The Muscle Protein Synthetic Response to the Ingestion of a Plant-Derived Protein Blend Does Not Differ from an Equivalent Amount of Milk Protein in Healthy Young Males

BACKGROUND

Plant-derived proteins are considered to have lesser anabolic properties when compared with animal-derived proteins. The attenuated rise in muscle protein synthesis rates following ingestion of plant-derived compared with animal-derived protein has been, at least partly, attributed to deficiencies in specific amino acids such as leucine, lysine, and/or methionine. Combining different plant-derived proteins could provide plant-derived protein blends with a more balanced amino acid profile.

OBJECTIVES

This study aimed to compare postprandial muscle protein synthesis rates following the ingestion of 30 g milk protein with a 30 g blend combining wheat, corn, and pea protein in healthy young men.

METHODS

In a randomized, double-blind, parallel-group design, 24 young males (aged 24 ± 4 y) received a primed continuous l-[ring-13C6]-phenylalanine infusion after which they ingested 30 g milk protein (MILK) or a 30 g plant-derived protein blend combining 15 g wheat, 7.5 g corn, and 7.5 g pea protein (PLANT-BLEND). Blood and muscle biopsies were collected frequently for 5 h to assess postprandial plasma amino acid profiles (secondary outcome) and subsequent muscle protein synthesis rates (primary outcome). Data were analyzed by 2-factor repeated measures ANOVA and 2-samples t tests.

RESULTS

MILK increased plasma essential amino acid concentrations more than PLANT-BLEND over the 5 h postprandial period (incremental AUC = 151 ± 31 compared with 79 ± 12 mmol·300 min·L-1, respectively; P < 0.001). Ingestion of both MILK and PLANT-BLEND increased myofibrillar protein synthesis rates (P < 0.001), with no significant differences between treatments (0.053 ± 0.013%/h and 0.064 ± 0.016%/h, respectively; P = 0.08).

CONCLUSIONS

Ingestion of 30 g plant-derived protein blend combining wheat-, corn-, and pea-derived protein increases muscle protein synthesis rates in healthy young males. The muscle protein synthetic response to the ingestion of 30 g of this plant-derived protein blend does not differ from the ingestion of an equivalent amount of a high-quality animal-derived protein.Clinical trial registry number for Nederlands Trial Register: NTR6548 (https://trialsearch.who.int/Trial2.aspx?TrialID=NTR6548).

The Association between Malnutrition and Physical Performance in Older Adults: A Systematic Review and Meta-Analysis of Observational Studies

In recent years the focus of healthcare and nutritional science in older adults has shifted from mortality towards physical performance and quality of life. The aim of this review was to summarize observational studies on physical performance in malnourished (MN) or at risk of malnutrition (RMN) older adults compared with well-nourished (WN) older adults. Eligible studies had to report on nutritional status and objectively measured physical performance in older adults (≥60 y). MN or RMN groups had to be compared with a WN group, measured with a validated nutrition screener. Ovid Medline and Web of Science were searched until 13 November, 2020. Study quality was scored using a modified Newcastle-Ottawa Scale (NOS). Results were analyzed by meta-analysis when possible, or narratively reviewed otherwise. Forty-five studies (16,911 participants in total) were included from studies in outpatient clinics (n = 6), nursing homes (n = 3), community-dwelling older adults (n = 20), hospitalized patients (n = 15), or a combination (n = 1). Studies used 11 different screeners of malnutrition, and 8 types of physical performance measures. Meta-analysis showed that compared with MN, WN groups had better hand grip strength (mean difference [MD] = 4.92 kg; 95% CI: 3.43, 6.41; P < 0.001; n = 23), faster gait speed (MD = 0.16 m/s; 95% CI: 0.05, 0.27; P = 0.0033; n = 7), performed faster on timed-up-and-go (MD = -5.94 s; 95% CI: -8.98, -2.89; P < 0.001; n = 8), and scored 1.2 more short physical performance battery points (95% CI: 1.32, 2.73; P < 0.001; n = 6). Results were less pronounced when compared with RMN. Narratively, all studies showed an association for knee extension strength, 6-min walking test, and multicomponent tests, except for the chair stand test. Study limitations include no studies scoring "good" on NOS, lack of confounder adjustment, and high heterogeneity. Overall, evidence from cross-sectional studies indicate an association between malnutrition and worse physical performance in older adults. This study is registered in PROSPERO as CRD42020192893.

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.

Vitamin B-6 intake is related to physical performance in European older adults: results of the New Dietary Strategies Addressing the Specific Needs of the Elderly Population for Healthy Aging in Europe (NU-AGE) study

BACKGROUND

Maintenance of high physical performance during aging might be supported by an adequate dietary intake of niacin, vitamins B-6 and B-12, and folate because these B vitamins are involved in multiple processes related to muscle functioning. However, not much is known about the association between dietary intake of these B vitamins and physical performance.

OBJECTIVES

The objectives of this study were to investigate the association between dietary intake of niacin, vitamins B-6 and B-12, and folate and physical performance in older adults and to explore mediation by niacin status and homocysteine concentrations.

METHODS

We used baseline data from the New Dietary Strategies Addressing the Specific Needs of the Elderly Population for Healthy Aging in Europe (NU-AGE) trial, which included n = 1249 healthy older adults (aged 65-79 y) with complete data on dietary intake measured with 7-d food records and questionnaires on vitamin supplement use and physical performance measured with the short physical performance battery and handgrip dynamometry. Associations were assessed by adjusted linear mixed models.

RESULTS

Intake of vitamin B-6 was related to lower chair rise test time [β: -0.033 ± 0.016 s (log); P = 0.043]. Vitamin B-6 intake was also significantly associated with handgrip strength, but for this association, a significant interaction effect between vitamin B-6 intake and physical activity level was found. In participants with the lowest level of physical activity, higher intake of vitamin B-6 tended to be associated with greater handgrip strength (β: 1.5 ± 0.8 kg; P = 0.051), whereas in participants in the highest quartile of physical activity, higher intake was associated with lower handgrip strength (β: -1.4 ± 0.7 kg; P = 0.041). No evidence was found for an association between intake of niacin, vitamin B-12, or folate and physical performance or for mediation by niacin status or homocysteine concentrations.

CONCLUSIONS

Vitamin B-6 intake was associated with better chair rise test time in a population of European healthy older adults and also with greater handgrip strength in participants with low physical activity only. Homocysteine concentrations did not mediate these associations. The NU-AGE trial was registered at clinicaltrials.gov as NCT01754012.

Protein Type, Protein Dose, and Age Modulate Dietary Protein Digestion and Phenylalanine Absorption Kinetics and Plasma Phenylalanine Availability in Humans

BACKGROUND

Dietary protein ingestion stimulates muscle protein synthesis by providing amino acids to the muscle. The magnitude and duration of the postprandial increase in muscle protein synthesis rates are largely determined by dietary protein digestion and amino acid absorption kinetics.

OBJECTIVE

We assessed the impact of protein type, protein dose, and age on dietary protein digestion and amino acid absorption kinetics in vivo in humans.

METHODS

We included data from 18 randomized controlled trials with a total of 602 participants [age: 53 ± 23 y; BMI (kg/m2): 24.8 ± 3.3] who consumed various quantities of intrinsically l-[1-13C]-phenylalanine-labeled whey (n = 137), casein (n = 393), or milk (n = 72) protein and received intravenous infusions of l-[ring-2H5]-phenylalanine, which allowed us to assess protein digestion and phenylalanine absorption kinetics and the postprandial release of dietary protein-derived phenylalanine into the circulation. The effect of aging on these processes was assessed in a subset of 82 young (aged 22 ± 3 y) and 83 older (aged 71 ± 5 y) individuals.

RESULTS

A total of 50% ± 14% of dietary protein-derived phenylalanine appeared in the circulation over a 5-h postprandial period. Casein ingestion resulted in a smaller (45% ± 11%), whey protein ingestion in an intermediate (57% ± 10%), and milk protein ingestion in a greater (65% ± 13%) fraction of dietary protein-derived phenylalanine appearing in the circulation (P < 0.001). The postprandial availability of dietary protein-derived phenylalanine in the circulation increased with the ingestion of greater protein doses (P < 0.05). Protein digestion and phenylalanine absorption kinetics were attenuated in older when compared with young individuals, with 45% ± 10% vs. 51% ± 14% of dietary protein-derived phenylalanine appearing in the circulation, respectively (P = 0.001).

CONCLUSIONS

Protein type, protein dose, and age modulate dietary protein digestion and amino acid absorption kinetics and subsequent postprandial plasma amino acid availability in vivo in humans. These trials were registered at clinicaltrials.gov as NCT00557388, NCT00936039, NCT00991523, NCT01317511, NCT01473576, NCT01576848, NCT01578590, NCT01615276, NCT01680146, NCT01820975, NCT01986842, and NCT02596542, and at http://www.trialregister.nl as NTR3638, NTR3885, NTR4060, NTR4429, and NTR4492.

A Combined Nutrition and Exercise Intervention Influences Serum Vitamin B-12 and 25-Hydroxyvitamin D and Bone Turnover of Healthy Chinese Middle-Aged and Older Adults

BACKGROUND

Hong Kong faces several public health problems including malnutrition and osteoporosis. Considering the typical Chinese diet and overall low physical activity levels of Chinese adults, timely interventions to improve nutritional status and bone health are needed.

OBJECTIVES

We examined the effects of a nutrition plus exercise intervention on serum vitamin B-12 and 25-hydroxyvitamin D [25(OH)D], bone turnover markers, and parathyroid hormone (PTH) concentrations in apparently healthy Chinese middle-aged and older adults.

METHODS

In this 24-wk randomized controlled trial, 180 Chinese adults (85 women, mean ± SD age: 61 ± 6 y) were randomly assigned to receive a fortified milk supplement (2 × 30 g/d) and an exercise program (2 × 1 h/wk including resistance, balance, and aerobic training) or no intervention. The primary outcome was physical performance. In this article we analyzed the secondary outcomes serum vitamin B-12 and 25(OH)D concentrations, assessed at baseline, 12 wk, and 24 wk. Also, bone turnover markers and PTH concentrations were studied. Linear mixed models evaluated group differences over time.

RESULTS

A significant time × group interaction (P < 0.001) was found for serum vitamin B-12 and 25(OH)D concentrations and the bone turnover markers, but not for serum PTH concentrations (P = 0.09). The intervention increased mean ± SD vitamin B-12 concentrations from baseline (345 ± 119 pmol/L) to 24 wk (484 ± 136 pmol/L), whereas concentrations remained stable within the control. For 25(OH)D concentrations, the intervention group had a greater increase from baseline (54.7 ± 14.2 nmol/L) to 24 wk (80.1 ± 19.2 nmol/L) than the control (60.6 ± 15.2 compared with 65.6 ± 14.6 nmol/L). The ratio of the net effect of bone formation and resorption was greater in the intervention group, suggesting less bone remodeling, irrespective of sex.

CONCLUSIONS

A fortified milk supplement and exercise intervention successfully improved vitamin B-12 and 25(OH)D concentrations as well as the balance of bone turnover markers of Chinese middle-aged and older adults.This trial was registered at trialregister.nl as NTR6214.

The association between dietary and skin advanced glycation end products: the Rotterdam Study

BACKGROUND

Advanced glycation end products (AGEs) accumulate in tissues with age and in conditions such as diabetes mellitus and chronic kidney disease (CKD), and they may be involved in age-related diseases. Skin AGEs measured as skin autofluorescence (SAF) are a noninvasive reflection of long-term AGE accumulation in tissues. Whether AGEs present in the diet (dAGEs) contribute to tissue AGEs is unclear.

OBJECTIVES

Our aim was to investigate the association between dietary and skin AGEs in the Rotterdam Study, a population-based cohort of mainly European ancestry.

METHODS

In 2515 participants, intake of 3 dAGEs [carboxymethyl-lysine (CML), N-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MGH1), and carboxyethyl-lysine (CEL)] was estimated using FFQs and the content of AGEs measured in commonly consumed foods. SAF was measured 5 y (median value) later using an AGE Reader. The association of dAGEs with SAF was analyzed in linear regression models and stratified for diabetes and chronic kidney disease (CKD, defined as estimated glomerular filtration rate ≤60 mL/min) status.

RESULTS

Mean ± SD intake was 3.40 ±0.89 mg/d for CML, 28.98 ±7.87 mg/d for MGH1, and 3.11 ±0.89 mg/d for CEL. None of them was associated with SAF in the total study population. However, in stratified analyses, CML was positively associated with SAF after excluding both individuals with diabetes and individuals with CKD: 1 SD higher daily CML intake was associated with a 0.03 (95% CI: 0.009, 0.05) arbitrary units higher SAF. MGH1 and CEL intake were not significantly associated with SAF. Nevertheless, the associations were stronger when the time difference between dAGEs and SAF measurements was shorter.

CONCLUSIONS

Higher dietary CML intake was associated with higher SAF only among participants with neither diabetes nor CKD, which may be explained by high AGE formation in diabetes and decreased excretion in CKD or by dietary modifications in these disease groups. The dAGE-SAF associations were also modified by the time difference between measurements. Our results suggest that dAGEs can influence tissue AGE accumulation and possibly thereby age-related diseases. This trial was registered at the Netherlands National Trial Register as NTR6831 (http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=6831) and at the WHO International Clinical Trials Registry Platform as NTR6831 (http://www.who.int/ictrp/network/primary/en/).

Dietary Intakes of Vegetable Protein, Folate, and Vitamins B-6 and B-12 Are Partially Correlated with Physical Functioning of Dutch Older Adults Using Copula Graphical Models

BACKGROUND

In nutritional epidemiology, dealing with confounding and complex internutrient relations are major challenges. An often-used approach is dietary pattern analyses, such as principal component analysis, to deal with internutrient correlations, and to more closely resemble the true way nutrients are consumed. However, despite these improvements, these approaches still require subjective decisions in the preselection of food groups. Moreover, they do not make efficient use of multivariate dietary data, because they detect only marginal associations. We propose the use of copula graphical models (CGMs) to model and make statistical inferences regarding complex associations among variables in multivariate data, where associations between all variables can be learned simultaneously.

OBJECTIVE

We aimed to reconstruct nutritional intake and physical functioning networks in Dutch older adults by applying a CGM.

METHODS

We addressed this issue by uncovering the pairwise associations between variables while correcting for the effect of remaining variables. More specifically, we used a CGM to infer the precision matrix, which contains all the conditional independence relations between nodes in the graph. The nonzero elements of the precision matrix indicate the presence of a direct association. We applied this method to reconstruct nutrient-physical functioning networks from the combined data of 4 studies (Nu-Age, ProMuscle, ProMO, and V-Fit, total n = 662, mean ± SD age = 75 ± 7 y). The method was implemented in the R package nutriNetwork which is freely available at https://cran.r-project.org/web/packages/nutriNetwork.

RESULTS

Greater intakes of vegetable protein and vitamin B-6 were partially correlated with higher scores on the total Short Physical Performance Battery (SPPB) and the chair rise test. Greater intakes of vitamin B-12 and folate were partially correlated with higher scores on the chair rise test and the total SPPB, respectively.

CONCLUSIONS

We determined that vegetable protein, vitamin B-6, folate, and vitamin B-12 intakes are partially correlated with improved functional outcome measurements in Dutch older adults.

Changing from a Western to a Mediterranean-style diet does not affect iron or selenium status: results of the New Dietary Strategies Addressing the Specific Needs of the Elderly Population for Healthy Aging in Europe (NU-AGE) 1-year randomized clinical trial in elderly Europeans

BACKGROUND

Mediterranean diets limit red meat consumption and increase intakes of high-phytate foods, a combination that could reduce iron status. Conversely, higher intakes of fish, a good source of selenium, could increase selenium status.

OBJECTIVES

A 1-y randomized controlled trial [New Dietary Strategies Addressing the Specific Needs of the Elderly Population for Healthy Aging in Europe (NU-AGE)] was carried out in older Europeans to investigate the effects of consuming a Mediterranean-style diet on indices of inflammation and changes in nutritional status.

METHODS

Selenium and iron intakes and status biomarkers were measured at baseline and after 1 y in 1294 people aged 65-79 y from 5 European countries (France, Italy, the Netherlands, Poland, and the United Kingdom) who had been randomly allocated either to a Mediterranean-style diet or to remain on their habitual, Western diet.

RESULTS

Estimated selenium intakes increased significantly with the intervention group (P < 0.01), but were not accompanied by changes in serum selenium concentrations. Iron intakes also increased (P < 0.001), but there was no change in iron status. However, when stratified by study center, there were positive effects of the intervention on iron status for serum ferritin for participants in Italy (P = 0.04) and France (P = 0.04) and on soluble transferrin receptor (sTfR) for participants in Poland (P < 0.01). Meat intake decreased and fish intake increased to a greater degree in the intervention group, relative to the controls (P < 0.01 for both), but the overall effects of the intervention on meat and fish intakes were mainly driven by data from Poland and France. Changes in serum selenium in the intervention group were associated with greater changes in serum ferritin (P = 0.01) and body iron (P = 0.01), but not sTfR (P = 0.73); there were no study center × selenium status interactions for the iron biomarkers.

CONCLUSIONS

Consuming a Mediterranean-style diet for 1 y had no overall effect on iron or selenium status, although there were positive effects on biomarkers of iron status in some countries. The NU-AGE trial was registered at clinicaltrials.gov as NCT01754012.

Disentangling the genetics of lean mass

Background

Lean body mass (LM) plays an important role in mobility and metabolic function. We previously identified five loci associated with LM adjusted for fat mass in kilograms. Such an adjustment may reduce the power to identify genetic signals having an association with both lean mass and fat mass.

Objectives

To determine the impact of different fat mass adjustments on genetic architecture of LM and identify additional LM loci.

Methods

We performed genome-wide association analyses for whole-body LM (20 cohorts of European ancestry with n = 38,292) measured using dual-energy X-ray absorptiometry) or bioelectrical impedance analysis, adjusted for sex, age, age2, and height with or without fat mass adjustments (Model 1 no fat adjustment; Model 2 adjustment for fat mass as a percentage of body mass; Model 3 adjustment for fat mass in kilograms).

Results

Seven single-nucleotide polymorphisms (SNPs) in separate loci, including one novel LM locus (TNRC6B), were successfully replicated in an additional 47,227 individuals from 29 cohorts. Based on the strengths of the associations in Model 1 vs Model 3, we divided the LM loci into those with an effect on both lean mass and fat mass in the same direction and refer to those as "sumo wrestler" loci (FTO and MC4R). In contrast, loci with an impact specifically on LM were termed "body builder" loci (VCAN and ADAMTSL3). Using existing available genome-wide association study databases, LM increasing alleles of SNPs in sumo wrestler loci were associated with an adverse metabolic profile, whereas LM increasing alleles of SNPs in "body builder" loci were associated with metabolic protection.

Conclusions

In conclusion, we identified one novel LM locus (TNRC6B). Our results suggest that a genetically determined increase in lean mass might exert either harmful or protective effects on metabolic traits, depending on its relation to fat mass.