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Background Protein ingestion increases muscle protein synthesis rates. The food matrix in which protein is provided can strongly modulate the postprandial muscle protein synthetic response. So far, the muscle protein synthetic response to the ingestion of whole foods remains largely unexplored. Objectives To compare the impact of ingesting 30 g protein provided as milk protein or cheese on postprandial plasma amino acid concentrations and muscle protein synthesis rates at rest and during recovery from exercise in vivo in young males. Methods In this randomized, parallel-group intervention trial, 20 healthy males aged 18-35 y ingested 30 g protein provided as cheese or milk protein concentrate following a single-legged resistance-type exercise session consisting of 12 sets of leg press and leg extension exercises. Primed, continuous intravenous L-[ring-C-13(6)]-phenylalanine infusions were combined with the collection of blood and muscle tissue samples to assess postabsorptive and 4-h postprandial muscle protein synthesis rates at rest and during recovery from exercise. Data were analyzed using repeated measures Time x Group (x Leg) ANOVA. Results Plasma total amino acid concentrations increased after protein ingestion (Time: P < 0.001), with 38% higher peak concentrations following milk protein than cheese ingestion (Time x Group: P < 0.001). Muscle protein synthesis rates increased following both cheese and milk protein ingestion from 0.037 +/- 0.014 to 0.055 +/- 0.018%center dot h(-1) and 0.034 +/- 0.008 to 0.056 +/- 0.010%center dot h(-1) at rest and even more following exercise from 0.031 +/- 0.010 to 0.067 +/- 0.013%center dot h(-1) and 0.030 +/- 0.008 to 0.063 +/- 0.010%center dot h(-1), respectively (Time: all P < 0.05; Time x Leg: P = 0.002), with no differences between cheese and milk protein ingestion (Time x Group: both P > 0.05). Conclusion Cheese ingestion increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial muscle protein synthetic response to the ingestion of cheese or milk protein does not differ when 30 g protein is ingested at rest or during recovery from exercise in healthy, young males.

Background Poor nutritional status is frequently observed in end-stage renal disease patients and associated with adverse clinical outcomes and increased mortality. Loss of amino acids (AAs) during hemodialysis (HD) may contribute to protein malnutrition in these patients. Objective We aimed to assess the extent of AA loss during HD in end-stage renal disease patients consuming their habitual diet. Methods Ten anuric chronic HD patients (mean ± SD age: 67.9 ± 19.3 y, BMI: 23.2 ± 3.5 kg/m2), undergoing HD 3 times per week, were selected to participate in this study. Spent dialysate was collected continuously and plasma samples were obtained directly before and after a single HD session in each participant. AA profiles in spent dialysate and in pre-HD and post-HD plasma were measured through ultra-performance liquid chromatography to determine AA concentrations and, as such, net loss of AAs. In addition, dietary intake before and throughout HD was assessed using a 24-h food recall questionnaire during HD. Paired-sample t tests were conducted to compare pre-HD and post-HD plasma AA concentrations. Results During an HD session, 11.95 ± 0.69 g AAs were lost via the dialysate, of which 8.26 ± 0.46 g were nonessential AAs, 3.69 ± 0.31 g were essential AAs, and 1.64 ± 0.17 g were branched-chain AAs. As a consequence, plasma total and essential AA concentrations declined significantly from 2.88 ± 0.15 and 0.80 ± 0.05 mmol/L to 2.27 ± 0.11 and 0.66 ± 0.05 mmol/L, respectively (P < 0.05). AA profiles of pre-HD plasma and spent dialysate were similar. Moreover, AA concentrations in pre-HD plasma and spent dialysate were strongly correlated (Spearman's ρ = 0.92, P < 0.001). Conclusions During a single HD session, ∼12 g AAs are lost into the dialysate, causing a significant decline in plasma AA concentrations. AA loss during HD can contribute substantially to protein malnutrition in end-stage renal disease patients. This study was registered at the Netherlands Trial Registry (NTR7101).

Background: Vitamin D supplementation is proposed as a potential treatment strategy to counteract functional decline in older adults. However, data from randomized trials are either limited or inconsistent. Objective: This study investigated the effect of daily supplementation with 25-hydroxycholecalciferol [25(OH)D3] or cholecalciferol (vitamin D3) on muscle strength and physical performance in older adults. Methods: This was a randomized, double-blind, placebo-controlled trial of 6 mo including 78 prefrail or frail (according to the Fried criteria), community-dwelling older adults (n = 43 men) aged ≥65 y, with a baseline 25-hydroxyvitamin D [25(OH)D] concentration between 20 and 50 nmol/L. Participants were supplemented daily with 10 µg 25(OH)D3, 20 µg vitamin D3, or a placebo capsule. Serum 25(OH)D was measured by liquid chromatography–tandem mass spectrometry. The primary outcome was maximal isometric knee-extension strength (Biodex System 4); secondary outcomes included knee-flexion and hand grip strength, Short-Physical Performance Battery score, Timed Up and Go score, postural sway, muscle mass (dual-energy X-ray absorptiometry), and muscle fiber type and size. Results: The mean baseline serum 25(OH)D concentration was 37.7 nmol/L (95% CI: 35.4, 39.9 nmol/L). After 6 mo of supplementation, concentrations increased to 98.7 nmol/L (95% CI: 93.1, 104.4 nmol/L) in the 25(OH)D3 group and to 72.0 nmol/L (95% CI: 66.1, 77.8 nmol/L) in the vitamin D3 group, compared with 47.5 nmol/L (95% CI: 41.8, 53.3 nmol/L) in the placebo group (P-interaction < 0.01). Knee-extension strength did not significantly change in the 25(OH)D3group (5.9 Nm; 95% CI: −6.2, 18.0 Nm), in the vitamin D3 group (5.5 Nm; 95% CI: −6.8, 17.8 Nm), or in the placebo group (1.8 Nm; 95% CI: −10.7, 14.4 Nm) (P-interaction = 0.74). Furthermore, mean changes in physical performance tests, muscle mass, and muscle fiber type and size did not differ between the groups. Conclusion: Increasing the serum 25(OH)D concentration over a period of 6 mo did not significantly change muscle strength and physical performance in prefrail and frail older adults. This trial was registered at www.clinicaltrials.gov as NCT02349282.

Background: The age-related decline in skeletal muscle mass is partly attributed to anabolic resistance to food intake. Dietary protein ingestion before sleep could be used as a nutritional strategy to compensate for anabolic resistance. Objective: The present study assessed whether physical activity performed in the evening can augment the overnight muscle protein synthetic response to presleep protein ingestion in older men. Methods: In a parallel group design, 23 healthy older men (mean SEM age: 71 1 y) were randomly assigned to ingest 40 g protein intrinsically labeled with L[1-C-13]-phenylalanine and L-[1-C-13]-leucine before going to sleep with (PRO+EX) or without (PRO) performing physical activity earlier in the evening. Overnight protein digestion and absorption kinetics and myofibrillar protein synthesis rates were assessed by combining primed, continuous infusions of L-[ring-H-2(5)]-phenylalanine, L-[1-C-13]-leucine, and L-[ring-H-2(2)]-tyrosine with the ingestion of intrinsically labeled casein protein. Muscle and blood samples were collected throughout overnight sleep. Results: Protein ingested before sleep was normally digested and absorbed, with 54% +/- 2% of the protein-derived amino acids appearing in the circulation throughout overnight sleep. Overnight myofibrillar protein synthesis rates were 31 % (0.058% +/- 0.002%/h compared with 0.044% +/- 0.003%/h; P

Background: Dietary protein is required to attenuate the loss of muscle mass and to support recovery during a period of hospitalization. Jejunal feeding is preferred over gastric feeding in patients who are intolerant of gastric feeding. However, the impact of gastric vs. jejunal feeding on postprandial dietary protein digestion and absorption kinetics in vivo in humans remains largely unexplored. Objective: We compared the impact of gastric vs. jejunal feeding on subsequent dietary protein digestion and amino acid (AA) absorption in vivo in healthy young men. Methods: In a randomized crossover study design, 11 healthy young men (aged 21 +/- 2 y) were administered 25 g specifically produced intrinsically L-[1-C-13] phenylalanine-labeled intact casein via a nasogastric and a nasojejunal tube placed similar to 30 cm distal to the ligament of Treitz. Protein was provided in a 240-mL solution administered over a 65-min period in both feeding regimens. Blood samples were collected during the 7-h postprandial period to assess the increase in plasma AA concentrations and dietary protein-derived plasma L-[1-C-13] phenylalanine enrichment. Results: Jejunal feeding compared with gastric feeding resulted in higher peak plasma phenylalanine, leucine, total essential AA (EAA), and total AA concentrations (all P

Recently, we identified several flavonoids as inhibitors of the nuclear enzyme poly(ADP-ribose) polymerase (PARP)-1 in vitro and in vivo. PARP-1 is recognized as coactivator of nuclear factor-kappaB and plays a role in the pathophysiology of diseases with low-grade systemic inflammation, such as chronic obstructive pulmonary disease (COPD) and type 2 diabetes (T2D). In this study, we assessed the antiinflammatory effects of flavonoids with varying PARP-1-inhibiting effects in whole blood from male patients with COPD or T2D and healthy men. A total of 10 COPD, 10 T2D patients, and 10 healthy volunteers matched for age and BMI were recruited. Blood from each participant was exposed to 1 microg/L lipopolysaccharide (LPS) over 16 h with or without preincubation with 10 micromol/L of flavone, fisetin, morin, or tricetin. Concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, -8, and -10 were measured in the supernatant. Preincubation with fisetin and tricetin strongly attenuated LPS-induced increases in concentrations of TNFalpha in blood from COPD patients [mean (+/- SEM): -41 +/- 4% (fisetin) and -31 +/- 4% (tricetin); P < 0.001] and IL-6 in blood from T2D patients [-31 +/- 5% (fisetin) and -29 +/- 6% (tricetin); P < or = 0.001]. Moreover, LPS-induced changes in TNFalpha and IL-6 concentrations were positively correlated with the extent of reduction by fisetin and tricetin. The PARP-1-inhibiting flavonoids fisetin and tricetin were able to attenuate LPS-induced cytokine release from leukocytes of patients with chronic systemic inflammation, indicating a potential application as nutraceutical agents for these patient groups.

Our objective was to determine the impact of carbohydrate and/or protein ingestion before and after exercise on ribosomal protein S6 kinase (S6K1) and S6 phosphorylation status in human skeletal muscle tissue. Seven healthy, untrained men (22.5 +/- 0.9 y) were randomly assigned to 2 cross-over experiments. Before, immediately after, and 1 h after a single bout of resistance exercise, subjects consumed 0.3 g.kg(-1) carbohydrate with or without 0.3 g.kg(-1) protein hydrolysate (CHO+PRO and CHO, respectively). Muscle biopsies were taken before and immediately after exercise and after 1 and 4 h of postexercise recovery to determine 4E-BP1, S6K1 (both T(421)/S(424) and T(389)), and S6 phosphorylation status. Following resistance exercise, 4E-BP1 phosphorylation was reduced to a greater extent in the CHO treatment (-48 +/- 7%) than in the CHO+PRO treatment (-15 +/- 14%, P < 0.01). During recovery, 4E-BP1 phosphorylation increased in both experiments (P < 0.01), and tended to be higher in the CHO+PRO test (P = 0.08). S6K1 phosphorylation at T(421)/S(424) substantially increased following exercise and remained elevated during recovery with no differences between treatments. In contrast to the CHO treatment (-4 +/- 2%), S6K1 phosphorylation at T(389) was higher following exercise in the CHO+PRO treatment only (+78 +/- 2%, P < 0.01). During recovery, S6K1 phosphorylation at T(389) remained higher in CHO+PRO than in CHO (P < 0.05). S6 phosphorylation was substantially higher following exercise in the CHO+PRO (1.69 +/- 0.35) than in the CHO experiment (0.45 +/- 0.07, P < 0.01) and remained elevated during recovery (P < 0.05). We conclude that the availability of dietary protein further enhances phosphorylation of S6K1 during recovery from resistance type exercise. AD - Departments of Movement Sciences and 3Human Biology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, Maastricht 6200 MD, The Netherlands.