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

Effect of protein and amino acids supplements on muscle strength and physical performance: A scoping review of randomized controlled trials

Protein and amino acid supplementation is an effective intervention that significantly enhances physical function and reduces frailty and sarcopenia in older adults. This scoping review aims to map and synthesize the available evidence on the effects of various types of protein and amino acid supplementation in this population. Following the PRISMA-ScR guidelines, we conducted a literature search to identify clinical trials examining the effects of protein and amino acid supplementation, with or without physical exercise, on muscle strength, physical performance, and body composition in healthy, frail, or sarcopenic older adults. Our analysis of 80 trials with a total of 5290 participants examines the evidence for the effectiveness of protein supplementation in enhancing muscle strength and body composition. Whey protein, creatine, milk protein, leucine, essential amino acids, and soy protein were the most used types of protein, and our findings indicate that whey protein, creatine, and milk protein yield the best results when used in conjunction with resistance training. Additionally, leucine and milk protein have shown the potential to enhance body composition even without concurrent resistance training. In conclusion, studies on the effectiveness of whey protein in improving muscle strength and body composition in older adults with resistance training are inconsistent. More research is required to explore the potential benefits of soy and leucine-enriched supplements. Protein supplementation's impact on physical performance remains inconclusive. Further studies are needed to determine the effects of protein types and supplementation on muscle-related parameters in older adults.

The Effect of Protein Intake on Bone Disease, Kidney Disease, and Sarcopenia: A Systematic Review

Background

Protein is essential for optimal growth, function, and maintenance of health. Its impact on bone, kidney health, and sarcopenia progression remains debated.

Objectives

This review examines the association between dietary protein intake and the risk of bone disease, kidney disease, and sarcopenia to inform protein dietary reference intake updates.

Methods

We searched Medline, EMBASE, AGRICOLA, and Scopus from January 2000 to May 2024, supplemented by citation searching for relevant reviews and original research. We included randomized and nonrandomized controlled trials, prospective cohort studies, and nested case-control studies examining dietary protein intake without exercise. We assessed the risk of bias (RoB), performed a qualitative synthesis of low to moderate RoB studies, and evaluated the strength of evidence.

Results

Of 82 articles detailing 81 unique studies, only 13 were assessed with low to moderate RoB and synthesized, comprising bone disease [4 randomized controlled trials (RCTs) and 1 prospective cohort study], kidney disease (1 RCT), and sarcopenia (9 RCTs). The overarching evidence was insufficient, largely due to the limited number of low to moderate RoB studies, the diversity of dietary protein interventions, and the broad range of outcomes, which complicated synthesis and comparison. Notably, sparse literature addressed children and adolescents, and only a single study each examined the impact of dietary protein intake on bone disease risk (yielding mixed findings) in these populations and on kidney disease risk (showing no significant effects) in adults. The findings on the impact of protein intake on bone disease in adults and sarcopenia risk were mixed; some studies showed no effect, whereas others indicated benefits.

Conclusions

The evidence since 2000 on associations between dietary protein intake and the risks of bone disease, kidney disease, and sarcopenia is unclear, indicating a need for more rigorous research.This trial was registered at PROSPERO as CRD42023446621.

Effect of high plant protein/peptide nutrition supplementation on knee osteoarthritis in older adults with sarcopenia: A randomized, double-blind, placebo-controlled trial

BACKGROUND & AIMS

Skeletal muscle is an important contributor to joint health. Previous studies have shown that age-related muscle mass and strength loss are closely associated with the development of knee osteoarthritis. The objective of this study is to investigate whether a high plant protein/peptide nutrition supplementation can alleviate knee osteoarthritis by improving muscle mass and strength.

METHODS

This randomized, double-blind, placebo-controlled trial that included participants aged 50-70 years diagnosed with knee osteoarthritis and sarcopenia was conducted in China from February 2022 to September 2022 (ChiCTR2200056415). Participants were randomly assigned to receive either a 12-week high plant protein/peptide nutrition supplementation or a placebo twice daily, with one serving each after breakfast and dinner, respectively. The primary outcome analyzed using intention-to-treat analysis was difference in Short Physical Performance Battery (SPPB) from baseline to week 12 between the two groups. The secondary outcomes included changes in muscle mass, strength, symptom and imaging of knee osteoarthritis, body composition, biochemical parameters, and health quality scores.

RESULTS

After 12 weeks, a total of 124 participants (38.7% male) completed the trial and were included in the final analysis. Over the 12-week follow-up, the experimental group showed a significant improvement in the SPPB total score (1.03, 95% CI, 0.69 to 1.38, P < 0.0001) compared with the placebo group. Grip strength (2.83 kg, 95% CI, 2.13 to 3.53, P < 0.0001) and skeletal muscle mass index (0.66 kg/m2, 95% CI, 0.45 to 0.86, P < 0.0001) were also significantly increased in the experimental group relative to the placebo group. The mean change in Western Ontario and McMaster Universities Osteoarthritis Index total score was -3.95 points (95% CI, -5.02 to -2.89, P < 0.0001) in the experimental group and 0.23 points (95% CI, -0.17 to 0.63, P = 0.253) in the placebo group. Additionally, within the experimental group, nine participants experienced an improvement in osteophyte magnetic resonance imaging results, while no improvement was observed in the placebo group. The experimental group also exhibited significant improvements in health quality compared with the placebo group as assessed by Short Form 36, the World Health Organization Quality of Life Brief Scale, and the Chalder Fatigue Scale. No serious adverse events were reported during the trial.

CONCLUSION

Oral supplementation with high levels of plant protein/peptides can alleviate symptoms of osteoarthritis in elderly individuals with minor or mild knee osteoarthritis and sarcopenia. This improvement may be attributed to the enhancements of muscle mass, strength, and physical performance.

Association of dietary protein intake, inflammation with muscle mass, physical performance and incident sarcopenia in Chinese community-dwelling older adults

OBJECTIVES

Inflammation and impaired muscle synthesis are important factors of sarcopenia. Plant protein may reduce inflammation but may not be as efficient as animal protein in providing essential amino acids. We therefore examined the associations between dietary protein intake and changes in muscle mass and physical performance, incident sarcopenia, and the interaction effect of inflammation.

DESIGN

Prospective cohort study.

SETTING

The Mr. OS and Ms. OS (Hong Kong) cohort.

PARTICIPANTS

A total of 2,811 sarcopenia-free participants and 569 sarcopenia participants aged ≥65 years were recruited from communities.

MEASUREMENTS

Dietary protein intake was assessed using a validated food frequency questionnaire. Serum high-sensitivity C-reactive protein (hs-CRP) was measured. Linear regression examined the associations between dietary protein intake and 4-year changes in muscle mass and physical performance. Cox regression examined the association between dietary protein intake and incident sarcopenia.

RESULTS

Higher plant protein intake, but not total and animal protein, was associated with less decline in muscle mass and gait speed among sarcopenia-free participants. Conversely, higher ratio of animal-to-plant protein was associated with reduced muscle mass loss among participants with sarcopenia. The highest tertile of plant protein intake was associated with lower incident sarcopenia risk (HR: 0.75, 95% CI: 0.57-0.98; P-trend = 0.034) compared to the lowest tertile. Notably, this association was observed among participants with higher serum hs-CRP levels (HR: 0.57, 95% CI: 0.34-0.95), but not in those with lower hs-CRP levels.

CONCLUSION

Dietary animal and plant protein intake have differential associations with muscle mass and physical performance in older adults with and without sarcopenia. The role of plant protein in preventing sarcopenia involves modulation of inflammation.

Dietary protein intake in midlife in relation to healthy aging - results from the prospective Nurses' Health Study cohort

BACKGROUND

Protein intake plays an important role in maintaining the health status of older adults. However, few epidemiologic studies examined midlife protein intake in relation to healthy aging.

OBJECTIVES

The objective of this study was to evaluate the long-term role of dietary protein intake in healthy aging among female participants in the prospective Nurses' Health Study (NHS) cohort.

METHODS

We included 48,762 NHS participants aged <60 y in 1984. Total protein, animal protein, dairy protein (a subset of animal protein), and plant protein were derived from validated food frequency questionnaires. Healthy aging was defined as being free from 11 major chronic diseases, having good mental health, and not having impairments in either cognitive or physical function, as assessed in the 2014 or 2016 NHS participant questionnaires. We used multivariate logistic regression adjusted for lifestyle, demographics, and health status to estimate the odds ratios (ORs) and 95% confidence intervals for protein intake in relation to healthy aging.

RESULTS

A total of 3721 (7.6%) NHS participants met our healthy aging definition. Protein intake was significantly associated with higher odds of healthy aging. The ORs (95% confidence intervals) per 3%-energy increment with healthy aging were 1.05 (1.01, 1.10) for total protein, 1.07 (1.02, 1.11) for animal protein, 1.14 (1.06, 1.23) for dairy protein, and 1.38 (1.24, 1.54) for plant protein. Plant protein was also associated with higher odds of absence of physical function limitations and good mental status. In substitution analyses, we observed significant positive associations for the isocaloric replacement of animal or dairy protein, carbohydrate, or fat with plant protein (ORs for healthy aging: 1.22-1.58 for 3% energy replacement with plant protein).

CONCLUSIONS

Dietary protein intake, especially plant protein, in midlife, is associated with higher odds of healthy aging and with several domains of positive health status in a large cohort of female nurses.

The Association of Isocaloric Substitution of Dietary Protein in Middle Age with Muscle Mass and Strength in Old Age: The Hordaland Health Study

Background

Age-associated loss of muscle mass and strength is an important predictor of disability in older persons. Although several mechanisms contribute to the decline in muscle mass and function seen with aging, the process is thought to be accelerated by an inadequate protein intake. However, the optimal amount and source of protein and the role of dietary protein intake over the life course remain uncertain.

Objectives

In a sample of community-dwelling adults in Western Norway, the current study examined both cross-sectional and longitudinal associations over 20 y of dietary protein intake with appendicular skeletal muscle mass (ASMM) and muscle strength measured by handgrip strength (HGS) in older age.

Methods

Dietary intake was assessed using food frequency questionnaires (FFQs) in middle age (46-49 y) and older age (67-70 y) within the community-based Hordaland Health Study.

Results

Adjusted, multivariate linear regression analyses revealed a negative cross-sectional association between the substitution of total protein (TP) and animal protein (AP), with fat and carbohydrates, on ASMM in women but not in men. No longitudinal associations were found between substitution of dietary protein intake and ASMM in either sex in adjusted models. Similarly, no cross-sectional or longitudinal associations were evident between substitution of dietary protein intake and HGS in either sex in adjusted models.

Conclusion

The findings in the current study highlight the need to clarify the role of dietary protein intake in the maintenance of muscle mass and muscle strength in healthy older adults.

Dietary protein intake and changes in muscle mass measurements in community-dwelling middle-aged and older adults: A prospective cohort study

BACKGROUND & AIMS

Increasing dietary protein intake can be an efficient strategy to prevent sarcopenia. Nevertheless, due to the discrepancy in the population and their dietary pattern, evidence suggested the effects of dietary protein amount or source on sarcopenia prevention varies. This prospective cohort study investigated the correlation between dietary protein intakes or sources and changes in muscle mass measurements. Additionally, the study explored the link between dietary protein and the prevalence of sarcopenia.

METHODS

Participants aged 40 to 75 were from Guangzhou Nutrition and Health Study (GNHS) 2011-2013 and returned in 2014-2017. Validated 79-item food frequency questionnaires were applied to calculate the amount of total, animal, and plant protein intakes and animal-to-plant protein ratio (APR). The body composition was examined by dual-energy x-ray absorptiometry (DXA) to calculate the appendicular lean mass (ALM) and its index (ASMI). Sarcopenia was diagnosed based on the 2019 Asia Working Group of Sarcopenia's criteria. ANCOVA was utilized to compare the differences of Δ ALM and Δ ASMI across the quartiles of the dietary protein, and linear regression was employed to examine dose-response associations. Multilinear mixed-effect models were employed to evaluate whether protein intake relates to annual changes in ALM and ASMI. Multivariable logistic regressions were performed to analyze the associations between dietary protein and sarcopenia.

RESULTS

In total, 2709 participants during the 3.2-year follow-up period were considered eligible for analysis. Higher dietary protein intakes (total, animal, plant) in both sexes could preserve more ALM and ASMI in a dose-response manner (all P-trend < 0.05). The annual estimated preservations of ASMI were greater in the highest dietary protein intakes (total, animal, plant) quartile than the lowest (0.05-0.13 kg/m2/y, all P < 0.05). In women, the risk of sarcopenia was reduced by 35%-50 % in the highest protein intake (total, animal, plant) quartile than the lowest. The APR did not display any significant associations.

CONCLUSIONS

Higher dietary protein intake, regardless of animal or plant sources, is associated with less muscle loss and a lower prevalence of sarcopenia in middle-aged and older Chinese, particularly women.

CLINICALTRIALS

GOV IDENTIFIER

NCT03179657.

Association between plant protein intake and grip strength in Koreans aged 50 years or older: Korea National Health and Nutrition Examination Survey 2016-2018

BACKGROUND/OBJECTIVES

We investigated the association of plant and animal protein intake with grip strength in Koreans aged ≥ 50 yrs.

SUBJECTS/METHODS

The data was collected from 3,610 men and 4,691 women (≥ 50 yrs) from the 2016-2018 Korea National Health and Nutrition Examination Survey. We calculated the total energy intake, and the intake of animal and plant protein and collected dietary data using 1-day 24-h dietary recalls. Low grip strength (LGS) was defined as the lowest quintile (men: up to 26.8 kg, women: up to 15.7 kg). The association of protein intake with grip strength was examined using Pearson's correlation and multiple linear regression analysis.

RESULTS

The results proved that participants with LGS had lower daily energy, protein and fat intake, and percent energy from protein than those with normal or high grip strength (P < 0.0001). Total energy intake, animal protein, and plant protein were positively associated with grip strength. A higher intake of total plant protein (P for trend = 0.004 for men, 0.05 for women) and legumes, nuts, and seeds (LNS) protein (P for trend = 0.01 for men, 0.02 for women) was significantly associated with a lower prevalence of LGS. However, non-LNS plant protein intake was not associated with LGS (P for trend = 0.10 for men, 0.15 for women). In women, a higher total animal protein intake was significantly associated with decreased LGS (P for trend = 0.03).

CONCLUSIONS

Higher total plant protein and LNS protein intake are negatively associated with LGS.

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.

Relationship between protein intake and grip strength in qualitative and quantitative aspects among the elderly in Korea: results from the Korea National Health and Nutrition Examination Survey

BACKGROUND

This study investigated the association between quantitative and qualitative protein intake and grip strength (GS) in the South Korean population to explore nutritional management for the prevention of sarcopenia.

METHODS

This cross-sectional study was based on data from a nationally representative sample of the South Korean elderly population, consisting of 1,531 men and 1,983 women aged 65 years and older who participated in the Korean National Health and Nutrition Examination Survey from 2016 to 2019. Low GS was defined as GS < 28 kg in men and GS < 18 kg in women. Protein intake was assessed using 1-day 24-h recall, and we analyzed absolute protein intake, protein intake by food source, and protein intake compared to dietary reference intake with per body weight or absolute daily recommended value.

RESULTS

The total and animal protein intake and protein intake from legumes, fish and shellfish were significantly lower in women with a low GS than in those with a normal GS. After adjusting for confounding factors, women who consumed more protein than the estimated average requirement (EAR, 40 g/day for women) were 0.528 times less likely to have low GS than women consuming less protein than the EAR (95% CI: 0.373-0.749), and consuming any amount of protein from legumes were 0.656 times less likely (95% CI: 0.500-0.860) to have low GS than women who did not consume any amount of legume protein.

CONCLUSIONS

This study provides epidemiological evidence that adequate protein intake above EAR and protein intake from legumes should be guided for preventing low GS, especially in elderly women.

HOMEFOOD randomized trial-beneficial effects of 6-month nutrition therapy on body weight and physical function in older adults at risk for malnutrition after hospital discharge

BACKGROUND/OBJECTIVES

Malnutrition is common among older adults. Dietary intervention studies in older adults aiming to improve anthropometrics measures and physical function have been inconsistent. We aimed to investigate the effects of nutrition therapy in combination with home delivered meals and oral nutritional supplements (ONS) in community-dwelling older adults discharged from hospital.

METHODS

A total of 106 participants (>65 years) were randomized into the intervention group (n = 53) and into the control group (n = 53). The intervention group received individual nutrition therapy (five in person visits and three phone calls) and freely delivered energy- and protein- rich foods, while the control group received standard care. Dietary intake, anthropometrics, and short physical performance battery (SPPB) were assessed at baseline and at endpoint.

RESULTS

Energy intake at baseline was similar in both groups (~1500 kcal at the hospital) but there was a significant increase in energy intake and body weight in the intervention group (+919 kcal/day and 1.7 kg, P < 0.001 in both cases) during the study period, compared to a significant decrease in both measures among controls (-815 kcal/day and -3.5 kg, P < 0.001 in both cases). SPPB score increased significantly in the intervention group while no changes were observed among controls.

CONCLUSIONS

Most Icelandic older adults experience substantial weight loss after hospital discharge when receiving current standard care. However, a 6-month multi-component nutrition therapy, provided by a clinical nutritionist in combination with freely delivered supplemental energy- and protein-dense foods has beneficial effects on body weight, physical function, and nutritional status.

STUDY REGISTRATION

This study was registered at ClinicalTrials.gov ( NCT03995303 ).

Assessing the Effects of Dietary Protein Supplementation on Sarcopenia in Community-Dwelling Older Adults

Sarcopenia, an age-associated skeletal muscle disorder characterized by muscle loss, is associated with disability in elderly populations. This literature review summarizes the impact of protein intake and supplementation on the indicators of severe sarcopenia-muscle mass, muscle strength, and physical function in community-dwelling older adults. We performed a literature search on PubMed, EMBASE, and MedLine, and included studies that evaluated the effects of protein intake with or without exercise intervention and on sarcopenia in community-dwelling older adults. Information regarding study participants, protein intervention, and sarcopenia-related outcomes were collected. Protein supplementation with or without exercise positively improves muscle mass, and aspects of muscle strength and physical function in sarcopenic and pre-frail older adults, while it elicited inconclusive effects in healthy populations. Greater dietary animal-based and soy-based protein diets can improve muscle mass in older adults. In conclusion, protein supplementation can improve muscle mass and reduce the risk of sarcopenia in sarcopenia and pre-frail older adults, while future studies should continue to investigate the effects of protein supplementation on indicators of sarcopenia in healthy older adults.

Protein intake and physical function in older adults: A systematic review and meta-analysis

BACKGROUND

The present study explored cross-sectional and longitudinal associations between protein intake and physical function in older adults.

METHODS

We conducted a systematic review and meta-analysis of cross-sectional and longitudinal studies that investigated the association between protein intake and measures of physical function in older adults. Cross-sectional, case-control, and longitudinal cohort studies that investigated the association between protein intake and physical function as a primary or secondary outcome in people aged 60 + years were included. Studies published in languages other than English, Italian, Portuguese, or Spanish were excluded. Studies were retrieved from MEDLINE, SCOPUS, EMBASE, CINAHL, AgeLine, and Food Science Source databases through January 31, 2022. A pooled effect size was calculated based on standard mean differences (SMD), MD, log odds ratio (OR) and Z-score..

RESULTS

Twenty-two cross-sectional studies examined a total of 11,332 community-dwellers, hospitalized older adults, and elite senior athletes with a mean age of approximately 75 years. The pooled analysis indicated that a protein intake higher than the recommended dietary allowance (RDA) was significantly associated with higher Short Physical Performance Battery (SPPB) scores (SMD: 0.63, 95% CI: 0.27, 0.99, P-value: 0.0006), faster walking speed, greater lower-limb (SMD: 0.22, 95% CI: 0.04, 0.40, P-value: 0.02) and isometric handgrip strength (Z-score: 0.087, 95% CI: 0.046-0.128, P-value: 0.0001), and better balance (SMD: 0.33, 95% CI: 0.05, 0.62, P-value: 0.02). Nine longitudinal studies investigated 12,424 community-dwelling and native older adults with a mean age of approximately 85 years. A protein intake higher than the current RDA was not associated with lower decline in either isometric handgrip strength (logOR: 0.99, 95% CI: 0.97-1.02, P-value= 0.67) or walking speed (logOR: 0.92, 95% CI: 0.77-1.10, P-value= 0.35).

CONCLUSIONS

A protein intake higher than the RDA is cross-sectionally associated with better physical performance and greater muscle strength in older adults. However, a high consumption of proteins does not seem to prevent physical function decline over time.

Association of Plant Protein Intake with Change in Physical Performance in Chinese Community-Dwelling Older Adults

(1) Background: Dietary protein intake might be beneficial in optimizing physical performance, yet whether this is dependent on protein source and sex is unclear. We examined the association between dietary protein intake and change in physical performance among Chinese community-dwelling older adults. (2) Methods: This prospective study included older Chinese adults (≥65 years) in Hong Kong. Total, plant and animal protein intakes at baseline were assessed using a food frequency questionnaire. Physical performance at baseline and 4-year follow-up were assessed by the time to complete a 6-m walking test. Adjusted linear regression examined the association between total, plant and animal protein intakes (g/kg of body weight (BW)) and 4-year change in physical performance. (3) Results: 3133 participants (49.8% males) aged 71.8 ± 4.9 years were included. In males, total, plant and animal protein intakes were not associated with a change in physical performance. In females, higher plant protein intake was associated with less decline in physical performance (β 0.723, SE 0.288, p = 0.012). No associations were observed for total animal protein intakes. (4) Conclusion: In Chinese community-dwelling older adults, total and animal protein intakes were not associated with a 4-year change in physical performance. Higher plant protein intake was associated with less decline in physical performance in females.

Animal foods and mobility limitations in community-dwelling young-old adults: longitudinal analysis of the EpiDoC cohort

Background

Nutrition and particularly protein play a role in optimally stimulating muscle protein synthesis and maintaining function. Animal foods are excellent sources of high-quality protein. Therefore, we aimed to determine the association between the consumption of animal foods and mobility limitations in young-old adults.

Methods

The analytic sample was composed of 2860 community-dwelling adults aged 50 and over from a nationally representative longitudinal cohort of Portuguese adults who were followed up to 2.7 years. An animal food intake score was derived from the frequency of consumption of meat, fish, and dairy products. Mobility limitations were defined as the difficulty standing up from a chair, walking, and climbing stairs. To determine the association between animal food intake and mobility limitations mixed effects logistic models were fitted.

Results

Associations between quartiles of animal food intake and mobility limitations (for example, for walking outdoors Quartile 4 v Q1: OR: 0.29; 95%CI: 0.15, 0.56) in unadjusted models were present, but there was no difference in the rate of change of mobility limitations over time in unadjusted models. These associations were no longer present when models were adjusted for sociodemographic, lifestyle and health variables. For example, participants in Q4 of animal food intake were not more or less likely to have difficulty climbing stairs than those in Q1 (OR: 0.95; 95%CI: 0.65, 1.38) nor have a different rate of change over time (OR: 0.86; 95%CI: 0.54, 1.37).

Conclusions

No convincing evidence was found to support an effect of animal foods intake measured at baseline on self-reported mobility limitations over a short period of time.

The Isocaloric Substitution of Plant-Based and Animal-Based Protein in Relation to Aging-Related Health Outcomes: A Systematic Review

Plant-based and animal-based protein intake have differential effects on various aging-related health outcomes, but less is known about the health effect of isocaloric substitution of plant-based and animal-based protein. This systematic review summarized current evidence of the isocaloric substitutional effect of plant-based and animal-based protein on aging-related health outcomes. PubMed and Embase databases were searched for epidemiologic observational studies published in English up to 15 March 2021. Studies that included adults ≥18 years old; use of a nutritional substitution model to define isocaloric substitution of plant protein and animal protein; health outcomes covering mortality, aging-related diseases or indices; and reported association estimates with corresponding 95% confidence intervals were included. Nine cohort studies and 3 cross-sectional studies were identified, with a total of 1,450,178 subjects included in this review. Consistent and significant inverse association of substituting plant protein for various animal proteins on all-cause mortality was observed among 4 out of 5 studies with relative risks (RRs) from 0.54 to 0.95 and on cardiovascular disease (CVD) mortality among all 4 studies with RRs from 0.58 to 0.91. Among specific animal proteins, the strongest inverse association on all-cause and CVD mortality was identified when substituting plant protein for red and/or processed meat protein, with the effect mainly limited to bread, cereal, and pasta protein when replacing red meat protein. Isocaloric substitution of plant-based protein for animal-based protein might prevent all-cause and CVD-specific mortality. More studies are needed on this topic, particularly for cancer incidence and other specific aging-related diseases.

Association of dietary protein intake with skeletal muscle mass in older adults: A systematic review

Protein supplementation has been shown to be effective in attenuating the loss of lean body mass and muscle mass in older adults; however, its benefits as dietary protein remain unclear. This systematic review of observational studies aimed to investigate the association of dietary protein intake with skeletal muscle mass (SM). Observational studies that investigated the association of dietary protein intake with SM in older adults were retrieved from MEDLINE, Web of Science and Cochrane-CENTRAL databases. Of the 26 analyses in the 17 studies, 18 showed a significant positive association. In cohort studies, 55.6% (five of nine analyses) showed a significant positive association. Of these, four analyses were adjusted for well-known confounding factors, used energy-adjusted protein intake, and used the amount of change of SM between baseline and follow-up as the outcome, with two of them showing a significant positive association. Although 69.2% (18 of 26 analyses) of the 17 studies showed a significant positive association between dietary protein intake and SM in older adults, most studies were cross-sectional and had at least one important methodological limitation. Therefore, we could not draw any conclusions. Thus, well-designed cohort studies are needed in future to identify the association between dietary protein intake and SM in older adults. Geriatr Gerontol Int 2021; 21: 1077-1083.

Low protein intake, physical activity, and physical function in European and North American community-dwelling older adults: a pooled analysis of four longitudinal aging cohorts

BACKGROUND

Dietary protein may slow the decline in muscle mass and function with aging, making it a sensible candidate to prevent or modulate disability progression. At present, studies providing reliable estimates of the association between protein intake and physical function, and its interaction with physical activity (PA), in community-dwelling older adults are lacking.

OBJECTIVES

We investigated the longitudinal relation between protein intake and physical function, and the interaction with PA.

METHODS

We undertook a pooled analysis of individual participant data from cohorts in the PROMISS (PRevention Of Malnutrition In Senior Subjects in the European Union) consortium (the Health Aging and Body Composition Study, Quebec Longitudinal Study on Nutrition and Successful Aging, Longitudinal Aging Study Amsterdam, and Newcastle 85+) in which 5725 community-dwelling older adults were followed up to 8.5 y. The relation between protein intake and walking speed was determined using joint models (linear mixed-effects and Cox proportional hazards models) and the relation with mobility limitation was investigated using multistate models.

RESULTS

Higher protein intake was modestly protective of decline in walking speed in a dose-dependent manner [e.g., protein intake ≥1.2 compared with 0.8 g/kg adjusted body weight (aBW)/d: β = 0.024, 95% CI: 0.009, 0.032 SD/y], with no clear indication of interaction with PA. Participants with protein intake ≥0.8 g/kg aBW/d had also a lower likelihood of incident mobility limitation, which was observed for each level of PA. This association seemed to be dose-dependent for difficulty walking but not for difficulty climbing stairs. No associations between protein intake and other mobility limitations transitions were observed.

CONCLUSIONS

Higher daily protein intake can reduce physical function decline not only in older adults with protein intake below the current RDA of 0.8 g/kg BW/d, but also in those with a protein intake that is already considered sufficient. This dose-dependent association was observed for each level of PA, suggesting no clear synergistic association between protein intake and PA in relation to physical function.

Association between dietary protein intake and skeletal muscle mass in older Korean adults

PURPOSE

We investigated the association of low and high daily protein intakes on skeletal muscle mass status in Korean adults aged 60 years and older.

METHODS

This cross-sectional study used data from the Korean National Health and Nutrition Examination Survey conducted between 2008 and 2011. The participants' dietary protein intake was assessed using the 24-h dietary recall method and was classified as low (< 0.8 g/kg body weight/day), moderate (0.8-1.2 g/kg/day), and high (> 1.2 g/kg/day). Amount of skeletal muscle mass was measured using whole-body dual-energy X-ray absorptiometry. Low skeletal muscle mass was defined as appendicular skeletal muscle mass index < 7.0 kg/m² in men and < 5.4 kg/m² in women.

RESULTS

The study included data from 4585 participants (2022 men and 2563 women). All skeletal muscle parameters in women and total lean mass in men decreased as the amount of protein consumed daily increased. However, there was no association between high or low protein intake and low skeletal muscle mass in men or women.

CONCLUSIONS

No association was found between the amount of daily protein intake and skeletal muscle mass status in older Korean adults. Gender-specific further studies focussing on the interactions of dietary protein intake under specific conditions including physical activity status and the daily distribution of protein intake and the quality and source of the protein are needed to evaluate the impact of protein intake status on muscle health in older Koreans.

Protein Source and Muscle Health in Older Adults: A Literature Review

Research shows that higher dietary protein of up to 1.2 g/kg_bodyweight/day may help prevent sarcopenia and maintain musculoskeletal health in older individuals. Achieving higher daily dietary protein levels is challenging, particularly for older adults with declining appetites and underlying health conditions. The negative impact of these limitations on aging muscle may be circumvented through the consumption of high-quality sources of protein and/or supplementation. Currently, there is a debate regarding whether source of protein differentially affects musculoskeletal health in older adults. Whey and soy protein have been used as the most common high-quality proteins in recent literature. However, there is growing consumer demand for additional plant-sourced dietary protein options. For example, pea protein is rapidly gaining popularity among consumers, despite little to no research regarding its long-term impact on muscle health. Therefore, the objectives of this review are to: (1) review current literature from the past decade evaluating whether specific source(s) of dietary protein provide maximum benefit to muscle health in older adults; and (2) highlight the need for future research specific to underrepresented plant protein sources, such as pea protein, to then provide clearer messaging surrounding plant-sourced versus animal-sourced protein and their effects on the aging musculoskeletal system.

Dietary Protein Intake in Older Adults from Ethnic Minorities in the Netherlands, a Mixed Methods Approach

Optimizing protein intake is a novel strategy to prevent age associated loss of muscle mass and strength in older adults. Such a strategy is still missing for older adults from ethnic minority populations. Protein intake in these populations is expected to be different in comparison to the majority of the population due to several socio-cultural factors. Therefore, the present study examined the dietary protein intake and underlying behavioral and environmental factors affecting protein intake among older adults from ethnic minorities in the Netherlands. We analyzed frequency questionnaire (FFQ) data from the Healthy Life in an Urban Setting (HELIUS) cohort using ANCOVA to describe dietary protein intake in older adults from ethnic minorities in the Netherlands (N = 1415, aged >55 years, African Surinamese, South Asian Surinamese, Moroccan, and Turkish). Additionally, we performed focus groups among older adults from the same ethnic minority populations (N = 69) to discover behavioral and environmental factors affecting protein intake; 40-60% of the subjects did not reach minimal dietary protein recommendations needed to maintain muscle mass (1.0 g/kg bodyweight per day (BW/day)), except for Turkish men (where it was 91%). The major sources of protein originated from animal products and were ethnic specific. Participants in the focus groups showed little knowledge and awareness about protein and its role in aging. The amount of dietary protein and irregular eating patterns seemed to be the major concern in these populations. Optimizing protein intake in these groups requires a culturally sensitive approach, which accounts for specific protein product types and sociocultural factors.

The Association between Dietary Variety and Physical Frailty in Community-Dwelling Older Adults

The aim of this cross-sectional study was to examine the association between diet variety and physical frailty in community-dwelling older adults. Data of 577 older adults (mean age: 74.0 ± 6.3 years, women: 62.5%) were analyzed. Diet variety was assessed using the Food Frequency Score (FFS) (maximum, 30 points). The FFS assessed the one-week consumption frequency of ten foods (meat, fish/shellfish, eggs, milk & dairy products, soybean products, green & yellow vegetables, potatoes, fruits, seafood, and fats & oil). Physical frailty was assessed using Fried's component (slowness, weakness, exhaustion, low physical activity, and weight loss). The participants were classified into frail, pre-frail, and non-frail groups. The prevalence of physical frailty was 6.6%. This study found significant associations between physical frailty and low FFS after adjusting for covariates (odds ratio (OR) 0.90, 95% confidence interval (CI) 0.84-0.97, p < 0.01). The optimal cutoff point of the FFS for physical frailty was ≤16 points. FFS lower than the cutoff point were significantly associated with physical frailty after adjusting for covariates (OR 3.46, 95% CI 1.60-7.50, p < 0.01). Diet variety assessed using the FFS cutoff value of ≤16 points was related to the physical frailty status in community-dwelling older adults.

Low Protein Diets and Plant-Based Low Protein Diets: Do They Meet Protein Requirements of Patients with Chronic Kidney Disease?

A low protein diet (LPD) has historically been used to delay uremic symptoms and decrease nitrogen (N)-derived catabolic products in patients with chronic kidney disease (CKD). In recent years it has become evident that nutritional intervention is a necessary approach to prevent wasting and reduce CKD complications and disease progression. While a 0.6 g/kg, high biological value protein-based LPD has been used for years, recent observational studies suggest that plant-derived LPDs are a better approach to nutritional treatment of CKD. However, plant proteins are less anabolic than animal proteins and amino acids contained in plant proteins may be in part oxidized; thus, they may not completely be used for protein synthesis. In this review, we evaluate the role of LPDs and plant-based LPDs on maintaining skeletal muscle mass in patients with CKD and examine different nutritional approaches for improving the anabolic properties of plant proteins when used in protein-restricted diets.

A research agenda for ageing in China in the 21st century (2nd edition): Focusing on basic and translational research, long-term care, policy and social networks

One of the key issues facing public healthcare is the global trend of an increasingly ageing society which continues to present policy makers and caregivers with formidable healthcare and socio-economic challenges. Ageing is the primary contributor to a broad spectrum of chronic disorders all associated with a lower quality of life in the elderly. In 2019, the Chinese population constituted 18 % of the world population, with 164.5 million Chinese citizens aged 65 and above (65+), and 26 million aged 80 or above (80+). China has become an ageing society, and as it continues to age it will continue to exacerbate the burden borne by current family and public healthcare systems. Major healthcare challenges involved with caring for the elderly in China include the management of chronic non-communicable diseases (CNCDs), physical frailty, neurodegenerative diseases, cardiovascular diseases, with emerging challenges such as providing sufficient dental care, combating the rising prevalence of sexually transmitted diseases among nursing home communities, providing support for increased incidences of immune diseases, and the growing necessity to provide palliative care for the elderly. At the governmental level, it is necessary to make long-term strategic plans to respond to the pressures of an ageing society, especially to establish a nationwide, affordable, annual health check system to facilitate early diagnosis and provide access to affordable treatments. China has begun work on several activities to address these issues including the recent completion of the of the Ten-year Health-Care Reform project, the implementation of the Healthy China 2030 Action Plan, and the opening of the National Clinical Research Center for Geriatric Disorders. There are also societal challenges, namely the shift from an extended family system in which the younger provide home care for their elderly family members, to the current trend in which young people are increasingly migrating towards major cities for work, increasing reliance on nursing homes to compensate, especially following the outcomes of the 'one child policy' and the 'empty-nest elderly' phenomenon. At the individual level, it is important to provide avenues for people to seek and improve their own knowledge of health and disease, to encourage them to seek medical check-ups to prevent/manage illness, and to find ways to promote modifiable health-related behaviors (social activity, exercise, healthy diets, reasonable diet supplements) to enable healthier, happier, longer, and more productive lives in the elderly. Finally, at the technological or treatment level, there is a focus on modern technologies to counteract the negative effects of ageing. Researchers are striving to produce drugs that can mimic the effects of 'exercising more, eating less', while other anti-ageing molecules from molecular gerontologists could help to improve 'healthspan' in the elderly. Machine learning, 'Big Data', and other novel technologies can also be used to monitor disease patterns at the population level and may be used to inform policy design in the future. Collectively, synergies across disciplines on policies, geriatric care, drug development, personal awareness, the use of big data, machine learning and personalized medicine will transform China into a country that enables the most for its elderly, maximizing and celebrating their longevity in the coming decades. This is the 2nd edition of the review paper (Fang EF et al., Ageing Re. Rev. 2015).

Trajectories of Body Composition during Advanced Aging in Consideration of Diet and Physical Activity: A 20-Year Longitudinal Study

This prospective study investigates age-dependent changes in anthropometric data and body composition over a period of two decades in consideration of physical activity and diet in community-dwelling subjects ≥60 years. Overall, 401 subjects with median follow-up time of 12 years were examined. Fat-free mass (FFM) and fat mass (FM) were analyzed using bioelectrical impedance analysis. Physical activity was assessed via a self-administered questionnaire. Dietary intake was examined by 3-day dietary records. Linear mixed-effects models were used to analyze the influence of age, sex, physical activity and energy/protein intake on anthropometric data and body composition by considering year of entry, use of diuretics and diagnosis of selected diseases. At baseline, median values for daily energy and protein intakes were 8.5 megajoule and 81 g and physical activity index was 1.7. After adjusting for covariates, advancing age was associated with parabolic changes indicating overall changes from age 60 to 90 years in women and men in body mass: −4.7 kg, −5.0 kg; body mass index: +0.04 kg/m², −0.33 kg/m²; absolute FFM: −2.8 kg, −3.5 kg; absolute FM: −1.8 kg, −1.2 kg and waist circumference: +16 cm, +12 cm, respectively. No age-dependent changes were found for upper arm circumference and relative (%) FFM. Dietary and lifestyle factors were not associated with changes in anthropometric or body composition parameters. In summary, the results indicate non-linear age-dependent changes in anthropometric data and body composition, which are largely unaffected by the degree of habitual physical activity and dietary protein intake in well-nourished community-dwelling subjects.

Fighting Sarcopenia in Ageing European Adults: The Importance of the Amount and Source of Dietary Proteins

While an adequate protein intake is important for the maintenance of muscle mass during ageing, the amount and source of protein necessary for optimal prevention of sarcopenia remains to be determined. The present study aimed to investigate the influence of the amount and source of dietary proteins on sarcopenia risk in a cohort of 65–79-year-old European adults within the frame of the NU-AGE study. A total of 986 participants were included in the analysis. Skeletal muscle index (SMI), assessed by dual-energy X-ray absorptiometry (DXA), and handgrip strength (HG) were employed to create a continuous sex-specific sarcopenia risk score (SRS). Total amount together with animal- and plant-derived sources of proteins were obtained from a 7-day food record. Differences in SRS were analysed across groups of total protein intake (<0.8 g/body weight (BW); 0.8–<1.0 g/BW; 1.0–<1.2 g/BW; and ≥1.2 g/BW). The association between SRS and the different sources of protein was assessed using isocaloric substitution models adjusted by demographic, medical, and lifestyle factors. A significant linear dose-response relationship was observed, with a lower SRS linked to higher protein intakes. Based on the isocaloric substitution modelling, a reduced SRS was observed when increasing plant protein to the detriment of animal protein, while holding total protein intake constant. Further, this result remained significant after stratifying the analysis by adherence to different levels of protein intake. Our findings suggest that older adults may benefit from increasing protein intakes above current recommendations. Besides total amount, protein source should be considered when promoting health dietary habits in older adults for the prevention of sarcopenia.

Prevalence of protein intake below recommended in community-dwelling older adults: a meta-analysis across cohorts from the PROMISS consortium

BACKGROUND

Lower protein intake in older adults is associated with loss of muscle mass and strength. The present study aimed to provide a pooled estimate of the overall prevalence of protein intake below recommended (according to different cut-off values) among community-dwelling older adults, both within the general older population and within specific subgroups.

METHODS

As part of the PRevention Of Malnutrition In Senior Subjects in the EU (PROMISS) project, a meta-analysis was performed using data from four cohorts (from the Netherlands, UK, Canada, and USA) and four national surveys [from the Netherlands, Finland (two), and Italy]. Within those studies, data on protein and energy intake of community-dwelling men and women aged ≥55 years were obtained by either a food frequency questionnaire, 24 h recalls administered on 2 or 3 days, or food diaries administered on 3 days. Protein intake below recommended was based on the recommended dietary allowance of 0.8 g/kg body weight (BW)/d, by using adjusted BW (aBW) instead of actual BW. Cut-off values of 1.0 and 1.2 were applied in additional analyses. Prevalences were also examined for subgroups according to sex, age, body mass index (BMI), education level, appetite, living status, and recent weight loss.

RESULTS

The study sample comprised 8107 older persons. Mean ± standard deviation protein intake ranged from 64.3 ± 22.3 (UK) to 80.6 ± 23.7 g/d [the Netherlands (cohort)] or from 0.94 ± 0.38 (USA) to 1.17z ± 0.30 g/kg aBW/d (Italy) when related to BW. The overall pooled prevalence of protein intake below recommended was 21.5% (95% confidence interval: 14.0-30.1), 46.7% (38.3-55.3), and 70.8% (65.1-76.3) using the 0.8, 1.0, and 1.2 cut-off value, respectively. A higher prevalence was observed among women, individuals with higher BMI, and individuals with poor appetite. The prevalence differed only marginally by age, education level, living status, and recent weight loss.

CONCLUSIONS

In community-dwelling older adults, the prevalence of protein intake below the current recommendation of 0.8 g/kg aBW/d is substantial (14-30%) and increases to 65-76% according to a cut-off value of 1.2 g/kg aBW/d. To what extent the protein intakes are below the requirements of these older people warrants further investigation.

Protein Intake and Frailty: A Matter of Quantity, Quality, and Timing

Frailty is a geriatric syndrome that refers to a state of reduced resiliency to stressful events that occurs in response to physiological and/or psychosocial detriments. Frailty is a predictor of poor prognosis, given that frail older adults are at higher risk of many adverse health-related events. Hence, the identification of potential strategies to prevent the development and progression of frailty is of extreme importance for avoiding its negative outcomes. An adequate protein consumption is advocated as a possible intervention for the management of frailty in older adults due to its effects on muscle mass and physical function. However, empirical evidence is still needed to support this proposition. On the other hand, substantial evidence from observational studies has provided important information on the association between frailty and dietary protein-related parameters. Here, we provide a narrative review of the current literature regarding the association between protein intake (amount (how much?), quality (what type?), and distribution across meals (when?)) and frailty-related parameters. The ultimate aim of this work is to offer practical, evidence-based indications to healthcare professionals responsible for the care of frail older adults.

Protein Intake and Functional Integrity in Aging: The Framingham Heart Study Offspring

BACKGROUND

Higher protein intake is linked to maintenance of muscle mass and strength, but few studies have related protein to physical function and disability in aging.

METHODS

In participants of the Framingham Heart Study Offspring, we examined associations between protein intake (g/d), estimated from food frequency questionnaires, and maintenance of functional integrity, as a functional integrity score based on responses to 17 questions from Katz Activities of Daily Living, Nagi, and Rosow-Breslau questionnaires, repeated up to five times (1991/1995-2011/2014) over 23 years of follow-up. Cox proportional hazard models were used to estimate risk of incident loss of functional integrity (functional integrity score ≤ 15th percentile).

RESULTS

In 2,917 participants (age 54.5 [9.8] years), baseline protein intake was 77.2 (15.6) g/d. The functional integrity score (baseline, mean 98.9, range 82.4-100.0) was associated with objective performance (gait speed, grip strength) and lower odds of falls, fractures, and frailty. Across follow-up, there were 731 incident cases of loss of functional integrity. In fully adjusted models, participants in the highest category of protein intake (median 92.2 g/d) had 30% lower risk of loss of functional integrity (hazard ratio [95% confidence interval] 0.70 [0.52, 0.95], p trend = .03), versus those with the lowest intake (median 64.4 g/d). However, sex-stratified analyses indicated the association was driven by the association in women alone (hazard ratio [95% confidence interval] 0.49 [0.32, 0.74], p trend = .002) and was nonsignificant in men (hazard ratio [95% confidence interval] 1.14 [0.70, 1.86], p trend = .59).

CONCLUSIONS

Higher protein intake was beneficially associated with maintenance of physical function in middle-aged, high-functioning U.S. adults over the span of two decades. This association was particularly evident in women.

Longitudinal Association of Built Environment Pattern with Physical Activity in a Community-Based Cohort of Elderly Hong Kong Chinese: A Latent Profile Analysis

A large number of studies have focused on the associations between single built environment (BE) characteristics and physical activity (PA). Combinations of BE characteristics offer a more comprehensive approach to identify the BE–PA associations. We aimed to examine the BE–PA associations in a cohort of elderly Hong Kong Chinese. Between 2001 and 2003, 3944 participants (65–98 years of age) were recruited and followed for a mean of 7.8 years. BE characteristics were assessed via geographic information system. PA levels were obtained using the Physical Activity Scale for the Elderly questionnaire at baseline and three follow-ups. Latent profile analysis was first conducted to classify the BE characteristics, and linear mixed-effects models were then used to explore the longitudinal associations between the BE classes and changes in the PA levels. Three classes of BE were identified. Class 3 (characterized by greater green space and sky view factor) demonstrated a significant decline in household PA (β = −1.26, 95% confidence interval: −2.20, −0.33) during the study period, and a slower decline in walking PA (1.19 (0.42, 1.95)) compared with Class 2 (characterized by a greater proportion of residential land use). Our results indicate that BE patterns characterized by high green space and a sky view factor may help promote the walking PA level.

Changes in Dietary Intake of Animal and Vegetable Protein and Unhealthy Aging

BACKGROUND

Animal and vegetable-based proteins differ on their effect on many health outcomes, but their relationship with unhealthy aging is uncertain. Thus, we examined the association between changes in animal and vegetable protein intake and unhealthy aging in older adults.

METHODS

Data came from 1951 individuals aged ≥60 years recruited in the Seniors-ENRICA cohort in 2008-2010 (wave 0) and followed-up in 2012 (wave 1), 2015 (wave 2), and 2017 (wave 3). Dietary protein intake was measured with a validated diet history at waves 0 and 1, and unhealthy aging was measured with a 52-item health deficit accumulation index at each wave.

RESULTS

Compared with participants with a >2% decrease in energy intake from vegetable protein from wave 0 to wave 1, those with a >2% increase showed less deficit accumulation over 3.2 years (multivariable β [95% confidence interval (CI)]: -1.05 [-2.03, -0.06]), 6 years (-1.28 [-2.51, -0.03]), and 8.2 years of follow-up (-1.68 [-3.27, -0.09]). No associations were found for animal protein. Less deficit accumulation over 8.2 years was observed when substituting 1% of energy from vegetable protein for an equal amount of carbohydrate or fat (-0.50 [-0.93, -0.07]), animal protein (-0.44 [-0.81, -0.07]), dairy protein (-0.51 [-0.91, -0.12]), or meat protein (-0.44 [-0.84, -0.04]).

CONCLUSIONS

Increasing dietary intake of vegetable protein may delay unhealthy aging when replacing carbohydrates, fats, or animal protein, especially from meat and dairy.

Circulating amino acids are associated with bone mineral density decline and ten-year major osteoporotic fracture risk in older community-dwelling adults

With aging, poor bone mineral density (BMD) and accelerated decrease in BMD are strong risk factors for fracture. Reports of the associations of dietary protein intake with bone strength are inconsistent, possibly owing to differences in protein sources and amino acid (AA) composition. We examined the associations of serum AA with 4-year hip BMD loss and subsequent fracture risk within 10 years in older community-dwelling adults, and further addressed whether lifestyle, dietary protein intake and its source, and body composition would affect the associations. In 1424 men and 1573 women (mean age 72 years), using binary logistic regression, higher serum valine, leucine, isoleucine and tryptophan concentrations were associated (or approaching a borderline significance in case of the last three ones) with less hip BMD decline (defined as BMD loss ≥ 2.8 times the precision error of the BMD measurement at femoral neck) in 4 years later, with the OR (95%CI) /SD of AA increase, ranging from 0.83 (0.75, 0.91) to 0.92 (0.87, 0.98) after multiple adjustments for baseline age, gender, BMI, BMD, estimated glomerular filtration rate (eGFR), dietary protein intake (animal- and plant-derived protein intakes), calcium intake, established lifestyles (physical activity level, smoking and alcohol drinking status), osteoporosis medications, and changes of body fat and lean muscle mass. Higher serum total homocysteine (tHcy) concentration was independently associated with BMD decline 4 years later (OR (95%CI) /SD of 1.16 (1.05, 1.27)). Using multivariate Cox regression, higher serum tryptophan concentration potentially predicted low risk of incident major osteoporotic fractures (MOFs) (HR/SD (95%CI)=0.86 (0.75, 0.98)) after multiple adjustments. Higher serum tHcy was associated with MOFs (HR/SD (95%CI)=1.29 (1.12, 1.50)) risk after multiple adjustments in men. These findings suggest that a specific AA profile correlates with greater BMD and lower subsequent fracture risk, independent of diet and lifestyle factors.

Dietary Protein and Amino Acids in Vegetarian Diets-A Review

While animal products are rich in protein, the adequacy of dietary protein intake from vegetarian/vegan diets has long been controversial. In this review, we examine the protein and amino acid intakes from vegetarian diets followed by adults in western countries and gather information in terms of adequacy for protein and amino acids requirements, using indirect and direct data to estimate nutritional status. We point out that protein-rich foods, such as traditional legumes, nuts and seeds, are sufficient to achieve full protein adequacy in adults consuming vegetarian/vegan diets, while the question of any amino acid deficiency has been substantially overstated. Our review addresses the adequacy in changes to protein patterns in people newly transitioning to vegetarian diets. We also specifically address this in older adults, where the issues linked to the protein adequacy of vegetarian diets are more complex. This contrasts with the situation in children where there are no specific concerns regarding protein adequacy because of their very high energy requirements compared to those of protein. Given the growing shifts in recommendations from nutrition health professionals for people to transition to more plant-based, whole-food diets, additional scientific evidence-based communications confirming the protein adequacy of vegetarian and vegan diets is warranted.

Vegetable but not animal protein intake is associated to a better physical performance: a study on a general population sample of adults

Background

The research was conducted in the frame of a population-based, case control study, called Genes Environment Interaction in Respiratory Disease.

Objective

To assess the association between protein intake and physical performance in a general population sample.

Design

Researchers investigated the association between the participants’ dietary information and their physical performance using the 6-min walking test and the distance walked in metres (6MWD) as main outcome measure. Information on dietary intake was collected using the validated European Investigation into Cancer and Nutrition food frequency questionnaires (FFQs). Then, daily intake of energy and macronutrients was estimated by means of the NAF software (nutritional analysis of FFQ). Linear regression models were used to evaluate the associations between vegetable, animal and total protein intakes and the 6MWD. The models were adjusted for socio-demographic features, total fats and available carbohydrate intakes.

Results

The participants were 223 subjects (57% females) aged between 23 and 68 years. Their mean vegetable and animal proteins intake for gram/kg of body weight/day were, respectively, 0.4 and 0.7. After adjusting for all the potential confounders, there was a significant increase of 20.0 (95% CI 0.8; 39.2) m in the distance walked for an increase in 10 g/day of vegetable proteins and non-significant variations of −1.8 (95% CI −9.3; 5.7) m for an increase in 10 g/day of animal proteins and of 0.5 (95% CI −6.8; 7.7) for an increase in 10 g/day of total proteins.

Discussion and conclusions

Our result suggests a positive role of vegetable proteins on physical performance. Whether this result is related to the high protein intake itself or may be a consequence of the other properties of plant-based foods deserves further investigation.

Alcohol Consumption Reduces the Beneficial Influence of Protein Intake on Muscle Mass in Middle-Aged Korean Adults: A 12-Year Community-Based Prospective Cohort Study

The influence of alcohol consumption on the association of protein intake with muscle mass was assessed using data from the Korean Genome and Epidemiology Study. Dietary protein intakes of 4412 middle-aged participants with normal baseline muscle mass were assessed using a semi-quantitative Food Frequency Questionnaire, and baseline alcohol consumption data (e.g., frequency and amount) were collected using a structured questionnaire. The skeletal muscle mass index (SMI), defined as the weight-adjusted skeletal muscle mass, was measured using multi-frequency bioelectrical impedance analyses every 2 years until the study endpoint. Low muscle mass was defined as a SMI <2 standard deviations below the sex-specific normal mean for a young reference group. During a 12-year follow-up, 395 subjects developed a low SMI. After multivariate adjustments, high protein intake (≥1.2 g/kg body weight (BW)) was shown to reduce the risk of low SMI development in both men (hazard ratio (HR): 0.24; 95% confidence interval (CI): 0.12, 0.51; p for trend < 0.001) and women (HR: 0.29; 95% CI: 0.16, 0.53; p for trend < 0.001), compared with low protein intake (<0.8 g/kg BW). Alcohol consumption attenuated the protective influence of protein intake against low SMI development in women (HR: 0.64; 95% CI: 0.18, 2.25; p for trend = 0.478). Among the total subjects, heavy drinkers with high protein intake were not significantly associated with the development of a low SMI (HR: 0.20; 95% CI: 0.03, 1.50; p = 0.117). Additional research should clarify the dose-response effects of alcohol consumption on muscle mass relative to daily protein intake.

The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review

Plant-sourced proteins offer environmental and health benefits, and research increasingly includes them in study formulas. However, plant-based proteins have less of an anabolic effect than animal proteins due to their lower digestibility, lower essential amino acid content (especially leucine), and deficiency in other essential amino acids, such as sulfur amino acids or lysine. Thus, plant amino acids are directed toward oxidation rather than used for muscle protein synthesis. In this review, we evaluate the ability of plant- versus animal-based proteins to help maintain skeletal muscle mass in healthy and especially older people and examine different nutritional strategies for improving the anabolic properties of plant-based proteins. Among these strategies, increasing protein intake has led to a positive acute postprandial muscle protein synthesis response and even positive long-term improvement in lean mass. Increasing the quality of protein intake by improving amino acid composition could also compensate for the lower anabolic potential of plant-based proteins. We evaluated and discussed four nutritional strategies for improving the amino acid composition of plant-based proteins: fortifying plant-based proteins with specific essential amino acids, selective breeding, blending several plant protein sources, and blending plant with animal-based protein sources. These nutritional approaches need to be profoundly examined in older individuals in order to optimize protein intake for this population who require a high-quality food protein intake to mitigate age-related muscle loss.

Impact of dietary protein intake and obesity on lean mass in middle-aged individuals after a 12-year follow-up: the Korean Genome and Epidemiology Study (KoGES)

The present study investigated the association between protein intake and lean mass according to obesity status over a 12-year period. Data on 4412 participants aged 40-69 years were obtained from the Korean Genome and Epidemiology Study. The usual dietary protein intake of these participants was assessed at baseline using a semi-quantitative FFQ. Body composition was measured using bioelectrical impedance analysis at baseline and after a 12-year follow-up. Linear mixed-effects models were used to examine the associations between lean mass after a 12-year follow-up and protein intake at baseline. After adjusting for covariates and lean mass at baseline, comparisons between the highest and lowest tertiles revealed that dietary protein intake was positively associated with lean mass in both men (β = 0·79, P = 0·001) and women (β = 0·28, P = 0·082) after the 12-year period; however, those differences were attenuated after additional adjustment for fat mass at baseline and were stronger in the normal-weight group (men, β = 0·85, P = 0·002; women, β = 0·97, P < 0·001) but were not detected in the obese group. In the obese group, age (men, β = 4·08, P < 0·001; women, β = 2·61, P < 0·001) and regular physical activity (men, β = 0·88, P = 0·054; women, β = 0·76, P < 0·001) were significantly associated with lean mass after 12 years of follow-up. The results of the present study showed that protein intake may contribute to the prevention of ageing-related lean mass loss; however, the impact of this intake may vary depending on obesity status. Therefore, the maintenance of a healthy body weight during ageing through enhanced protein intake is likely to confer health benefits.

Amount Rather than Animal vs Plant Protein Intake Is Associated with Skeletal Muscle Mass in Community-Dwelling Middle-Aged and Older Chinese Adults: Results from the Guangzhou Nutrition and Health Study

BACKGROUND

Current literature does not indicate if the amount and animal vs plant protein are equally important in the prevention of muscle loss in middle-aged and older Chinese adults.

OBJECTIVE

The aim of the study was to examine the associations between amount or animal vs plant protein and skeletal muscle mass in Chinese adults aged 40 to 80 years.

DESIGN

A cross-sectional analysis of a prospective, community-based cohort was performed.

PARTICIPANTS/SETTING

Participants included 1,044 men and 2,169 women aged 40 to 80 years from the Guangzhou Nutrition and Health Study 2011-2013 with body composition measurements by dual-energy x-ray absorptiometry.

MAIN OUTCOME MEASURE

The skeletal muscle index (SMI) was defined as appendicular skeletal muscle mass divided by body weight. Participants in the lowest quartile of the sex-specific SMI were considered to have low muscle mass (LMM).

STATISTICAL ANALYSIS

Analyses of covariance were performed to estimate the SMI across quintiles of relative dietary intake of total, animal, and plant protein and the ratio of animal-to-plant protein. Logistic regression models were applied to assess the associations between quintiles of protein intake and LMM.

RESULTS

The SMI increased significantly across quintiles of relative dietary intake of total, animal, and plant protein (all P trends<0.001). Odds ratios (95% CIs) for LMM among participants in the highest (vs lowest) quintile were 0.3 (0.2, 0.4) for total protein, 0.3 (0.2, 0.5) for animal protein, and 0.4 (0.3, 0.7) for plant protein, respectively (all P trends<0.001). However, the ratio of animal-to-plant protein was not associated with either the SMI or the presence of LMM.

CONCLUSION

Higher dietary intakes of total, animal, and plant protein, regardless of the ratio of animal-to-plant protein, are associated with greater skeletal muscle mass in community-dwelling middle-aged and older Chinese adults with a mean protein intake above the current recommendation for protein of 0.8 g/kg per day.

Inadequate Protein Intake at Specific Meals Is Associated with Higher Risk of Impaired Functionality in Middle to Older Aged Mexican Adults

Purpose

To describe the proportions of inadequate protein intake (IPI) per day and per meal and their association with functionality in middle to older aged Mexican adults.

Materials and Methods

In a cross-sectional design, we evaluated the protein intake and functionality of instrumental activities of daily living (IADL) and activities of daily living (ADL) of 190 middle to older aged Mexican adults. IPI was considered as any protein intake: <1.2 g/kg/day, <30 g/meal, or <0.4 g/kg/meal. Functionality was organized into three groups: high, middle, and low scores. The first was set as the reference, and the other was considered as impaired functionality. With a multinomial logistic regression, we analyzed the association between IPI per day and per meal with impaired functionality.

Results

A high proportion of participants showed IPI per day. The meal with the highest proportion of IPI was dinner, followed by breakfast and lunch for both criteria. IPI at lunch was a significant risk factor for impaired functionality in ADL when assessed with the 30 g/meal criterion (low scores, OR 3.82 (95% CI, 1.15–12.65); middle scores, OR 2.40 [1.03–5.62]). For the 0.4 g/kg/meal criterion, IPI at dinner was a significant risk factor for IADL middle scores only (OR 7.64, [1.27–45.85]).

Conclusion

IPI per meal is high in middle to older aged Mexican adults, and at specific meals, it is a significant risk factor for impaired functionality in activities of daily living.

Dietary protein intake is not associated with 5-y change in mid-thigh muscle cross-sectional area by computed tomography in older adults: the Health, Aging, and Body Composition (Health ABC) Study

BACKGROUND

A higher protein intake is suggested to preserve muscle mass during aging and may therefore reduce the risk of sarcopenia.

OBJECTIVES

We explored whether the amount and type (animal or vegetable) of protein intake were associated with 5-y change in mid-thigh muscle cross-sectional area (CSA) in older adults (n = 1561).

METHODS

Protein intake was assessed at year 2 by a Block food-frequency questionnaire in participants (aged 70-79 y) of the Health, Aging, and Body Composition (Health ABC) Study, a prospective cohort study. At year 1 and year 6 mid-thigh muscle CSA in square centimeters was measured by computed tomography. Multiple linear regression analysis was used to examine the association between energy-adjusted protein residuals in grams per day (total, animal, and vegetable protein) and muscle CSA at year 6, adjusted for muscle CSA at year 1 and potential confounders including prevalent health conditions, physical activity, and 5-y change in fat mass.

RESULTS

Mean (95% CI) protein intake was 0.90 (0.88, 0.92) g · kg-1 · d-1 and mean (95% CI) 5-y change in muscle CSA was -9.8 (-10.6, -8.9) cm2. No association was observed between energy-adjusted total (β = -0.00; 95% CI: -0.06, 0.06 cm2; P = 0.982), animal (β = -0.00; 95% CI: -0.06, 0.05 cm2; P = 0.923), or plant (β = +0.07; 95% CI: -0.06, 0.21 cm2; P = 0.276) protein intake and muscle CSA at year 6, adjusted for baseline mid-thigh muscle CSA and potential confounders.

CONCLUSIONS

This study suggests that a higher total, animal, or vegetable protein intake is not associated with 5-y change in mid-thigh muscle CSA in older adults. This conclusion contradicts some, but not all, previous research. This trial was registered at www.trialregister.nl as NTR6930.

A cross-sectional analysis of dietary protein intake and body composition among Chinese Americans

Favourable body composition has been associated with higher dietary protein intake. However, little is known regarding this relationship in a population of Chinese Americans (CHA), who have lower BMI compared with other populations. The aim of the present study was to assess the relationship between dietary protein intake, fat mass (FM) and fat-free mass (FFM) in CHA. Data were from the Chinese American Cardiovascular Health Assessment (CHA CHA) 2010-2011 (n 1707); dietary intake was assessed using an adapted and validated FFQ. Body composition was assessed using bioelectrical impedance analysis. The associations between protein intake (% energy intake) and BMI, percentage FM (FM%), percentage FFM (FFM%), FM index (FMI) and FFM index (FFMI) were examined using multiple linear regression adjusted for age, sex, physical activity, acculturation, total energy intake, sedentary time, smoking status, education, employment and income. There was a significant positive association between dietary protein and BMI (B = 0·056, 95 % CI 0·017, 0·104; P = 0·005), FM (B = 0·106, 95 % CI 0·029, 0·184; P = 0·007), FM% (B = 0·112, 95 % CI 0·031, 0·194; P = 0·007) and FMI (B = 0·045, 95 % CI 0·016, 0·073; P = 0·002). There was a significant negative association between dietary protein and FFM% (B = -0·116, 95 % CI -0·196, -0·036; P = 0·004). In conclusion, higher dietary protein intake was associated with higher adiposity; however, absolute FFM and FFMI were not associated with dietary protein intake. Future work examining the relationship between protein source (i.e. animal) and body composition is warranted in this population of CHA.

High Protein Intake Is Associated with Lower Risk of All-Cause Mortality in Community-Dwelling Chinese Older Men and Women

OBJECTIVES

To examine the association of the quantity and the source of protein intake with mortality risk in Chinese older adults.

DESIGN

Prospective cohort study.

SETTING

Community.

PARTICIPANTS

Community-dwelling Chinese adults aged >=65 (1,480 men, 1,540 women) in Hong Kong.

MEASUREMENTS

Food frequency questionnaire was used to capture baseline dietary intakes including protein, fiber, total grains, vegetables and fruit intakes. Primary outcome measures, identified from the death registry, were death from all causes, cancer and cardiovascular disease (CVD). Other demographic and lifestyle risk factors were also collected. Multivariate Cox proportion hazards regression was used to examine the association of protein intake with mortality risk.

RESULTS

During a median of 13.8 follow-up years, 963 all-cause deaths, 336 cancer deaths, and 205 CVD deaths were identified. Among men in the highest quintile of total protein intake, all-cause mortality and cancer mortality decreased by 29% [95% confidence interval (CI): 0.55-0.92, p-trend=0.017] and 38% [95% CI: 0.39-0.97, p-trend=0.041] respectively compared with men in the lowest quintile after adjustment for demographics, lifestyle factors and medical conditions. Men in the highest quintile of animal protein intake showed 20% reduced risk of all-cause mortality than men in the lowest quintile (p-trend=0.042). Women in the highest quintile of plant protein intake showed 39% decreased risk of all-cause mortality [95% CI: 0.44-0.85, p-trend=0.019] than those in the lowest quintile. In women, protein intake was not associated with cancer mortality. In both men and women, protein intake was not associated with CVD morality. Further adjustment for other dietary variables attenuated the significant associations.

CONCLUSIONS

Contrary to findings from Caucasian populations of all ages, among Chinese older adults, higher total protein intake was associated with lower all-cause and cancer mortality in Chinese older men. While higher animal protein intake was associated with reduced all-cause mortality in Chinese older men, higher plant protein intake was protective against all-cause mortality in Chinese women. The attenuated associations between protein intake and mortality risk after adjustment for other dietary variables also highlight the role of whole diet approach in mortality risk reduction among older adults.

Efficacy of non-pharmacological interventions to treat malnutrition in older persons: A systematic review and meta-analysis. The SENATOR project ONTOP series and MaNuEL knowledge hub project

INTRODUCTION

We aimed to perform a review of SRs of non-pharmacological interventions in older patients with well-defined malnutrition using relevant outcomes agreed by a broad panel of experts.

METHODS

PubMed, Cochrane, EMBASE, and CINHAL databases were searched for SRs. Primary studies from those SRs were included. Quality assessment was undertaken using Cochrane and GRADE criteria.

RESULTS

Eighteen primary studies from seventeen SRs were included. Eleven RCTs compared oral nutritional supplementation (ONS) with usual care. No beneficial effects of ONS treatment, after performing two meta-analysis in body weight changes (six studies), mean difference: 0.59 (95%CI -0.08, 1.96) kg, and in body mass index changes (two studies), mean difference: 0.31 (95%CI -0.17, 0.79) kg/m2 were found. Neither in MNA scores, muscle strength, activities of daily living, timed Up&Go, quality of life and mortality. Results of other intervention studies (dietary counselling and ONS, ONS combined with exercise, nutrition delivery systems) were inconsistent. The overall quality of the evidence was very low due to risk of bias and small sample size.

CONCLUSIONS

This review has highlighted the lack of high quality evidence to indicate which interventions are effective in treating malnutrition in older people. High quality research studies are urgently needed in this area.

Pretiree lifestyles in relation to musculoskeletal health: cross-sectional data from the Geelong Osteoporosis Study

Background: What happens in the early-elderly ‘pretiree’ period potentially influences the divergent paths of healthy or unhealthy ageing. In this cross-sectional study, we aimed to profile musculoskeletal health and lifestyle behaviours for men and women in their late-fifties and sixties.Methods: For 482 participants from the Geelong Osteoporosis Study, we measured DXA-derived appendicular lean mass (rALM), bone mineral density (BMD) at the femoral neck and percentage body fat mass (%BF). Low-rALM and low-BMD referred to sex-specific T-scores<-1.0. Associations between exposures and low-rALM and/or low-BMD were explored using multivariable logistic regression.Results: Three-quarters of participants had high %BF, 98(20.3%) had low-rALM, 202(41.9%) had low-BMD and 63(13.1%) had both low-rALM and low-BMD. Eight-two (17.0%) were very active and one-third participated in sports/recreational activities. Most [n=416(87.8%)] met the recommended daily intake (RDI) for protein; only 119(25.1%) met the RDI for calcium. Less than 10% smoked and one-third exceeded recommended alcohol intakes. Independent of age, weight and sex, greater %BF and sedentary behaviour increased the likelihood of low-rALM; high-alcohol consumption increased the likelihood of low-BMD; and greater %BF increased the likelihood of low-rALM and low-BMD combined.Conclusions: One-half of participants had rALM and BMD in the normal range. Only a few were involved in resistance-training or weight-bearing exercise, despite having the capacity to be physically active. As sedentary lifestyles, excessive adiposity and high alcohol use were associated with low-rALM and/or low-BMD, we propose that these adverse factors be potential targets among pretirees to minimise their risk of entering old age with poor musculoskeletal health. 

Relative Protein Intake and Physical Function in Older Adults: A Systematic Review and Meta-Analysis of Observational Studies

(1) Background: The present work aims to conduct a systematic review and meta-analysis of observational studies, in order to investigate the association of relative protein intake and physical function in older adults; (2) Methods: Observational studies, that investigated the association between protein intake and physical function in older adults, were retrieved from MEDLINE, SCOPUS, CINAHL, AgeLine, EMBASE, and Cochrane-CENTRAL. Two independent researchers conducted study selection and data extraction; (3) Results: Very high protein intake (≥1.2 g/kg/day) and high protein intake (≥1.0 g/kg/day) groups showed better lower limb physical functioning and walking speed (WS) performance, respectively, in comparison to individuals who present relative low protein (<0.80 g/kg/day) intake. On the other hand, relative high protein intake does not seem to propitiate a better performance on isometric handgrip (IHG) and chair rise in comparison to relative low protein intake. In addition, there were no significant differences in the physical functioning of high and middle protein intake groups; (4) Conclusions: In conclusion, findings of the present study indicate that a very high (≥1.2 g/kg/day) and high protein intake (≥1.0 g/kg/day) are associated with better lower-limb physical performance, when compared to low protein (<0.80 g/kg/day) intake, in community-dwelling older adults. These findings act as additional evidence regarding the potential need to increase protein guidelines to above the current recommendations. However, large randomized clinical trials are needed to confirm the addictive effects of high-protein diets (≥1.0 g/kg/day) in comparison to the current recommendations on physical functioning. All data are available in the Open ScienceFramework.

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

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.

Chronic dietary supplementation with soy protein improves muscle function in rats

Athletes as well as elderly or hospitalized patients use dietary protein supplementation to maintain or grow skeletal muscle. It is recognized that high quality protein is needed for muscle accretion, and can be obtained from both animal and plant-based sources. There is interest to understand whether these sources differ in their ability to maintain or stimulate muscle growth and function. In this study, baseline muscle performance was assessed in 50 adult Sprague-Dawley rats after which they were assigned to one of five semi-purified “Western” diets (n = 10/group) differing only in protein source, namely 19 kcal% protein from either milk protein isolate (MPI), whey protein isolate (WPI), soy protein isolate (SPI), soy protein concentrate (SPC) or enzyme-treated soy protein (SPE). The diets were fed for 8 weeks at which point muscle performance testing was repeated and tissues were collected for analysis. There was no significant difference in food consumption or body weights over time between the diet groups nor were there differences in terminal organ and muscle weights or in serum lipids, creatinine or myostatin. Compared with MPI-fed rats, rats fed WPI and SPC displayed a greater maximum rate of contraction using the in vivo measure of muscle performance (p<0.05) with increases ranging from 13.3–27.5% and 22.8–29.5%, respectively at 60, 80, 100 and 150 Hz. When the maximum force was normalized to body weight, SPC-fed rats displayed increased force compared to MPI (p<0.05), whereas when normalized to gastrocnemius weight, WPI-fed rats displayed increased force compared to MPI (p<0.05). There was no difference between groups using in situ muscle performance. In conclusion, soy protein consumption, in high-fat diet, resulted in muscle function comparable to whey protein and improved compared to milk protein. The benefits seen with soy or whey protein were independent of changes in muscle mass or fiber cross-sectional area.

Even mealtime distribution of protein intake is associated with greater muscle strength, but not with 3-y physical function decline, in free-living older adults: the Quebec longitudinal study on Nutrition as a Determinant of Successful Aging (NuAge study)

Background: Functional status declines with aging, thus impeding autonomy. Recently, a more even mealtime distribution of dietary protein was positively associated with muscle mass, but the relation of this distribution to physical performance remains unknown.Objective: We examined the relation between mealtime protein-intake distribution and physical performance and its 3-y decline in community-dwelling older adults.Design: Three-year follow-up data from 827 men and 914 women (67-84 y) in the longitudinal study on nutrition and aging [Quebec longitudinal study on Nutrition as a Determinant of Successful Aging (NuAge study); Quebec, Canada] were analyzed. Physical performance, which was measured yearly, was grouped into the following 2 functional composite scores: muscle strength (handgrip, arm, and leg) and mobility (timed-up-and-go, chair stand, and walking speed). Dietary data were collected in 2 sets of three 24-h food recalls at baseline and year 2. The individual mealtime protein distribution was calculated as the CV (i.e., SD divided by the mean) of grams of protein per meal. A mixed model analysis was used to examine trajectories of muscle strength and mobility across time by sex as conditioned by the protein distribution and adjusted for potential covariates.Results: Physical performance deteriorated over 3 y with muscle strength declining more than the mobility score in men (-1.51 ± 1.68 compared with -0.66 ± 2.81) and women (-1.35 ± 1.77 compared with -0.78 ± 2.63) (means ± SD, P < 0.001). More-evenly distributed protein intake, independent of the total quantity, was associated with a higher muscle-strength score in both sexes throughout follow-up. It was also associated with a greater mobility score, but only in men and only before adjustment for covariates. Strength and mobility rates of decline were not affected by protein-intake distribution in either sex.Conclusions: In addition to the previously observed association with lean mass, an even distribution of daily protein intake across meals is independently associated with greater muscle strength, but not with the mobility score, in older adults. A longer-term investigation of the role of protein intake and its distribution on physical performance is warranted, as are intervention studies, to support future recommendations.

Sarcopenia

Sarcopenia refers to age-related muscle loss, defined using a combination of appendicular muscle mass, muscle strength, and physical performance measures. The pathogenesis depends on a balance between positive and negative regulators of muscle growth. Sarcopenia increases the risk for falls, fractures, dependency, use of hospital services, institutionalization, poor quality of life, and mortality. In clinical practice, brief screening tools, such as the 5-item SARC-F score, may be useful. Although pharmacologic treatments are actively being studied, the current mainstay consists of optimizing nutrition status, in particular protein and vitamin D status, and resistance exercises.

Protein Intake and Mobility Limitation in Community-Dwelling Older Adults: the Health ABC Study

OBJECTIVES

The current Recommended Dietary Allowance (RDA) for protein is based on short-term nitrogen balance studies in young adults and may underestimate the amount needed to optimally preserve physical function in older adults. We examined the association between protein intake and the onset of mobility limitation over 6 years of follow-up in older adults in the Health ABC study.

DESIGN

Prospective cohort study.

SETTING

Memphis, Tennessee and Pittsburgh, Pennsylvania.

PARTICIPANTS

Community-dwelling, initially well-functioning adults aged 70-79 years (n = 1998).

MEASUREMENTS

Protein intake (g/kg body weight/d) was calculated using an interviewer-administered 108-item food frequency questionnaire at baseline. Mobility limitation was assessed semi-annually and defined as reporting any difficulty walking one-quarter of a mile or climbing 10 steps on 2 consecutive 6-month contacts. The association between protein intake and incident mobility limitation was examined using Cox proportional hazard regression models adjusting for demographics, behavioral characteristics, chronic conditions, total energy intake, and height.

RESULTS

Mean (SD) protein intake was 0.91 (0.38) g/kg body weight/d, with 43% reporting intakes less than the RDA (0.8 g/kg body weight/d). During 6 years of follow-up, 705 participants (35.3%) developed mobility limitations. Compared to participants in the upper tertile of protein intake (≥1.0 g/kg body weight/d), participants in the lower two tertiles of protein intake (<0.7 and 0.7 -<1.0 g/kg body weight/d) were at greater risk of developing mobility limitation over 6 years of follow-up (RR (95% CI): 1.86 (1.41-2.44) and 1.49 (1.20-1.84), respectively).

CONCLUSION

Lower protein intake was associated with increased risk of mobility limitation in community-dwelling, initially well-functioning older adults. These results suggest that protein intakes of ≥1.0 g/kg body weight/d may be optimal for maintaining physical function in older adults.