Dietary Protein Intake Is Protective Against Loss of Grip Strength Among Older Adults in the Framingham Offspring Cohort

Effect of Relative Protein Intake on Hypertension and Mediating Role of Physical Fitness and Circulating Fatty Acids: A Mendelian Randomization Study

OBJECTIVE

To investigate the causal effect of protein intake on hypertension and the related mediating pathways.

PATIENTS AND METHODS

Using genome-wide association study summary statistics of European ancestry, we applied univariable and multivariable Mendelian randomization to estimate the bidirectional associations of relative protein intake and related metabolomic signatures with hypertension (FinnGen: Ncase=42,857/Ncontrol=162,837; UK Biobank: Ncase=77,723/Ncontrol=330,366) and blood pressure (International Consortium of Blood Pressure: N=757,601) and two-step Mendelian randomization to assess the mediating roles of 40 cardiometabolic factors therein. Mendelian randomization estimates of hypertension from FinnGen and UK Biobank were meta-analyzed without heterogeneity. We performed the study from May 15, 2023, to September 15, 2023.

RESULTS

Each 1-SD higher relative protein intake was causally associated with 69% (odds ratio, 0.31; 95% CI, 0.11 to 0.89) lower hypertension risk independent of the effects of other macronutrients, and was the only macronutrient associated with 2.21 (95% CI, 0.52 to 3.91) mm Hg lower pulse pressure, in a unidirectional manner. Higher plant protein-related metabolomic signature (glycine) was associated with lower hypertension risk and pulse pressure, whereas higher animal protein-related metabolomic signatures (leucine, isoleucine, valine, and isovalerylcarnitine [only systolic blood pressure]) were associated with higher hypertension risk, pulse pressure, and systolic blood pressure. The effect of relative protein intake on hypertension was causally mediated by frailty index (mediation proportion, 40.28%), monounsaturated fatty acids (13.81%), saturated fatty acids (11.39%), grip strength (5.34%), standing height (3.99%), and sitting height (3.61%).

CONCLUSION

Higher relative protein intake causally reduces the risk of hypertension, partly mediated by physical fitness and circulating fatty acids.

Association of diet quality with hand grip strength weakness and asymmetry in a multi-ethnic Asian cohort

Hand grip strength (HGS) is an important diagnostic tool for sarcopenia and a reliable predictor for age-related chronic diseases and mortality. Interventions in nutrition have been shown as a low-cost strategy to maintain muscular strength and mass. However, there are limited data on the effect of diet on HGS in Southeast Asian populations. This study aims to investigate the association of diet quality with HGS weakness and asymmetry in a multi-ethnic population in Singapore. This cross-sectional study used data from the Singapore Multi-Ethnic Cohort (n = 1547). Dietary data were collected using a validated semi-quantitative FFQ and summarised as the Dietary Quality Index - International (DQI-I). HGS was calculated as the maximum value of six measurements from both hands. HGS weakness and asymmetry were defined using well-recognised criteria. Multivariable linear regression and logistic regression were utilised for continuous and binary outcomes, respectively, adjusting for age, sex, ethnicity, physical activity and smoking status. It was found that the highest quartile of DQI-I was significantly associated with higher HGS (β = 1·11; 95 % CI 0·41, 1·82; Pfor trend < 0·001) and lower odds of HGS asymmetry (OR = 0·71; 95 % CI 0·53, 0·94; Pfor trend = 0·035) and both HGS weakness and asymmetry (OR = 0·50; 95 % CI 0·32, 0·76; Pfor trend = 0·004). Among the different components of DQI-I, only dietary adequacy was significantly associated with higher HGS (Pfor trend < 0·001) and lower odds for both HGS weakness and asymmetry (Pfor trend = 0·006). Our findings support that DQI-I, an indicator of overall diet quality, can be used to provide dietary guidelines for prevention and management of muscle wasting, sarcopenia and frailty.

Implications of Protein and Sarcopenia in the Prognosis, Treatment, and Management of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) is a common cause of chronic liver disease globally, with prevalence rapidly increasing in parallel with rising rates of obesity and metabolic syndrome. MASLD is defined by the presence of excess fat in the liver, which may induce inflammatory changes and subsequent fibrosis in high-risk patients. Though MASLD occurs frequently, there is still no approved pharmacological treatment, and the mainstay of therapy remains lifestyle modification via dietary changes, enhancement of physical activity, and management of metabolic comorbidities. Most nutrition research and clinical guidance in this disease centers on the reduction in fructose and saturated fat in the diet, although the emerging literature suggests that protein supplementation is important and implicates muscle mass and sarcopenia in disease-related outcomes. This review will assess the current data on these topics, with the goal of defining best practices and identifying research gaps in care.

Association between the risk of malnutrition and sarcopenia at 4.2 years of follow-up in community-dwelling older adults

Introduction

Currently, there is only scarce evidence of a causal association between risk of malnutrition (RM) by the mini-nutritional assessment (MNA) and the incidence of sarcopenia. This study was designed to assess such an association at 4.2 years of follow-up in community-dwelling subjects over 60 years old.

Methods

The data used were from the FraDySMex cohort study. The exposition variables were RM diagnosed by the long forma of the MNA (MNA-LF) and short form (MNA-SF). The last one included the body mass index and calf circumference at baseline, while sarcopenia was diagnosed by the EWGSOP2 at follow-up and taken as the response variable. Several covariates involved in the association were also considered. A multiple logistic regression analysis was performed to test the association.

Results

At baseline, 27.0 and 37.9% of subjects had RM by the MNA-LF and MNA-SF, respectively. The incidence of sarcopenia was 13.7%. The fat mass variable significantly modified the association, so it was tested in each stratum. Two independent models showed that subjects with RM by the MNA-LF in the normal fat mass stratum were at a higher risk for developing sarcopenia at follow-up than those without RM (OR 9.28; IC 95% 1.57-54.76) after adjusting for age, sex, and waist circumference. No association was found for the excess fat mass stratum subjects. Subjects with RM by the MNA-SF in the excess fat mass stratum were more likely to develop sarcopenia at follow-up than those without RM by the MNA-SF (OR 3.67; IC 95% 1.29-10.43). This association was not found in the subjects in the normal fat mass stratum.

Conclusion

The association was dependent on the variable fat mass. The two forms of the MNA should not be applied indistinctly with older adults. Based on these results, it is clear that the risk of malnutrition precedes the onset of sarcopenia.

Effect of breakfast protein intake on muscle mass and strength in adults: a scoping review

BACKGROUND

The distribution of protein intake throughout the day is frequently skewed, with breakfast having the lowest protein intake across all age groups. There is no review that addresses the association between breakfast protein intake and muscle mass and strength.

OBJECTIVE

This scoping review aims to summarize the literature on the relationship between protein intake during breakfast and muscle mass and strength in adults.

METHODS

This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. Two independent reviewers screened and appraised the articles identified from 3 electronic databases (Medline, Web of Science, and Scopus) that focused on protein intake per meal and its impact on muscle-related outcomes.

RESULTS

A total of 14 763 articles were retrieved from 3 databases, and after the screening process, 15 articles were included for analysis. Approximately 58.8% of findings from 11 studies examining the association between high protein intake during breakfast and muscle mass indicated an increase in muscle mass among participants. Half of 6 studies (50.0%) exploring the relationship between high protein intake at breakfast and muscle strength demonstrated an increase in muscle strength. Consuming high amounts of protein at breakfast or more protein in the morning than in the evening was associated with an increase in the skeletal muscle index and lean body mass.

CONCLUSION

Protein consumption at breakfast revealed potential benefits in increasing muscle mass across 5 studies involving an elderly population and 2 studies encompassing middle-aged women and young men in our review. However, the relationship between protein intake at breakfast and muscle strength remains unclear. Further high-quality randomized controlled trials are required to examine whether adults can preserve skeletal muscle health outcomes by consuming higher amounts of protein at breakfast.

Decreased Neuromuscular Function and Muscle Quality along with Increased Systemic Inflammation and Muscle Proteolysis Occurring in the Presence of Decreased Estradiol and Protein Intake in Early to Intermediate Post-Menopausal Women

Menopause causes a reduction in estradiol (E2) and may be associated with neuromuscular degeneration. Compared to pre-menopausal (PRE-M) women, this study sought to determine dietary protein intake and whether lower levels of circulating E2 in post-menopausal women (POST-M) were occurring alongside increased levels of biomarkers of axonal and neuromuscular junction degeneration (NMJ), inflammation, muscle protein degradation, and reduced indices of muscle quality and performance. Employing a cross-sectional design, PRE-M (n = 6) and POST-M (n = 6) dietary analysis data were collected and participants then donated a blood and urine sample followed by assessments for body composition, motor unit activation, and muscle performance. Independent group t-tests were performed to determine differences between groups (p ≤ 0.05). In POST-M women, E2, motor unit activity, muscle quality, and muscle performance were significantly less than those for PRE-M women; however, the levels of c-terminal fragment of agrin, tumor necrosis factor-α, and urinary titin were significantly greater (p < 0.05). POST-M women were also shown to be ingesting fewer total calories and less protein than PRE-M (p < 0.05). Reduced E2 and dietary protein intake in POST-M women occurs in conjunction with increased levels of biomarkers of NMJ degradation, inflammation, and muscle proteolysis, which may be associated with reduced motor unit activation and muscle quality.

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.

Associations of protein intake, sources and distribution on muscle strength in community-dwelling older adults living in Auckland, New Zealand

Protein intake, sources and distribution impact on muscle protein synthesis and muscle mass in older adults. However, it is less clear whether dietary protein influences muscle strength. Data were obtained from the Researching Eating Activity and Cognitive Health (REACH) study, a cross-sectional study aimed at investigating dietary patterns, cognitive function and metabolic syndrome in older adults aged 65-74 years. Dietary intake was assessed using a 4-d food record and muscle strength using a handgrip strength dynamometer. After adjusting for confounders, in female older adults (n 212), total protein intake (β = 0⋅22, P < 0⋅01); protein from dairy and eggs (β = 0⋅21, P = 0⋅03) and plant food sources (β = 0⋅60, P < 0⋅01); and frequently consuming at least 0⋅4 g/kg BW per meal (β = 0⋅08, P < 0⋅01) were associated with higher BMI-adjusted muscle strength. However, protein from meat and fish intake and the coefficient of variance of protein intake were not related to BMI-muscle strength in female older adults. No statistically significant associations were observed in male participants (n = 113). There may be sex differences when investigating associations between protein intake and muscle strength in older adults. Further research is needed to investigate these sex differences.

Effects of 8 weeks of resistance training in combination with a high protein diet on body composition, muscular performance, and markers of liver and kidney function in untrained older ex-military men

Background

The effects of a high protein diet in combination with chronic resistance training (RT) on skeletal muscle adaptation responses in untrained older ex-military men is unknown. Therefore, we compared the effects of 8 weeks of RT in combination with either a high (1.6 g/kg/d) or low protein diet (0.8 g/kg/d) on body composition [skeletal muscle mass (SMM) and body fat percentage (BFP)], muscular strength, power, and endurance (upper and lower body), markers of liver [alanine transaminase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT)] and kidney (creatinine and urea) function, and lipid profile low-density lipoprotein (LDL), high-density lipoprotein (HDL), and cholesterol levels in a cohort of healthy, untrained older ex-military males.

Methods

Forty healthy untrained older ex-military males (age: 61 ± 2 yr, body mass index: 23.2 ± 1.3 kg.m^-2) performed 8 weeks (three sessions·w^-1) of RT with either 1.6 g/kg/d (RHP; n = 20) or 0.8 g/kg/d of protein (RLP; n = 20). Body composition (assessed by Inbody 720), muscular strength (1-RM for chest and leg press), power (Wingate test), endurance (75% 1-RM for chest and leg press), and markers of liver and kidney function (biochemical kits) were assessed pre and post-intervention.

Results

SMM and muscular strength (upper and lower body) increased post-intervention in both groups and were significantly greater in RHP compared to RLP, while muscular power increased to the same extent in both groups (p < 0.05) with no between-group differences (p > 0.05). In contrast, there were no post-intervention changes in muscular endurance, HDL, and BFP remained in either group (p > 0.05). ALT and creatinine significantly increased in RHP compared to RLP while GGT, AST, and urea only increased in the RLP group (p < 0.05). LDL and cholesterol significantly decreased in both groups (p < 0.05).

Conclusion

A daily intake of 1.6 g/kg/d protein was superior to 0.8 g/kg/d (current recommended daily intake) for promoting greater improvements in SMM and muscle strength and thus may be a more suitable level of intake for promoting such adaptive responses. Notwithstanding observed between-group differences in ALT and creatinine and the fact that levels remained within normal ranges, it is feasible to conclude that this daily protein intake is efficacious and well tolerated by healthy, untrained older ex-military males.

"Diet for the prevention and management of sarcopenia"

Sarcopenia is a geriatric condition characterized by a progressive loss of skeletal muscle mass and strength, with an increased risk of adverse health outcomes (e.g., falls, disability, institutionalization, reduced quality of life, mortality). Pharmacological remedies are currently unavailable for preventing the development of sarcopenia, halting its progression, or impeding its negative health outcomes. The most effective strategies to contrast sarcopenia rely on the adoption of healthier lifestyle behaviors, including adherence to high-quality diets and regular physical activity. In this review, the role of nutrition in the prevention and management of sarcopenia is summarized. Special attention is given to current "blockbuster" dietary regimes and agents used to counteract age-related muscle wasting, together with their putative mechanisms of action. Issues related to the design and implementation of effective nutritional strategies are discussed, with a focus on unanswered questions on the most appropriate timing of nutritional interventions to preserve muscle health and function into old age. A brief description is also provided on new technologies that can facilitate the development and implementation of personalized nutrition plans to contrast sarcopenia.

Nutritional Interventions: Dietary Protein Needs and Influences on Skeletal Muscle of Older Adults

BACKGROUND

This narrative review describes foundational and emerging evidence of how dietary protein intakes may influence muscle-related attributes of older adults.

METHODS

PubMed was used to identify pertinent research.

RESULTS

Among medically stable older adults, protein intakes below the recommended dietary allowance (RDA) (0.8 g/kg body weight [BW]/d) exacerbate age-related reductions in muscle size, quality, and function. Dietary patterns with total protein intakes at or moderately above the RDA, including one or preferably more meals containing sufficient dietary protein to maximize protein anabolism, promote muscle size and function. Some observational studies suggest protein intakes from 1.0 to 1.6 g/kg BW/d may promote greater muscle strength and function more so than muscle size. Experimental findings from randomized controlled feeding trials indicate protein intakes greater than the RDA (averaging ~1.3 g/kg BW/d) do not influence indices of lean body mass or muscle and physical functions with non-stressed conditions, but positively influence changes in lean body mass with purposeful catabolic (energy restriction) or anabolic (resistance exercise training) stressors. Among older adults with diagnosed medical conditions or acute illness, specialized protein or amino acid supplements that stimulate muscle protein synthesis and improve protein nutritional status may attenuate the loss of muscle mass and function and improve survival of malnourished patients. Observational studies favor animal versus plant protein sources for sarcopenia-related parameters.

CONCLUSIONS

Quantity, quality, and patterning of dietary protein consumed by older adults with varied metabolic states, and hormonal and health status influence the nutritional needs and therapeutic use of protein to support muscle size and function.

Associations between the muscle quality index and adult lung functions from NHANES 2011-2012

Background

The muscle quality index (MQI), as an important component of sarcopenia, is defined as the ratio of muscle strength to muscle mass. Lung function, is a clinical indicator to assess ventilation and air exchange function. This study investigated the relationship between lung function indices and MQI in the NHANES database from 2011 to 2012.

Methods

This study included 1,558 adults from the National Health and Nutrition Examination Survey from 2011 to 2012. Muscle mass and muscle strength were assessed using DXA and handgrip strength, and all participants underwent pulmonary function measurements. Multiple linear regression and multivariable logistic regression were used to assess the correlation between the MQI and lung function indices.

Results

In the adjusted model, MQI was significantly correlated with FVC% and PEF%. And, after quartiles of MQI in Q3, where FEV₁%, FVC%, and PEF% were all associated with MQI, in Q4, a lower relative risk of a restrictive spirometry pattern was linked to increased MQI. Compared to the lower age group, the relationship between the MQI and lung function indices was more significant in the higher age group.

Conclusion

There was an association between the MQI and lung function indices. Furthermore, in the middle-aged and older adult populations, lung function indicators and restrictive ventilation impairment were significantly associated with MQI. This implies that improving lung function through muscle training may be beneficial to this group.

Dairy Food Intake Is Not Associated With Frailty in Adults From the Framingham Heart Study

BACKGROUND

Nutrients, including protein, calcium, and fat may be associated with risk of frailty, yet specific contributions from whole dairy foods rich in these nutrients remain understudied.

OBJECTIVE

To determine associations between dairy intake (milk, yogurt, cheese, total (milk + yogurt + cheese), low-fat and high-fat dairy, and servings per week) and frailty onset and frailty phenotype components.

DESIGN

Prospective cohort study. All dairy intake exposures (servings per week) were assessed via a food frequency questionnaire.

PARTICIPANTS AND SETTING

Participants (aged 33 to 86 years) from the Framingham Offspring Study who were not frail at baseline (1998-2001) completed a food frequency questionnaire and had 1 or 2 follow-up frailty assessments (2005-2008 and 2011-2014) were included.

MAIN OUTCOME MEASURES

Frailty was defined as the presence of ≥3 Fried frailty phenotype components: unintentional weight-loss, exhaustion, slowness (gait speed), weakness (grip strength), and low physical activity. Individuals with zero to two components were considered nonfrail.

STATISTICAL ANALYSES PERFORMED

Repeated measures logistic regression estimated odds ratios and 95% CIs for frailty onset. Logistic (exhaustion and weight loss) and linear regression (gait speed, grip strength, and physical activity) estimated the association between baseline dairy intake and each frailty component at follow-up, adjusting for baseline values for age, sex, energy intake (residual analysis), current smoking, and multivitamin use. Models were further adjusted for health status in a secondary analysis.

RESULTS

Mean baseline age ± SD was 61 ± 9 years (range = 33 to 87 years), and 54% were women. Of 2,550 nonfrail individuals at baseline, 8.8% (2005-2008) and 13.5% (2011-2014) became frail. Higher yogurt intake was associated with decreased odds of frailty (odds ratio 0.96, 95% CI 0.93 to 0.99; P = 0.02). Each additional serving of yogurt (β ± SE) .004 ± .001; P < 0.01) and low-fat dairy (β ± SE) .001 ± .0006; P = 0.04) was associated with significantly faster follow-up gait speed. Dietary intakes of high-fat dairy were associated with increased odds of frailty (odds ratio 1.02, 95% CI 1.00 to 1.04; P = 0.05), but the P value was of borderline significance. No associations were observed for other dairy foods. After adjusting for health status, the associations of high-fat dairy and yogurt with frailty became nonsignificant, although the magnitudes of the associations did not change. The association between yogurt and gait speed decreased in magnitude after adjusting for health status (β ± SE) .002 ± .001; P = 0.01).

CONCLUSIONS

Dietary intakes of yogurt were modestly associated with reduced frailty onset and dietary intakes of high-fat dairy had a borderline association with increased odds of frailty, but other dairy food intakes showed no association in this study of healthy adults. Some dairy food intakes were modestly associated with follow-up gait speed. However, effect sizes were small, and the clinical importance of these associations remains undetermined.

The association between meat consumption and muscle strength index in young adults: the mediating role of total protein intake and lean mass percentage

PURPOSE

The aim of this study was to analyse the associations between the consumption of different types of meat and the muscle strength index (MSI) and to examine whether this relationship is mediated by total protein intake (TPI) and lean mass percentage (LM%) in young adults.

METHODS

We conducted a cross-sectional study with first-year university students from Castilla-La Mancha, Spain. Different types of meat consumption (total, red, processed, and white and fish) were separately evaluated using a Food-Frequency Questionnaire. MSI was determined from the handgrip and standing long jump tests. ANCOVA models were used to test the mean differences in MSI by categories of meat consumption. Serial multiple mediation models were used to explore the mediating role of TPI and LM% in the relationship between meat consumption and MSI. All analyses were adjusted for age, sex, and socioeconomic level, identified through a directed acyclic graph. Additional analyses were performed with a small subsample including alcohol intake, tobacco smoking, physical activity, cardiorespiratory fitness, and total energy intake as covariates in the multiple mediation models.

RESULTS

A total of 230 students (mean age 21.1 ± 2.1 years, 66.5% women) were included in the analysis. Young adults with higher meat consumption (total, red, and white and fish) had higher MSI adjusted means than their peers with lower meat consumption (p < 0.05). These associations did not remain after controlling for TPI and LM%. In adjusted mediation analyses, a significant indirect effect was observed through TPI and LM% in the associations between each of the types of meat consumption and MSI. In the additional analyses, a greater effect of white and fish meat consumption on muscle strength through mediation of TPI and LM% was reported compared to red or processed meat consumption, and no significant effects were observed between processed meat consumption and MSI.

CONCLUSION

Higher consumption of total, red, and white and fish meat was associated with increased MSI in young adults. TPI and LM% mediated this relationship.

'I eat to not die': Diet and exercise experiences of older adults living alone

INTRODUCTION

Living alone is a critical health risk factor among older adults. Regular exercise and a balanced diet are important for maintaining an independent and healthy life. However, it can be more difficult for older adults living alone to maintain healthy exercise and dietary habits due to their lack of social support. This study aimed to explore the life changes that accompany living alone and their needs, focussing on exercise and diet.

METHODS

This was a qualitative descriptive study. Purposeful sampling was conducted to recruit community-dwelling older adults living alone. Thematic analyses were applied to analyse the qualitative data collected from semistructured interviews.

RESULTS

Fifteen subjects, including 5 men and 10 women, participated in the interviews. The median age was 77 years, ranging from 66 to 88, and the median duration of living alone was 16 years, ranging from 3 to 35. Six main themes were developed, namely unavoidable difficulties of living alone: lack of someone to depend on and loneliness, just eating 'to not die', exercise that is good for health but hard to do consistently, conflict between maintaining independence and dependence on others, coping with available resources, and resources needed for regular exercise and a balanced diet.

CONCLUSION

Living alone leads to poor dietary habits, such as skipping meals or insufficient food intake. Food security should be ensured through the reinforcement of social support, financial assistance and the operation of public cafeterias. In addition, an individually tailored group exercise programme that can meet the need for social interaction and improve self-efficacy would help older adults living alone maintain regular exercise habits.

Association of Protein Intake with Handgrip Strength and Its Relation to Strength Exercise in Korean Adults Aged over 60 Years in the KNHANES (2014-18)

Weak handgrip strength (HGS) is associated with many negative health outcomes in older adults. There is evidence that with strength exercise, high protein intake leads to increased HGS. The goal of this study was to examine the relationship between weak HGS in older adults and dietary protein and it's relation to resistance exercise. Data on 8497 Korean adults aged over 60 years from the Korea National Health and Nutrition Examination Survey (2014-18) were analyzed. Dietary protein intake measured by 24-h recall were categorized as three levels: low (<0.8 g/kg body weight (BW)), adequate (≥0.8 g/kg BW and <1.2 g/kg BW), and high (≥1.2 g/kg BW). Complex sample multiple logistic regression analyses were carried out. The prevalence of weak HGS was 18.3 (0.7)% in men and 28.8 (0.9)% in women. In a multiple logistic regression analysis, low protein intake was significantly associated with higher risk of weak HGS in men, as compared with adequate protein intake, but this relationship was not statistically significant in women. The risk of weak HGS was significantly reduced for both men and women who engaged in strength exercise and increased their dietary protein intake. In this study, based on a representative sample of Koreans aged over 60, men with low protein intake had a higher risk of weak HGS than did men with adequate protein intake. Men and women with a higher protein intake who also engaged in strength exercises had a lower risk of weak HGS. Increasing protein intake and engaging in strength exercises may be an effective way to preserve muscle strength in older men and women.

Is It Time to Reconsider the U.S. Recommendations for Dietary Protein and Amino Acid Intake?

Since the U.S. Institute of Medicine's recommendations on protein and amino acid intake in 2005, new information supports the need to re-evaluate these recommendations. New lines of evidence include: (1) re-analysis/re-interpretation of nitrogen balance data; (2) results from indicator amino acid oxidation studies; (3) studies of positive functional outcomes associated with protein intakes higher than recommended; (4) dietary guidance and protein recommendations from some professional nutrition societies; and (5) recognition that the synthesis of certain dispensable amino acids may be insufficient to meet physiological requirements more often than previously understood. The empirical estimates, theoretical calculations and clinical functional outcomes converge on a similar theme, that recommendations for intake of protein and some amino acids may be too low in several populations, including for older adults (≥65 years), pregnant and lactating women, and healthy children older than 3 years. Additional influential factors that should be considered are protein quality that meets operational sufficiency (adequate intake to support healthy functional outcomes), interactions between protein and energy intake, and functional roles of amino acids which could impact the pool of available amino acids for use in protein synthesis. Going forward, the definition of "adequacy" as it pertains to protein and amino acid intake recommendations must take into consideration these critical factors.

Association of Dental Caries with Muscle Mass, Muscle Strength, and Sarcopenia: A Community-Based Study

OBJECTIVES

Changes in the oral cavity can reflect other changes throughout the body. This study aimed to investigate the association of dental caries with muscle mass, muscle strength, and sarcopenia, and also to describe the microbial diversity, composition, and community structure of severe dental caries and sarcopenia.

DESIGN

Cross-sectional study based on a Chinese population aged from 50 to 85 years.

SETTING

Communities from Lanxi City, Zhejiang Province, China.

PARTICIPANTS

A total of 1,442 participants aged from 50 to 85 years from a general community (62.8% women; median age 61.0 [interquartile range: 55.0, 68.0]).

MEASUREMENTS

Dental caries was assessed by the decayed, missing, and filled teeth (DMFT) index. Sarcopenia was defined as the presence of both low muscle mass (assessed by dual-energy X-ray absorptiometry scanning) and low muscle strength (assessed by handgrip strength). Multivariate logistic regression models were used to analyze the association of dental caries with muscle mass, muscle strength, and sarcopenia. Fecal samples underwent 16S rRNA profiling to evaluate the diversity and composition of the gut microbiota in patients with severe dental caries and/or sarcopenia.

RESULTS

In the fully adjusted logistic models, dental caries was positively associated with low muscle strength (DMFT ≥ 7: OR, 1.61; 95% CI, 1.25-2.06), and sarcopenia (DMFT ≥ 7: OR, 1.51; 95% CI, 1.01-2.26), but not low muscle mass. Severe dental caries was positively associated with higher alpha-diversity indices (richness, chao1, and ACE, all p < 0.05) and associated with beta-diversity based on Bray-Curtis distance (p = 0.006). The severe dental caries group and the sarcopenia group overlapped with 11 depleted and 13 enriched genera.

CONCLUSION

Dental caries was positively associated with low muscle strength and sarcopenia but not muscle mass, and this association was more pronounced in male individuals. Significant differences were observed in gut microbiota composition both in severe dental caries and sarcopenia, and there was an overlap of the genera features. Future longitudinal studies are needed to clarify causal relationships.

Trends in intake and sources of dietary protein in Korean adults, 1998-2018

Although a decrease in carbohydrate intake and an increase in fat intake among Koreans have been reported, investigations of changes in protein intake have been limited. Thus, this study aimed to explore trends in the dietary intake of total, plant and animal proteins overall and by socio-demographic subgroups in Korea over the past two decades. A total of 78 716 Korean adults aged ≥ 19 years who participated in the seven survey cycles of the Korea National Health and Nutrition Examination Survey 1998-2018 were included. Dietary protein intake, overall and by source, was calculated using a single 24-h dietary recall data. Changes in dietary protein over 20 years were estimated using multiple linear regression analysis after adjusting for potential covariates. For total protein intake, a significant decrease was reported from 1998 to 2016-2018 (P for trend_linearity < 0·001), whereas an increasing trend was observed from 2007-2009 to 2016-2018 (P for trend_linearity < 0·001). In terms of protein intake by source, plant protein intake decreased while animal protein intake increased over the past two decades, indicating steeper trends during the recent decade (P for trend_linearity < 0·001). These trends were more pronounced among younger adults and those with higher household income and education levels. These findings suggest that continuous monitoring of dietary protein intake overall and by source (plant v. animal) across socio-demographic group is needed.

Associations between dietary magnesium intake and handgrip strength were modified by serum vitamin D level among the US elderly

Objective

The present study aimed to evaluate the associations between dietary magnesium intake and handgrip strength, and whether these associations were affected by serum vitamin D status.

Methods

A total of 2,127 participants aged 60 and above from the National Health and Nutrition Examination Survey (NHANES) of the 2011-2014 cycles were included in the analyses. Magnesium intake was obtained by 24-h dietary recalls and 30-day dietary supplement. Participants in the lowest sex-specific tertile of magnesium intake were defined as having low magnesium intake. Serum 25-hydroxyvitamin D [25(OH)D)] concentrations were examined by using ultra-high performance liquid chromatography tandem mass spectrometry and categorized into three levels: deficient, suboptimal, and sufficient. Handgrip strength was determined by using a dynamometer. Multivariable linear regression models were used to investigate the associations between dietary magnesium intake and handgrip strength.

Results

Low magnesium intake was not associated with handgrip strength, but interactions between low magnesium intake and serum 25(OH)D level existed on handgrip strength. The stratified analyses found that only in participants with deficient serum 25(OH)D, low magnesium intake was associated with reduced handgrip strength. The combined analyses shown that participants with both low magnesium intake and deficient serum 25(OH)D had highest decrease of handgrip strength.

Conclusion

Findings suggested that low magnesium intake was associated with reduced handgrip strength only in participants with deficient serum 25(OH)D. Increased magnesium intake was recommended for participants with deficient serum 25(OH)D in maintaining muscle strength.

Triglyceride Level- and MTHFR- Specific Mediation Effect of Handgrip Strength on the Association of Dietary Protein Intake and Cognitive Function in the Chinese Elderly

BACKGROUND

Recent findings suggest that both dietary protein intake and hand grip strength (HGS) were associated with cognitive function, however, few studies have been devoted specifically to the mediation effect of HGS on the association of dietary protein with cognitive function.

OBJECTIVES

To confirm the hypothesis that HGS mediated the association of dietary protein intake with cognitive function in the elderly, which was modified by triglyceride level and methylenetetrahydrofolate reductase (MTHFR) gene status.

METHODS

This cross-sectional study included 3,268 participants. Dietary protein intake, HGS, and cognitive function were collected by food frequency questionnaires (FFQ), grip measurements and mini mental state examination (MMSE), respectively. In this mediation analysis, dietary protein intake was entered as independent variable, HGS was entered as mediator, and cognitive function was entered as dependent variable.

RESULTS

HGS significantly mediated the associations of dietary protein (β = 0.0013, 95% CI: 0.0007, 0.0022), animal protein (β = 0.0024, 95% CI: 0.0012, 0.0037), and plant protein intake (β = 0.0011, 95% CI: 0.0001, 0.0023) with cognitive function in total participants, with the mediated proportion of 16.19%, 12.45% and 20.57%, respectively. Furthermore, significant mediation effects of HGS on the associations of dietary protein, animal protein, and plant protein intake with MMSE score were found in the elderly without hypertriglyceridemia or in MTHFR C677T CC/CT carriers.

CONCLUSION

This study suggested that HGS mediated the association of dietary protein intake with cognitive function, and this mediation effect was modified by triglyceride level and MTHFR C677T gene status.

Sex and Diet-Related Disparities in Low Handgrip Strength among Young and Middle-Aged Koreans: Findings Based on the Korea National Health and Nutrition Examination Survey (KNHANES) from 2014 to 2017

“Possible sarcopenia” may be defined as a low muscle strength assessed by handgrip strength (HGS) by sex. We examined the sex-specific association between low handgrip strength (LGS) and dietary factors for the prevention of sarcopenia in young and middle-aged Koreans. We used data from the 2014–2017 Korea National Health and Nutrition Examination Survey of 11,635 Korean adults with LGS and normal handgrip strength (NGS). The relationship between dietary factors, e.g., nutrients, foods, and dietary patterns, and HGS was evaluated by multivariate logistic regression analyses. In men, the LGS group had a higher proportion of energy from carbohydrates and a lower proportion of energy from proteins than the NGS group. The LGS group had lower protein, niacin, phosphorus, and iron densities in their diet than the NGS group. The odds of having LGS increased as intake of vitamin B1 (odds ratio (OR) 2.916, 95% confidence interval (CI) 1.265–6.719), niacin (OR 2.286, 95% CI 1.095–4.774), phosphorus (OR 2.731, 95% CI 1.036–7.199), and iron (OR 2.591, 95% CI 1.102–6.088) decreased. In women with LGS, the odds of insufficient protein intake (OR 1.976, 95% CI 1.248–3.127) was significantly higher. This study suggests that adequate intake of protein, vitamin B1, niacin, phosphorus, and iron is beneficial for maintaining HGS.

The partner in the plate: the association between changes in partnership status and protein consumption among older people in Europe

Experiencing a change in partnership status at older ages might have detrimental effects on an individual's habits, including eating behaviours. Prior studies presented evidence that widowhood is related to altered diets with a decrease in the amount of protein consumed, which is considered to be an important risk factor of frailty among older people. Using data from Waves 4–8 of the Survey of Health, Ageing and Retirement in Europe (N = 134,313), we investigate the association between stability and changes in partnership status and changes in the frequency of protein consumption at older ages. We also explore the potential moderating role played by changes in economic resources. Having never been married, being divorced and being widowed were significantly associated with a lower frequency of protein consumption among both men and women. The transition to widowhood was significantly associated with a reduction in the frequency of protein consumption, while this same association was not found in the transition to divorce. Subjective evaluation of economic resources did not moderate the relationship between changes in partnership status and frequency of protein consumption. In short, changes in eating behaviours after having experienced the loss of a partner due to widowhood might contribute to accounting for health differentials between those ageing alone and those with a partner.

Management of Sarcopenia in Patients with Rheumatoid Arthritis

This review summarizes the evidence for the management of sarcopenia in patients with rheumatoid arthritis (RA) in terms of drugs, exercise, and nutrition. Sarcopenia is a decrease in skeletal muscle mass and muscle strength or physical function. The prevalence of sarcopenia in patients with RA is higher than that in the general population. The treatment and management of sarcopenia in patients with RA are clinically important for long-term prognosis. One of the mechanisms of muscle metabolism is the pro-inflammatory cytokine pathway, which involves tumour necrosis factor α (TNF-α) and interleukin 6 (IL-6), and is a common pathway in the pathogenesis of RA. Thus, TNF-α and IL-6 inhibitors may play a potential role in controlling sarcopenia. In exercise therapy, a combination of moderate resistance and aerobic exercise may be effective in improving muscle strength, muscle mass, and physical function; however, intense exercise may exacerbate the inflammatory response in RA. Regarding nutrition, protein intake is generally considered beneficial, but other nutrients such as vitamin D and carotenoids have also been studied. Overall, there remains a lack of concrete evidence on sarcopenia treatment and management in patients with RA from any perspective; more longitudinal and intervention studies are needed in the future.

Relative protein intake and associations with markers of physical function in those with type 2 diabetes

AIMS

To examine the independent associations between relative protein intake (g kg^-1  day ¹ ) and markers of physical function in those with type 2 diabetes, while also comparing with current guidelines for protein intake.

METHODS

This analysis reports data from the ongoing Chronotype of Patients with Type 2 Diabetes and Effect on Glycaemic Control (CODEC) study. Functional assessments included: Short Physical Performance Battery (SPPB), 60 s sit-to-stand (STS-60), 4-m gait speed, time to rise from a chair (×5) and handgrip strength. Participants also completed a self-reported 4 day diet diary. Regression analyses assessed whether relative protein intake was associated with markers of physical function. Interaction terms assessed whether the associations were modified by sex, age, HbA1c or body mass index (BMI).

RESULTS

413 participants were included (mean ± SD:age = 65.0 ± 7.7 years, 33% female, BMI = 30.6 ± 5.1 kg/m² ). The average total protein intake was 0.88 ± 0.31 g kg^-1  day^-1 . 33% of individuals failed to meet the reference nutrient intake for the United Kingdom (≥0.75 g kg^-1  day^-1 ), and 87% for European recommendations (≥1.2 g kg^-1  day^-1 ). After adjustment, each 0.5 g/kg of protein intake was associated with an 18.9% (95% CI: 2.3, 35.5) higher SPPB score, 22.7% (1.1, 44.3) more repetitions in STS-60, 21.1% (4.5, 37.7) faster gait speed and 33.2% (16.9, 49.5) lower chair rise time. There were no associations with handgrip strength or any interactions.

CONCLUSIONS

Relative protein intake was positively associated with physical function outcomes, even after consideration of total energy intake. As a number of individuals were below the current guidelines, protein intake may be a modifiable factor of importance for people with type 2 diabetes.

Pea Peptide Supplementation in Conjunction With Resistance Exercise Promotes Gains in Muscle Mass and Strength

It is generally considered that protein supplementation and resistance exercise significantly increase muscle mass and muscle growth. As the hydrolysis products of proteins, peptides may play the crucial role on muscle growth. In this study, male rats were orally administrated 0.4 g/kg body weight of pea peptide combined with 8 weeks of moderate intensity resistance exercise training. After treatment, the body gains, upper limb grip, muscle thickness, and wet weight of biceps brachii were tested, and the cross-sectional area of biceps brachii muscle fiber and the types of muscle fibers were determined by HE staining, immunofluorescence staining, and lactate dehydrogenase activity, respectively. Western blot analysis was used to investigate the level of growth-signaling pathway-related proteins. The results showed that pea peptide supplementation combined with resistance exercise training significantly increased body weight, upper limb grip, muscle thickness, wet weight of biceps brachii, and cross-sectional area of muscle fiber. Meanwhile, pea peptide supplementation obviously elevated the ratio of fast-twitch fiber (type II) and the expression of muscle growth-signaling pathway-related proteins. In addition, the PP2 oligopeptide in pea peptide with the amino acid sequence of LDLPVL induced a more significant promotion on C2C12 cell growth than other oligopeptides.

Protein intake, physical activity and grip strength in European and North American community-dwelling older adults: a pooled analysis of individual participant data from four longitudinal ageing cohorts

INTRODUCTION

Higher dietary protein, alone or in combination with physical activity (PA), may slow the loss of age-related muscle strength in older adults. We investigated the longitudinal relationship between protein intake and grip strength, and the interaction between protein intake and PA, using four longitudinal ageing cohorts.

METHODS

Individual participant data from 5584 older adults (52% women; median: 75, IQR: 71.6, 79.0 years) with up to 8.5 years (mean: 4.9, SD: 2.3 years) of follow-up from the Health ABC, NuAge, LASA and Newcastle 85+ cohorts were pooled. Baseline protein intake was assessed with food frequency questionnaires and 24h recalls and categorized into <0.8, 0.8-<1.0, 1.0-<1.2 and ≥1.2 g/kg adjusted body weight (aBW)/d. The prospective association between protein intake, its interaction with PA, and grip strength (sex- and cohort-specific) was determined using joint models (hierarchical linear mixed effects and a link function for Cox proportional hazards models).

RESULTS

Grip strength declined on average by 0.018 SD (95%CI: -0.026, -0.006) every year. No associations were found between protein intake, measured at baseline, and grip strength, measured prospectively, or rate of decline of grip strength in models adjusted for sociodemographic, anthropometric, lifestyle and health variables (e.g., protein intake ≥1.2 vs <0.8 g/kg aBW/d: β= -0.003, 95%CI: -0.014,0.005 SD per year). There also was no evidence of an interaction between protein intake and PA.

CONCLUSIONS

We failed to find evidence in this study to support the hypothesis that higher protein intake, alone or in combination with higher PA, slowed the rate of grip strength decline in older adults.

Sarcopenia definition: Does it really matter? Implications for resistance training

The loss of muscle mass, strength and function, known as sarcopenia, is common in older adults, and is associated with falls, fractures, cardiometabolic diseases, and lower quality of life. Sarcopenia can also occur secondarily to chronic diseases. Recently, sarcopenia was recognized as a disease with an International Classification of Disease (ICD) code, yet, at least five definitions for its clinical identification exist. Most definitions include three themes: low muscle mass, strength and physical performance. However, the definitions vary by the number of themes needed to diagnose sarcopenia and, within each theme various parameters and cut-off levels exist. The lack of consensus on what constitutes a diagnosis can create confusion and hesitation in sarcopenia diagnosis. Currently, no pharmacological treatment exists for sarcopenia. Resistance training (RT) is safe and effective to improve muscle mass, strength and physical performance in older adults and clinical populations. Based on current guidelines, whether an individual is defined as "sarcopenic", or not, does not change the way RT is prescribed. Here, we present evidence and the inconsistencies in sarcopenia definitions and recommend that focus should be on optimizing ways to prescribe RT and increase long-term adherence, rather than on slight modifications to sarcopenia definitions.

Association of Dietary Protein Intake and Grip Strength Among Adults Aged 19+ Years: NHANES 2011–2014 Analysis

Background

Research on the role of protein in the diet has evolved beyond a focus on quantity to include the impact of its quality and distribution across meal times in an effort to optimize dietary protein recommendations.

Objective

To determine the association of dietary protein amount, type, and intake pattern with grip strength in adults.

Design

Data from the National Health and Nutrition Examination Survey (NHANES) 2011–2014 for adults 19 + years (N = 9,214) were used with exclusions for pregnant and lactating women. Intakes of dietary total protein (TP), animal protein (AP, including dairy), plant protein (PP), and leucine (Leu) were determined using day 1 24 h dietary recall data after adjusting for the complex sample design of NHANES. Regression analyses were used to assess the association of dietary protein and leucine intake quartiles, and whether consuming &gt; 20 g of dietary protein at one or more meals was related to grip strength with adjustment for age, gender, and ethnicity.

Results

Mean intake of TP among adults aged 19 + years was 83.6 ± 0.5 g/day, and 2/3rd of this was from animal sources (including dairy). Grip strength increased (p &lt; 0.05) with increasing quartiles of TP, AP, PP, and leucine among all adults 19 + years (β = 1.340.19, 1.27 ± 0.19, 0.76 ± 0.20, and 1.33 ± 0.23, respectively), 19–50 years (β = 1.14 ± 0.27, 1.06 ± 0.25, 0.77 ± 0.30, and 1.18 ± 0.27, respectively), and 51 + years (β = 0.95 ± 0.26, 1.08 ± 0.27, and 1.05 ± 0.27, respectively, for TP, AP, and Leu); however, the increase was more pronounced for AP than PP. Grip strength also increased (p &lt; 0.05) with increasing the number of meal occasions containing &gt; 20 g of dietary protein (β = 1.50 ± 0.20, 1.41 ± 0.25, and 0.91 ± 0.37 for 19+, 19–50, and 51 + years, respectively), and significant increases were detected for two meals compared to zero meals.

Conclusion

Dietary protein quantity, quality, and distribution should be considered collectively when looking to optimize protein intake to support muscle strength and function.

The effect of animal versus plant protein on muscle mass, muscle strength, physical performance and sarcopenia in adults: protocol for a systematic review

BACKGROUND

The evidence base for the role of dietary protein in maintaining good muscle health in older age is strong; however, the importance of protein source remains unclear. Plant proteins are generally of lower quality, with a less favourable amino acid profile and reduced bioavailability; therefore, it is possible that their therapeutic effects may be less than that of higher quality animal proteins. This review aims to evaluate the effectiveness of plant and animal protein interventions on muscle health outcomes.

METHODS

A robust search strategy was developed to include terms relating to dietary protein with a focus on protein source, for example dairy, meat and soy. These were linked to terms related to muscle health outcomes, for example mass, strength, performance and sarcopenia. Five databases will be searched: MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, Embase and Web of Science. Studies included will be randomised controlled trials with an adult population (≥ 18) living in the community or residential homes for older adults, and only English language articles will be included. Two independent reviewers will assess eligibility of individual studies. The internal validity of included studies will be assessed using Cochrane Risk of Bias 2.0 tool. Results will be synthesised in narrative format. Where applicable, standardised mean differences (SMD) (95% confidence interval [CI]) will be combined using a random-effects meta-analysis, and tests of homogeneity of variance will be calculated.

DISCUSSION

Dietary guidelines recommend a change towards a plant-based diet that is more sustainable for health and for the environment; however, reduction of animal-based foods may impact protein quality in the diet. High-quality protein is important for maintenance of muscle health in older age; therefore, there is a need to understand whether replacement of animal protein with plant protein will make a significant difference in terms of muscle health outcomes. Findings from this review will be informative for sustainable nutritional guidelines, particularly for older adults and for those following vegan or vegetarian diets.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD420201886582.

Association between total protein intake and low muscle mass in Korean adults

Background

Adults with low muscle mass have a poor prognosis. Studies that examined the association between total protein intake and low muscle mass among adults are limited. Thus, we investigated the association between total protein intake and low muscle mass among Korean adults aged ≥19 years.

Methods

We included 15,995 adults (6528 male and 9467 female) aged ≥19 years from the Korea National Health and Nutrition Examination Surveys (2008–2011). We divided the participants into groups according to protein intake quartile: Q1, Q2, Q3 and Q4 groups. The odds ratios (ORs) and 95% confidence intervals (CIs) of low muscle mass according to protein intake were analysed via multivariable logistic regression analysis. Stratified analyses according to sex, age and comorbidities were also performed.

Results

Of the participants, 3.8% had weight-adjusted low muscle mass. The prevalence rates of low muscle mass were 1.5, 3.0, 3.9 and 7.2% in the Q4, Q3, Q2 and Q1 groups, respectively (p < 0.001). Compared with the Q4 group, the Q1 group had the highest ORs for low muscle mass, followed by the Q2 and Q3 groups (Model 5; OR, 95% CI: 2.03, 1.36–3.02 for Q3; 2.44, 1.64–3.61 for Q2; and 4.32, 2.89–6.45 for Q4) after adjusting for confounding variables (p for trend < 0.001). The associations between protein intake and low muscle mass were stronger in younger individuals, men, individuals without hypertension, those with diabetes mellitus and those without dyslipidemia.

Conclusions

The prevalence of low muscle mass in Korean adults significantly increased with lower protein intake. Nutrition education for proper protein intake is also important for adults.

Trial registration

Retrospectively registered.

Perspective: Vegan Diets for Older Adults? A Perspective On the Potential Impact On Muscle Mass and Strength

Consumers are increasingly encouraged to consume more plant-based foods and lower their consumption of foods from animal origin. Concurrently, older adults are recommended to consume an adequate amount of high-quality dietary protein for the prevention of age-related muscle loss. In the current Perspective article, we discuss why it may not be preferred to consume a vegan diet at an older age. Our perspective is based on the proposed lower bioavailability and functionality of proteins in a vegan diet due to the matrix of the whole-food protein sources, the lower essential amino acid (EAA) content, and specific EAA deficiencies in proteins derived from plant-based foods. We propose that a vegan diet increases the risk of an inadequate protein intake at an older age and that current strategies to improve the anabolic properties of plant-based foods are not feasible for many older adults. We provide recommendations for further research to substantiate the remaining knowledge gaps regarding the consequences of a vegan diet on skeletal muscle mass and strength at an older age.

Individually tailored nutritional guidance improved dietary intake of older family caregivers: a randomized controlled trial

PURPOSE

Older family caregivers (FCs) are vulnerable to insufficient dietary intake and risk of malnutrition. The aim of this study was to assess the impact of individually tailored nutritional guidance on the dietary intake and nutritional status of older FCs and their care recipients' (CRs') nutritional status.

METHODS

This study was a randomized controlled 6-month nutrition intervention in Eastern Finland. The inclusion criteria for FCs were having a home-living CR aged 65 or above and a valid care allowance. The exclusion criterion was CR receiving end-of-life care at baseline. Participants were randomly assigned to an intervention (FCs n = 63, CRs n = 59) and a control (FCs n = 50, CRs n = 48) group. Individually tailored nutritional guidance targeted to FCs was given to an intervention group by a clinical nutritionist. The main outcomes were dietary intake (3-day food record).

RESULTS

After the 6-month intervention, 63 FCs and 59 CRs in the intervention group and 50 FCs and 48 CRs in the control group were analyzed. In the intervention group of FCs, the intakes of protein, riboflavin, calcium, potassium, phosphorus, and iodine differed significantly (p < 0.05) compared to the control group. In addition, the intake of vitamin D supplementation improved in the intervention group of the FCs and CRs (p < 0.001).

CONCLUSION

Individually tailored nutrition guidance improves the intake levels of crucial nutrients, such as the intake levels of protein, vitamin D, and calcium of the FCs. Further studies are warranted to optimize the methods to improve the nutrition of FCs. Registration number of Clinical Trials: ClinicalTrials.gov NCT04003493 (1 July 2019).

Intakes of Total and Branched-Chain Essential Amino Acids are Positively Associated with Handgrip Strength in African American and White Urban Younger and Older Adults

Essential amino acids (EAAs) initiate amino acid-induced stimulation of muscle protein synthesis. Study objectives were to calculate intake of EAAs after creating an EAA database, to explore the association of EAAs and branched-chain amino acids (BCAAs) with handgrip strength (HS) in a younger (<50 y) and older (≥50 y) sample, and to identify major food groups contributing EAAs. The sample consisted of African American and White adults aged, 33-71 years from the Healthy Aging in Neighborhoods of Diversity across the Life Span study, 2009-2013. Intake of total EAAs and BCAAs/kg body weight were positively associated (p < 0.001) with HS per body mass index (HS/BMI) ratio. Being male, African American, a nonsmoker, physically active, euglycemic, and normotensive were associated with higher HS/BMI ratio. EAAs were mainly obtained from red meats/poultry and mixed dishes groups. Findings support the role of high-quality proteins and being active in promoting HS.

A review of recent evidence of dietary protein intake and health

The Korea National Health and Nutrition Examination Survey of 2013 to 2017 reported that the average protein consumption of the Korean population is above the current recommended nutrient intake of protein proposed by the Dietary Reference Intakes for Koreans. Some health professionals and the media often advise consuming diets high in protein for promoting metabolic regulation, weight control, and muscle synthesis. However, due to lack of scientific evidence, the validity and safety of high protein consumption are yet to be fully ascertained. The present review assesses recent evidence published in 2014–2020 from human studies, focusing on adequate protein intake and protein sources for the prevention of chronic diseases, particularly metabolic disorders and sarcopenia.

Positive Association between High Protein Food Intake Frequency and Physical Performance and Higher-Level Functional Capacity in Daily Life

Nutritional factors, including low protein intake and poor dietary variety, affect age-associated impairment in physical performance resulting in physical frailty. This cross-sectional study investigated the association between intake frequency of major high protein foods and both physical performance and higher-level functional capacity using the food frequency score (FFS) and high protein food frequency score (PFFS) among community-dwelling older adults. The data of 1185 older adults categorized into quartiles based on FFS and PFFS were analyzed. After adjusting for covariates, FFS and PFFS were significantly associated with physical performance [FFS, usual gait speed (p for trend = 0.007); PFFS, usual gait speed (p for trend < 0.001), maximum gait speed (p for trend = 0.002), timed up and go (p for trend = 0.025)], and higher-level functional capacity [FFS (p for trend < 0.001); PFFS (p for trend < 0.001)]. After excluding PFFS data, the participants’ scores were associated with only higher-level functional capacity. Multi-regression analysis with higher-level functional capacity as the covariate showed that FFS and PFFS were significantly correlated with physical performance. Hence, improving food intake frequency, particularly that of high protein foods, and dietary variety may help maintain higher-level functional capacity and physical performance in community-dwelling older adults.

Major dietary patterns in relation to muscle strength status among middle-aged people: A cross-sectional study within the RaNCD cohort

Grip strength in midlife can predict physical disability in senior years. Recent evidence shows the critical role of nutritional status on muscle function. We aimed to elucidate whether adherence to a particular dietary pattern would be associated with abnormal muscle strength among middle-aged people. In this cross-sectional study, a semiquantitative Food Frequency Questionnaire was used to assess the dietary intake of 2781 participants in the Ravansar Non-Communicable Chronic Disease (RaNCD) cohort. Major dietary patterns from 28 main food groups were extracted using principal component analysis. Binary logistic regression was used to determine the association between the tertiles of the major dietary patterns and muscle strength status. Two major dietary patterns were identified: the "mixed dietary pattern" that heavily loaded with fruits, vegetables, nuts, dairies, sweets, legumes, dried fruits, fish, red meat, butter, whole grains, natural juices, poultry, pickles, olive, industrial juice, egg, processed meat, and snacks and "unhealthy dietary pattern" that heavily loaded by fats, sugar, refined grains, soft drink, salt, organ meat, tea, and coffee. Adherence to the mixed dietary pattern (OR = 1.03, 95% CI = 0.8-1.33, P for trend = 0.77) and the unhealthy dietary pattern (OR = 1.01, 95% CI = 0.79-0.13, P for trend = 0.89) did not associate with abnormal muscle strength. This study suggests that the dietary pattern involving the consumption of healthy and unhealthy food does not have an effect on muscle strength in middle-aged adults.

Animal protein intake is inversely associated with mortality in older adults: the InCHIANTI study

BACKGROUND

In general, plant protein intake was inversely associated with mortality in studies in middle-aged adults. Our aim was to evaluate the long-term associations of animal and plant protein intake with mortality in older adults.

METHODS

A prospective cohort study including 1,139 community-dwelling older adults (mean age 75 years, 56% women) living in Tuscany, Italy, followed for 20 years (InCHIANTI study) was analyzed. Dietary intake by food frequency questionnaires and clinical information were assessed five times during the follow-up. Protein intakes were expressed as percentages of total energy. Time-dependent Cox regression models adjusted for confounders were used to assess the association between plant and animal protein intake, and mortality.

RESULTS

During the 20-years of follow up (mean: 12y), 811 deaths occurred (292 of cardiovascular- and 151 of cancer-related causes). Animal protein intake was inversely associated with all-cause (HR per 1% of total energy from protein increase, 95%CI: 0.96, 0.93-0.99) and cardiovascular mortality (HR per 1% of total energy from protein increase, 95%CI: 0.93, 0.87-0.98). Plant protein intake showed no association with any of the mortality outcomes, but an interaction with baseline hypertension was found for all-cause and cardiovascular mortality (p<0.05).

CONCLUSIONS

Animal protein was inversely associated with all-cause and cardiovascular mortality in older adults. Further studies are needed to provide recommendations on dietary protein intake for older adults.

Does the combination of resistance training and a nutritional intervention have a synergic effect on muscle mass, strength, and physical function in older adults? A systematic review and meta-analysis

BACKGROUND

Health-promoting interventions are important for preventing frailty and sarcopenia in older adults. However, there is limited evidence that nutritional interventions yield additional effects when combined with resistance training. This systematic review and meta-analysis aimed to compare the effectiveness of nutritional interventions with resistance training and that of resistance training alone.

METHODS

Randomized controlled trials published in peer-reviewed journals prior to July 2020 were retrieved from databases and other sources. The articles were screened according to the inclusion and exclusion criteria. The methodological quality of the included studies was assessed using Cochrane's risk of bias tool 2. A meta-analysis was performed using the RevMan 5.4 program and STATA 16 program.

RESULTS

A total of 22 studies were included in the meta-analysis. The results of the meta-analysis showed no significant differences between groups in muscle mass, muscle strength, or physical functional performance. In the subgroup analysis regarding the types of nutritional interventions, creatine showed significant effects on lean body mass (n = 4, MD 2.61, 95% CI 0.51 to 4.72). Regarding the other subgroup analyses, there were no significant differences in appendicular skeletal muscle mass (p = .43), hand grip strength (p = .73), knee extension strength (p = .09), chair stand test results (p = .31), or timed up-and-go test results (p = .31). In the meta-regression, moderators such as the mean age of subjects and duration of interventions were not associated with outcome variables.

CONCLUSIONS

This meta-analysis showed that nutritional interventions with resistance training have no additional effect on body composition, muscle strength, or physical function. Only creatine showed synergistic effects with resistance training on muscle mass.

TRIAL REGISTRATION

CRD42021224843 .

Healthy Eating Index-2015 Is Associated with Grip Strength among the US Adult Population

The Healthy Eating Index-2015 (HEI-2015) was designed to reflect adherence to the 2015-2020 Dietary Guidelines for Americans (DGA). The study aims to examine the association between HEI-2015 and grip strength in a nationally representative sample of the U.S. adult population. This cross-sectional study used data from the National Health and Nutrition Examination Surveys of 2011-2014. Low grip strength was defined as <35.5 kg for men and <20 kg for women. HEI-2015 was computed from two days of 24-h dietary recalls and comprised 13 components. Each component was scored on the density out of 1000 calories and summed to a total score divided into quartiles. Weighted logistic regressions examined the study aim while controlling for associated covariates. The sample included 9006 eligible participants, of those, 14.4% (aged 20+ years), and 24.8% (aged ≥50 years) had low grip strength. Mean (±SD) HEI-2015 total score was 54.2 ± 13.6 and in the lowest and highest quartiles 37.3 ± 5.1 and 72.0 ± 6.5, respectively. In the multivariable model, participants in the highest vs. lowest HEI-2015 quartile had 24% lower odds of having low grip strength (Odds Ratio (OR) = 0.76; 95% CI: 0.60-0.96). Specifically, participants who met the DGA for protein intakes, whole grains, greens and beans, vegetables, or whole fruits had 20-35% lower odds of having low grip strength than those who did not. Higher compliance to the DGA might reduce the risk for low grip strength as a proxy measure for sarcopenia among U.S. adults, particularly adequate intakes of proteins, whole grains, greens and beans, vegetables, and whole fruits.

A poor appetite or ability to eat and its association with physical function amongst community-dwelling older adults: age, gene/environment susceptibility-Reykjavik study

A poor appetite or ability to eat and its association with physical function have not been explored considerably amongst community-dwelling older adults. The current study examined whether having an illness or physical condition affecting one's appetite or ability to eat is associated with body composition, muscle strength, or physical function amongst community-dwelling older adults. This is a secondary analysis of cross-sectional data from the age, gene/environment susceptibility-Reykjavik study (n = 5764). Illnesses or physical conditions affecting one's appetite or ability to eat, activities of daily living, current level of physical activity, and smoking habits were assessed with a questionnaire. Fat mass, fat-free mass, body mass index, knee extension strength, and grip strength were measured, and the 6-m walk test and timed up-and-go test were administered. Individuals who reported illnesses or physical conditions affecting their appetite or ability to eat were considered to have a poor appetite. The associations of appetite or the ability to eat with body composition and physical function were analysed with stepwise linear regression models. A total of 804 (14%) individuals reported having conditions affecting their appetite or ability to eat and had a significantly lower fat-free mass and body mass index, less grip strength, and poorer physical function than did those without any conditions affecting their appetite or ability to eat. Although the factors reported to affect one's appetite or ability to eat are seldom considered severe, their strong associations with physical function suggest that any condition affecting one's appetite or ability to eat requires attention.

Comparative Assessment of the Acute Effects of Whey, Rice and Potato Protein Isolate Intake on Markers of Glycaemic Regulation and Appetite in Healthy Males Using a Randomised Study Design

Global protein consumption has been increasing for decades due to changes in demographics and consumer shifts towards higher protein intake to gain health benefits in performance nutrition and appetite regulation. Plant-derived proteins may provide a more environmentally sustainable alternative to animal-derived proteins. This study, therefore, aimed to investigate, for the first time, the acute effects on glycaemic indices, gut hormones, and subjective appetite ratings of two high-quality, plant-derived protein isolates (potato and rice), in comparison to a whey protein isolate in a single-blind, triple-crossover design study with nine male participants (30.8 ± 9.3 yrs). Following a 12 h overnight fast, participants consumed an equal volume of the three isocaloric protein shakes on different days, with at least a one-week washout period. Glycaemic indices and gut hormones were measured at baseline, then at 30, 60, 120, 180 min at each visit. Subjective palatability and appetite ratings were measured using visual analogue scales (VAS) over the 3 h, at each visit. This data showed significant differences in insulin secretion with an increase in whey (+141.8 ± 35.1 pmol/L; p = 0.011) and rice (−64.4 ± 20.9 pmol/L; p = 0.046) at 30 min compared to potato protein. A significantly larger total incremental area under the curve (iAUC) was observed with whey versus potato and rice with p < 0.001 and p = 0.010, respectively. There was no significant difference observed in average appetite perception between the different proteins. In conclusion, this study suggests that both plant-derived proteins had a lower insulinaemic response and improved glucose maintenance compared to whey protein.

Association between dietary protein intake and change in grip strength over time among adults of advanced age: Life and Living in Advanced Age: A Cohort Study in New Zealand (LiLACS NZ)

OBJECTIVE

To determine the association between dietary protein intake and change in grip strength (GS) over time among Māori and non-Māori of advanced age.

METHODS

Protein intake was estimated from 2×24h multiple pass recall (MPR) in 554 participants, and GS was measured yearly over five years. Anthropometric, physical activity and health data were collected.

RESULTS

The median weight-adjusted protein intake was low (for Māori and non-Māori men 1.05 and 0.98g/kg/day; for Māori and non-Māori women 0.87 and 0.91g/kg/day, respectively). There was a general decrease in GS over five years (mean % change of -2.38 ± 15.32 and -4.49 ± 21.92 for Māori and non-Māori women and -5.47 ± 16.09 and -1.81 ± 13.16 for Māori and non-Māori men yearly). Intake of protein was not related to GS at any of the five-year assessment points nor was it related to change over time.

CONCLUSION

Protein intake was low in this cohort of octogenarians and was not protective against loss of GS over five years.

Effects of caloric restriction on human physiological, psychological, and behavioral outcomes: highlights from CALERIE phase 2

Caloric restriction (CR) is a strategy that attenuates aging in multiple nonhuman species. The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) trials are part of a research program aiming to test the effects of CR on aging and longevity biomarkers in humans. Building on CALERIE phase 1, CALERIE phase 2 (CALERIE 2) was the largest study to date to assess sustained CR in healthy humans without obesity. In a 24-month randomized controlled trial comprising 218 participants at baseline, CALERIE 2 showed that moderate CR, 11.9% on average, induced improvements in aging-related biomarkers without adversely affecting psychological or behavioral outcomes. The objectives of this report are to summarize and review the highlights of CALERIE 2 and report previously unpublished results on eating disorder symptoms and cognitive function. This article specifically summarizes the physiological, psychological, aging, behavioral, and safety results of the trial. Also provided are research directions beyond CALERIE 2 that highlight important opportunities to investigate the role of CR in aging, longevity, and health span in humans.

Nutrition in Physical Therapist Practice: Setting the Stage for Taking Action

Diet and nutrition are critical components of health, recovery from disease and illness, performance, and normal growth across the lifespan. Thus, it is important for physical therapists to be knowledgeable about nutrition and to have competency in providing information and guidance to patients/clients. Yet, there is an overwhelming amount of diet and nutrition information available from numerous sources, which makes it difficult to reach conclusions and determine the importance and relevance to patient care. The purpose of this perspective paper is to increase the knowledge and skills of physical therapists by providing guidelines for healthy eating and outlining diet and nutrition information most relevant for physical therapist practice and to clarify professional scope of practice related to diet and nutrition, including boundaries created by law, and the connection between healthy eating and health outcomes, muscle strength, bone health, and wound healing.

Higher Branched-Chain Amino Acid Intake Is Associated with Handgrip Strength among Korean Older Adults

Sarcopenia is a disease of old age characterized by decreased muscle mass and strength. Branched-chain amino acids (BCAAs) promote muscle mass synthesis and increase muscle strength. We aimed to develop a dietary amino acid database and to examine the association between BCAA intake and handgrip strength in Korean older adults. Data from the Korea National Health and Nutrition Examination Survey 2014–2018 were used. Overall, 4852 participants aged ≥65 years were included in the study. Demographic, lifestyle, and health data were obtained through interviews and questionnaires. The 24-h recall method was used to assess dietary intake. An amino acid database was established using the 9th revision of the Korean Standard Food Composition Table. The mean handgrip strength was estimated from triplicate measurements obtained using the dominant hand. Multivariable linear regression analysis was performed to assess the association between BCAA intake and handgrip strength. Grains greatly contributed to amino acid intake; however, a significant negative association was observed between handgrip strength and increased BCAA intake through grains. In the fully adjusted model, leucine intake and handgrip strength showed a positive association. Thus, consuming BCAAs (especially leucine) via a variety of food sources can help maintain muscle health in older people.

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.