L-arabinose co-ingestion delays glucose absorption derived from sucrose in healthy men and women : A double-blind, randomized crossover trial

Dietary interventions to delay carbohydrate digestion or absorption can effectively prevent hyperglycaemia in the early postprandial phase. L-arabinose can specifically inhibit sucrase. It remains to be assessed whether co-ingestion of L-arabinose with sucrose delays sucrose digestion, attenuates subsequent glucose absorption and impacts hepatic glucose output. In this double-blind, randomised crossover study, we assessed blood glucose kinetics following ingestion of a 200-ml drink containing 50 g of sucrose with 7·5 g of L-arabinose (L-ARA) or without L-arabinose (CONT) in twelve young, healthy participants (24 ± 1 years; BMI: 22·2 ± 0·5 kg/m2). Plasma glucose kinetics were determined by a dual stable isotope methodology involving ingestion of (U-13C6)-glucose-enriched sucrose, and continuous intravenous infusion of (6,6–2H2)-glucose. Peak glucose concentrations reached 8·18 ± 0·29 mmol/l for CONT 30 min after ingestion. In contrast, the postprandial rise in plasma glucose was attenuated for L-ARA, because peak glucose concentrations reached 6·62 ± 0·18 mmol/l only 60 min after ingestion. The rate of exogenous glucose appearance for L-ARA was 67 and 57 % lower compared with CONT at t = 15 min and 30 min, respectively, whereas it was 214 % higher at t = 150 min, indicating a more stable absorption of exogenous glucose for L-ARA compared with CONT. Total glucose disappearance during the first hour was lower for L-ARA compared with CONT (11 ± 1 v. 17 ± 1 g, P < 0·0001). Endogenous glucose production was not differentially affected at any time point (P = 0·27). Co-ingestion of L-arabinose with sucrose delays sucrose digestion, resulting in a slower absorption of sucrose-derived glucose without causing adverse effects in young, healthy adults

Intradialytic protein ingestion and exercise do not compromise uremic toxin removal throughout hemodialysis

Objective Dietary protein and physical activity interventions are increasingly implemented during hemodialysis to support muscle maintenance in patients with end-stage renal disease (ESRD). Although muscle maintenance is important, adequate removal of uremic toxins throughout hemodialysis is the primary concern for patients. It remains to be established whether intradialytic protein ingestion and/or exercise modulate uremic toxin removal during hemodialysis. Methods We recruited 10 patients with ESRD (age: 65 ± 16 y, BMI: 24.2 ± 4.8 kg/m2) on chronic hemodialysis treatment to participate in this randomized cross-over trial. During hemodialysis, patients were assigned to ingest 40 g protein or a nonprotein placebo both at rest (protein [PRO] and placebo [PLA], respectively) and following 30 min of exercise (PRO + exercise [EX] and PLA + EX, respectively). Blood and spent dialysate samples were collected throughout hemodialysis to assess reduction ratios and removal of urea, creatinine, phosphate, cystatin C, and indoxyl sulfate. Results The reduction ratios of urea and indoxyl sulfate were higher during PLA (76 ± 6% and 46 ± 9%, respectively) and PLA + EX interventions (77 ± 5% and 45 ± 10%, respectively) when compared to PRO (72 ± 4% and 40 ± 8%, respectively) and PRO + EX interventions (73 ± 4% and 43 ± 7%, respectively; protein effect: P = .001 and P = .023, respectively; exercise effect: P = .25 and P = .52, respectively). Nonetheless, protein ingestion resulted in greater urea removal (P = .046) during hemodialysis. Reduction ratios and removal of creatinine, phosphate, and cystatin C during hemodialysis did not differ following intradialytic protein ingestion or exercise (protein effect: P > .05; exercise effect: P>.05). Urea, creatinine, and phosphate removal were greater throughout the period with intradialytic exercise during PLA + EX and PRO + EX interventions when compared to the same period during PLA and PRO interventions (exercise effect: P = .034, P = .039, and P = .022, respectively). Conclusion The removal of uremic toxins is not compromised by protein feeding and/or exercise implementation during hemodialysis in patients with ESRD

Does supplementation with leucine-enriched protein alone and in combination with fish-oil-derived n–3 PUFA affect muscle mass, strength, physical performance, and muscle protein synthesis in well-nourished older adults? A randomized, double-blind, placebo-controlled trial

peer-reviewedBackground Leucine-enriched protein (LEU-PRO) and long-chain (LC) n–3 (ω–3) PUFAs have each been proposed to improve muscle mass and function in older adults, whereas their combination may be more effective than either alone. Objective The impact of LEU-PRO supplementation alone and combined with LC n–3 PUFAs on appendicular lean mass, strength, physical performance and myofibrillar protein synthesis (MyoPS) was investigated in older adults at risk of sarcopenia. Methods This 24-wk, 3-arm parallel, randomized, double-blind, placebo-controlled trial was conducted in 107 men and women aged ≥65 y with low muscle mass and/or strength. Twice daily, participants consumed a supplement containing either LEU-PRO (3 g leucine, 10 g protein; n = 38), LEU-PRO plus LC n–3 PUFAs (0.8 g EPA, 1.1 g DHA; LEU-PRO+n–3; n = 38), or an isoenergetic control (CON; n = 31). Appendicular lean mass, handgrip strength, leg strength, physical performance, and circulating metabolic and renal function markers were measured pre-, mid-, and postintervention. Integrated rates of MyoPS were assessed in a subcohort (n = 28). Results Neither LEU-PRO nor LEU-PRO+n–3 supplementation affected appendicular lean mass, handgrip strength, knee extension strength, physical performance or MyoPS. However, isometric knee flexion peak torque (treatment effect: −7.1 Nm; 95% CI: −12.5, −1.8 Nm; P < 0.01) was lower postsupplementation in LEU-PRO+n–3 compared with CON. Serum triacylglycerol and total adiponectin concentrations were lower, and HOMA-IR was higher, in LEU-PRO+n–3 compared with CON postsupplementation (all P < 0.05). Estimated glomerular filtration rate was higher and cystatin c was lower in LEU-PRO and LEU-PRO+n–3 postsupplementation compared with CON (all P < 0.05). Conclusions Contrary to our hypothesis, we did not observe a beneficial effect of LEU-PRO supplementation alone or combined with LC n–3 PUFA supplementation on appendicular lean mass, strength, physical performance or MyoPS in older adults at risk of sarcopenia. This trial was registered at clinicaltrials.gov as NCT03429491.Horizon 2020 Framework ProgrammeThis work was supported by the Department of Agriculture, Food and the Marine Food Institutional Research Measure grant entitled NUTRIMAL “Novel Nutritional Solutions for the Prevention of Malnutrition” (grant 14F822), the European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie Grant Agreement No. 666010, and a Research Fellowship awarded to CHM by the European Society of Clinical Nutrition and Metabolism (ESPEN). HMR was supported by funding from the Joint Programming Initiative Healthy Diet for a Healthy Life (JPI HDHL) EU Food Biomarkers Alliance “FOODBAll” with Science Foundation Ireland (14/JPHDHL/B3076)

Protein type, protein dose, and age modulate dietary protein digestion and phenylalanine absorption kinetics and plasma phenylalanine availability in humans

This is the final version. Available from the publisher via the DOI in this record.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

Muscle Atrophy Due to Nerve Damage Is Accompanied by Elevated Myofibrillar Protein Synthesis Rates

Muscle loss is a severe complication of many medical conditions such as cancer, cardiac failure, muscular dystrophies, and nerve damage. The contribution of myofibrillar protein synthesis (MPS) to the loss of muscle mass after nerve damage is not clear. Using deuterium oxide (D2O) labeling, we demonstrate that MPS is significantly increased in rat m. tibialis anterior (TA) compared to control (3.23 +/- 0.72 [damaged] to 2.09 +/- 0.26%*day(-1) [control]) after 4 weeks of nerve constriction injury. This is the case despite substantial loss of mass of the TA (350 +/- 96 mg [damaged] to 946 +/- 361 mg [control]). We also show that expression of regulatory proteins involved with MPS (p70s6k1: 2.4 +/- 0.3 AU [damaged] to 1.8 +/- 0.2 AU [control]) and muscle protein breakdown (MPB) (MAFbx: 5.3 +/- 1.2 AU [damaged] to 1.4 +/- 0.4 AU [control]) are increased in nerve damaged muscle. Furthermore, the expression of p70s6k1 correlates with MPS rates (r(2) = 0.57). In conclusion, this study shows that severe muscle wasting following nerve damage is accompanied by increased as opposed to decreased MPS

Substantial skeletal muscle loss occurs during only 5 days of disuse

Aim The impact of disuse on the loss of skeletal muscle mass and strength has been well documented. Given that most studies have investigated muscle atrophy after more than 2 weeks of disuse, few data are available on the impact of shorter periods of disuse. We assessed the impact of 5 and 14 days of disuse on skeletal muscle mass, strength and associated intramuscular molecular signalling responses

The Effect of Beetroot Juice Supplementation on Dynamic Apnea and Intermittent Sprint Performance in Elite Female Water Polo Players

Nitrate-rich beetroot juice is thought to have ergogenic effects, particularly in conditions where oxygen availability is limited. Whether these effects also apply to elite athletes is currently unknown. The aim of this study was to assess the effects of beetroot juice supplementation on dynamic apnea and intermittent sprint performance in elite female water polo players. In a doubleblinded, randomized, crossover manner, the Dutch National female water polo team (N = 14) was subjected to two 6-day supplementation periods (1 and 2), with either 140 ml/day of nitrate-rich (BR; ∼800 mg/day nitrate) or nitrate-depleted (PLA) beetroot juice. Following blood sampling on Day 6, the athletes performed amaximal-distance front crawl swimming test without breathing (dynamic apnea test). In addition, intermittent sprint performance was assessed by performing 16 swim sprints of 15 m, in a 4 × 4 block with 30-s recovery between blocks (intermittent test). Distance covered during the dynamic apnea test did not differ between BR (49.5 ± 7.8 m) and PLA (46.9 ± 9.1 m, p = .178). However, when correcting for test order, the distance covered was significantly larger in BR versus PLA when BR was ingested in Period 2 (50.1 ± 8.5 vs. 42.8 ± 5.7 m, p = .002), whereas no difference was observed when BR was ingested in Period 1 (48.8 ± 7.4 vs. 52.3 ± 10.4 m, p = .10). The time to complete the intermittent test was not different between BR and PLA (316.0 ± 7.9 vs. 316.3 ± 6.9 s, p = .73). In conclusion, beetroot juice supplementation does not improve intermittent performance in elite female water polo players, but there may be a potential for ergogenic effects during dynamic apnea

Intragastric protein administration stimulates overnight muscle protein synthesis in elderly men

The loss of skeletal muscle mass with aging has been attributed to an impaired muscle protein synthetic response to food intake. Therefore, nutritional strategies are targeted to modulate postprandial muscle protein accretion in the elderly. The purpose of this study was to assess the impact of protein administration during sleep on in vivo protein digestion and absorption kinetics and subsequent muscle protein synthesis rates in elderly men. Sixteen healthy elderly men were randomly assigned to an experiment during which they were administered a single bolus of intrinsically l-[1-13C]phenylalanine-labeled casein protein ( PRO ) or a placebo ( PLA ) during sleep. Continuous infusions with l-[ring-2H5]phenylalanine and l-[ring-2H2]tyrosine were applied to assess in vivo dietary protein digestion and absorption kinetics and subsequent muscle protein synthesis rates during sleep. We found that exogenous phenylalanine appearance rates increased following protein administration. The latter stimulated protein synthesis, resulting in a more positive overnight whole body protein balance ( 0.30 ± 0.1 vs. 11.8 ± 1.0 μmol phenylalanine·kg−1·h−1 in PLA and PRO, respectively; P < 0.05 ). In agreement, overnight muscle protein fractional synthesis rates were much greater in the PRO experiment ( 0.045 ± 0.002 vs. 0.029 ± 0.002%/h, respectively; P < 0.05 ) and showed abundant incorporation of the amino acids ingested via the intrinsically labeled protein ( 0.058 ± 0.006%/h ). This is the first study to show that dietary protein administration during sleep is followed by normal digestion and absorption kinetics, thereby stimulating overnight muscle protein synthesis. Dietary protein administration during sleep stimulates muscle protein synthesis and improves overnight whole body protein balance. These findings may provide a basis for novel interventional strategies to attenuate muscle mass loss

Beetroot juice supplementation reduces whole body oxygen consumption but does not improve indices of mitochondrial efficiency in human skeletal muscle

Ingestion of sodium nitrate ( NO3− ) simultaneously reduces whole body oxygen consumption ( ) during submaximal exercise while improving mitochondrial efficiency, suggesting a causal link. Consumption of beetroot juice ( BRJ ) elicits similar decreases in but potential effects on the mitochondria remain unknown. Therefore we examined the effects of 7-day supplementation with BRJ ( 280 ml day−1, ∼26 mmol NO3− ) in young active males ( n = 10 ) who had muscle biopsies taken before and after supplementation for assessments of mitochondrial bioenergetics. Subjects performed 20 min of cycling ( 10 min at 50% and 70% ) 48 h before ‘Pre’ ( baseline ) and ‘Post’ ( day 5 of supplementation ) biopsies. Whole body decreased ( P < 0.05 ) by ∼3% at 70% following supplementation. Mitochondrial respiration in permeabilized muscle fibres showed no change in leak respiration, the content of proteins associated with uncoupling ( UCP3, ANT1, ANT2 ), maximal substrate-supported respiration, or ADP sensitivity ( apparent Km ). In addition, isolated subsarcolemmal and intermyofibrillar mitochondria showed unaltered assessments of mitochondrial efficiency, including ADP consumed/oxygen consumed ( P/O ratio ), respiratory control ratios and membrane potential determined fluorometrically using Safranine-O. In contrast, rates of mitochondrial hydrogen peroxide ( H2O2 ) emission were increased following BRJ. Therefore, in contrast to sodium nitrate, BRJ supplementation does not alter key parameters of mitochondrial efficiency. This occurred despite a decrease in exercise , suggesting that the ergogenic effects of BRJ ingestion are not due to a change in mitochondrial coupling or efficiency. It remains to be determined if increased mitochondrial H2O2 contributes to this response