Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Plasma cytokine responses to resistance exercise with different nutrient availability on a concurrent exercise day in trained healthy males
Knuiman, Pim ; Hopman, Maria T.E. ; Hangelbroek, Roland ; Mensink, Marco - \ 2018
Physiological Reports 6 (2018)11. - ISSN 2051-817X
Circulating cytokines - endurance exercise - Nutrient availability - resistance exercise

Carbohydrate availability is proposed as a potential regulator of cytokine responses. We aimed to evaluate the effect of a preresistance exercise carbohydrate meal versus fat meal on plasma cytokine responses to resistance exercise after an endurance exercise earlier that day. Thirteen young, healthy, recreationally active males performed two experimental days with endurance exercise in the morning and resistance exercise in the afternoon. Either a carbohydrate (110 g carbohydrate, 52 g protein, 9 g fat; ~750 kcal) or an isocaloric fat meal (20 gr carbohydrate, 52 g protein, 51 g fat) was provided 2 h before resistance exercise. Blood was taken at baseline and at regular time intervals to measure circulating plasma cytokine levels (e.g. IL-6, IL-8, IL-10, IL-15, TNFα, ANGPTL4, decorin and MCP-1). Plasma glucose and insulin were higher in the postprandial period before the start of the resistance exercise on the carbohydrate condition, while free fatty acids were reduced. At 2 h postresistance exercise, IL-6 concentrations were higher in the fat condition compared to the carbohydrate condition (P < 0.05). In addition, in both conditions IL-6 levels were higher at all time points compared with baseline (P < 0.05). The pattern of increase in plasma IL-8 and IL-10 did not differ significantly between conditions (P > 0.05). There were no differences between conditions on TNFα levels and levels remain constant when compared with baseline (P > 0.05). ANGPTL4, IL-15, Decorin and MCP-1 showed no differences between the fat and carbohydrate condition (P > 0.05). The composition of the pre-exercise meal did in general not influence cytokine responses in the postresistance exercise period, except postresistance exercise circulating plasma IL-6 levels being higher in the fat condition compared with carbohydrate. Our findings support the view that pre-exercise carbohydrate availability does not have a major impact on acute responses of circulating plasma cytokines in humans.

Protein and the Adaptive Response With Endurance Training: Wishful Thinking or a Competitive Edge?
Knuiman, P. ; Hopman, Maria ; Verbruggen, Conor ; Mensink, M.R. - \ 2018
Frontiers in Physiology 9 (2018). - ISSN 1664-042X - 8 p.
The significance of carbohydrates for endurance training has been well established, whereas the role of protein and the adaptive response with endurance training is unclear. Therefore, the aim of this perspective is to discuss the current evidence on the role of dietary protein and the adaptive response with endurance training. On a metabolic level, a single bout of endurance training stimulates the oxidation of several amino acids.
Although the amount of amino acids as part of total energy expenditure during exercise is relatively low compared to other substrates (e.g., carbohydrates and fat), it may depress the rates of skeletal muscle protein synthesis, and thereby have a negative effect on training adaptation. A low supply of amino acids relative to that of carbohydrates may also have negative effects on the synthesis of capillaries, synthesis and turn-over of mitochondrial proteins and proteins involved in oxygen transport including hamoglobin and myoglobin. Thus far, the scientific evidence demonstrating the significance of dietary protein is mainly derived from research with resistance exercise training regimes. This is
not surprising since the general paradigm states that endurance training has insignificant effects on skeletal muscle growth. This could have resulted in an underappreciation of the role of dietary protein for the endurance athlete. To conclude, evidence of the role of protein on endurance training adaptations and performance remains scarce and is mainly derived from acute exercise studies. Therefore, future human intervention studies must unravel whether dietary protein is truly capable of augmenting endurance training adaptations and ultimately performance.
Onderzoek naar voorkoelsystemen bij chrysantentelers legt problemen bloot
Wissink, E.B. ; Mensink, M.G.J. ; Hogeveen-van Echtelt, Esther - \ 2018
RCC Koude & Luchtbehandeling
The effect of exercise on intestinal integrity and protein permeability
Janssen Duijghuijsen, L.M. ; Keijer, J. ; Mensink, M.R. ; Bastiaan-Net, S. ; Mes, J.J. ; Luiking, Yvette ; Wichers, H.J. ; Witkamp, R.F. ; Norren, K. van - \ 2018
Krachtsporter heeft geen extra bord pasta nodig
Mensink, Marco - \ 2018
The acute effects on duodenal gene expression in healthy men following consumption of a low-fat meal enriched with theobromine or fat
Smolders, Lotte ; Mensink, Ronald P. ; Boekschoten, Mark V. ; Ridder, Rogier J.J. De; Plat, Jogchum - \ 2018
Scientific Reports 8 (2018)1. - ISSN 2045-2322
Increasing apoA-I synthesis may improve HDL functionality and lower CVD risk. As theobromine and fat increase fasting apoA-I concentrations, and the intestine is involved in apoA-I production, the acute effects of both were studied on duodenal gene transcription to better understand underlying mechanisms. In this crossover study, 8 healthy men received once a low fat (LF) meal, a LF meal plus theobromine (850 mg), or a high fat (HF) meal. Five hours after meal intake duodenal biopsies were taken for microarray analysis. Theobromine and HF consumption did not change duodenal apoA-I expression. Theobromine did not change gene expression related to lipid and cholesterol metabolism, whereas those related to glycogen/glucose breakdown were downregulated. HF consumption increased gene expression related to lipid and cholesterol uptake and transport, and to glucose storage, while it decreased those related to glucose uptake. Furthermore, genes related to inflammation were upregulated, but inflammation markers in plasma were not changed. In healthy men, acute theobromine and fat consumption did not change duodenal apoA-I mRNA, but inhibited expression of genes related to glucose metabolism. Furthermore, HF intake activated in the duodenum expression of genes related to lipid and cholesterol metabolism and to inflammation.
Select skeletal muscle mRNAs related to exercise adaptation are minimally affected by different pre-exercise meals that differ in macronutrient profile
Knuiman, Pim ; Hopman, Maria T.E. ; Wouters, Jeroen A. ; Mensink, Marco - \ 2018
Frontiers in Physiology 9 (2018)JAN. - ISSN 1664-042X
Endurance exercise - Gene expression - Humans - Nutrient availability - Resistance exercise
Background: Substantial research has been done on the impact of carbohydrate and fat availability on endurance exercise adaptation, though its role in the acute adaptive response to resistance exercise has yet to be fully characterized. Purpose: We aimed to assess the effects of a pre-resistance exercise isocaloric mixed meal containing different amounts of carbohydrates and fat, on post-resistance exercise gene expression associated with muscle adaptation. Methods: Thirteen young (age 21.2 ± 1.6 year), recreationally trained (VO2max 51.3 ± 4.8 ml/kg/min) men undertook an aerobic exercise session of 90-min continuous cycling (70% VO2max) in the morning with pre- and post-exercise protein ingestion (10 and 15 g casein in a 500 ml beverage pre- and post-exercise, respectively). Subjects then rested for 2 h and were provided with a meal consisting of either 3207 kJ; 52 g protein; 51 g fat; and 23 g carbohydrate (FAT) or 3124 kJ; 53 g protein; 9 g fat; and 109 g carbohydrate (CHO). Two hours after the meal, subjects completed 5 × 8 repetitions (80% 1-RM) for both bilateral leg press and leg extension directly followed by 25 g of whey protein (500 ml beverage). Muscle biopsies were obtained from the vastus lateralis at baseline (morning) and 1 and 3 h post-resistance exercise (afternoon) to determine intramuscular mRNA response. Results: Muscle glycogen levels were significantly decreased post-resistance exercise, without any differences between conditions. Plasma free fatty acids increased significantly after the mixed meal in the FAT condition, while glucose and insulin were higher in the CHO condition. However, PDK4 mRNA quantity was significantly higher in the FAT condition at 3 h post-resistance exercise compared to CHO. HBEGF, INSIG1, MAFbx, MURF1, SIRT1, and myostatin responded solely as a result of exercise without any differences between the CHO and FAT group. FOXO3A, IGF-1, PGC-1a, and VCP expression levels remained unchanged over the course of the day. Conclusion: We conclude that mRNA quantity associated with muscle adaptation after resistance exercise is not affected by a difference in pre-exercise nutrient availability. PDK4 was differentially expressed between CHO and FAT groups, suggesting a potential shift toward fat oxidation and reduced glucose oxidation in the FAT group.
Airborne Emissions from Livestock Farms and Exposure of Nearby Residents using an Atmospheric Dispersion Model
Sterk, H.A.M. ; Swart, A.N. ; Leuken, J.P.G. van; Schijven, J.F. ; Aarnink, A.J.A. ; Wouters, I.M. ; Janse, I. ; Wichink Kruit, R.J. ; Pul, W.A.J. van - \ 2018
In: ITM 2016: Air Pullution Modeling and its Application XXV. - Springer (Springer Proceedings in Complexity ) - ISBN 9783319576442 - p. 487 - 494.
To estimate the exposure of local residents to substances emitted by livestock farms, we applied a dispersion model to calculate the air concentrations in the surroundings following from these emissions. At several livestock farms, indoor air measurements were performed to determine emission strengths, while ambient measurements were carried out to compare with model results. Measured substances were particulate matter (PM), endotoxins and micro-organisms. The dispersion model only simulated PM concentrations, which were used as a proxy to determine the dispersion concentrations of endotoxins and micro-organisms. For the living micro-organisms, the process of inactivation has to be taken into account. Here we describe the followed methodology and preliminary results.
Associations between dietary factors and markers of NAFLD in a general Dutch adult population
Rietman, A. ; Sluik, D. ; Feskens, E.J.M. ; Kok, F.J. ; Mensink, M.R. - \ 2018
European Journal of Clinical Nutrition 72 (2018). - ISSN 0954-3007 - p. 117 - 123.
Background/Objectives: The objective of this sudy was to assess the relationship between dietary intake and fatty liver as scored by the validated Fatty Liver Index (FLI) in a large cross-sectional study among a general Dutch adult population. Diet is known to affect liver fat accumulation in humans. Subjects/Methods: 1128 men and women aged 20–70 years were included. Dietary intake was assessed using a validated semiquantitative food frequency questionnaire. FLI was derived from body mass index (BMI), waist circumference, triglycerides and gamma-glutamyltransferase. Associations were adjusted for energy intake, alcohol intake, age, sex, education, smoking and prevalence of hypertension and diabetes. Results: In this population (mean age 53.0±11.4 years; BMI 25.9±4.0 kg/m2; FLI 35.0±27.7), the prevalence of fatty liver as indicated by an FLI>60 was 21.5%. Subjects in the highest FLI category were more likely to be male, older and less physically active. Total protein intake and animal protein intake were positively associated with the highest FLI score versus the lowest (odds ratio (OR) 1.25 per 1 en%, 95% confidence interval (CI) 1.15–1.37 and OR 1.27, 95% CI 1.17–1.38, respectively); for vegetable protein, an inverse association was observed (OR 0.81, 95% CI 0.69–0.94). A similar positive association with FLI was observed when carbohydrates and fat were iso-calorically exchanged for total and animal proteins. Conclusions: Subjects in the high FLI group consumed more protein, especially from animal origin, less carbohydrates and less dietary fibre. The presence of fatty liver was associated with a higher intake of animal protein and total fat, soft drinks and snacks.
Theobromine does not affect postprandial lipid metabolism and duodenal gene expression, but has unfavorable effects on postprandial glucose and insulin responses in humans
Smolders, Lotte ; Mensink, Ronald P. ; Boekschoten, Mark V. ; Ridder, Rogier J.J. de; Plat, Jogchum - \ 2018
Clinical Nutrition 37 (2018)2. - ISSN 0261-5614 - p. 719 - 727.
Glucose metabolism - Lipid metabolism - Microarray - Postprandial - Theobromine
Background & aims: Chocolate consumption is associated with a decreased risk for CVD. Theobromine, a compound in cocoa, may explain these effects as it favorably affected fasting serum lipids. However, long-term effects of theobromine on postprandial metabolism as well as underlying mechanisms have never been studied. The objective was to evaluate the effects of 4-week theobromine consumption (500 mg/day) on fasting and postprandial lipid, lipoprotein and glucose metabolism, and duodenal gene expression. Methods: In a randomized, double-blind crossover study, 44 healthy men and women, with low baseline HDL-C concentrations consumed 500 mg theobromine or placebo daily. After 4-weeks, fasting blood was sampled and subjects participated in a 4-h postprandial test. Blood was sampled frequently for analysis of lipid and glucose metabolism. In a subgroup of 10 men, 5 h after meal consumption duodenal biopsies were taken for microarray analysis. Results: 4-weeks theobromine consumption lowered fasting LDL-C (-0.21 mmol/L; P = 0.006), and apoB100 (-0.04 g/L; P = 0.022), tended to increase HDL-C (0.03 mmol/L; P = 0.088) and increased hsCRP (1.2 mg/L; P = 0.017) concentrations. Fasting apoA-I, TAG, FFA, glucose and insulin concentrations were unchanged. In the postprandial phase, theobromine consumption increased glucose (P = 0.026), insulin (P = 0.011) and FFA (P = 0.003) concentrations, while lipids and (apo)lipoproteins were unchanged. In duodenal biopsies, microarray analysis showed no consistent changes in expression of genes, pathways or gene sets related to lipid, cholesterol or glucose metabolism. Conclusions: It is not likely that the potential beneficial effects of cocoa on CVD can be ascribed to theobromine. Although theobromine lowers serum LDL-C concentrations, it did not change fasting HDL-C, apoA-I, or postprandial lipid concentrations and duodenal gene expression, and unfavorably affected postprandial glucose and insulin responses.This trial was registered on under study number NCT02209025.
Antimicrobial peptides within the Yellowtail Kingfish (Seriola lalandi)
Muncaster, Simon ; Kraakman, Kirsty ; Gibbons, Olivia ; Mensink, Koen ; Forlenza, Maria ; Jacobson, Gregory ; Bird, Steve - \ 2018
Developmental and Comparative Immunology 80 (2018). - ISSN 0145-305X - p. 67 - 80.
Antimicrobial peptide - Hepcidin - Immunology - Piscidin - Transcriptomics - Yellowtail kingfish (Seriola lalandi)

A number of Seriola species are currently farmed or being investigated as future aquaculture species in countries around the world. However they face a number of issues and limitations which will need to be overcome to ensure future stability and growth, one of which are disease outbreaks. Despite this, very little has been done to understand the immune system of Seriola species and very few immune genes have been characterised. Antimicrobial peptides (AMP) are naturally occurring low molecular weight polypeptides that play a major role in an organism's immune system and act effectively as a first line of defence. This investigation isolates the full length cDNA sequences of two AMP's, piscidin and hepcidin from the yellowtail kingfish (Seriola lalandi). The full-length cDNA of the piscidin gene encodes a 65 amino acid prepropeptide, containing a 25-residue peptide, predicted to form an amphipathic helix-loop-helix structure. Phylogenetic analysis using fish piscidin sequences, showed that this AMP is only found in bony fish within the Acanthomorpha clade and that a possible three groups within the piscidin family exists, with S. lalandi belonging to a particular group. The full-length cDNA of the hepcidin gene encodes a 90 amino acid preprohepcidin, which contains a typical RX(R/K)R motif for cleavage of the mature peptide which comprises of eight conserved cysteine residues. Phylogenetic analysis of known vertebrate hepcidin antimicrobial peptide (HAMP) sequences, shows sequences from the Neoteleostei clade of bony fish form two very separate groups, HAMP1 and HAMP2, with the S. lalandi hepcidin gene grouped with the HAMP1 sequences. HAMP2 sequences are found to have multiple copies within fish and genome analysis showed very clearly that these two groups of genes are located on separate regions on the genome, with the multiple HAMP2 copies formed from tandem gene duplications. Lastly, using qPCR the expression of the S. lalandi piscidin gene within healthy fish was highest within, spleen and gills and lowest in liver, whereas hepcidin was highest in the liver with little or no expression in the spleen and gills.

Effect of theobromine consumption on serum lipoprotein profiles in apparently healthy humans with low HDL-cholesterol concentrations
Jacobs, Doris M. ; Smolders, Lotte ; Lin, Yuguang ; Roo, Niels de; Trautwein, Elke A. ; Duynhoven, John van; Mensink, Ronald P. ; Plat, Jogchum ; Mihaleva, Velitchka V. - \ 2017
Frontiers in Molecular Biosciences 4 (2017)AUG. - ISSN 2296-889X
HDL - Lipoprotein - NMR - PLS model - Theobromine
Scope: Theobromine is a major active compound in cocoa with allegedly beneficial effect on high-density-lipoprotein-cholesterol (HDL-CH). We have investigated the effect of theobromine (TB) consumption on the concentrations of triglyceride (TG) and cholesterol (CH) in various lipoprotein (LP) subclasses. Methods: In a randomized, double-blind, placebo-controlled, cross-over study, 44 apparently healthy women and men (age: 60 ± 6 years, BMI: 29 ± 3 kg/m2) with low baseline HDL-CH concentrations consumed a drink supplemented with 500 mg/d theobromine for 4 weeks. TG and CH concentrations in 15 LP subclasses were predicted from diffusion-edited 1H NMR spectra of fasting serum. Results: The LP phenotype of the subjects was characterized by low CH concentrations in the large HDL particles and high TG concentrations in large VLDL and chylomicron (CM) particles, which clearly differed from a LP phenotype of subjects with normal HDL-CH. TB only reduced CH concentrations in the LDL particles by 3.64 and 6.79%, but had no effect on TG and CH in any of the HDL, VLDL and CM subclasses. Conclusion: TB was not effective on HDL-CH in subjects with a LP phenotype characterized by low HDL-CH and high TG in VLDL.
A floor cover to improve temperature distribution and quality preservation in maritime refrigerated container transport of grapes : GreenCHAINge WP1 - Table Grapes
Lukasse, Leo ; Mensink, Manon ; Wissink, Edo - \ 2017
Wageningen : Wageningen Food & Biobased Research (Wageningen Food &amp; Biobased Research report 1733) - ISBN 9789463436601 - 32
refrigerated transport - containers - sea transport - grapes - covers - temperature - food quality - koeltransport - zeetransport - druiven - bedekkingsmaterialen - temperatuur - voedselkwaliteit
Like many other fruits, table grapes depend on accurate temperature management during transport in maritime refrigerated containers. Ideally the temperature inside the container is equal to set point in every location in the container. Unfortunately door-end temperatures are always higher due to poor air flow distribution. In climate chamber tests Lukasse & Staal (2016a and 2016b) investigated the effect of covering sections of the container’s T-bar floor. The best T-bar floor cover found in that study was a trapezoid-shape floor cover. The aim of this study is to assess the effect of that trapezoid-shape T-bar floor cover on temperature and fruit quality in commercial reefer container transports of grapes. A field experiment was done in a commercial container shipment of six standard 40 ft. HC reefer containers travelling from South Africa to The Netherlands taking 24 days. The three test containers contained a T-bar floor cover. The three reference containers did not contain the T-bar floor cover. All other parameters were, to the extent possible, the same for all containers. In 31 locations air temperature between the fruit was logged at an interval of 10 min. with an accuracy of approx. ± 0.1 °C. 15 Trays, evenly distributed in a vertical plane on the container’s longitudinal centre line, were weighed at origin and at destination. At destination the fruit quality of these 15 trays was analysed. A clear positive effect on temperature was observed. The floor cover reduces the average difference between warmest and coldest temperature in the trays by approx. 30%. An effect on grape quality could not be assessed.
Amino acid absorption in the large intestine of humans and porcine models
Wielen, Nikkie van der; Moughan, Paul J. ; Mensink, Marco - \ 2017
The Journal of Nutrition 147 (2017)8. - ISSN 0022-3166 - p. 1493 - 1498.
Absorption - Amino acid - Digestible Indispensable Amino Acid Score - Digestion - Large intestine
Dietary protein quality has been recognized as a critical issue by international authorities because it can affect important functions of the body. To predict protein quality, the FAO introduced the Digestible Indispensable Amino Acid Score. This score depends on ileal amino acid (AA) digestibility; therefore, the assumption is made that AAs are not absorbed in nutritionally relevant amounts from the large intestine. This article reviews the evidence for this assumption by considering the role of themammalian large intestine in dietary protein and AA digestion and absorption,with particular reference to adult humans. Althoughmost dietary AAs and peptides are absorbed in the small intestine, substantial amounts can enter the large intestine. Nitrogen is absorbed in the large intestine, and a series of animal experiments indicate a potential small degree of AA absorption. In humans, colonocytes have the capacity for AA absorption because AA transporters are present in the large intestine. The absorption of nutritionally relevant amounts of dietary indispensable AAs and peptides in the human large intestine has not been convincingly demonstrated, however.
Omics and cytokine discovery in fish : Presenting the Yellowtail kingfish (Seriola lalandi) as a case study
Jacobson, Gregory ; Muncaster, Simon ; Mensink, Koen ; Forlenza, Maria ; Elliot, Nick ; Broomfield, Grant ; Signal, Beth ; Bird, Steve - \ 2017
Developmental and Comparative Immunology 75 (2017). - ISSN 0145-305X - p. 63 - 76.
Cytokine - Fish Immunology - Genomics - RNA-Seq - Seriola lalandi - Transcriptomics
A continued programme of research is essential to overcome production bottlenecks in any aquacultured fish species. Since the introduction of genetic and molecular techniques, the quality of immune research undertaken in fish has greatly improved. Thousands of species specific cytokine genes have been discovered, which can be used to conduct more sensitive studies to understand how fish physiology is affected by aquaculture environments or disease. Newly available transcriptomic technologies, make it increasingly easier to study the immunogenetics of farmed species for which little data exists. This paper reviews how the application of transcriptomic procedures such as RNA Sequencing (RNA-Seq) can advance fish research. As a case study, we present some preliminary findings using RNA-Seq to identify cytokine related genes in Seriola lalandi. These will allow in-depth investigations to understand the immune responses of these fish in response to environmental change or disease and help in the development of therapeutic approaches.
Decrease in ionized and total magnesium blood concentrations in endurance athletes following an exercise bout restores within hours-potential consequences for monitoring and supplementation
Terink, Rieneke ; Balvers, Michiel G.J. ; Hopman, Maria T. ; Witkamp, Renger F. ; Mensink, Marco ; Klein Gunnewiek, J.M.T. - \ 2017
International Journal of Sport Nutrition & Exercise Metabolism 27 (2017)3. - ISSN 1526-484X - p. 164 - 170.
Blood analysis - Micronutrients - Status monitoring

Magnesium is essential for optimal sport performance, generating an interest to monitor its status in athletes. However, before measuring magnesium status in blood could become routine, more insight into its diurnal fluctuations and effects of exercise itself is necessary. Therefore, we measured the effect of an acute bout of exercise on ionized (iMg) and total plasma magnesium (tMg) in blood obtained from 18 healthy well-trained endurance athletes (age, 31.1 ± 8.1 yr.; VO2max, 50.9 ± 7.5 ml/kg/min) at multiple time points, and compared this with a resting situation. At both days, 7 blood samples were taken at set time points (8:30 fasted, 11:00, 12:30, 13:30, 15:00, 16:00, 18:30). The control day was included to correct for a putative diurnal fluctuation of magnesium. During the exercise day, athletes performed a 90 min bicycle ergometer test (70% VO2max) between 11:00 and 12:30. Whole blood samples were analyzed for iMg and plasma for tMg concentrations. Both concentrations decreased significantly after exercise (0.52 ± 0.04-0.45 ± 0.03 mmol/L and 0.81 ± 0.07-0.73 ± 0.06 mmol/L, respectively, p <.001) while no significant decline was observed during that time-interval on control days. Both, iMg and tMg, returned to baseline, on average, 2.5 hr after exercise. These findings suggest that timing of blood sampling to analyze Mg status is important. Additional research is needed to establish the recovery time after different types of exercise to come to a general advice regarding the timing of magnesium status assessment in practice.

Protein Supplementation Augments Muscle Fiber Hypertrophy but Does Not Modulate Satellite Cell Content During Prolonged Resistance-Type Exercise Training in Frail Elderly
Dirks, Marlou L. ; Tieland, Michael ; Verdijk, Lex B. ; Losen, Mario ; Nilwik, Rachel ; Mensink, Marco ; Groot, Lisette C.P.G.M. de; Loon, Luc J.C. van - \ 2017
Journal of the American Medical Directors Association 18 (2017)7. - ISSN 1525-8610 - p. 608 - 615.
Amino acids - Resistance exercise - Sarcopenia - Skeletal muscle

Objective: Protein supplementation increases gains in lean body mass following prolonged resistance-type exercise training in frail older adults. We assessed whether the greater increase in lean body mass can be attributed to muscle fiber type specific hypertrophy with concomitant changes in satellite cell (SC) content. Design: A total of 34 frail elderly individuals (77 ± 1 years, n = 12 male adults) participated in this randomized, double-blind, placebo-controlled trial with 2 arms in parallel. Intervention: Participants performed 24 weeks of progressive resistance-type exercise training (2 sessions per week) during which they were supplemented twice-daily with milk protein (2 × 15 g) or a placebo. Methods: Muscle biopsies were taken at baseline, and after 12 and 24 weeks of intervention, to determine type I and type II muscle fiber specific cross-sectional area (CSA), SC content, and myocellular characteristics. Results: In the placebo group, a trend for a 20% ± 11% increase in muscle fiber CSA was observed in type II fibers only (P = .051), with no increase in type I muscle fiber CSA. In the protein group, type I and II muscle fiber CSA increased by 23% ± 7% and 34% ± 10% following 6 months of training, respectively (P < .01). Myonuclear domain size increased over time in both groups and fiber types (P < .001), with no significant differences between groups (P > .05). No changes in myonuclear content and SC contents were observed over time in either group (both P > .05). Regression analysis showed that changes in myonuclear content and domain size are predictive of muscle fiber hypertrophy. Conclusions: Protein supplementation augments muscle fiber hypertrophy following prolonged resistance-type exercise training in frail older people, without changes in myonuclear and SC content.

Micronutrient Intakes in 553 Dutch Elite and Sub-Elite Athletes: Prevalence of Low and High Intakes in Users and Non-Users of Nutritional Supplements
Wardenaar, Floris ; Brinkmans, Naomi ; Ceelen, Ingrid ; Rooij, Bo Van; Mensink, Marco ; Witkamp, Renger ; Vries, Jeanne De - \ 2017
Nutrients 9 (2017)2. - ISSN 2072-6643
This study investigated whether athletes meet micronutrient recommendations and whether the adequacy of their intake is related to the use of dietary supplements, sport nutrition products or a combination. Micronutrient intakes of 553 Dutch (sub-) elite athletes were assessed using web-based 24-h dietary recalls with accompanying nutritional supplement questionnaires. In the majority of both users and non-users of dietary supplements, vitamin D intake was below the estimated average requirement (AR) if supplements were not included in the analysis. Including dietary supplements improved vitamin D intake, but still a part of the athletes, both men and women, reported an intake below the AR. Non-users of dietary supplements were particularly at risk for low intakes of vitamins B1, B2, B3 and vitamins A, C and selenium. Mean iron intake was reported below the AR in a substantial group of women, both users and non-users. The use of sport nutrition products contributed only slightly to micronutrient intake. A small prevalence of athletes using dietary supplements showed intakes of some micronutrients above the Upper Level. In conclusion, both users and non-users of nutritional supplements reported inadequate intake of micronutrients. For most micronutrients, use of nutritional supplements does not completely compensate for intakes below AR. Athletes should consider making better food choices and the daily use of a low-dosed multivitamin supplement. View Full-Text
Macronutrient Intakes in 553 Dutch Elite and Sub-Elite Endurance, Team, and Strength Athletes: Does Intake Differ between Sport Disciplines?
Wardenaar, Floris ; Brinkmans, Naomi ; Ceelen, Ingrid ; Rooij, Bo Van; Mensink, Marco ; Witkamp, Renger ; Vries, Jeanne De - \ 2017
Nutrients 9 (2017)2. - ISSN 2072-6643
Web-based 24-h dietary recalls and questionnaires were obtained from 553 Dutch well-trained athletes. The total energy and macronutrient intake was compared between discipline-categories (endurance, team, and strength) within gender, and dietary inadequacy, i.e., too low or high intakes, according to selected recommendations and guidelines, was evaluated by applying a probability approach. On average, 2.83 days per person were reported with a mean energy intake of 2566–2985 kcal and 1997–2457 kcal per day, for men and women, respectively. Between disciplines, small differences in the mean intake of energy and macronutrients were seen for both men and women. Overall, 80% of the athletes met the suggested lower-limit sport nutrition recommendation of 1.2 g·kg−1 of protein per day. The carbohydrate intake of 50%–80% of athletes was between 3 and 5 g·kg−1 bodyweight, irrespective of the category of their discipline. This can be considered as low to moderate, in view of their daily total exercise load (athletes reported on average ~100 minutes per day). In conclusion, only small differences in the mean energy and macronutrient intake between elite endurance, strength, and team sport athletes, were found. The majority of the athletes were able to meet the generally accepted protein recommendation for athletes, of 1.2 g·kg−1. However, for most athletes, the carbohydrate intake was lower than generally recommended in the existing consensus guidelines on sport nutrition. This suggests that athletes could either optimize their carbohydrate intake, or that average carbohydrate requirements merit a re-evaluation.
Nutritional Supplement Use by Dutch Elite and Sub-Elite Athletes: Does Receiving Dietary Counselling Make a Difference?
Wardenaar, F.C. ; Ceelen, I.J.M. ; Dijk, J.W. van; Hangelbroek, R.W.J. ; Roy, L. van; Pouw, B. van der; Vries, J.H.M. de; Mensink, M.R. ; Witkamp, R.F. - \ 2017
International Journal of Sport Nutrition & Exercise Metabolism 27 (2017)1. - ISSN 1526-484X - p. 32 - 42.
The use of nutritional supplements is highly prevalent among athletes. In this cross-sectional study we assessed the prevalence of nutritional supplement use by a large group of Dutch competitive athletes in relation to dietary counselling. A total of 778 athletes (407 males and 371 females) completed a web-based questionnaire about the use of nutritional supplements. Log-binomial regression models were applied to estimate crude and adjusted prevalence ratios (PR) for the use of individual nutritional supplements in athletes receiving dietary counselling as compared to athletes not receiving dietary counselling. Of the athletes 97.2% had used nutritional supplements at some time during their sports career, whereas 84.7% indicated having used supplements during the last 4 weeks. The top ranked supplements used over the last 4 weeks from dietary supplements, sport nutrition products and ergogenic supplements were multivitamin and mineral preparations (42.9%), isotonic sports drinks (44.1%) and caffeine (13.0%). After adjustment for elite status, age, and weekly exercise duration, dietary counselling was associated with a higher prevalence of the use of vitamin D, recovery drinks, energy bars, isotonic drinks with protein, dextrose, beta-alanine, and sodium bicarbonate. In contrast, dietary counselling was inversely associated with the use of combivitamins, calcium, vitamin E, vitamin B2, retinol, energy drinks and BCAA and other amino acids. In conclusion, almost all athletes had used nutritional supplements at some time during their athletic career. Receiving dietary counselling seemed to result in better informed choices with respect to the use of nutritional supplements related to performance, recovery, and health.
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