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

Nutrition as the foundation for successful aging: a focus on dietary protein and omega-3 polyunsaturated fatty acids

Skeletal muscle plays a critical role throughout the aging process. People living with sarcopenia, a progressive and generalized loss of skeletal muscle mass and function, often experience diminished quality of life, which can be attributed to a long period of decline and disability. Therefore, it is important to identify modifiable factors that preserve skeletal muscle and promote successful aging (SA). In this review, SA was defined as (1) low cardiometabolic risk, (2) preservation of physical function, and (3) positive state of wellbeing, with nutrition as an integral component. Several studies identify nutrition, specifically high-quality protein (eg, containing all essential amino acids), and long-chain omega-3 polyunsaturated fatty acids (n-3 PUFAs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), as positive regulators of SA. Recently, an additive anabolic effect of protein and n-3 PUFAs has been identified in skeletal muscle of older adults. Evidence further suggests that the additive effect of protein and n-3 PUFAs may project beyond skeletal muscle anabolism and promote SA. The key mechanism(s) behind the enhanced effects of intake of protein and n-3 PUFAs needs to be defined. The first objective of this review is to evaluate skeletal muscle as a driver of cardiometabolic health, physical function, and wellbeing to promote SA. The second objective is to examine observational and interventional evidence of protein and n-3 PUFAs on skeletal muscle to promote SA. The final objective is to propose mechanisms by which combined optimal intake of high-quality protein and n-3 PUFAs likely play a key role in SA. Current evidence suggests that increased intake of protein above the Recommended Dietary Allowance and n-3 PUFAs above the Dietary Guidelines for Americans recommendations for late middle-aged and older adults is required to maintain skeletal muscle mass and to promote SA, potentially through the mechanistical target of rapamycin complex 1 (mTORC1).

The Impact of Whey Protein Supplementation on Sarcopenia Progression among the Elderly: A Systematic Review and Meta-Analysis

We conducted a systematic literature review and meta-analysis to investigate the role of whey protein supplementation in the functioning of the elderly with sarcopenia. The aim was to investigate the available scientific evidence and determine the best recommendations with respect to whey protein supplementation in sarcopenic patients. Methods: Databases, including CINAHL, Embase PubMed, and Web of Science, were searched from database inception until 31 December 2022 for randomised controlled trials (RCTs) comparing the efficacy of whey protein supplementation in the elderly with sarcopenia. Data on study design, risk of bias, patient, illness, and treatment characteristics from each study were independently extracted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The tool "assessing risk of bias" from the Cochrane Handbook was used to evaluate the quality of the included papers. Results: The search identified 629 records; 590 articles were excluded as duplicates or after evaluation at the title or abstract level. Out of 39 full-text articles that were reviewed, 29 were excluded for not fulfilling the inclusion criteria. There is some evidence that whey protein supplementation combined with age-appropriate physical exercise might improve muscle mass and lower limb function in the elderly with sarcopenia. The present meta-analysis demonstrated overall that whey supplementation does not improve any of the tested sarcopenia-linked parameters. However, we found that study duration (weeks) and age significantly affect the handgrip strength rate and the chair and stand test rate, respectively, so consideration should be given to oral supplementation combined with the age of participants and an appropriate physical activity as a form of sarcopenia prevention in the high-risk group.

Impact of process and composition of formulas for elderly on in vitro digestion using the dynamic DIDGI® model

Due to the lower efficiency of the elderly digestion system, new formulations are needed in order to increase the bioaccessibility of macronutrients. The aim of the work was to evaluate the effect of the process of protein sources production using either liquid (F2) vs spray dried milk proteins (F1/F3) and the source of lipids (vegetable oil (F1) vs mix of vegetable oil + bovine milk cream (F2/F3)) ingredients on the macronutrient digestion of three experimental elderly formulas. The dynamic in vitro digestion model DIDGI®^, was adapted to simulate the digestive conditions of the elderly. An exhaustive review of the literature was carried out in order to simulate as closely as possible the elderly digestive parameters and constituted the starting point towards a consensus in vitro digestion model that will be proposed soon by the INFOGEST scientific network. The three experimental formulas (F1/F2/F3) differing by the composition and process applied were submitted to the DIDGI® dynamic in vitro digestion over four hours using parameters adapted to the elderly. The three formulas were compared in terms of proteolysis and lipolysis. A slight impact of the process (liquid vs spray-dried) on the degree of proteolysis at the end of digestion was observed with 50.8% for F2 compared to 56.8% for F1 and 52.9% for F3 with<5% of difference between the 3 formulas. Concerning the degree of lipolysis, the addition of bovine cream led to a lesser extent of lipolysis with 63.7 and 60.2% for F2 and F3 respectively versus 66.3% for F1 (containing only vegetable oil). Our results highlighted the beneficial input of the milk fat with a higher level of phospholipids and a lower ω6/ω3 PUFA ratio and can be a good alternative to the use of the vegetable fat in drinks for elderly people.

Chinese residents' knowledge about and behavior towards dairy products: a cross-sectional study

BACKGROUND

Chinese residents generally had insufficient intake of dairy products. The correct mastery of dairy related knowledge helps to develop a good habit of dairy intake. Dairy intake and purchasing behavior were related to multiple factors. As an attempt to lay a scientific basis for guiding the rational intake of dairy by Chinese residents, we launched a survey to discover Chinese residents' knowledge about dairy product, intake and purchasing behavior of dairy and its influencing factors.

METHODS

An online survey was conducted from May to June 2021, and 2500 Chinese residents aged 16-65 were selected using the convenient sampling method. A self-designed questionnaire was adopted. Analysis of the demographic and sociological factors influencing Chinese residents' knowledge about dairy products, behavior towards dairy intake and purchasing were measured.

RESULTS

The average score of knowledge about dairy product of Chinese residents was 4.13 ± 1.50 points. 99.7% of the respondents considered that drinking milk was beneficial, whereas only 12.8% gained a correct insight into the specific benefits of drinking milk. 4.6% of the respondents correctly knew what nutrients they could get from milk. 4.0% of the respondents could correctly identify the type of dairy product. 50.5% of the respondents knew that adult should drink at least 300 ml milk per day. Female, young and high-income residents had better dairy knowledge, while residents with lactose intolerance and whose family members do not have a milk-drinking habit had worse dairy knowledge (P < 0.05). On average, Chinese residents consumed 255.61 ± 88.40 ml dairy product per day. The elderly residents, residents with low education level, residents who lived with family members without milk-drinking habits and residents with poor knowledge of dairy product had worse dairy intake behavior (P < 0.05). When purchasing dairy products, young and middle-aged people (54.20% of those aged ≤ 30, 58.97% of those aged 31-44, and 57.08% of those aged 45-59) were most concerned about whether probiotics were added to dairy products. The elderly (47.25%) were most concerned about whether dairy products were low sugar / sugar free. Chinese residents (52.24%) tended to purchase small-packaged dairy products that could be consumed easily anytime and anywhere.

CONCLUSION

Chinese residents had a lack of knowledge regarding dairy products, and their dairy intake was insufficient. We should further strengthen the popularization of dairy product related knowledge, guide residents to choose dairy products correctly, and increase the intake of dairy products by Chinese residents.

Acute Benefits of Acidified Milk Drinks with 10-g and 15-g Protein on Shifting and Updating Performances in Young Adults: A Randomized Controlled Trial

BACKGROUND

Accumulating evidence has shown that protein-rich milk drinks can rapidly improve cognitive performance. However, the optimum doses of milk protein that are needed to improve cognitive function remain to be investigated.

OBJECTIVE

This study aimed to determine whether acidified milk drinks with 10-g and 15-g milk protein have acute benefits on key cognitive functions in healthy young adults.

DESIGN

In this double-blinded randomized control trial, 66 young adults were randomly assigned to one of three groups (0-g, 10-g, and 15-g milk protein groups). Key cognitive functions (processing speed, inhibition, shifting, updating, and working memory capacity) were assessed before and 15 and 60 min after the drink intake.

RESULTS

We found that the shifting performance improved at 15 min after intake of the acidified 10-g and 15-g milk protein drinks compared to intake of the 0-g milk protein drink, and this acute effect of the acidified 15-g milk protein drink lasted for 60 min. In addition, updating performance improved at 60 min after intake of the acidified 10-g and 15-g milk protein drinks compared to intake of the 0-g milk protein drink.

CONCLUSION

Our findings suggest that the acidified 10-g and 15-g milk protein drinks have an acute benefit on shifting and updating performance in healthy young adults.

Raw Eggs To Support Postexercise Recovery in Healthy Young Men: Did Rocky Get It Right or Wrong?

BACKGROUND

Egg protein is ingested during recovery from exercise to facilitate the postexercise increase in muscle protein synthesis rates and, as such, to support the skeletal muscle adaptive response to exercise training. The impact of cooking egg protein on postexercise muscle protein synthesis is unknown.

OBJECTIVES

We sought to compare the impact of ingesting unboiled (raw) compared with boiled eggs during postexercise recovery on postprandial myofibrillar protein synthesis rates.

METHODS

In a parallel design, 45 healthy, resistance-trained young men (age: 24 y; 95% CI: 23, 25 y) were randomly assigned to ingest 5 raw eggs (∼30 g protein), 5 boiled eggs (∼30 g protein), or a control breakfast (∼5 g protein) during recovery from a single session of whole-body resistance-type exercise. Primed continuous l-[ring-13C6]-phenylalanine infusions were applied, with frequent blood sampling. Muscle biopsies were collected immediately after cessation of resistance exercise and at 2 and 5 h into the postexercise recovery period. Primary (myofibrillar protein synthesis rates) and secondary (plasma amino acid concentrations) outcomes were analyzed using repeated-measures (time × group) ANOVA.

RESULTS

Ingestion of eggs significantly increased plasma essential amino acid (EAA) concentrations, with 20% higher peak concentrations following ingestion of boiled compared with raw eggs (time × group: P < 0.001). Myofibrillar protein synthesis rates were significantly increased during the postexercise period when compared with basal, postabsorptive values in all groups (2-4-fold increase: P < 0.001). Postprandial myofibrillar protein synthesis rates were 20% higher after ingesting raw eggs [0.067%/h; 95% CI: 0.056, 0.077%/h; effect size (Cohen d): 0.63], and 18% higher after ingesting boiled eggs (0.065%/h; 95% CI: 0.058, 0.073%/h; effect size: 0.69) when compared with the control breakfast (0.056%/h; 95% CI: 0.048, 0.063%/h), with no significant differences between groups (time × group: P = 0.077).

CONCLUSIONS

The ingestion of raw, as opposed to boiled, eggs attenuates the postprandial rise in circulating EAA concentrations. However, postexercise muscle protein synthesis rates do not differ after ingestion of 5 raw compared with 5 boiled eggs in healthy young men. This trial was registered at the Nederlands Trial Register as NL6506 (www.trialregister.nl).

Prevalence of lactose intolerance and nutrients intake in an older population regarded as lactase non-persistent

BACKGROUND AND AIMS

Energy and nutrient intakes of community-dwelling older adults in Indonesia are inadequate whereby milk consumption is among the lowest in the world. Lactose intolerance is probably one of the reasons for such low milk consumption, but information on the burden of this problem and its consequences for dietary intake is lacking. We obtained data on the prevalence of lactose intolerance and dietary intakes in Indonesian older outpatients, thereby comparing dairy users and non-dairy users.

METHODS

A cross-sectional study was conducted in 2019 involving 103 community-dwelling older adults in the outpatient geriatric clinic, Dr. Cipto Mangunkusumo Hospital, Jakarta. A structured questionnaire was used to categorize participants as dairy- or non-dairy users. Food records were collected to assess nutrients intake from the diet. The prevalence of lactose intolerance (LI) was estimated based on the results of the hydrogen breath test (HBT) and on symptoms of lactose malabsorption. The difference in LI prevalence between dairy- and non-dairy user group was presented as a prevalence ratio (with 95% confidence interval). Chi-square tests, t-test, and Mann-Whitney tests were used to evaluate differences in demographic and clinical characteristics, as well as in nutrient intake profiles between dairy and non-dairy users.

RESULTS

The prevalence of lactose intolerance amounted to 66% (57-75%), 54% (37-70%), and 73% (61-84%) in the total population, dairy- and non-dairy users, respectively. Lactose intolerance tended to be higher among non-dairy users (PR 1.36 95% CI 0.99-1.89). On the other hand, we found no pronounced differences in symptoms of lactose intolerance between dairy and non-dairy users. The overall mean protein, calcium, vitamin D, and vitamin B12 intakes of the older adults were low. Intakes of protein, calcium, vitamin D and vitamin B12 were higher among dairy than among non-dairy users.

CONCLUSIONS

This study uncovered the large size of the lactose intolerance problem in Indonesian older adults. Especially in non-dairy users, the intakes of proteins and some micronutrients are a concern. Strategies to tackle lactose intolerance are most relevant as to open the door for more nutrient-dense foods in the diet of Indonesian older adults.

Prehabilitation for the Anesthesiologist

Prehabilitation aims at enhancing patient’s preoperative functional capacity to better withstand the stress of surgery and recovery.

The Effects of Cow-Milk Protein Supplementation in Elderly Population: Systematic Review and Narrative Synthesis

BACKGROUND

To review currently available evidence on the effect of cow-milk proteins supplementation (CPS) on health in the elderly.

METHODS

Five electronic databases (Pubmed, Web of Science, Embase, Cochrane Library, ClinicalTrials.gov) were searched for studies about CPS among older people. All types of publications were included, with the exception of systematic reviews, meta-analyses, opinion letters, editorials, case reports, conference abstracts and comments. An additional search in Google Scholar and a manual review of the reference lists were performed.

RESULTS

Overall, 103 studies were included. Several studies explored the role of CPS in the preservation or improvement of muscle mass among healthy subjects (40 studies) and pre-frail, frail or sarcopenic patients (14), with evidence of beneficial effects. Other studies assessed the effect of CPS on bones (12), cardiovascular disease (8), inflamm-aging (7), chronic pulmonary disease (4), neurocognitive function (4), and vaccines (2), with weak evidence of positive effects. Seven studies in the field of protein metabolism investigated the role of CPS as an important contributor to nutritional needs. Other investigational areas are considered in the last five studies.

CONCLUSIONS

The beneficial effects of CPS in achieving aged-related nutritional goals, in preserving muscle mass and in recovering after hospitalization may be particularly relevant in the elderly.

Effect of Dairy Protein Intake on Muscle Mass among Korean Adults: A Prospective Cohort Study

This cohort study aimed to identify the associations of dairy protein intake with the risk of developing a low muscle mass during a 12-year follow-up period, using data from 4412 middle-aged Korean Genome and Epidemiology Study participants with a normal baseline muscle mass. Dairy protein intake at baseline was assessed using a semi-quantitative Food Frequency Questionnaire. Skeletal muscle mass index (SMI), defined as the weight-adjusted skeletal muscle mass, was measured biennially using multi-frequency bioelectrical impedance analyses. Cox proportional hazards regression analysis was used to calculate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Overall, 395 subjects developed a low SMI (%) during an average follow-up of 141 (19-152) months. The average consumption of milk and other dairy products was 73.6 and 104.1 g/day, respectively. In men, a higher dairy protein intake was associated with a decreased risk of developing a low SMI (tertile 3 [T3] vs. T1, HR: 0.63; 95% CI: 0.42, 0.94; p for trend = 0.029). In a stratified analysis according to a total protein intake, this association was stronger in the lower-protein intake group (HR: 0.59; 95% CI: 0.35, 0.99; p for trend = 0.036) but not detected in the higher-protein intake group. Men who consumed milk ≥1 time/day had a significantly lower risk of developing a low SMI (HR: 0.62; 95% CI: 0.39, 0.98; p for trend = 0.023). No significant associations were observed in women. In summary, dairy consumption appears to be beneficial for decreasing the risk of developing a low muscle mass in middle-aged Korean men.

The association between dietary protein intake and esophageal cancer risk: a meta-analysis

Several papers studied dietary protein intake as a potential influence factor for esophageal cancer, but their findings were inconsistent. Thus, this meta-analysis was performed to identify the effect of protein intake on esophageal cancer risk. Potential case–control studies or cohort studies from the databases of Embase, Web of Science and PubMed were searched. The strength of association was quantified by pooling odds ratio (OR) and 95% confidence interval (CI). In total, 11 articles involving 2537 cases and 11432 participants were included in this meta-analysis. As a result, dietary protein intake had non-significant association on esophageal cancer risk overall (pooled OR = 1.11, 95% CI = 0.88–1.40). Meanwhile, we obtained consistent results in the subgroups analyses by study design, protein type, geographic locations and number of cases. Interestingly, dietary protein intake could significantly increase the risk of esophageal squamous cell carcinoma (pooled OR = 1.29, 95% CI = 1.02–1.62), instead of other disease type. To sum up, dietary protein intake had no significant association with esophageal cancer risk in the overall analysis; but, protein intake may be associated with the risk of esophageal squamous cell carcinoma. While some limitations existed in the present paper, more studies with large sample size are warranted to further confirm this result.

Consumption of Milk and Alternatives and Their Contribution to Nutrient Intakes among Canadian Adults: Evidence from the 2015 Canadian Community Health Survey-Nutrition

As a staple food and dense source of nutrients, milk and alternatives play an important role in nutrient adequacy. The aims of this study were to quantify the consumption of milk and alternatives within Canadian self-selected diets and determine their contribution to intakes of nutrients and energy. First, 24-h dietary recalls from the 2015 Canadian Community Health Survey—Nutrition were used to assess 1-d food and nutrient intakes among Canadian adults ≥19 y (n = 13,616). Foods were classified as milk and alternatives according to the 2007 Canada’s Food Guide. Descriptive statistics were used to calculate daily servings of milk and alternatives by different age groups and demographic characteristics. Population ratios were used to discern their contribution to total intakes of nutrients and energy. Mean daily servings (±SE) were highest for milk (0.60 ± 0.02) and cheese (0.42 ± 0.01), intermediate for frozen dairy (0.16 ± 0.01) and yoghurt (0.14 ± 0.01), and lowest for soy and other dairy (<0.03). Intakes were lowest among Canadians 51 + y (1.3 ± 0.03), females (1.25 ± 0.03), non-Caucasians (1.06 ± 0.05), those with less than a secondary education (1.19 ± 0.05), and British Columbians (1.17 ± 0.05). Milk and alternatives contributed >20% to total intakes of calcium (52.62 ± 0.46%), vitamin D (38.53 ± 0.78%), saturated fat (28.84 ± 0.51%), vitamin B12 (27.73 ± 0.57%), vitamin A (26.16 ± 0.58%), phosphorus (24.76 ± 0.35%), and riboflavin (24.43 ± 0.37%), of which milk was the top source. Milk and alternatives contribute substantially to nutrient intakes and thus warrant further attention in terms of mitigating nutrient inadequacy among the Canadian population.

Preserved anabolic threshold and capacity as estimated by a novel stable tracer approach suggests no anabolic resistance or increased requirements in weight stable COPD patients

BACKGROUND & AIMS

Assessing the ability to respond anabolic to dietary protein intake during illness provides important insight in the capacity of lean body mass maintenance. We applied a newly developed stable tracer approach to assess in one session in patients with chronic obstructive pulmonary disease (COPD) and healthy older adults both the minimal amount of protein intake to obtain protein anabolism (anabolic threshold) and the efficiency of dietary protein to promote protein anabolism (anabolic capacity).

METHODS

We studied 12 clinically and weight stable patients with moderate to very severe COPD (mean ± SE forced expiratory volume in 1 s: 36 ± 3% of predicted) and 10 healthy age-matched older adults. At 2-h intervals and in consecutive order, all participants consumed a mixture of 0.0, 0.04, 0.10 and 0.30 g hydrolyzed casein protein×kg ffm-1×2 h-1 and carbohydrates (2:1). We assessed whole body protein synthesis (PS), breakdown (PB), net PS (PS-PB) and net protein balance (phenylalanine (PHE) intake - PHE to tyrosine (TYR) hydroxylation) by IV primed and continuous infusion of L-[ring-2H5]PHE and L-[13C9,15N]-TYR. Anabolic threshold (net protein balance = 0) and capacity (slope) were determined on an individual basis from the assumed linear relationship between protein intake and net protein balance.

RESULTS

We confirmed a linear relationship between protein intake and net protein balance for all participants (R2 range: 0.9988-1.0, p ≤ 0.0006). On average, the anabolic threshold and anabolic capacity were comparable between the groups (anabolic threshold COPD vs. healthy: 3.82 ± 0.31 vs. 4.20 ± 0.36 μmol PHE × kg ffm-1 × hr-1; anabolic capacity COPD vs. healthy: 0.952 ± 0.007 and 0.954 ± 0.004). At protein intake around the anabolic threshold (0.04 and 0.10 g protein×kg ffm-1×2 h-1), the increase in net PS resulted mainly from PB reduction (p < 0.0001) whereas at a higher protein intake (0.30 g protein×kg ffm-1×2 h-1) PS was also stimulated (p < 0.0001).

CONCLUSIONS

The preserved anabolic threshold and capacity in clinically and weight stable COPD patients suggests no disease related anabolic resistance and/or increased protein requirements.

TRIAL REGISTRY

ClinicalTrials.gov; No. NCT01734473; URL: www.clinicaltrials.gov.

American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on Nutrition Screening and Therapy Within a Surgical Enhanced Recovery Pathway

Perioperative malnutrition has proven to be challenging to define, diagnose, and treat. Despite these challenges, it is well known that suboptimal nutritional status is a strong independent predictor of poor postoperative outcomes. Although perioperative caregivers consistently express recognition of the importance of nutrition screening and optimization in the perioperative period, implementation of evidence-based perioperative nutrition guidelines and pathways in the United States has been quite limited and needs to be addressed in surgery-focused recommendations. The second Perioperative Quality Initiative brought together a group of international experts with the objective of providing consensus recommendations on this important topic with the goal of (1) developing guidelines for screening of nutritional status to identify patients at risk for adverse outcomes due to malnutrition; (2) address optimal methods of providing nutritional support and optimizing nutrition status preoperatively; and (3) identifying when and how to optimize nutrition delivery in the postoperative period. Discussion led to strong recommendations for implementation of routine preoperative nutrition screening to identify patients in need of preoperative nutrition optimization. Postoperatively, nutrition delivery should be restarted immediately after surgery. The key role of oral nutrition supplements, enteral nutrition, and parenteral nutrition (implemented in that order) in most perioperative patients was advocated for with protein delivery being more important than total calorie delivery. Finally, the role of often-inadequate nutrition intake in the posthospital setting was discussed, and the role of postdischarge oral nutrition supplements was emphasized.

Dairy consumption and risk of functional disability in an elderly Japanese population: the Hisayama Study

BACKGROUND

Little is known about the association between dairy intake and risk of functional disability in the elderly.

OBJECTIVES

We examined the influence of dairy intake on the development of declining functional capacity and activities of daily living (ADL) in a prospective cohort study of an elderly population.

METHODS

A total of 859 community-dwelling Japanese residents, aged ≥65 y without functional disability, were followed up for 7 y. Functional capacity impairment was defined as a Tokyo Metropolitan Institute of Gerontology Index of Competence score of ≤12, and ADL disability was defined as a Barthel Index score of ≤95. Dairy intake was evaluated using a 150-item semiquantitative food frequency questionnaire, grouped into quartiles. The RR of dairy intake on incident functional disability was computed using a Poisson regression model.

RESULTS

The multivariable-adjusted RR of impaired functional capacity decreased significantly with increasing dairy intake levels (RR [95% CI]: quartile 1, 1.00 [reference]; quartile 2, 0.85 [0.71, 1.02]; quartile 3, 0.81 [0.68, 0.98]; and quartile 4, 0.74 [0.61, 0.90]; P-trend = 0.001). Regarding the three subscales of functional capacity, the inverse association between dairy intake and risk for impairment of intellectual activity and social role remained significant (P-trend = 0.0009 and 0.02, respectively), but such an association was not observed for instrumental ADL. The multivariable-adjusted risk of ADL disability also decreased weakly but significantly with elevating dairy intake (P-trend = 0.04). A similar association was seen for severity of functional disability (P-trend = 0.002). However, the magnitude of these associations was attenuated after further adjustment for protein intake.

CONCLUSION

Our findings suggest that higher dairy intake is associated with a lower risk of functional disability and its progression in the elderly, probably via an increase in protein intake.

Dietary Patterns, Skeletal Muscle Health, and Sarcopenia in Older Adults

In recent decades, the significance of diet and dietary patterns (DPs) for skeletal muscle health has been gaining attention in ageing and nutritional research. Sarcopenia, a muscle disease characterised by low muscle strength, mass, and function is associated with an increased risk of functional decline, frailty, hospitalization, and death. The prevalence of sarcopenia increases with age and leads to high personal, social, and economic costs. Finding adequate nutritional measures to maintain muscle health, preserve function, and independence for the growing population of older adults would have important scientific and societal implications. Two main approaches have been employed to study the role of diet/DPs as a modifiable lifestyle factor in sarcopenia. An a priori or hypothesis-driven approach examines the adherence to pre-defined dietary indices such as the Mediterranean diet (MED) and Healthy Eating Index (HEI)—measures of diet quality—in relation to muscle health outcomes. A posteriori or data-driven approaches have used statistical tools—dimension reduction methods or clustering—to study DP-muscle health relationships. Both approaches recognise the importance of the whole diet and potential cumulative, synergistic, and antagonistic effects of foods and nutrients on ageing muscle. In this review, we have aimed to (i) summarise nutritional epidemiology evidence from four recent systematic reviews with updates from new primary studies about the role of DPs in muscle health, sarcopenia, and its components; (ii) hypothesise about the potential mechanisms of ‘myoprotective’ diets, with the MED as an example, and (iii) discuss the challenges facing nutritional epidemiology to produce the higher level evidence needed to understand the relationships between whole diets and healthy muscle ageing.

Pre-operative nutrition and the elective surgical patient: why, how and what?

Pre-operative nutrition therapy is increasingly recognised as an essential component of surgical care. The present review has been formatted using Simon Sinek's Golden Circle approach to explain 'why' avoiding pre-operative malnutrition and supporting protein anabolism are important goals for the elective surgical patient, 'how' peri-operative malnutrition develops leading in part to a requirement for pre-operative anabolic preparation, and 'what' can be done to avoid pre-operative malnutrition and support anabolism for optimal recovery.

Myofibrillar and Mitochondrial Protein Synthesis Rates Do Not Differ in Young Men Following the Ingestion of Carbohydrate with Milk Protein, Whey, or Micellar Casein after Concurrent Resistance- and Endurance-Type Exercise

BACKGROUND

Whey and micellar casein are high-quality dairy proteins that can stimulate postprandial muscle protein synthesis rates. How whey and casein compare with milk protein in their capacity to stimulate postprandial myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis rates during postexercise recovery is currently unknown.

OBJECTIVE

The objective of this study was to compare postprandial MyoPS and MitoPS rates after protein-carbohydrate co-ingestion with milk protein, whey, or micellar casein during recovery from a single bout of concurrent resistance- and endurance-type exercise in young healthy men.

METHODS

In a randomized, double-blind, parallel-group design, 48 healthy, young, recreationally active men (mean ± SEM age: 23 ± 0.3 y) received a primed continuous infusion of L-[ring-13C6]-phenylalanine and L-[ring-3,5-2H2]-tyrosine and ingested 45 g carbohydrate with 0 g protein (CHO), 20 g milk protein (MILK), 20 g whey protein (WHEY), or 20 g micellar casein protein (CASEIN) after a sequential bout of resistance- and endurance-type exercise (i.e., concurrent exercise). Blood and muscle biopsies were collected over 360 min during recovery from exercise to assess MyoPS and MitoPS rates and signaling through mammalian target of rapamycin complex 1 (mTORC1).

RESULTS

Despite temporal differences in postprandial plasma leucine concentrations between treatments (P < 0.001), MyoPS rates over 360 min of recovery did not differ between treatments (CHO: 0.049% ± 0.003%/h; MILK: 0.059% ± 0.003%/h; WHEY: 0.054% ± 0.002%/h; CASEIN: 0.059% ± 0.005%/h; P = 0.11). When MILK, WHEY, and CASEIN were pooled into a single group (PROTEIN), protein co-ingestion resulted in greater MyoPS rates compared with CHO (PROTEIN: 0.057% ± 0.002%/h; CHO: 0.049% ± 0.003%/h; P = 0.04). MitoPS rates and signaling through the mTORC1 pathway were similar between treatments.

CONCLUSION

MyoPS and MitoPS rates do not differ after co-ingestion of either milk protein, whey protein, or micellar casein protein with carbohydrate during recovery from a single bout of concurrent resistance- and endurance-type exercise in recreationally active young men. Co-ingestion of protein with carbohydrate results in greater MyoPS, but not MitoPS rates, when compared with the ingestion of carbohydrate only during recovery from concurrent exercise. This trial was registered at Nederlands Trial Register: NTR5098.

Evaluation of the biological quality of defatted pequi (Caryocar brasiliense Cambess) seed flour protein supplemented with lysine to rats (Rattus norvegicus)

ABSTRACT Objective In the biome of the Brazilian Cerrado, there are a lot of fruit tree species that stand out for their sensory quality and for presenting potentialities in the market of pulp and almond. Among these species, the pequi deserves attention because it has an almond rich in proteins and that is little explored. The aim of this study was to evaluate the biological quality of defatted pequi seed flour supplemented with lysine. Methods Two designs were done in this study; in the first, the animals were divided into four diet groups: control, protein-free, defatted pequi seed flour and defatted pequi seed flour supplemented with lysine. The protein-free diet was exempt of proteins and the other diets had a protein content of 10% and differed in protein source (casein: control diet or defatted pequi seed flour: test diets). The experiment lasted for 14 days. In the second design, 36 animals were used and followed-up for 28 days. The division of the experimental groups was kept, except for the protein-free diet group, which was excluded. By the end of the test, the animals were anaesthetised and euthanized. Results The results showed that the protein efficiency ratio of the control group was significantly higher than the other groups. For the other indices, the groups that received defatted pequi seed flour did not differ statistically among themselves. Conclusion These findings have shown an effect of supplementation on the protein efficiency ratio when comparing the test diets, however, when compared to the control group, no improvement was found.

Quality of meal protein determines anabolic response in older adults

BACKGROUND & AIMS

It has been demonstrated that the relative content and profile of essential amino acids (EAA) play a determining role for stimulation of muscle protein synthesis (MPS) following intake of pure EAA or protein alone.

METHODS

To test if this also holds in the context of mixed meals at both whole body and muscle levels, twelve older subjects (57-74 yrs) received primed continuous infusion of L-[ring-²H₅]phenylalanine and L-[ring-²H₂]tyrosine over a 9-h experimental period to determine whole body protein kinetics and MPS in the fasted state and following consumption of egg-based (EGG) or cereal-based (CEREAL) isocaloric and isonitrogenous breakfast. A standardized lunch, primarily consisting of beef protein was also consumed by each group. Whole body protein kinetics [protein synthesis (PS), breakdown (PB), and net balance (NB)] were expressed as changes from basal fasted period.

RESULTS

We found that EGG breakfast resulted in a greater NB through a greater suppression of PB compared with the CEREAL breakfast. The greater NB during the post-breakfast period with the EGG was normalized following the standard lunch despite the sustained elevations in plasma EAA concentrations. However, the EGG breakfast stimulated both PS and PB compared with the CEREAL breakfast during the post-lunch period. MPS was not different between meals despite larges differences in the plasma EAA responses.

CONCLUSIONS

We conclude that in the context of mixed meals, quality of protein affects NB through changes in protein breakdown and affects protein turnover following subsequent meal intake.

Dietary protein, aging and nutritional geometry

Nearly a century of research has shown that nutritional interventions can delay aging and age- related diseases in many animal models and possibly humans. The most robust and widely studied intervention is caloric restriction, while protein restriction and restriction of various amino acids (methionine, tryptophan) have also been shown to delay aging. However, there is still debate over whether the major impact on aging is secondary to caloric intake, protein intake or specific amino acids. Nutritional geometry provides new perspectives on the relationship between nutrition and aging by focusing on calories, macronutrients and their interactions across a landscape of diets, and taking into account compensatory feeding in ad libitum-fed experiments. Nutritional geometry is a state-space modelling approach that explores how animals respond to and balance changes in nutrient availability. Such studies in insects and mice have shown that low protein, high carbohydrate diets are associated with longest lifespan in ad libitum fed animals suggesting that the interaction between macronutrients may be as important as their total intake.

Animal Models for the Study of the Relationships between Diet and Obesity: A Focus on Dietary Protein and Estrogen Deficiency

Obesity is an increasing major public health concern asking for dietary strategies to limit weight gain and associated comorbidities. In this review, we present animal models, particularly rats and mice, which have been extensively used by scientists to understand the consequences of diet quality on weight gain and health. Notably, modulation of dietary protein quantity and/or quality has been shown to exert huge effects on body composition homeostasis through the modulation of food intake, energy expenditure, and metabolic pathways. Interestingly, the perinatal window appears to represent a critical period during which the protein intake of the dam can impact the offspring’s weight gain and feeding behavior. Animal models are also widely used to understand the processes and mechanisms that contribute to obesity at different physiological and pathophysiological stages. An interesting example of such aspect is the situation of decreased estrogen level occurring at menopause, which is linked to weight gain and decreased energy expenditure. To study metabolic disorders associated with such situation, estrogen withdrawal in ovariectomized animal models to mimic menopause are frequently used. According to many studies, clear species-specific differences exist between rats and mice that need to be taken into account when results are extrapolated to humans.

Promoting a culture of prehabilitation for the surgical cancer patient

BACKGROUND

Traditional rehabilitative approaches to perioperative cancer care have focused on the postoperative period to facilitate the return to presurgical baseline conditions. However, there is some realization that the preoperative period can be a very effective time for intervention as the patients are more amenable to target their physiological condition to prepare to overcome the metabolic cost of the surgical stress.

METHODS

We undertook a narrative review of the current literature on surgical prehabilitation and discussed the current evidence of preoperative interventions before cancer surgery in order to increase physiological reserve before surgery and accelerate postoperative recovery.

RESULTS

Published data indicate the positive impact of prehabilitation on postoperative functional capacity and return to daily activities. However, the current evidence on the impact on short- and long-term clinical outcome is limited, and more research needs to be conducted.

CONCLUSION

Preliminary findings indicate that a group of interventions such as exercise, nutrition and anxiety reduction in the preoperative period can complement the enhanced recovery program and facilitate the return to baseline activities of daily living. It is not clear at this stage whether the preoperative increase in functional capacity mitigates the burden of postoperative morbidities and subsequent cancer therapies. Therefore, more research is warranted.

Dietary Protein Sources and Incidence of Breast Cancer: A Dose-Response Meta-Analysis of Prospective Studies

Protein is important to the human body, and different sources of protein may have different effects on the risk of breast cancer. Thus, we conducted a meta-analysis to investigate the association between different dietary protein sources and breast cancer risk. PubMed and several databases were searched until December 2015. Relevant articles were retrieved according to specific searching criteria. Forty-six prospective studies were included. The summary relative risk (RR) for highest versus lowest intake was 1.07 (95% confidence interval (CI) 1.01-1.14, I² = 34.6%) for processed meat, 0.92 (95% CI 0.84-1.00, I² = 0%) for soy food, 0.93 (95% CI 0.85-1.00, I² = 40.1%) for skim milk, and 0.90 (95% CI 0.82-1.00, I² = 0%) for yogurt. Similar conclusions were obtained in dose-response association for each serving increase: total red meat (RR: 1.07; 95% CI 1.01-1.14, I² = 7.1%), fresh red meat (RR: 1.13; 95% CI 1.01-1.26, I² = 56.4%), processed meat (RR: 1.09; 95% CI 1.02-1.17, I² = 11.8%), soy food (RR: 0.91; 95% CI 0.84-1.00, I² = 0%), and skim milk (RR: 0.96; 95% CI 0.92-1.00, I² = 11.9%). There was a null association between poultry, fish, egg, nuts, total milk, and whole milk intake and breast cancer risk. Higher total red meat, fresh red meat, and processed meat intake may be risk factors for breast cancer, whereas higher soy food and skim milk intake may reduce the risk of breast cancer.

Emerging Evidence for the Importance of Dietary Protein Source on Glucoregulatory Markers and Type 2 Diabetes: Different Effects of Dairy, Meat, Fish, Egg, and Plant Protein Foods

Observational studies provide evidence that a higher intake of protein from plant-based foods and certain animal-based foods is associated with a lower risk for type 2 diabetes. However, there are few distinguishable differences between the glucoregulatory qualities of the proteins in plant-based foods, and it is likely their numerous non-protein components (e.g., fibers and phytochemicals) that drive the relationship with type 2 diabetes risk reduction. Conversely, the glucoregulatory qualities of the proteins in animal-based foods are extremely divergent, with a higher intake of certain animal-based protein foods showing negative effects, and others showing neutral or positive effects on type 2 diabetes risk. Among the various types of animal-based protein foods, a higher intake of dairy products (such as milk, yogurt, cheese and whey protein) consistently shows a beneficial relationship with glucose regulation and/or type 2 diabetes risk reduction. Intervention studies provide evidence that dairy proteins have more potent effects on insulin and incretin secretion compared to other commonly consumed animal proteins. In addition to their protein components, such as insulinogenic amino acids and bioactive peptides, dairy products also contain a food matrix rich in calcium, magnesium, potassium, trans-palmitoleic fatty acids, and low-glycemic index sugars-all of which have been shown to have beneficial effects on aspects of glucose control, insulin secretion, insulin sensitivity and/or type 2 diabetes risk. Furthermore, fermentation and fortification of dairy products with probiotics and vitamin D may improve a dairy product's glucoregulatory effects.

New Horizons: Dietary protein, ageing and the Okinawan ratio

Nutrition has profound effects on ageing and lifespan. Caloric restriction is the major nutritional intervention that historically has been shown to influence lifespan and/or healthspan in many animal models. Studies have suggested that a reduction in protein intake can also increase lifespan, albeit not as dramatically as caloric restriction. More recent research based on nutritional geometry has attempted to define the effects of nutrition on ageing over a broad landscape of dietary macronutrients and energy content. Such studies in insects and mice indicate that animals with ad libitum access to low-protein, high-carbohydrate diets have longest lifespans. Remarkably, the optimum content and ratio of dietary protein to carbohydrates for ageing in experimental animals are almost identical to those in the traditional diets of the long-lived people on the island of Okinawa.

Diet-induced acidosis and alkali supplementation

Western diet, high in protein-rich foods and poor in vegetables, is likely to be responsible for the development of a moderate acid excess leading to metabolism deregulation and the onset or worsening of chronic disturbances. Available findings seem to suggest that diets with high protein/vegetables ratio are likely to induce the development of calcium lithiasis, especially in predisposed subjects. Moreover, some evidence supports the hypothesis of bone metabolism worsening and enhanced bone loss following acid-genic diet consumption although available literature seems to lack direct and conclusive evidence demonstrating pathological bone loss. According to other evidences, diet-induced acidosis is likely to induce or accelerate muscle wasting or sarcopenia, especially among elderlies. Furthermore, recent epidemiological findings highlight a specific role of dietary acid load in glucose metabolism deregulation and insulin resistance. The aim of this review is to investigate the role of acid-genic diets in the development of the mentioned metabolic disorders focusing on the possible clinical improvements exerted by alkali supplementation.

An approach to including protein quality when assessing the net contribution of livestock to human food supply

The production of protein from animal sources is often criticized because of the low efficiency of converting plant protein from feeds into protein in the animal products. However, this critique does not consider the fact that large portions of the plant-based proteins fed to animals may be human-inedible and that the quality of animal proteins is usually superior as compared with plant proteins. The aim of the present study was therefore to assess changes in protein quality in the course of the transformation of potentially human-edible plant proteins into animal products via livestock production; data from 30 Austrian dairy farms were used as a case study. A second aim was to develop an approach for combining these changes with quantitative aspects (e.g. with the human-edible feed conversion efficiency (heFCE), defined as kilogram protein in the animal product divided by kilogram potentially human-edible protein in the feeds). Protein quality of potentially human-edible inputs and outputs was assessed using the protein digestibility-corrected amino acid score and the digestible indispensable amino acid score, two methods proposed by the Food and Agriculture Organization of the United Nations to describe the nutritional value of proteins for humans. Depending on the method used, protein scores were between 1.40 and 1.87 times higher for the animal products than for the potentially human-edible plant protein input on a barn-gate level (=protein quality ratio (PQR)). Combining the PQR of 1.87 with the heFCE for the same farms resulted in heFCE×PQR of 2.15. Thus, considering both quantity and quality, the value of the proteins in the animal products for human consumption (in this case in milk and beef) is 2.15 times higher than that of proteins in the potentially human-edible plant protein inputs. The results of this study emphasize the necessity of including protein quality changes resulting from the transformation of plant proteins to animal proteins when evaluating the net contribution of livestock to the human food supply. Furthermore, these differences in protein quality might also need to be considered when choosing a functional unit for the assessment of environmental impacts of the production of different proteins.