Search Results (427)

Background: Creatine is one of the most widely used dietary supplements for enhancing physical performance and is increasingly investigated for a range of health-related applications. Although creatine monohydrate is the most commonly used formulation, concerns have been raised regarding its oral bioavailability, prompting the development of alternative formulations and delivery strategies. However, it is unclear to what extent randomized controlled trials (RCTs) evaluating oral creatine supplementation address issues related to bioavailability. Therefore, we aimed to assess how bioavailability of oral creatine is considered and reported in RCTs. Methods: We conducted a meta-research study of published RCTs in which orally administered creatine was used as an intervention or comparator, regardless of participant characteristics or outcomes. MEDLINE and Embase were searched from inception to 1 March 2024. We extracted data on trial characteristics, creatine formulations used, mentions of bioavailability, and comparisons between different creatine products. Data were summarized descriptively. Results: We included 357 reports corresponding to 343 RCTs published between 1994 and 2023. Creatine monohydrate was the most commonly used formulation, reported in 275 (80.2%) trials; however, 53 (15.5%) reports did not specify the exact creatine form used. Bioavailability was mentioned in only 38 (11.1%) reports, most frequently in the discussion section. Four trials (1.2%) reported specific measures intended to enhance bioavailability, including instructions regarding supplement dissolution or co-ingestion with food or carbohydrates. Five trials (1.5%) compared more than one creatine formulation, but only three (0.9%) discussed bioavailability. These formulation comparisons were frequently limited by non-equimolar dosing regimens. Conclusions: RCTs of oral creatine supplementation rarely address bioavailability and often provide insufficient information on the exact creatine formulation used. Few trials reported strategies to enhance bioavailability, and direct comparisons between creatine formulations were uncommon and methodologically limited, particularly because of non-equimolar dosing. Future trials should improve reporting of creatine formulations, incorporate bioavailability-related outcomes, and use appropriate dosing strategies when evaluating alternative creatine products. Full article

Background: Sarcopenia, the age-related loss of muscle mass and strength, affects over 20% of older adults in Taiwan and contributes to frailty and functional decline. Nutritional supplementation offers a promising strategy for those unable to engage in structured exercise, yet multi-ingredient MCT–leucine–creatine-based interventions remain understudied in clinically defined sarcopenic populations. Methods: We conducted an 8-week randomized, double-blind, placebo-controlled trial at National Taiwan University Hospital (ClinicalTrials.gov NCT06376266). Seventy-three older adults (mean age 77.3 ± 7.7 years) meeting AWGS 2019 sarcopenia criteria were randomized to TLN-01 (a multi-ingredient supplement containing whey protein, branched-chain amino acids, medium-chain triglycerides, creatine, resveratrol, and vitamin D₃, n = 34) or isocaloric placebo (n = 39). Primary outcomes were changes in appendicular skeletal muscle mass (ASM) assessed by DXA and handgrip strength. Targeted plasma amino acid metabolomics (LC-MS) was performed as an exploratory endpoint. Results: ASM increased significantly in the TLN-01 group (+0.42 kg, +3.2%; p < 0.001) but remained unchanged in controls (p = 0.785), with a significant between-group difference (ANCOVA p < 0.01); this absolute change was below the commonly cited minimal clinically important difference. Handgrip strength did not differ significantly between groups (p = 0.32); within-group analysis showed a significant decline in the placebo group (−7.0%; p < 0.001) that was not observed in the intervention group (p = 0.537). Metabolomic analysis revealed reductions in plasma taurine and 1-methylhistidine and an increase in kynurenine; given the absence of clear separation on PCA/PLS-DA, these findings are considered exploratory and hypothesis-generating rather than confirmatory evidence of altered amino acid utilization or proteolysis. No clinically significant adverse metabolic or renal events occurred. Conclusions: Eight weeks of this multi-ingredient MCT–leucine–creatine-based supplement induced a modest increase in muscle mass and attenuated the decline in handgrip strength observed in the placebo group among sarcopenic older adults without a structured exercise program, supporting further investigation as a safe and practical nutritional adjunct in geriatric care. Full article

Creatine monohydrate is well supported as an ergogenic aid in adults, but age-specific evidence in adolescent athletes remains limited. This critical narrative review examined performance, safety, dosing, and responsible-use considerations. PubMed/MEDLINE was the primary source; citation tracking, the Cochrane Library, ClinicalTrials.gov, Google Scholar, and Semantic Scholar were used through 19 June 2026. The core athletic synthesis included 17 primary studies: five Tier 1 studies with direct adolescent samples, eleven Tier 2 age-adjacent or mixed-age studies, and one Tier 4 adult study retained for contextual interpretation. Across soccer, swimming, basketball, rehabilitation, and resistance-training settings, controlled studies reported possible task-specific improvements in selected power, repeated-sprint, jumping, technical, and rehabilitation outcomes, whereas other outcomes were unchanged and some favorable findings were limited to within-group analyses. Short-term controlled studies and a 32-week mixed-age cohort did not identify a consistent clinically important safety signal within the protocols studied; however, safety monitoring was often secondary and the evidence remains underpowered for uncommon or long-term events. Creatine monohydrate should therefore be neither routinely recommended nor categorically prohibited in adolescent athletes. Any consideration represents a precautionary, individualized risk-management approach—not a validated adolescent protocol—and should be food-first, family-involved, professionally supervised, and accompanied by product-quality control and planned reassessment. Full article

Background: Endurance exercise is known to induce the excessive production of reactive oxygen metabolites due to enhanced metabolic activity and inflammation, leading to oxidative stress and related injuries. Sulforaphane (SFN), an isothiocyanate, is broadly acknowledged for its potential antioxidant and anti-inflammatory properties, along with other protective functions. Objective: The purpose of this study was to investigate the effects of short-term SFN precursor supplementation on maximal exercise-induced muscle damage, oxidative stress and endurance capacity in healthy adults. Methods: In a double-blind placebo-controlled crossover design, 14 healthy participants (7 males, 7 females; age, 25.07 ± 1.04 years; weight, 65.28 ± 4.13 kg; height, 170.07 ± 3.46 cm; BMI, 22.48 ± 0.91) received SFN glucosinolate capsules (200 µmol/day) or placebo for 2 weeks during the first trial. Following a three-week washout period, the participants crossed over to the alternate treatment. Maximal exercise tests were performed following each supplementation (SFN or placebo) period. Blood samples were collected at baseline (before treatment), pre-exercise, post-exercise and 2 h after each exercise session. Results: SFN supplementation did not alter endurance capacity or blood cell counts; however, it significantly attenuated serum creatine kinase (CK) activity (p = 0.034; SFN, 121.52 ± 16.89; placebo, 291.84 ± 133.07) and the myoglobin (Mb) concentration (p = 0.011; SFN, 15.82 ± 1.95; placebo; 27.31 ± 5.71) following exercise. Analysis of oxidative stress markers showed no significant changes in the absolute values; however, in the d-ROMs (p = 0.038; SFN, 107.42 ± 2.39; placebo; 112.32 ± 2.11) and OXY-adsorbent tests (p = 0.032; SFN, 115.97 ± 4.15; placebo; 107.73 ± 3.88), the percent changes from the baseline showed a significant interaction with the supplement. These findings suggest that short-term SFN supplementation may mitigate exercise-induced muscle damage and oxidative stress, suggesting a modest influence on the circulating biomarkers associated with muscle damage without altering the endurance capacity of healthy people. Conclusion: SFN intake may be a beneficial, non-invasive strategy to modulate acute biochemical responses to exercise via the antioxidant defense system in physically active individuals. Full article

Background/Objectives: Recovery nutrition must restore near-term readiness without indiscriminately suppressing biological signals that contribute to repair and training adaptation. This review evaluates recovery–adaptation coupling (RAC) as a research framework and clarifies its contribution relative to established recovery, nutrient-periodization, and athlete-monitoring models. Methods: Targeted narrative searches of PubMed/MEDLINE, Scopus, and Web of Science were supplemented by Google Scholar citation tracking and backward and forward screening. Peer-reviewed English-language literature available through 31 May 2026 was considered. Human athlete studies, randomized trials, systematic reviews, meta-analyses, consensus statements, and position stands were prioritized; mechanistic evidence was used to explain pathways rather than to support stand-alone performance recommendations. The final cited corpus comprised 130 records. No formal risk-of-bias tool, certainty grading, PRISMA denominator, or quantitative pooling was used. Claims were instead identified as established practice (EP), context-dependent evidence (CDE), mechanistic rationale (MR), or RAC hypothesis (RH). Results: The most consistent applied support concerns adequate energy availability, distributed high-quality protein, carbohydrate restoration when recovery windows are short, and individualized fluid and sodium replacement. Evidence for polyphenol-rich products, curcumin, omega-3 fatty acids, and creatine is context- and product-dependent. Collagen or gelatin evidence is mainly mechanistic or pilot-level, while RAC recovery-pattern categories and multimodal monitoring rules remain unvalidated hypotheses. RAC differs from existing frameworks by jointly specifying the next athletic demand, dominant recovery bottleneck, possible adaptive cost of intervention, and response-verification plan. Conclusions: RAC should presently be interpreted as an evidence-organization and hypothesis-generation architecture, not as a validated predictive, diagnostic, or treatment algorithm. Prospective comparative studies are required before RAC-specific decision rules can guide individualized practice. Full article

Background: Gut microbiota may influence metabolic and inflammatory responses to exercise through the gut–muscle axis, and probiotic supplementation has been proposed to support adaptation and recovery in endurance athletes. However, evidence in trained populations is inconsistent and is confounded by variability in diet, probiotic strains, dose, and intervention duration. We tested whether a multistrain probiotic, administered against a fully standardized diet, would affect exercise performance and inflammatory, metabolic, and muscle-damage responses. Methods: In this randomized, double-blind, placebo-controlled trial, 30 trained male long-distance runners were randomized and 27 completed the study (probiotic [PRO], n = 13; placebo [PLA], n = 14). All participants followed a standardized, normocaloric meal-box diet for four weeks. Aerobic capacity (peak oxygen uptake, VO₂peak; primary outcome) was assessed by an incremental treadmill test and anaerobic performance by a 30 s Wingate test, before (PRE) and after (POST) supplementation. Interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), creatine kinase (CK), and lactate (LA) were measured around exercise. Outcomes were analyzed with linear mixed-effects models; the primary estimand was the group × phase interaction. Results: VO₂peak did not differ between groups over time (PLA 55.00 ± 7.60 → 57.33 ± 8.41; PRO 55.40 ± 7.85 → 53.14 ± 5.95 mL·kg⁻¹·min⁻¹; group × phase −3.5 mL·kg⁻¹·min⁻¹, 95% CI −7.0 to −0.1; nominal p = 0.044, not significant after FDR correction, adjusted p = 0.707). No group × phase or group × phase × sampling-time interaction was significant for IL-6, TNF-α, LA, or CK (all interaction p > 0.15), indicating that supplementation did not modify the exercise-induced response of any biomarker; exercise itself robustly increased IL-6, TNF-α, and LA in both groups (p < 0.001). Conclusions: In trained male endurance runners consuming a standardized diet, four weeks of multistrain probiotic supplementation did not significantly affect aerobic or anaerobic performance, LA response, muscle-damage markers, or circulating inflammatory cytokines compared with placebo. Adequately powered trials with prespecified primary endpoints and direct microbiome assessment are needed. Full article

Guanidinoacetic acid (GAA), a natural precursor of creatine, plays a pivotal role in cellular energy metabolism. This study investigated the effects of dietary GAA supplementation at varying levels (0, 0.6, and 1.2 g/kg) combined with standard or reduced (−100 kcal/kg) dietary energy on growth performance, carcass characteristics, meat quality, and heat stress tolerance (during the finisher phase) in broiler chickens. A total of 360 one-day-old male Ross-308 broiler chicks were randomly allocated to 36 floor pens in a 3 × 2 factorial arrangement under a completely randomized design. Six treatments with six replicates, each having 10 birds, were evaluated over 35 days. Growth performance parameters were recorded weekly. On day 35, samples were collected for carcass characteristics (dressing percentage, breast and thigh yield, and organ weights), meat quality analysis (drip loss, cooking loss, and color parameters), and heat stress response. The heat stress response (panting frequency) was recorded during the finisher phase of the trial. GAA supplementation at 1.2 g/kg significantly (p < 0.001) improved final body weight, total weight gain, feed conversion ratio, dressing percentage, breast yield, and thigh yield. Meat quality parameters showed significant improvement (p < 0.001) with GAA in a dose-dependent manner for drip loss, cooking loss, and all color parameters (L*; a*; b*). Significant GAA × energy interactions (p < 0.001) were observed for final body weight, total weight gain, feed intake, FCR, cooking loss, live body weight at slaughter, breast yield, liver weight, gizzard weight, intestine weight, and panting frequency. The effect of GAA on heat stress tolerance was context-dependent, with a significant GAA × energy interaction (p < 0.001) for panting frequency. Under reduced-energy conditions, 1.2 g/kg GAA decreased panting frequency, suggesting improved thermoregulatory capacity, while under standard-energy conditions, GAA increased panting frequency. The main effect of GAA on panting frequency was not significant (p = 0.38), while the main effect of energy was highly significant (p < 0.001). In conclusion, GAA supplementation at 1.2 g/kg significantly improves growth performance, feed efficiency, meat quality (reduced drip and cooking losses and improved color parameters), and carcass yield in broiler chickens. Importantly, GAA supplementation largely compensated for a 100 kcal/kg reduction in dietary energy while maintaining performance. These findings support GAA as a promising nutritional strategy for sustainable broiler production, particularly in hot-climate regions. Full article

Sarcopenia is an age-related progressive decline in skeletal muscle mass, strength, and physical performance that increases the risk of falls, disability, and reduced quality of life among older adults. Its pathogenesis is multifactorial and involves chronic low-grade inflammation, hormonal disturbances, insulin resistance, and mitochondrial dysfunction, leading to an imbalance between muscle protein synthesis and degradation. The aim of this study was to summarise current knowledge regarding the mechanisms underlying sarcopenia, contemporary diagnostic methods, and the effectiveness of modern nutritional and exercise-based strategies, with particular emphasis on technologies supporting patient monitoring. This study is a structured narrative review conducted across PubMed, Scopus, and Web of Science databases, with the literature search completed on 1 March 2026. Separate searches were performed for thematic sections, including pathophysiology, diagnosis, physical activity, nutritional interventions, plant-derived compounds, and digital health technologies. While the core search focused on publications from 2023–2025, specific time-bound deviations were applied: the search for plant-derived compounds was extended back to 2020, and combined interventions were searched up to March 2026 to ensure the inclusion of the most recent evidence. The review included 53 peer-reviewed primary studies (RCTs and observational) and secondary literature (reviews and meta-analyses) involving individuals aged ≥60 years. The most robust evidence supports multicomponent interventions, particularly the synergy between resistance training and adequate protein intake (1.2–1.5 g/kg/day), often supplemented with leucine, vitamin D, omega-3 fatty acids, and creatine. Such strategies effectively counteract anabolic resistance by combining mechanical loading with the stimulation of the mTORC1 signalling pathway, leading to significant improvements in muscle mass, strength, and physical function. While isolated protein or micronutrient supplementation shows limited effectiveness in the absence of exercise, their role as supportive elements in multimodal strategies is well-documented. Furthermore, emerging digital health technologies—including wearable sensors and telerehabilitation—are proving essential for clinical practice, enabling precise, continuous monitoring of physical activity and gait parameters under free-living conditions, which enhances both patient adherence and long-term therapeutic outcomes. Full article

Background/Objectives: Tendon and ligament injuries are challenging conditions because of limited vascularization, slow collagen turnover, and prolonged rehabilitation timelines. This narrative review aimed to synthesize current evidence on nutritional strategies that may support connective tissue rehabilitation and return-to-activity or return-to-sport progression. Methods: This narrative review synthesized the relevant clinical, mechanistic, and applied sports nutrition literature identified through targeted database searches and manual reference screening. Results: Adequate energy availability and protein intake emerged as foundational priorities for tissue repair, endocrine and immune function, and tolerance to progressive loading. Collagen or gelatin supplementation with vitamin C before tendon- or ligament-loading exercise may provide targeted substrate and cofactor support for collagen remodeling. Creatine may assist muscle preservation during reduced loading, while micronutrient adequacy and omega-3 fatty acids may support musculoskeletal health and inflammation resolution. Conclusions: Nutrition should be viewed as an adjunct to, rather than a replacement for, structured rehabilitation loading. Phase-specific and individualized nutritional strategies may support rehabilitation when integrated with structured loading; however, additional well-designed clinical trials are needed to determine their effects on clinically meaningful outcomes, including return-to-sport time, reinjury risk, and long-term tissue outcomes. Full article

Background/Objectives: Intensified training in adolescent soccer players increases oxidative stress, muscle damage, inflammation, and immune suppression, but direct comparisons of nutritional countermeasures are lacking. This randomised, double-blind, placebo-controlled trial compared the effects of 14-day coenzyme Q10 (CoQ10) versus taurine supplementation on haematological, oxidative, muscle damage, inflammatory, hormonal, and immune biomarkers in under-19 soccer players undergoing three repeated 90 min Soccer Match Simulation (SMS) sessions. Methods: Twenty-four male players (age 17.9 ± 0.7 years) received placebo (n = 8), CoQ10 (300 mg/day, n = 8), or taurine (4 g/day plus 4 g pre-session, n = 8). Blood was collected at baseline (T0), post-first session (T1), post-third session (T2), and 24 h post-third session (T3). Biomarkers included creatine kinase (CK), lactate dehydrogenase (LDH), malondialdehyde (MDA), total antioxidant capacity (TAC), interleukins (IL-6, IL-10, TNF-α), cortisol, testosterone, CD4/CD8 ratio, immunoglobulins (IgA, IgG), and plasma volume (Dill–Costill). Data were analysed by two-way repeated-measures ANOVA. Results: CoQ10 was superior in reducing MDA (T2: 0.83 ± 0.02 vs. 1.24 ± 0.03 μmol/L, p < 0.001), LDH (434 ± 9 vs. 684 ± 12 U/L, p < 0.001), and cortisol (20.2 ± 0.6 vs. 30.4 ± 0.8 μg/dL, p < 0.001), and preserved the testosterone:cortisol ratio (24.5 ± 1.1 vs. 13.6 ± 1.0 × 10⁻³, p < 0.001). CoQ10 was more effective than taurine in lowering IL-6 at T2 (3.5 ± 0.2 vs. 3.9 ± 0.2 pg/mL, p = 0.03), whereas taurine was more effective in increasing IL-10 (7.5 ± 0.2 vs. 5.7 ± 0.2 pg/mL, p = 0.005). Both supplements preserved CD4 counts (CoQ10: 790 ± 13, taurine: 795 ± 14 vs. placebo: 680 ± 15 cells/μL, p < 0.01) and the CD4/CD8 ratio, as well as IgA and IgG levels, with no between-supplement differences for immune outcomes (p > 0.05). No adverse events occurred. Conclusions: For adolescent soccer players undergoing intensified training, CoQ10 may be preferred when the goal is reducing oxidative stress, muscle damage, and catabolic load; taurine may be preferred for targeted anti-inflammatory support (IL-10 elevation). Either supplement effectively attenuated changes in circulating immune biomarkers. These preliminary findings provide evidence-based guidance for targeted sports nutrition, pending confirmation in larger trials. Full article

Background: Resistance training increases lean mass, muscle accretion and performance. These adaptations from resistance training can be further increased with 5 g of creatine monohydrate supplementation (CrM). In addition to dose, it has been proposed that the timing of CrM may be an important factor to consider to help improve these adaptations. However, whether the strategic ingestion of CrM during a resistance training program influences lean mass, muscle accretion and performance in trained young healthy adults compared to a placebo is unknown. Therefore, this study examined whether consuming CrM immediately before or after resistance training sessions for 16 weeks differentially affected body composition, limb muscle thickness or muscle performance in trained young healthy adults. Twenty-seven participants were randomized into one of three groups: Creatine Before (n = 10; 24 ± 6 years of age; 5 g CrM immediately before resistance training sessions and placebo immediately after training), Creatine After (n = 9; 26 ± 7 years of age, 5 g of CrM immediately after resistance training sessions and placebo immediately before training) or the Placebo (n = 8; 25 ± 6 years of age; placebo immediately before and after training). Body composition, limb muscle thickness and muscle performance was assessed before and following 16 weeks. Results showed that the strategic ingestion of CrM (before or after resistance training sessions compared to a placebo) had no effect on measures of body composition, limb muscle thickness or muscle performance (p > 0.05). In conclusion, 5 g of CrM (independent of the timing of ingestion) on resistance training days (or 280 g of CrM in total) was ineffective at augmenting muscle growth and performance in a small group of trained young healthy adults (18–39 years of age). Full article

Background: Lepidium meyenii Walp (L. meyenii), traditionally known as maca, is widely recognized for its health-promoting properties, including potential protection against exercise-induced muscle damage (EIMD). However, its precise effect on post-exercise blood biomarkers remains unclear. Objective: This study aimed to qualitatively review research published until April 2026 examining L. meyenii supplementation to reduce blood markers of muscle damage and protein degradation post-exertion in animal studies. Specifically, the effect size (ES) of L. meyenii supplementation on post-exercise levels of creatine kinase (CK), lactate dehydrogenase (LDH), and blood urea nitrogen (BUN) was estimated. Methods: This systematic review and meta-analysis were conducted in accordance with the PRISMA guidelines. The certainty of the evidence was assessed using the GRADE framework. Relevant studies were identified through Web of Science, Scopus, SPORTDiscus, PubMed, and MEDLINE. Eligible studies included in vivo experiments in animals with controlled designs and pre-/post-intervention assessments. Methodological quality and risk of bias were evaluated using the CAMARADES tool. Statistical analysis involved standardized mean differences (SMD) using Hedges’ g with 95% confidence intervals. Results: 15 studies were included in the systematic review, and 14 studies in animals in the meta-analysis. The CAMARADES scores ranged from 5 to 7 points, indicating moderate methodological quality. Supplementation with L. meyenii was not associated with statistically significant changes in LDH (SMD = −1.37; 95% CI −3.34 to 0.59), BUN (SMD = −0.37; 95% CI −2.16 to 1.42) nor CK (SMD = 0.29; 95% CI −5.45 to 6.03), with very high heterogeneity (I² > 97%). Exploratory subgroup analyses and meta-regression analyses by formulation type and dose did not identify any moderators that could robustly explain this heterogeneity. Conclusions: The available evidence does not support a robust overall effect of L. meyenii supplementation on blood biomarkers of muscle damage or protein catabolism in animals subjected to physical stress. The high degree of heterogeneity could not be robustly explained by either the type of formulation or the dose. These findings, which are exploratory and hypothesis-generating in nature, highlight the need for standardized, well-characterized formulations and trials with adequate statistical power. Full article

As the direct biosynthetic precursor of creatine, guanidinoacetic acid (GAA) exerts a pivotal regulatory role in energy homeostasis and protein metabolism. Rabbit meat has garnered increasing global recognition as a healthy food source, characterized by its outstanding high-protein and low-fat nutritional profile. Accordingly, the optimization of rabbit meat quality has attracted growing attention from both consumers and animal production practitioners. In the present study, we evaluated the impacts of dietary GAA supplementation on meat quality traits, in vivo antioxidant capacity, muscle fiber characteristics, and fatty acid metabolism in New Zealand white rabbits. A total of 960 male New Zealand white rabbits were assigned to two age groups: 40-day-old group and 60-day-old group (40 ± 2 days, 1.19 ± 0.09 kg; 60 ± 2 days, 1.82 ± 0.15 kg). Within each age group, rabbits were randomly allocated to a control diet or a diet supplemented with 100 mg/kg GAA (CON-40, GAA-40, CON-60, GAA-60). After a 45-day feeding period, two-way ANOVA revealed that GAA supplementation significantly reduced shear force (p < 0.01, diet main effect) and muscle fiber density (p < 0.01, diet main effect), with an age-dependent effect on shear force (age × diet interaction, p < 0.05). Moreover, GAA enhanced systemic antioxidant capacity, as indicated by increased serum superoxide dismutase (SOD) activity (p < 0.01) and total antioxidant capacity (T-AOC) (p < 0.05), while no significant effect on malondialdehyde (MDA) was detected under the current experimental conditions. GAA also regulated the expression of lipid metabolism-related genes (FAS, HSL, ACC) in intramuscular and perirenal fat, indicating its regulatory effect on fatty acid metabolism. In conclusion, dietary GAA supplementation improves rabbit meat tenderness and antioxidant capacity, with no negative effects on growth performance. These findings confirm that GAA has the potential to serve as a nutritional strategy to improve rabbit meat quality, supporting the development of rabbit meat as a functional food for human consumption. Full article

Guanidinoacetic acid (GAA) and methionine are two biologically active compounds related to cell energy metabolism. Both are metabolically linked, as the methyl group needed to transform GAA into creatine derives from S-adenonsylmethionine out of the homocysteine cycle. A broiler feeding study was conducted to evaluate potential interactions between 600 g/t supplemental GAA and feed additives with methionine activity. The experimental design comprised two parts. Part one consisted of three dietary treatments in which DL-methionine (DL-Met) was added to meet sulfur amino acid recommendations (1), DL-Met was replaced with liquid methionine hydroxy analogue-free acid (MHA-FA) assuming an 80% methionine activity in the product (2), and DL-Met was added at 65% of the MHA-FA dose used in Treatment 2 (on a product weight basis). Treatments 1, 2, and 3 reflect the range of commercial practice with assuming bioefficacies of either 80% (Trt 2 vs. 1) or 65% (Trt 3 vs. 2) for MHA-FA relative to DL-Met. Part two followed a 2 × 4 factorial design. Either DL-Met or MHA-FA (assuming 80% methionine activity) was added to diets with gradually reduced apparent metabolizable energy (AME; standard, −25, −50, −75 kcal/kg AME). For MHA-FA, a bioefficacy of 80% relative to DL-Met was applied in order to evaluate interactions with GAA efficiency assuming inadequate dietary Met+Cys supply with MHA-FA. AME-reduced diets were supplemented with 600 g/t GAA to evaluate its energy-sparing potential. A total of 2784 male Cobb 500 broilers were equally assigned to 116 floor pens, resulting in 13 replicates (one treatment with 12) per treatment. A five-phase feeding program was introduced from 1 to 40 days of age. Body weights (BW) and feed intake (FI) were recorded in weekly intervals allowing for calculating weight gain (BWG) and feed conversion ratio (FCR). At termination of the experiment, three birds per pen were obtained for carcass analysis. The results revealed that an overestimation of the bioefficacy of MHA-FA relative to DL-Met significantly compromised broiler growth (p < 0.05), while applying a bioefficacy of 65% for MHA-FA relative to DL-Met65 resulted in similar performance. However, on day 40, BW of broilers fed DL-Met65 were higher than with MHA-FA (p < 0.05). It is concluded that an overestimation of the bioefficacy of MHA-FA relative to DL-Met bears the risk of compromised broiler performance while a bioefficacy of 65% allows at least similar, potentially even better, performance and economic advantages. There were basically no interactions between MHA-FA or DL-Met and graded ME levels with concomitant GAA supplementation regarding overall performance of broilers. This means that final BW of DL-Met-fed broilers were higher than those of MHA-FA broilers independent of dietary ME (p < 0.05). In early feeding phases, interactions indicated that broiler performance (BW day 7, 21, p < 0.05) diminished with dietary energy reduction with DL-Met supplementation while this was not the case with MHA-FA-fed broilers. However, with standard AME, DL-Met outperformed MHA-FA (p < 0.05). Basically, GAA supplementation compensated AME reduction up to 50 kcal/kg as there were no differences in BW, BWG, FCR, FI, or breast meat yield. Additionally, −75 kcal/kg AME was compensated by GAA only up to a broiler age of 21 days. Full article

Background: The use of sports supplements among adolescents is rising globally, driven by fitness trends and social media influence, yet knowledge gaps persist. This study aimed to assess supplement usage patterns, knowledge, attitudes, information sources, and the impact of a social media educational intervention among Serbian secondary school students. Methods: A single-group pre–post educational intervention study was conducted in secondary school students (aged 14–18) in Vojvodina, Serbia. A 21-question anonymous questionnaire was distributed to 1000 students along with parental informed consent forms. Pre-intervention survey assessed sociodemographics, physical activity and social media habits, supplement use information sources, and awareness of risks and banned substances. Based on the initial findings, an educational campaign delivered 56 short videos (≈70 s each) on Instagram and TikTok covering most frequently used supplements (e.g., creatine, proteins, caffeine, energy drinks). After, the intervention survey was repeated. The data were analyzed using the McNemar–Bowker test of symmetry. Results: In this study, 65% of Serbian secondary school adolescents reported being physically active, engaging predominantly in gym workouts and team sports. The majority of participants initiate dietary supplement use independently, without consulting healthcare professionals or adults. The most commonly used supplements were vitamins and minerals, while energy drinks ranked notably high. Social media intervention had a limited impact due to its short duration; however, certain changes were detected. Conclusions: Serbian adolescents frequently use sports supplements without adequate professional guidance. Long-term TikTok/Instagram interventions could be used in the future in order to influence behaviors and improve knowledge about sport supplement use. Full article