging. The current Recommended Dietary Allowance (RDA) for protein is defined as the minimum amount required to prevent lean body mass loss, but is often misrepresented and misinterpreted as a recommended optimal intake. Over the past two decades, the potential muscle-related benefits achieved by consuming higher-protein diets have become increasingly clear. Despite greater awareness of how higher-protein diets might be advantageous for muscle mass, actual dietary patterns, particularly as they pertain to protein, have remained relatively unchanged in American adults. This lack of change may, in part, result from confusion over the purported detrimental effects of higher-protein diets. This manuscript will highlight common perceptions and benefits of dietary protein on muscle mass, address misperceptions related to higher-protein diets, and comment on the translation of academic advances to real-life application and health benefit. Given the vast research evidence supporting the positive effects of dietary protein intake on optimal health, we encourage critical evaluation of current protein intake recommendations and responsible representation and application of the RDA as a minimum protein requirement rather than one determined to optimally meet the needs of the population.

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Dietary protein intake does not modulate daily myofibrillar protein synthesis rates or loss of muscle mass and function during short-term immobilization in young men: a randomized controlled trial

American Journal of Clinical Nutrition ◽

10.1093/ajcn/nqaa136 ◽

2020 ◽

Cited By ~ 3

Author(s):

Sean Paul Kilroe ◽

Jonathan Fulford ◽

Sarah Jackman ◽

Andrew Holwerda ◽

Annemie Gijsen ◽

...

Keyword(s):

Muscle Mass ◽

Dietary Protein ◽

Protein Intake ◽

Quadriceps Muscle ◽

Myofibrillar Protein ◽

Muscle Volume ◽

Dietary Protein Intake ◽

Short Term ◽

Muscle Disuse ◽

Myofibrillar Protein Synthesis

ABSTRACT Background Short-term (<1 wk) muscle disuse lowers daily myofibrillar protein synthesis (MyoPS) rates resulting in muscle mass loss. The understanding of how daily dietary protein intake influences such muscle deconditioning requires further investigation. Objectives To assess the influence of graded dietary protein intakes on daily MyoPS rates and the loss of muscle mass during 3 d of disuse. Methods Thirty-three healthy young men (aged 22 ± 1 y; BMI = 23 ± 1 kg/m2) initially consumed the same standardized diet for 5 d, providing 1.6 g protein/kg body mass/d. Thereafter, participants underwent a 3-d period of unilateral leg immobilization during which they were randomly assigned to 1 of 3 eucaloric diets containing relatively high, low, or no protein (HIGH: 1.6, LOW: 0.5, NO: 0.15 g protein/kg/d; n = 11 per group). One day prior to immobilization participants ingested 400 mL deuterated water (D2O) with 50-mL doses consumed daily thereafter. Prior to and immediately after immobilization upper leg bilateral MRI scans and vastus lateralis muscle biopsies were performed to measure quadriceps muscle volume and daily MyoPS rates, respectively. Results Quadriceps muscle volume of the control legs remained unchanged throughout the experiment (P > 0.05). Immobilization led to 2.3 ± 0.4%, 2.7 ± 0.2%, and 2.0 ± 0.4% decreases in quadriceps muscle volume (P < 0.05) of the immobilized leg in the HIGH, LOW, and NO groups (P < 0.05), respectively, with no significant differences between groups (P > 0.05). D2O ingestion resulted in comparable plasma free [2H]-alanine enrichments during immobilization (∼2.5 mole percentage excess) across groups (P > 0.05). Daily MyoPS rates during immobilization were 30 ± 2% (HIGH), 26 ± 3% (LOW), and 27 ± 2% (NO) lower in the immobilized compared with the control leg, with no significant differences between groups (P > 0.05). Conclusions Three days of muscle disuse induces considerable declines in muscle mass and daily MyoPS rates. However, daily protein intake does not modulate any of these muscle deconditioning responses. Clinical trial registry number: NCT03797781

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Impact of Meeting Different Guidelines for Protein Intake on Muscle Mass and Physical Function in Physically Active Older Women

Nutrients ◽

10.3390/nu10091156 ◽

2018 ◽

Vol 10 (9) ◽

pp. 1156 ◽

Cited By ~ 12

Author(s):

Andreas Nilsson ◽

Diego Montiel Rojas ◽

Fawzi Kadi

Keyword(s):

Physical Activity ◽

Older Adults ◽

Physical Function ◽

Older Women ◽

Muscle Mass ◽

Dietary Protein ◽

Protein Intake ◽

Dietary Protein Intake ◽

Physical Limitations

The role of dietary protein intake on muscle mass and physical function in older adults is important for the prevention of age-related physical limitations. The aim of the present study was to elucidate links between dietary protein intake and muscle mass and physical function in older women meeting current guidelines of objectively assessed physical activity. In 106 women (65 to 70 years old), protein intake was assessed using a 6-day food record and participants were classified into high and low protein intake groups using two Recommended Dietary Allowance (RDA) thresholds (0.8 g·kg−1 bodyweight (BW) and 1.1 g·kg−1 BW). Body composition, aerobic fitness, and quadriceps strength were determined using standardized procedures, and self-reported physical function was assessed using the SF-12 Health Survey. Physical activity was assessed by accelerometry and self-report. Women below the 0.8 g·kg−1 BW threshold had a lower muscle mass (p < 0.05) with no differences in physical function variables. When based on the higher RDA threshold (1.1 g·kg−1 BW), in addition to significant differences in muscle mass, women below the higher threshold had a significantly (p < 0.05) higher likelihood of having physical limitations. In conclusion, the present study supports the RDA threshold of 0.8 g·kg−1 BW of proteins to prevent the loss of muscle mass and emphasizes the importance of the higher RDA threshold of at least 1.1 g·kg−1 BW to infer additional benefits on constructs of physical function. Our study also supports the role of protein intake for healthy ageing, even in older adults meeting guidelines for physical activity.

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Associations of dietary protein intake on subsequent decline in muscle mass and physical functions over four years in ambulant older Chinese people

The journal of nutrition health & aging ◽

10.1007/s12603-013-0379-y ◽

2013 ◽

Vol 18 (2) ◽

pp. 171-177 ◽

Cited By ~ 39

Author(s):

Ruth Chan ◽

J. Leung ◽

J. Woo ◽

T. Kwok

Keyword(s):

Muscle Mass ◽

Dietary Protein ◽

Protein Intake ◽

Dietary Protein Intake ◽

Chinese People ◽

Physical Functions ◽

Older Chinese

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DIETARY PROTEIN TO MAINTAIN MUSCLE MASS IN AGING: A CASE FOR PER-MEAL PROTEIN RECOMMENDATIONS

Journal of Frailty & Aging ◽

10.14283/jfa.2016.80 ◽

2016 ◽

pp. 1-10

Author(s):

C.H. MURPHY ◽

S.Y. OIKAWA ◽

S.M. PHILLIPS

Keyword(s):

Muscle Mass ◽

Dietary Protein ◽

Protein Intake ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Dietary Advice ◽

Age Related ◽

Meal Protein ◽

Single Meal ◽

And Function

It is well accepted that daily protein intake is an important dietary consideration to limit and treat age-related declines in muscle mass, strength, and function. Furthermore, we propose that there is a growing appreciation for the need to consider protein intake on a per-meal basis rather than simply focusing on the total daily protein intake. The existence of a saturable dose-response relationship between muscle protein synthesis (MPS) and the quantity of protein consumed in a single meal/bolus provides the rationale for promoting an even/balanced pattern of daily protein intake. We hypothesize that a balanced/even protein intake pattern with the ingestion a quantity of protein shown to optimally stimulate MPS at each meal may be an effective strategy to alleviate sarcopenic muscle loss. In this review we examine the available evidence supporting the influence of dietary protein intake pattern on muscle protein turnover, muscle mass, and muscle function. We present several practical considerations that, it is proposed, should be taken into account when translating a per-meal protein recommendation into dietary advice for older adults.

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Dietary Protein Intake and Lean Muscle Mass in Survivors of Childhood Acute Lymphoblastic Leukemia: Report From the St. Jude Lifetime Cohort Study

Physical Therapy ◽

10.2522/ptj.20150507 ◽

2016 ◽

Vol 96 (7) ◽

pp. 1029-1038 ◽

Cited By ~ 7

Author(s):

Alexandra M. Boland ◽

Todd M. Gibson ◽

Lu Lu ◽

Sue C. Kaste ◽

James P. DeLany ◽

...

Keyword(s):

Resistance Training ◽

Muscle Mass ◽

Dietary Protein ◽

Protein Intake ◽

Lymphoblastic Leukemia ◽

Cross Sectional Study ◽

Dietary Protein Intake ◽

Cross Sectional ◽

Childhood All ◽

Lean Muscle Mass

Abstract Background Survivors of childhood acute lymphoblastic leukemia (ALL) are at risk for low lean muscle mass and muscle weakness, which may contribute to inactivity and early development of chronic diseases typically seen in older adults. Although increasing protein intake, in combination with resistance training, improves lean muscle mass in other populations, it is not known whether muscular tissue among survivors of ALL, whose impairments are treatment-related, will respond similarly. Objective The aim of this study was to evaluate associations among dietary protein intake, resistance training, and lean muscle mass in survivors of ALL and age-, sex-, and race-matched controls. Design This was a cross-sectional study. Methods Lean muscle mass was determined with dual-energy x-ray absorptiometry, dietary information with 24-hour recalls, and participation in resistance training with a questionnaire. Participants were 365 survivors of ALL (52% male; 87% white; median age=28.5 years, range=23.6–31.7) and 365 controls with no previous cancer. Results Compared with controls, survivors of ALL had lower lean muscle mass (55.0 versus 57.2 kg, respectively) and lower percentage of lean muscle mass (68.6% versus 71.4%, respectively) than controls. Similar proportions of survivors (71.1%) and controls (69.7%) met recommended dietary protein intake (0.8 g/kg/d). Survivors (45.4%) were less likely to report resistance training than controls (53.8%). In adjusted models, 1-g higher protein intake per kilogram of body mass per day was associated with a 7.9% increase and resistance training ≥1×wk, with a 2.8% increase in lean muscle mass. Limitations The cross-sectional study design limits temporal evaluation of the association between protein intake and lean muscle mass. Conclusions The findings suggest that survivors of childhood ALL with low lean muscle mass may benefit from optimizing dietary protein intake in combination with resistance training. Research is needed to determine whether resistance training with protein supplementation improves lean muscle mass in survivors of childhood ALL.

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Glomerular uracil nucleotide synthesis: effects of diabetes and protein intake

AJP Renal Physiology ◽

10.1152/ajprenal.1988.255.4.f647 ◽

1988 ◽

Vol 255 (4) ◽

pp. F647-F655

Author(s):

P. Cortes ◽

F. Dumler ◽

D. L. Paielli ◽

N. W. Levin

Keyword(s):

Dietary Protein ◽

Protein Intake ◽

De Novo ◽

Plasma Concentrations ◽

Diabetic Glomerulosclerosis ◽

Nucleotide Synthesis ◽

Uracil Nucleotide ◽

Streptozotocin Induced Diabetes ◽

Protein Diets ◽

Control Sham

The biosynthesis of uridine 5'-triphosphate (UTP), uridine 5'-diphosphohexoses, and 5'-diphosphohexosamines (UDP-sugars) was studied in isolated rat glomeruli 48 h after streptozotocin-induced diabetes. Compared with control, diabetic glomeruli demonstrated an increase in the following: exogenous orotate utilization, orotate incorporation into UTP and UDP-sugars, UTP accretion rate, and UDP-sugar pool size. Since these phenomena were not associated with enhanced biosynthesis of orotate de novo, the increased glomerular UDP-sugar bioavailability in diabetes is due to enhanced utilization of exogenous orotate. Plasma concentrations of orotate and uridine were measured in control, sham operated, and unilaterally nephrectomized rats receiving 5, 20, or 60% protein diets. The concentration of pyrimidine precursors correlated directly with protein intake, with doubling at the 60% dietary protein level. In conclusion, glomerular uracil ribonucleotide biosynthesis may be modulated by the quantity of dietary protein. Because UDP-sugars are necessary for basement membrane material formation, an increase in their bioavailability may be part of the metabolic change responsible for diabetic glomerulosclerosis. Diets with high protein content could augment this metabolic alteration.

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Low Physical Activity in Patients with Complicated Type 2 Diabetes Mellitus Is Associated with Low Muscle Mass and Low Protein Intake

Journal of Clinical Medicine ◽

10.3390/jcm9103104 ◽

2020 ◽

Vol 9 (10) ◽

pp. 3104

Author(s):

Ilse J. M. Hagedoorn ◽

Niala den Braber ◽

Milou M. Oosterwijk ◽

Christina M. Gant ◽

Gerjan Navis ◽

...

Keyword(s):

Physical Activity ◽

Type 2 Diabetes ◽

Muscle Mass ◽

Dietary Protein ◽

Protein Intake ◽

Outcome Variable ◽

Dietary Protein Intake ◽

Cross Sectional ◽

Creatinine Excretion

Objective: In order to promote physical activity (PA) in patients with complicated type 2 diabetes, a better understanding of daily movement is required. We (1) objectively assessed PA in patients with type 2 diabetes, and (2) studied the association between muscle mass, dietary protein intake, and PA. Methods: We performed cross-sectional analyses in all patients included in the Diabetes and Lifestyle Cohort Twente (DIALECT) between November 2016 and November 2018. Patients were divided into four groups: <5000, 5000–6999, 7000–9999, ≥ 10,000 steps/day. We studied the association between muscle mass (24 h urinary creatinine excretion rate, CER) and protein intake (by Maroni formula), and the main outcome variable PA (steps/day, Fitbit Flex device) using multivariate linear regression analyses. Results: In the 217 included patients, the median steps/day were 6118 (4115–8638). Of these patients, 48 patients (22%) took 7000–9999 steps/day, 37 patients (17%) took ≥ 10,000 steps/day, and 78 patients (36%) took <5000 steps/day. Patients with <5000 steps/day had, in comparison to patients who took ≥10,000 steps/day, a higher body mass index (BMI) (33 ± 6 vs. 30 ± 5 kg/m2, p = 0.009), lower CER (11.7 ± 4.8 vs. 14.8 ± 3.8 mmol/24 h, p = 0.001), and lower protein intake (0.84 ± 0.29 vs. 1.08 ± 0.22 g/kg/day, p < 0.001). Both creatinine excretion (β = 0.26, p < 0.001) and dietary protein intake (β = 0.31, p < 0.001) were strongly associated with PA, which remained unchanged after adjustment for potential confounders. Conclusions: Prevalent insufficient protein intake and low muscle mass co-exist in obese patients with low physical activity. Dedicated intervention studies are needed to study the role of sufficient protein intake and physical activity in increasing or maintaining muscle mass in patients with type 2 diabetes.

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Considering Median Dietary Protein Intake Per Kg Body Weight of Representative Non-frail Elderlies in Establishing Protein Recommendation for Community-dwelling Elders? (P01-008-19)

Current Developments in Nutrition ◽

10.1093/cdn/nzz028.p01-008-19 ◽

2019 ◽

Vol 3 (Supplement_1) ◽

Author(s):

Wen-Harn Pan ◽

Szu-Yun Wu ◽

Naihua Yeh

Keyword(s):

Body Weight ◽

Muscle Mass ◽

Dietary Protein ◽

Protein Intake ◽

Age Groups ◽

Community Dwelling ◽

Acid Oxidation ◽

Adequate Intake ◽

Protein Requirement ◽

And Performance

Abstract Objectives Indicator of Amino Acid Oxidation (IAAO) method is a state-of-art method to determine protein requirement. A recent review summarized the estimated average requirement (EAR) derived from IAAO plus two standard deviations as around 1.15–1.29 g/Kg body weight (BW) for elderlies. However, emerging evidence shows that providing protein beyond nitrogen balance point (as high as 1.5 g/Kg BW) to frail or pre-frail elderlies seems to provide additional benefit on muscle mass and performance, compared to 1.2 g/Kg BW. It is not clear whether community-dwelling elders require higher than 1.2–1.3 g/Kg BW to maintain adequate muscle mass and quality. This study intends to derive dietary protein Adequate Intake (AI) from a group of representative community-dwelling non-frail elderlies in Taiwan. Methods Using the 24-hour recall data of 1430 elderly adults (65y) from the Nutrition and Health Survey in Taiwan, 2014–2016, protein intake by age groups (65–69; 70–79; 80+) and by frailty levels (robust; pre-frail; frail) in both genders was estimated. Frailty phenotypes were determined using Linda Fried criteria. SUDAAN was used for statistical analysis. Results Mean levels of protein intake were 1.2, 1.4, and 1.3 g per Kg body weight (BW) per day (d) for men aged 65–69, 70–79, and 80+; and 1.2, 1.3, and 0.9 g/Kg BW/d for women at the same age groups. The mean protein intakes were 1.4, 1.3, and 1.2 g/kg BW/d for elderly men at robust, pre-frail, and frail states, respectively; and they were 1.3, 1.2, and 1.0 for women. The median were 1.3, 1.2, and 1.1 for men and 1.3, 1.1, and 1.1 for women. Conclusions Adequate intake of the community-dwelling elderly Taiwanese men and women is estimated around 1.3 g/Kg BW/d, taking into consideration the frailty issue. This information may be considered complementary to IAAO data in establishing protein requirement. Funding Sources Health Promotion Agency; International Life Science Institutes; Academia Sinica.

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