Nitric Oxide Booster

Background: Pre-season training is critical for developing tolerance to high physical demands in professional soccer, and nitric oxide (NO) precursors such as dietary nitrate (NO3-) and citrulline malate (CM) can support performance and recovery during this demanding phase. This study aimed to examine the effects of a four-week supplementation protocol combining 500 mg of NO3- from amaranth extract and 8 g of CM (NIT + CM) on external training load and post-match recovery in professional female soccer players during pre-season. Methods: A randomized, double-blind, placebo-controlled trial was conducted with 34 female soccer players who received either the NIT + CM product or a placebo for four weeks during pre-season. Global positioning system (GPS)-derived external load was recorded throughout the intervention. Performance tests-a countermovement jump (CMJ) test and the Wingate anaerobic test (WAnT)-and blood sampling for plasma NO3- and nitrite (NO2-) concentrations were conducted at baseline and the day after a competitive match. Results: The supplementation with NIT + CM increased maximal speed (Vmax) throughout training and match play. During post-match testing, the NIT + CM group exhibited a significantly smaller decline in mean (Pmean) and minimum (Pmin) power during the WAnT, along with reduced power loss in both the first (0-15 s) and second (15-30 s) intervals. Plasma NO3- concentrations significantly increased from baseline in the NIT + CM group and remained elevated 24 h after the final dose, confirming sustained systemic exposure. Conclusions: Chronic NIT + CM supplementation may enhance Vmax and help preserve anaerobic performance the day after a match. These effects could reflect improved tolerance to high training loads and sustained NO3- availability during recovery.

INTRODUCTION: The market for dietary supplements in the sports sector has been growing rapidly for several years, though there is still lacking evidence regarding their claimed benefits. One group is that of nitric oxide increasing supplements, so-called "NO-boosters," which are claimed to improve the supply of oxygen and nutrients to the muscle by enhancing vasodilation.The aim of this study was to investigate 3 of these supplements in healthy male athletes for their muscle perfusion-enhancing potential using contrast-enhanced ultrasound (CEUS). METHODS: This placebo-controlled, double-blind, randomized cross-over trial will be carried out at the Center for Orthopedics, Trauma Surgery and Spinal Cord Injury of the University Hospital Heidelberg. Three commercial NO enhancing products including 300 mg of the specific green tea extract VASO6 and a combination of 8 g L-citrulline malate and 3 g L-arginine hydrochloride will be examined for their potential to increase muscular perfusion in 30-male athletes between 18 and 40 years and will be compared with a placebo. On each of the 3 appointments CEUS of the dominant biceps muscle will be performed at rest and after a standardized resistance training. Every athlete receives each of the 3 supplements once after a wash-out period of at least 1 week. Perfusion will be quantified via VueBox quantification software. The results of CEUS perfusion measurements will be compared intra- and interindividually and correlated with clinical parameters. DISCUSSION: The results of this study may help to establish CEUS as a suitable imaging modality for the evaluation of potentially vasodilatory drugs in the field of sports. Other supplements could also be evaluated in this way to verify the content of their advertising claims. TRIAL REGISTRATION: German Clinical Trials Register (DRKS), ID: DRKS00016972, registered on 25.03.2019.

Background/Objectives: Sexual dysfunction is a prevalent and multifactorial condition affecting a large proportion of the global population, with limited therapeutic options beyond pharmacological approaches primarily targeting erectile dysfunction. This has increased interest in botanical supplements for sexual health, although mechanistic evidence and clear links between phytochemical composition and biological activity remain scarce. The present study provides an integrative evaluation of a commercial Turnera diffusa extract (Liboost®) formulated to support sexual health by combining detailed phytochemical characterization with targeted in vitro mechanistic assays. Methods: The extract was characterized by HPLC-DAD-HRMS, enabling the identification and semi-quantification of its major constituents. A total of 49 compounds were detected, predominantly flavonoids, including luteolin- and apigenin-derived glycosides, flavonols, methoxyflavones, flavanones, and coumaroyl derivatives, with a total quantified flavonoid content of 15.9 mg·g-1. Biological activity was evaluated in human cell models without cytotoxic effects at the tested concentrations. Results: Liboost® significantly reduced PDE5 expression, inhibited aromatase activity, and moderately increased nitric oxide production. These complementary effects suggest a multi-target modulation of pathways involved in sexual function, integrating vascular, endocrine, and nitrergic mechanisms. Conclusions: Although limited to in vitro models, the findings provide mechanistic support for the biological activity of T. diffusa extracts and highlight the importance of linking phytochemical composition with functional evidence when evaluating botanical supplements.

Background/Objectives: Nitric oxide (NO) is a key mediator of vascular, metabolic, and redox pathways, influencing exercise performance. Beetroot, a natural source of inorganic nitrate, increases NO bioavailability and may modulate oxidative stress and inflammation, though data in endurance athletes remain limited. The aim of this study was to assess the effects of a novel beetroot-based nitrate supplement (B-bNs) on NO metabolism, oxidative stress, and inflammation in non-professional triathletes. Methods: This was a randomized 2 × 2 cross-over pilot study with two 7-day periods (B-bNs vs. No treatment), separated by a 15-day washout (4 visits: Day 1, 7, 22 and 28). Samples were collected at baseline (T0), 2 h post-first dose (T1), and after 7 days (T2) for the supplementation period (B-bNs) and at T0 and T2 for the "no treatment" period. The following biomarkers from plasma and urine were evaluated: NO pathway (NO metabolites (NOx), nitrite (NO2), inducible nitric oxide synthase (iNOS), peroxynitrite, 3-nitrotyrosine (3-NT)), oxidative stress (reactive oxygen species (ROS) production, 8-isoprostane, superoxide dismutase (SOD) activity), and cytokines (IL-6, IL-10). A total of 10 male triathletes (mean age 48.1 ± 9.8 years and BMI 23.9 ± 2.2 kg/m2) participated in this study. Results: No adverse events were reported. After 7 days of supplementation (T2 vs. T0), significant increases in NOx in plasma and urine (about +155%), iNOS (+56%), peroxynitrite (+60%), 3-NT (+8.6%), ROS (+413%) and IL-6 (+73%) were recorded. These values resulted significantly higher compared to "no treatment" (all p = 0.002), with no significant differences for 3-NT, SOD, 8-isoprostane, IL-6, and IL-10. Conclusions: Beetroot-based nitrate supplementation may enhance the NO-related pathway in non-professional endurance athletes with nitric-peroxydation activation, occurring without evidence of lipid oxidative damage. Larger placebo-controlled trials with standardized diet/training and performance outcomes are needed to determine the functional significance of these preliminary findings. This study was registered in the ISRCTN registry (ISRCTN10885376).

Vulvovaginal candidiasis (VVC) is a prevalent mucosal infection predominantly caused by Candida albicans (C. albicans). Vaginal lactobacilli contribute to colonization resistance and epithelial barrier integrity. However, therapeutic options remain limited and recurrence is common. In this study, we investigated the effects of a lactic acid bacteria mixture (LM; InoRexyne®) enriched with Lactiplantibacillus plantarum YC225 on antifungal activity and inflammation in vitro and in an estrogenized murine VVC model. In RAW264.7 macrophages and VK2/E6E7 vaginal epithelial cells, the LM cell-free supernatant inhibited C. albicans growth and reduced inflammatory readouts induced by lipopolysaccharide or C. albicans. In vivo, oral LM administration for 14 d attenuated VVC-associated histopathological damage, reduced vaginal IL-6 and nitric oxide levels, and decreased fungal burden compared with infected controls. LM also increased the expression of the tight junction marker gene Tjp1 and modulated inflammatory gene expression in vaginal tissue (NanoString panel), including downregulation of selected pro-inflammatory pathways and upregulation of the anti-fibrotic regulator Smad7. 16S rRNA profiling of fecal samples showed LM-associated shifts in gut microbial composition, including increased abundance of Lactobacillus/L. plantarum and decreased abundance of several opportunistic taxa. Correlation analysis suggested associations between specific gut taxa and VVC parameters. Collectively, these findings indicate that oral LM may mitigate VVC-associated inflammation, epithelial damage, and fungal burden, and these effects are accompanied by changes in gut microbiota composition.

Heat stress (HS) adversely affects rabbit production, reducing growth performance, physiological responses, and farm profitability. Nanoemulsified orange essential oil (NOEO) is a natural antioxidant with anti-inflammatory properties that may mitigate oxidative stress and enhance cellular defense mechanisms. This study evaluated the effects of dietary NOEO on growth performance, blood biochemistry, antioxidant status, immune and inflammatory responses, and liver and kidney histomorphology in heat-stressed rabbits. Forty-eight six-week-old male New Zealand White rabbits (752.91 ± 17.40 g) were randomly assigned to four groups: a control group fed a basal diet and three treatment groups receiving the same diet supplemented with 100, 200, or 400 mg NOEO/kg feed. Heat-stressed rabbits supplemented with NOEO showed significant (p < 0.05) improvements in body weight, feed conversion ratio, and performance index. Blood hematology and serum levels of total protein, albumin, total cholesterol, triglycerides, low-density lipoprotein, and very low-density lipoprotein were also enhanced in all treated groups compared with the control. NOEO supplementation improved antioxidant defenses, as indicated by increased total antioxidant capacity and elevated activities of key antioxidant enzymes (glutathione peroxidase, catalase, and superoxide dismutase), particularly in the NOEO400 treated group (p < 0.05). Nitric oxide levels were significantly higher, while malondialdehyde concentrations were significantly lower in NOEO200 and NOEO400 groups, reflecting reduced oxidative stress (p < 0.05). Immune responses were strengthened, with higher serum IgM and IgA levels, accompanied by downregulation of pro-inflammatory cytokines IL-6 and IFN-γ (p < 0.05). Furthermore, liver and kidney function and tissue structure were improved in NOEO-supplemented rabbits. In conclusion, dietary NOEO, particularly at 400 mg/kg, enhanced growth performance, antioxidant status, immune competence, and hepato-renal health in heat-stressed rabbits, likely through improved cellular defense mechanisms that protect against oxidative and inflammatory damage.

Multiple Sclerosis (MS) is a neuroinflammatory disease affecting the central nervous system (CNS), for which effective therapeutic strategies remain limited. Ganoderma Lucidum (GL) is a nature healthy food supplement whose effects on MS remain unknown. Using an experimental autoimmune encephalomyelitis (EAE) mouse model, we tested the hypothesis that GL could mitigate MS by inhibiting microglial activation and promoting a shift toward an anti-inflammatory M2-like phenotype. We demonstrate that early preventive administration of GL significantly reduced disease severity, inflammatory infiltration, demyelination, and microglial activation and polarization by promoting M2-like polarization in the spinal cord of EAE mice. Furthermore, using in vitro cellular experiments, GL revealed antioxidant and anti-inflammatory effects by scavenging superoxide (O2·-), nitric oxide (NO·) and peroxynitrite (ONOO-) and down-regulated the expression of IL-1β, TNF-α, IL-6, COX2, and iNOS in the LPS-stimulated microglial cells. GL inhibited the expression of nuclear factor-κB/signal transducer and activator of transcription 3 (NF-κB/STAT3). Taken together, Ganoderma lucidum is a promoting antioxidant and anti-inflammatory healthy supplement to inhibit microglial activation and attenuate the severity and progress of MS pathogenesis by reducing oxidative stress and modulating NF-κB/STAT3 signaling pathways. © 2026. The Author(s).

This study aimed to evaluate the impact of incorporating cysteamine-loaded nanoliposomes (CY-NPs) into a semen extender on semen quality, sperm kinematics, redox status, apoptosis-like changes, ultrastructure, and fertility outcomes. Semen was collected from seven healthy, fertile bulls (4-6 years old) using the artificial vagina technique, and a total of 42 ejaculates were obtained over six weeks. Each sample was analyzed in three replicates. Pooled ejaculates were cryopreserved in a Tris-based extender supplemented with 0, 25, 50, or 100 μg/mL of CY-NPs. Polynomial regression analysis showed that progressive motility, membrane functionality, and viability peaked at 60-75 μg/mL. CY-NPs supplementation enhanced sperm kinematics, increased total antioxidant capacity, and elevated activities of key antioxidant enzymes, including catalase, superoxide dismutase, and glutathione peroxidase, while significantly reducing malondialdehyde, nuclear factor kappa B, and nitric oxide levels in seminal plasma (p < 0.05). The percentage of apoptotic sperm cells decreased significantly, accompanied by upregulation of the anti-apoptotic Bcl-2 gene and downregulation of pro-apoptotic genes Bax and caspase 3. Electron microscopy confirmed that CY-NPs protect sperm ultrastructure, including the plasma membrane, acrosome, and mitochondria. Notably, supplementation with 50 μg/mL CY-NPs improved frozen-thawed semen fertility, increasing buffalo cow pregnancy rates by 23.33 % compared to controls (p = 0.0001). Overall, adding CY-NPs to the freezing extender enhanced semen quality, velocity, antioxidant status, and enzymatic balance, reduced apoptosis, preserved structural integrity, and improved fertility of cryopreserved buffalo sperm.

BACKGROUND: Atherosclerosis begins with dyslipidemia, vascular inflammation, and endothelial dysfunction. Rodent models that capture these early events are needed for mechanistic and interventional studies. This study evaluated whether a cholesterol-rich, high-fat diet (HFD) supplemented with vitamin D and propylthiouracil (PTU) promotes a pro-atherogenic phenotype in rats, as evidenced by dyslipidemia, inflammation, markers of endothelial dysfunction, and early vascular remodeling. METHODS: Male Sprague-Dawley rats (n = 18) received standard chow or a HFD containing 2% cholesterol, 3% lard, 0.5% cholate, vitamin D (200 000 IU/kg), and PTU (0.2% w/w) for 11 weeks. Terminal serum total cholesterol, high-density lipoprotein, low-density lipoprotein (LDL)/very low-density lipoprotein (VLDL), triglycerides, calcium, interleukin-6 (IL-6), C-reactive protein, serum amyloid A (SAA), circulating endothelial nitric oxide synthase (eNOS), and intracellular adhesion molecule-1 (ICAM-1) were measured. The aorta, the coronary arteries, and the liver were examined histologically. RESULTS: HFD-fed rats developed significant hypercholesterolemia with higher total cholesterol and LDL/VLDL (p < 0.0001) and lower triglycerides (p < 0.0001) versus controls. Serum calcium was higher (p < 0.0001) without vascular calcification. Aortae exhibited wall thickening, smooth-muscle disarray, mononuclear infiltrates, and focal foam cell-like changes; coronary arteries exhibited endothelial irregularities and perivascular infiltrates. Livers exhibited micro- and macrovesicular steatosis. IL-6 and SAA were higher (p < 0.05), and circulating eNOS was lower (p < 0.05); ICAM-1 did not differ significantly. CONCLUSION: An 11-week vitamin D/PTU-supplemented HFD induces an LDL-dominant dyslipidemia with systemic inflammation and evidence consistent with endothelial dysfunction, alongside histological features of early vascular remodeling and hepatic steatosis. This nongenetic model may be useful for studying early atherogenic changes. © 2026 The Author(s). Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal

BACKGROUND/OBJECTIVES: Acute beetroot juice (BJ) nitrate supplementation may enhance agility and change of direction performance by increasing nitric oxide bioavailability and improving cognitive and skeletal muscle functions, thereby potentially attenuating post-sprint performance decrements. METHODS: We investigated whether a single dose of BJ improves agility immediately after repeated maximal sprinting compared with a placebo (PL) in soccer players. Twenty-one male soccer players (competitive players: n = 8; recreational players: n = 13) completed a double-blind randomised crossover trial. Participants ingested 70 mL of BJ or PL; afterwards, they performed three sets of 6 × 20-m all-out sprints. Agility outcomes included simple response time (SRT), choice response time (CRT), and change-of-direction speed (CODS). Non-parametric analyses (Wilcoxon signed-rank test with effect size r) were applied. RESULTS: Compared with PL, BJ improved CRT (BJ: 2.376 ± 0.255; PL: 2.534 ± 0.322; p < 0.001; r = 0.74; Z = -5.881) and CODS (BJ: 13.046 ± 1.512; PL: 13.651 ± 1.811; p < 0.001; r = 0.47; Z = -4.314). SRT was unchanged overall (BJ: 1.671 ± 0.195; PL: 1.707 ± 0.261; p = 0.185; r = 0.05; Z = -1.327). CONCLUSIONS: Under practical field-based conditions, acute BJ intake enhanced post-sprint agility and change-of-direction performance, particularly CRT and CODS.

Vein graft disease remains a significant limitation to the long-term patency of venous conduits following coronary artery bypass grafting. Early oxidative stress, triggered by ischaemia-reperfusion injury and haemodynamic changes following the implantation of veins into the arterial circulation, disrupts endothelial integrity and initiates inflammation, apoptosis, and maladaptive remodelling. The KEAP1-NRF2 axis is a central regulator of cellular antioxidant responses; however, its role in the development of vein graft disease remains poorly defined. This narrative review aimed to summarise what is known about NRF2/KEAP1 signalling in modulating vein graft pathology. METHODS: A systematic search of PubMed was conducted to identify original research studies examining the NRF2/KEAP1 pathway in human saphenous vein tissue in vivo or ex vivo. Narrative synthesis was performed due to limited evidential availability and study heterogeneity. RESULTS: Only one study has directly evaluated NRF2 pathway activation directly in human saphenous vein tissue, and it demonstrated that Protandim (a herbal dietary supplement) treatment increased antioxidant enzyme activity and reduced oxidative stress markers, including superoxide and 4-hydroxynonenal, both known activators of MAPK-dependent smooth muscle proliferation. Adjacent studies in other cells and tissues reveal that NRF2 intersects with multiple pathways central to vein graft pathology: it suppresses NFκB-mediated inflammation, modulates eNOS-NO signalling, inhibits NADPH oxidase expression, regulates MAPK activation, and influences angiogenic responses. However, context-dependent activation of NRF2 under arterial cyclic stretch can paradoxically drive proliferation through p62-mediated KEAP1 sequestration and enhanced glutathione synthesis. CONCLUSIONS: The NRF2/KEAP1 pathway serves as a central integrator of oxidative stress responses that directly intersect with established mechanisms of intimal hyperplasia and pathological angiogenesis. Post-translational KEAP1 inhibition may offer a targeted intervention point to limit these processes. Critical gaps remain regarding our understanding of the role of NRF2 in human sap

Taurine (Tau) is a sulfur-containing amino acid that has therapeutic roles in several diseases, including inflammatory conditions. The involvement of Tau in modulating systemic lupus erythematosus (SLE) autoimmunity has been indicated in preclinical models, but reports are contradictory. This systematic review aimed to summarize current research regarding the potential role of Tau in SLE, to notice knowledge gaps, and to offer suggestions for the way ahead. The literature search was carried out using PubMed, Scopus, Web of Science, and Google Scholar databases until October 2025. Search alert services were also applied to notice related papers published after the primary search. All studies investigating the effects of Tau in SLE that met the inclusion criteria were eligible. Out of 77 articles initially found, only six preclinical studies (animal and in-vitro) were eligible, and no qualified clinical study was identified. Five studies indicated that Tau was helpful in improving clinical parameters, decreasing T helper 1 (Th1) and Th17 cells and inflammatory mediators (e.g., tumor necrosis factor-α, C-reactive protein, and inducible nitric oxide synthase), removing reactive oxygen species and decreasing oxidative markers like malondialdehyde, increasing regulatory T (Treg) and Th2 cells and anti-inflammatory interleukin-4 and interleukin-10 cytokines, increasing antioxidant enzymes superoxide dismutase and glutathione peroxidase, and inhibiting both FAS- and mitochondrial-dependent apoptotic signaling components. However, only one preclinical study reported that Tau aggravated SLE progression characterized by increased generation of type I interferons, enhanced autoantibodies and proteinuria, further lymphocyte activation, and critical nephritis. The current review provides evidence about the role of Tau in SLE and highlights the importance of further well-designed clinical trials to confirm these results, establish optimal dose and assess safety and long-term efficacy. © 2026. The Author(s).

INTRODUCTION: The use of ergogenic compounds has gained increasing popularity among individuals who wish to improve performance and recover faster from their workouts. Among these products is citrulline malate (CitMal), a popular dietary supplement that is suggested to enhance nitric oxide (NO)-mediated vasodilation and muscle blood flow. METHODS: To evaluate effects on arterial function, flow-mediated dilation (FMD) of the brachial artery during active hyperemia was measured in 12 healthy, recreationally active males (23 ± 3 years) before and after (60- and 120-min post) consuming either 6 g CitMal, 12 g CitMal, or a taste-matched placebo. The study used a randomized, double-blind, placebo-controlled, within-subject counterbalanced crossover design with ≥7-day washouts. RESULTS: Repeated measures ANOVA revealed no significant interaction (p = 0.315) or time effect (p = 0.649) in corrected FMD% at 60- and 120-min after intake of placebo, 6 g CitMal, and 12 g CitMal. There were also no significant differences (p = 0.301) between doses at any timepoint. A subgroup of six participants completed two additional visits to assess the effect of CitMal ingestion on serum markers involved in NO production. Over 120-min post-consumption, both doses significantly increased peak serum concentrations of citrulline (6 g: 504.7 ± 139.7; 12 g: 881.9 ± 216.7 μM), arginine (6 g: 70.2 ± 20.4; 12 g: 101.8 ± 36.2 μM), and ornithine (6 g: 27.9 ± 14.2; 12 g: 56.5 ± 30.0 μM) from baseline (all p < 0.001), with greater increases following 12 g (all p < 0.05). Likewise, arginine-to-dimethylarginine ratios (SDMA and ADMA) increased from baseline (SDMA, 6 g: 114.1 ± 24.2; 12 g: 166.2 ± 43.7; ADMA, 6 g: 119.2 ± 31.8; 12 g: 169.1 ± 29.1; all p < 0.001), with greater increases following 12 g (p < 0.05). DISCUSSION: Collectively, these findings suggest that neither 6 g nor 12 g of CitMal significantly enhance FMD within 120 min, despite marked increases in biochemical markers favorable to NO production. To our knowledge, this is the first study to compare acute doses of CitMal up to 12 g in relation to brachial artery FMD. These results indicate that acute vascular responses to CitMal may be li

Lactiplantibacillus plantarum WB4201, WB4202, and WB4203, which are known to possess probiotic properties, were assessed for their ability to alleviate intestinal inflammation and reinforce epithelial barrier function. These strains exhibited antimicrobial and anti-adhesion properties against pathogens. In HT-29 cells, the strains significantly reduced sodium nitroprusside-induced nitric oxide (NO) overproduction, thus indicating their capacity to mitigate nitrosative stress. In lipopolysaccharide (LPS)-stimulated cells, the strains markedly suppressed pro-inflammatory responses by downregulating interleukin (IL)-8, IL-6, IL-1β, cyclooxygenase-2 (COX-2), and tumor necrosis factor-α (TNF-α). Furthermore, barrier integrity was preserved through the restoration of tight junction proteins, including Occludin, Claudin-1, zonula occludens-1 (ZO-1), and mucin 2 (MUC2). Mechanistic analyses revealed that these protective effects were associated with the inhibition of nuclear factor-kappa B activation and the suppression of mitogen-activated protein kinase phosphorylation cascades. These findings demonstrate the anti-inflammatory and barrier-protective potential of L. plantarum WB4201, WB4202, and WB4203, thus underscoring their potential as probiotic-based interventions for intestinal health.

Pereskia aculeata Mill. is a leafy cactus native to Brazil, whose leaves are traditionally used as food and are characterized by high nutritional value and significant mucilage content. This study aimed to evaluate the functional potential of the carbohydrate-rich extract obtained from leaves and to investigate its metabolic effects in obese male rats subjected to a litter-size reduction model. The extract was chemically characterized by physicochemical analysis and FTIR-MIR spectroscopy, which revealed spectral features consistent with arabinogalactan-type carbohydrates (absorption bands between 1,000 and 1,050 cm⁻¹). In vitro assays demonstrated antioxidant activity, with DPPH radical inhibition exceeding 60% and nitric oxide reduction exceeding 30%. In addition to promoting the growth of lactic acid bacteria in culture medium supplemented with the extract, it also showed antagonistic activity against selected Gram-negative pathogens. FTIR-MIR analysis during an in vitro gastrointestinal simulation indicated relative spectral stability. In vivo, obese rats were supplemented with the extract for 75 days (0.3%, w/v, in drinking water; 300 mg/kg body weight/day). Supplemented animals showed a reduction in visceral adiposity (-20%) and serum triglycerides (-31%) compared to obese controls (p < 0.05). The obesity model increased fasting blood glucose by approximately 19%, and supplementation reduced blood glucose by approximately 10%. Data were analyzed using appropriate parametric tests (p < 0.05). Liver parameters and histological analyses indicated protection against non-alcoholic fatty liver disease. Overall, these results corroborate the functional potential of carbohydrate fractions and provide a basis for future studies addressing microbiota-mediated mechanisms and metabolic effects. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11130-026-01486-0.

The human gut microbiome harbors diverse beneficial bacteria with potential roles in supporting host health. Parabacteroides distasonis has recently attracted interest as a next-generation probiotic (NGP) candidate; however, functional evidence for human-derived strains remains limited. Here, three human gut-derived P. distasonis strains (B2-S-102, B2-Q-110, and Y3-G-102) were isolated from healthy individuals and characterized using comparative genomics and in vitro functional assays. Species-level identity was supported by 16S rRNA gene analysis and whole-genome relatedness metrics (ANI > 97% and dDDH > 70%), consistent with established species delineation thresholds. Under controlled laboratory conditions, the strains showed tolerance to acidic pH (pH 2.0), bile salts (0.3%), and simulated gastric and intestinal fluids. Functionally, the strains exhibited measurable antioxidant activity (35.03 ± 7.76% to 51.22 ± 5.60% DPPH inhibition) and α-amylase inhibitory activity (51.03 ± 32.12% to 69.23 ± 4.26%) in vitro. Cell-free supernatants inhibited albumin denaturation (47.65 ± 3.56% to 65.26 ± 4.15%), while live bacteria reduced nitric oxide production and pro-inflammatory cytokines (IL-6, TNF-α, IFN-γ, and IL-1β) in LPS-stimulated RAW 264.7 macrophages (p < 0.05). The strains also displayed in vitro growth-inhibitory activity against Escherichia coli, Acinetobacter baumannii, and Salmonella enteritidis. Genome mining identified multiple biosynthetic gene clusters, indicating genetic potential for secondary metabolite production; however, expression and metabolite identity were not experimentally validated. No haemolytic activity was observed, supporting a favorable preliminary safety profile. Overall, these findings provide preliminary in vitro evidence supporting the potential of human-derived P. distasonis strains as NGP candidates for further evaluation. © 2026. The Author(s).

ETHNOPHARMACOLOGICAL RELEVANCE: Arthrospira platensis (Spirulina) has been traditionally consumed in Africa, Asia and Central America as a nutrient-rich restorative food associated with metabolic balance and gastrointestinal health. Its longstanding ethnopharmacological use suggests biological activities related to antioxidant and anti-inflammatory effects, which are relevant in conditions associated with metabolic disorders. AIM OF THE STUDY: This study investigated whether A. platensis supplementation prevents the reduction in ileal relaxant reactivity induced by a hypercaloric diet (HCD) in rats and explored the involvement of prostanoid, nitric oxide and NADPH oxidase pathways in this response. MATERIALS AND METHODS: Male Wistar rats were fed standard or hypercaloric diets for eight weeks and treated with A. platensis (25 mg kg-1·day-1). Isolated ileum segments were subjected to cumulative concentration-response curves to verapamil in the absence or presence of indomethacin, tempol, L-NAME, 1400W, apocynin or combined L-NAME plus apocynin. Relaxant reactivity was assessed by maximal effect and potency parameters. RESULTS: The hypercaloric diet markedly reduced verapamil-induced relaxant potency, whereas A. platensis supplementation completely prevented this dysfunction without altering responses in healthy animals. In HCD-fed rats, indomethacin, tempol, L-NAME, 1400W and apocynin each fully restored relaxant potency, demonstrating the contribution of prostanoid overactivity, oxidative stress, excessive iNOS-derived nitric oxide and NADPH oxidase-dependent reactive oxygen species to the observed impairment. In supplemented animals, relaxant responses were fully or partially preserved across all pharmacological conditions. CONCLUSIONS: These findings provide mechanistic support for the traditional use of A. platensis, demonstrating that its protective effects on intestinal smooth muscle function are mediated by the modulation of convergent inflammatory and redox pathways. The results highlight A. platensis as an ethnopharmacologically relevant natural product with potential for preventing obesity-associated gastrointestinal dysmotility.

Background: Low estrogen levels during menopause reduce nitric oxide (NO) production, contributing to decline in skeletal muscle quality and function. Although acute and short-term dietary nitrate supplementation has demonstrated promising effects, long-term benefits, particularly on muscle quality in postmenopausal women, are not well established. Objectives: The objective was to investigate the effects of long-term (12-week) nitrate-rich beetroot extract supplementation on morphological and functional muscle quality, rate of force development (RFD), maximal strength, and circulating nitrate/nitrite concentrations in postmenopausal women. Methods: In a randomized, double-blind, placebo-controlled design, 20 postmenopausal women (21 years ± 7 since menopause) consumed 20 g/day of a nitrate-rich beetroot extract (BET; 548 mg nitrate/day) or a nitrate-depleted beetroot extract (PLA; 43 mg nitrate/day) for 12 weeks. Outcome measures, including muscle quality (functional via muscle strength/thickness ratio; morphological via ultrasound echo intensity), RFD, maximal voluntary isometric contraction (MVIC), and serum nitrate/nitrite levels, were evaluated at baseline, 8 weeks, and 12 weeks. Results: BET significantly increased serum nitrate (0.005) and nitrite (0.022) levels compared to PLA at both week 8 and week 12. Morphological muscle quality also improved significantly in the BET group (interaction effect, p = 0.014). Early-phase rate of force development (RFD) increased between 30 and 100 ms, whereas late-phase RFD increased between 100 and 200 ms. RFDpeak also improved by week 8, and these gains were maintained through week 12 (interaction effect, p < 0.05). Although there was no significant difference between groups for functional muscle quality, MVIC increased at week 12 in the BET group, but no significant Time × Group interaction was observed. Conclusions: Twelve weeks of nitrate-rich beetroot extract supplementation improved morphological muscle quality and RFD, suggesting potential clinical relevance for preventing structural and neuromuscular function decline in postmenopausal women. This study was registered with ReBEC (RBR-87qh649) and approved on 8 Oct

This study examined the anti-ulcer potential of chicken feather protein hydrolysate (Hyd) against indomethacin (Ind)-induced gastric ulcer. Hyd was prepared from feathers by microbial fermentation technique using locally isolated Bacillus licheniformis EYT2 (GenBank accession number: PV612017). Hyd was orally administrated to the rats at the doses of 100 mg/kg BW (low-dose group, Hyd100) and 200 mg/kg BW (high-dose group, Hyd200) before Ind treatment. The effectiveness of Hyd was compared with Ranitidin (Ran). Six experimental groups were designed: Control, Ind, Ran+Ind, Hyd100 + Ind, Hyd200 + Ind, and Ran+Hyd200 + Ind. Hyd was determined to have a high protein content (81.6%) and exhibit high water solubility in a wide pH range from 1 to 10. Ind-treatment caused severe erosion, ulceration, and degeneration in gastric tissue, elevated the levels of malondialdehyde, pro-inflammatory cytokines, inducible nitric oxide synthase, 8 hydroxy-2'-deoxyguanosine, Bax, caspase-3, nuclear factor kappa B (NF-kB) and mitogen-activated protein kinase-38 (MAPK-38) and reduced the levels of glutathione, antioxidant enzymes, anti-inflammatory cytokine IL-10, prostaglandin E2, anti-apoptotic gene Bcl-2 and nuclear factor erythroid 2-related factor 2 (Nrf2). Conversely, Hyd administration, especially high dose Hyd (Hyd200 + Ind group) reversed these alterations. Furthermore, a combination of Ran and high-dose Hyd (Ran+Hyd200 + Ind) completely prevented Ind toxicity. The protective effect of Hyd was attributed to its antioxidant, antiapoptotic and anti-inflammatory activites as well as prostaglandin synthesis-enhancing property. These results imply that Hyd may be used as a supplement with anti-ulcer activity in alternative medicine and/or as a protein source in animal and human nutrition. This is the first report on anti-ulcer potential of Hyd.

ObjectiveTo determine the influence of Spirulina supplementation on the response of bovine chondrocytes to mechanical compression with respect to extracellular matrix dynamics (proteoglycan and collagen) and inflammation [nitric oxide (NO)].MethodsBovine chondrocytes were embedded in agarose constructs and cultured for 14 days in basal media or media supplemented with Spirulina (30 or 90 µg/mL). Constructs were exposed to 10% dynamic compression. DNA content, NO levels, proteoglycan content and release, and collagen synthesis were measured to assess extracellular matrix (ECM) responses.ResultsDNA content did not differ among groups. Spirulina supplementation increased NO levels in constructs and media, with the highest effect observed at 90 µg/mL. Proteoglycan content decreased in Spirulina-treated constructs and declined further after compression, while proteoglycan release increased across all groups. Collagen synthesis and content were elevated by Spirulina, particularly at 90 µg/mL, and further increased following dynamic compression.ConclusionsSpirulina supplementation, particularly at higher concentrations, enhances ECM turnover and increases NO production in chondrocytes under mechanical loading, indicating potential modulation of matrix dynamics that may be beneficial. However, these results are derived from an in vitro model and may not fully represent in vivo physiological conditions.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder linked with oxidative imbalance, cholinergic dysfunction and neuroinflammation, necessitates developing new multitarget natural compounds with potential disease-modifying action. Piperitone was evaluated using in-silico, in-vitro and in-vivo methods. In-silico study identified the pharmacokinetic parameters (PK) and the interaction stability of piperitone with acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-secretase. In-vivo assessment of spatial memory in scopolamine-induced rat model was identified by behavioral assays with donepezil as a reference standard. In-vitro assays identified activity of cholinesterases, oxidative stress markers, levels of antioxidants and neuroinflammatory substrates, quantified with Reverse Transcription Polymerase Chain Reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). Piperitone demonstrated favorable PK properties & docking scores comparable to Donepezil, Tacrine & QUD. Molecular dynamics simulations (MDS) confirmed stable associations with catalytic residues of cholinesterases and beta-secretase. Dose dependent reduction was recorded in cholinesterases, improvement in behavioral outcomes, and supplemented defenses of antioxidants including Glutathione (Reduced Form (GSH), Glutathione S-Transferase (GST), Catalase (CAT), Superoxide Dismutase (SOD), and diminished Lipid Peroxidation (LPO), Nitric Oxide (NO), Tumor Necrosis Factor-alpha (TNF-α), Interleukin (IL)-1β, IL-18, Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB), NOD-like Receptor Family Pyrin Domain Containing 3 (NLRP3) and amyloid-β production, while improving Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Piperitone showed significant neuroprotective and cognitive enhancement benefits by modulating cholinergic signaling, oxidative stress, and neuroinflammation. These multitarget actions advocate piperitone as a prospective lead candidate for the development of disease modifying treatments for AD. © 2026. The Author(s), under exclusive licence to Springer Nature Switzerland AG.

The anti-inflammatory and neuroprotective potential of probiotic Lactobacillus strains has gained significant attention due to their ability to modulate oxidative stress and inflammation. In this study, two indigenous Lactiplantibacillus plantarum, LpJ5 and LpJ8, were evaluated for their anti-inflammatory and neuroprotective properties to mitigate oxidative stress and enhance cell viability in neuroinflammatory models. Results indicate that LpJ5 significantly upregulated glutathione peroxidase (gpx) and glutathione (gsh) expression at 0.9 mM hydrogen peroxide (H2O2). The probiotic strains also demonstrated significant anti-inflammatory effects in lipopolysaccharide (LPS)-induced BV2 and SH-SY5Y cell models. Pretreatment with LpJ5 resulted in a 59.7% reduction in nitric oxide (NO) production in BV2 cells and a 56.7% reduction in SH-SY5Y cells. LpJ8 showed comparable reductions of 49.2% and 47.3%, respectively. Additionally, LpJ5 pretreatment led to an increase in cell viability in BV2 and SH-SY5Y cells. Both strains also reduced the expression of inflammatory markers such as iNOS, COX-2, TNF-α, IL-1β, and upregulated BCL-2 and IL-10, with LpJ5 exhibiting stronger effects, particularly in the pretreatment phase. These findings demonstrate the antioxidant and anti-inflammatory capabilities of LpJ5 and LpJ8 and thereby highlight potential mechanistic links and lay the groundwork for subsequent translational and clinical investigations. Thus making them promising candidates for therapeutic applications. © 2026 Wiley‐VCH GmbH.

Aging is characterized by a gradual deterioration in skeletal muscle mass, strength, and vascular functionality, which ultimately leads to the development of sarcopenia and the subsequent loss of physical autonomy. Nutritional and exercise-based interventions that specifically address this interplay may offer viable, non-pharmacological approaches to maintaining both muscular and vascular integrity. L-citrulline (CIT), recognized as a precursor to nitric oxide (NO), has been demonstrated to enhance endothelial functionality, improve oxygen transport, and increase muscle perfusion, while leucine has been shown to stimulate muscle protein synthesis. Furthermore, exercise serves to modulate both NO availability and anabolic signaling pathways, thereby amplifying the effects of these amino acids. Recent clinical and experimental research indicates that the concurrent administration of CIT and leucine supplementation, in conjunction with structured exercise regimens, yields superior enhancements in muscle mass, vascular reactivity, and physical performance compared to isolated interventions alone. The aforementioned synergistic effects are facilitated through a comprehensive regulation of mitochondrial biogenesis, alongside a reduction in inflammation and oxidative stress. This review consolidates existing empirical evidence regarding the collective contributions of CIT, leucine, and physical exercise in fostering healthy aging, while also delineating prospective research avenues for the formulation of personalized nutritional and physical strategies aimed at enhancing both muscular and vascular well-being in the elderly population.

This study investigated the effects of combined L-arginine (Arg) and citrulline-malate (CM) supplementation on aerobic, anaerobic, and high-intensity interval training in healthy, trained men. Both Arg and CM are widely marketed for their potential ergogenic effects, as Arg serves as a precursor to nitric oxide (NO), which may support vasodilation, muscle contractility, and exercise performance. Arg and CM are hypothesized to exert synergistic effects due to their complementary roles in NO synthesis. Citrulline can potentially enhance and prolong Arg availability, thereby amplifying NO-mediated vasodilation, nutrient delivery, and muscle performance during exercise. In this randomized, double-blind, placebo-controlled trial, 46 healthy, trained men aged 24.8 ± 5.0 years were divided into 3 exercise groups subjected to consuming 0.15 g/kg bodyweight of Arg and 0.1 g/kg bodyweight of CM prior. The participants were then randomly divided into three groups based on the exercise protocol:: the Wingate Anaerobic Test (n = 16), a 20 min CrossFit workout 'Cindy' (n = 16) consisting of continuous rounds of pull-ups, push-ups, and air squats to measure functional fitness and muscular endurance, or the Harvard Step Test (n = 14) a measurement of cardiovascular endurance and recovery. This design allowed for the evaluation of supplementation effects across multiple exercise modalities. The results revealed no significant improvement in performance with supplementation in comparison to placebo, except for a shorter time to reach peak power in the Wingate test. Findings suggest that the combined acute supplementation of Arg and CM, at the given dosages, may not provide substantial benefits for aerobic and anaerobic or CrossFit performance in active individuals. Future research with larger sample sizes and higher dosages, potentially adjusted for muscle mass, is recommended to determine whether chronic supplementation might yield greater ergogenic effects. © 2025. The Author(s).

INTRODUCTION: L-Citrulline supplementation has been a topic of debate due to its potential to augment L-arginine bioavailability and nitric oxide production. However, it remains uncertain whether it can truly serve as an ergogenic aid in endurance exercise performance. While it was previously recommended to include higher continuous doses of L-citrulline over ≥7 days, this study aimed to investigate whether a relative dosing strategy using 100 mg·kg-1 per day over 10 days could improve time to exhaustion (TTE) in healthy young adults. METHODS: Twenty healthy, moderately active adult participants (nine females; age, 24.4 ± 0.9 years; BMI, 24.0 ± 2.5 kg·m-2; V̇O2max, 43.5 ± 6.3 mL·min-1·kg-1) received either 100 mg·kg-1 per day of L-citrulline (CIT) or a placebo (PLA) for 10 days in a double-blind, randomised, placebo-controlled crossover trial, before they performed two TTE tests at 5% above the second lactate turnpoint (LTP2). Cardiac output (Q̇), oxygen uptake (V̇O2), blood glucose ([Glu-]) and lactate concentrations ([La-]), and rating of perceived exertion (RPE) were quantified during each test. RESULTS: There was no statistically significant difference in TTE between the trial arms (CIT vs. PLA: 20.5 ± 7.3 vs. 19.8 ± 5.7 min, p = 0.43). However, a trend was observed in the female subgroup (24.4 ± 6.2 vs. 21.9 ± 4.8 min, p = 0.06). Cardiac output (Q̇) also did not show significant differences between mean (CIT, 18.3 ± 3.7 L·min-1; PLA, 19.0 ± 4.5 L·min-1; p = 0.40) and maximum values (CIT, 28.7 ± 5.7 L·min-1; PLA, 26.6 ± 4.9 L·min-1; p = 0.22) in both trial arms. Mean V̇O2 was 1.77 ± 0.28 and 1.84 ± 0.25 L·min-1 (p = 0.06) for CIT and PLA, respectively. Similarly, mean maximum systolic (165 ± 17 vs. 171 ± 18 mmHg, p = 0.23) and diastolic (81 ± 6 vs. 83 ± 6 mmHg, p = 0.19) blood pressure levels were not significantly different between CIT and PLA trial arms. DISCUSSION: Higher continuous doses of L-citrulline over 10 days do not increase TTE in healthy, moderately active individuals when compared with a placebo. Therefore, it is reasonable to assume that L-citrulline does not offer an ergogenic benefit for endurance performance. However, future research may fo

PURPOSE: This study aimed to investigate and compare the effects of chronic supplementation with L-Citrulline (LC) vs. L-Citrulline DL-malate (CM) on resistance training (RT) performance. METHODS: Thirty-three resistance-trained men were randomly assigned to ingest LC (8 g), CM (12 g), or Placebo (PL) daily, along with participation in a 6-week RT protocol. Muscular strength (1-repetition maximum [1RM] for hack squat [HS] and bench press [BP]), muscular endurance (repetitions to failure [RTF] for HS, leg extension [LE], BP, and incline press [IP]), rating of perceived exertion (RPE), and blood biomarkers (lactate, urea, and nitric oxide metabolites [NOX]) were assessed before and after the intervention. This study was registered on irct.ir (IRCTID: IRCT20221128056642N1). RESULTS: Comparing mean ∆ scores revealed a significant difference between LC and PL (p < 0.001) and between CM and PL (p = 0.026) for total upper body (the sum of BP and IP) RTF, but only a trend for difference between LC and PL (p = 0.070) for total lower body (the sum of HS and LE) RTF. A significant time effect for NOX was detected only for LC (p = 0.014) and CM (p = 0.003). In addition, a significant difference between CM and PL (p = 0.009) and a marginally significant difference between LC and PL (p = 0.057) was detected regarding post-exercise NOX values at post-intervention. There were no other between-group differences for any outcome measure. CONCLUSION: Chronic citrulline supplementation seems to enhance upper body muscular endurance and post-exercise NOX response to RT, but there is no apparent difference between LC and CM in these aspects.

BACKGROUND & AIMS: Disturbances in arginine (ARG) and protein metabolism, as well as in gut function have been observed in response to an endurance exercise session in patients with Chronic Obstructive Pulmonary Disease (COPD). We studied whether resistance exercise also affects the acute response in arginine (role in nitric oxide synthesis), citrulline (CIT, marker of gut health), and (muscle) protein metabolism differently in COPD as compared to healthy older adults. METHODS: Patients with stable moderate to severe COPD (n = 24) and healthy controls (n = 25) completed a high-intensity resistance exercise session in the postabsorptive state. We administered a pulse of multiple stable isotopes of amino acids before, and 1 h and 24 h post-resistance exercise to assess the whole body production (WBP) and intracellular productions by compartmental analysis of ARG and CIT, and of tau-methylhistidine (TauMETHIS), phenylalanine (PHE), tyrosine (TYR), and PHE > TYR conversion as markers of muscle (myofibrillar) protein breakdown and whole body (net) protein breakdown, respectively. Muscle fatigue was determined by assessing the decay in peak leg extension torque post-resistance exercise. RESULTS: COPD patients overall exhibited lower WBP ARG (p < 0.0001), CIT (p < 0.0001), PHE (p = 0.0001), TYR (p < 0.0001), and tau-METHIS (p = 0.0004) compared to controls. Resistance exercise did not change WBP of PHE, tau-METHIS, or PHE > TYR conversion, despite prolonged muscle fatigue in COPD. WBP CIT was increased at 1- and 24-h post-exercise in both groups (p < 0.003). Plasma CIT concentrations were reduced in both groups (p < 0.006) and remained lower at 24 h post-exercise in COPD only (p < 0.05) despite a third less work performed. CONCLUSIONS: Both COPD and healthy participants exhibited upregulated whole-body citrulline production following resistance exercise. However, in COPD, this increase was insufficient to counteract the sustained reduction in plasma citrulline concentration, despite performing significantly less work during the exercise session. This prolonged disturbance in citrulline metabolism in COPD points to a potential exercise-induced enterocyte dysfunction, hi

Background: The dietary supplement citrulline might increase nitric oxide levels, leading to vasodilation and improved blood flow, potentially benefiting athletes' aerobic exercise performance. However, rapid oxidative impairment of the L-arginine/nitric oxide (NO) pathway limits these effects. This is countered by Bergamot Polyphenolic Fraction Gold® (BPFG), a strong natural antioxidant. To investigate L-citrulline + BPFG supplementation's effects, we performed a randomized, double-blind, placebo-controlled pilot trial on athletic performance and blood flow in trained athletes (cyclists). Methods: Random assignment of 90 male athletes resulted in nine different groups: placebo for Group 1, BPFG at 500 and 1000 mg daily for Groups 2 and 3, L-citrulline at 1000 and 2000 mg/daily for Groups 4 and 5, and the combination product of BPFG plus citrulline (N.O. Max) for Groups 6-9. Baseline and 3-month pre- and post-exercise biochemical, reactive vasodilation (RHI), and maximal oxygen consumption measurements were taken for all subjects. Results: Three months of the combination of BPFG and L-citrulline (N.O. Max) produced a significant synergistic effect, markedly increasing NO (p < 0.001 vs. placebo) release and RHI (p < 0.001 vs. placebo). Cardiorespiratory fitness improved significantly with the BPFG and L-citrulline combination, resulting in substantially higher VO2 max, VT1, VT2, and peak power and a significantly lower heart rate (p < 0.01 vs. placebo). No harmful adverse effects were observed. Conclusions: N.O. Max supplementation, providing beneficial effects on the antioxidant state and preserving the vascular endothelium might be a supplementation strategy to improve athletic performance and potentiate results. Given the small sample size, this study serves as a pilot, and further research is needed to validate these findings on a larger scale.

Erratum in Heliyon. 2025 Oct 01;11(15):e43913. doi: 10.1016/j.heliyon.2025.e43913. Regular exercise is a practical non-pharmacological approach to maintaining physical and mental health through rehabilitation and prevention of chronic diseases due to its cardiovascular, cardiorespiratory, neurological, and neuromuscular benefits. Despite awareness of the benefits of exercise, a "lack of time" has proven to be the most common impediment to regular activity. Thus, a time-efficient and potentially enjoyable training modality with growing popularity is high-intensity interval training (HIIT). HIIT incorporates intermittent bouts of work and recovery intervals performed at an intensity close to maximal oxygen consumption (VO2max). HIIT is considered to have equivalent or superior benefits compared to moderate-intensity continuous training (MICT). This narrative review focuses on the mechanisms of Citrulline Malate (CM) supplementation and various modes of HIIT on exercise performance. CM serves as a nitric-oxide enhancer leading to improved aerobic and anaerobic exercise performance by increasing muscle adenosine triphosphate (ATP) production, vasodilation, and blood flow to the active musculature and boosting work capacity. This article reviews the mechanisms related to CM supplementation and different modes of HIIT on exercise performance. Even though a single, acute 8 g dose of CM has been recommended, its mechanism of action remains to be seen due to the synergistic impact of both components (citrulline and malate). Moreover, the limited evidence for the standard level of supplement use and source of purchase results in athletes' self-prescription of supplements. Therefore, to reduce the risk of accidental doping or toxicity, further studies should continue to investigate the optimal dose, timing, mechanism of action, as well as reliable sources of purchase for CM consumption. © 2025 The Author(s).

BACKGROUND: Metabolic-dysfunction-associated steatotic liver disease (MASLD) and obesity contribute to vascular dysfunction through oxidative stress, heightening cardiovascular risk. Oral supplementation with L-citrulline (L-cit), a precursor of L-arginine (L-arg) and nitric oxide, and high-intensity interval training (HIIT) may improve vascular function and cardiometabolic health. OBJECTIVES: This study aimed to evaluate the combined effects of L-cit supplementation and HIIT on arterial stiffness, body composition, glucose metabolism, lipid profile, and blood pressure (BP) in adolescents with MASLD and obesity. METHODS: In this double-blind, placebo-controlled, randomized clinical trial (ClinicalTrials.gov (NCT05778266), 44 adolescents (15-19 years) with MASLD and obesity were assigned to HIIT + L-cit (n = 14), HIIT + placebo (n = 14), or L-cit (n = 15) for 12 weeks. HIIT sessions (85% and 60% peak heart rate during intense and recovery periods) occurred thrice weekly. Training volume progressively increased, and participants performed 20 min of HITT per session in the last 8 weeks. RESULTS: Outcomes included pulse wave velocity (PWV), augmentation index (Aix75), VO2peak, body composition, BP, glucose and lipid profiles, and hepatic steatosis. Compared to L-cit, HIIT + L-cit improved non-high-density lipoprotein cholesterol (p = 0.04), very-low-density lipoprotein cholesterol (p = 0.01), triglycerides (p = 0.02), and VO2peak (p = 0.001). No significant between-group changes were found in PWV, AIx75, hepatic steatosis, and body composition. HIIT + placebo improved VO2peak (p = 0.002), and L-cit decreased the degree of steatosis (p = 0.038). CONCLUSIONS: HIIT + L-cit supplementation enhanced lipid profile and cardiorespiratory fitness, while HIIT + placebo improved cardiorespiratory capacity, and L-cit alone decreased hepatic steatosis. Thus, L-cit could be an adjuvant strategy to manage obesity-related MASLD in adolescents.

BACKGROUND: Quercetin (QCT) and citrulline (CIT) have been independently associated with improved antioxidant capacity and nitric oxide (NO) production, potentially enhancing cardiovascular function and exercise performance. This study aimed to evaluate the combined and independent effects of QCT and CIT supplementation on NO metabolites and antioxidant biomarkers in 50 trained cyclists undergoing a 20 km cycling time trial (TT). METHODS: In a randomized, double-blind, placebo-controlled design, forty-two male and eight female trained cyclists were assigned to QCT + CIT, QCT, CIT, or placebo (PL) groups. Supplements were consumed twice daily for 28 days. Biochemical assessments included NO metabolites (nitrate/nitrite), ferric reducing antioxidant power (FRAP), superoxide dismutase (SOD) activity, and antioxidant capacity, measured pre- and post-TT. RESULTS: NO metabolites were significantly elevated post-supplementation (p = 0.03); however, no significant interaction effects were observed for NO metabolites, FRAP, SOD, or antioxidant capacity across the groups (p > 0.05). Post-hoc analyses revealed that QCT significantly reduced FRAP concentrations compared to PL (p = 0.01), while no significant changes in SOD or antioxidant capacity were found across any groups. CONCLUSIONS: These findings suggest that combined and independent QCT and CIT supplementation did not significantly improve these biomarkers, suggesting that baseline training adaptations, supplementation timing, and individual variability may influence the efficacy of these compounds in enhancing exercise performance and oxidative stress markers. The ergogenic efficacy of QCT + CIT on antioxidant-related markers remains inconclusive.

L-citrulline (CIT) supplementation seems to improve resistance training performance; yet, whether malate has additive ergogenic effects when combined with CIT is unknown. This randomized, double-blind, placebo-controlled crossover trial aimed to compare the acute effects of CIT versus citrulline malate (CMA) supplementation on neuromuscular performance and exertion and emotional perceptions in young, trained men and women. 43 (21 women; 24.2 ± 3.7 years) participants ingested a placebo, CIT (5.3 g of CIT), or CMA (5.3 g of CIT, 2.7 g of malate) 45 min before three experimental sessions in a counterbalanced manner. We evaluated the upper and lower limb maximal neuromuscular and ballistic performance through the two-point method and countermovement jump. Strength-endurance was assessed across three sets of 10 repetitions in the squat and bench press exercises. Exertion and emotional perceptions were evaluated before and after the assessment and during the strength-endurance assessment. CIT and CMA supplementation did not enhance maximal neuromuscular performance (all p ≥ .061, ηp2≤.066), or ballistic strength (all p ≥ .348, ηp2≤.025). Neither CIT nor CMA supplementation improved strength-endurance as observed in the total number of repetitions (all p ≥ .590, ηp2≤.013), repetitions before reaching velocity loss threshold (all p ≥ .623, ηp2≤.010), mean velocity (all p ≥ .792, ηp2≤.004), mean velocity decline (all p ≥ .293, ηp2≤.029), and mean velocity maintenance (all p ≥ .393 ηp2≤.022), or exertion and emotional perceptions (both p ≥ .306, ηp2≤.028). In conclusion, CIT and CMA supplementation may not increase the neuromuscular performance during low- to moderate-volume resistance training sessions in young, trained adults. This trial was registered at ClinicalTrials.gov (No. NCT05183893).

Given the increasing popularity of CrossFit® as a high-intensity functional training program and the potential benefits of citrulline malate (CM) in enhancing exercise performance through its role as a precursor to L-arginine and nitric oxide production, this study aimed to investigate the acute effects of CM supplementation on CrossFit® performance and cardiovascular function. Using a randomized, double-blind, placebo-controlled, cross-over design, 21 recreationally active participants (mean age 22.2 ± 2.6 years, mean body weight 75.9 ± 10.4 kg) with CrossFit® experience completed the "Cindy" workout under CM and placebo conditions. Participants consumed 4.4 g of CM or a placebo 60 min before the workout, and the performance was measured by the number of rounds completed. Secondary outcomes included heart rate response, time spent in different heart rate intensity zones, and post-exercise recovery time. The results indicated no significant difference in the number of rounds completed between the CM and placebo conditions (13.5 ± 5.2 vs. 13.8 ± 6.7 rounds, respectively; p = 0.587). However, the time spent in zone 4 (80-90% of HR max) was significantly increased in the CM condition (527 ± 395 s vs. 453 ± 334 s; p = 0.017), suggesting a potential benefit for aerobic capacity and anaerobic threshold. No significant differences in post-exercise recovery time were observed (6.6 ± 4.7 h vs. 6.9 ± 4.7 h; p = 0.475). This study highlights the need for further research with larger sample sizes, both genders, and different CM dosages to clarify these findings and better understand CM's role in enhancing athletic performance.

PURPOSE: Citrulline (CIT) and beetroot extract (BR) supplements positively impacts exercise performance in elite rowers. However, its influence on metabolic outcomes such as whole-body volumes of oxygen consumption (VO2) and carbon dioxide production (VCO2), substrate oxidation, energy expenditure (EE), and gross efficiency remains unknown. We studied the effects of 1 week of daily co-supplementation of 3.5 g BR (500 mg NO3-) plus 6 g CIT on VO2 and VCO2 kinetics, substrate utilization, EE, and gross efficiency in elite male rowers compared to a placebo and to a BR supplementation. METHODS: Twenty elite rowers participated in this randomized, double-blind, placebo-controlled crossover trial completing 1 week of supplementation in each group of study: Placebo (PLAG); BRG; and BR-CITG. Efficiency (70% VO2max) and performance (incremental maximal) tests were performed, and gas-exchange data were collected via indirect calorimetry. RESULTS: Analysis of covariance (ANCOVA) showed no mean between-condition differences on respiratory exchange ratio (RER), EE, and gross efficiency in the efficiency test (all P > 0.06), and in the performance test (all P > 0.28). Moreover, in both tests no interaction Time × Supplement effects were observed for VO2, VCO2, RER, EE, substrate oxidation, and, gross efficiency (all P > 0.12). CONCLUSION: After 1 week, no effects on energy metabolism and substrate utilization were observed after the daily co-ingestion of BR extract plus CIT supplement, therefore longer (> 7 days) and higher doses of supplementation might be needed to influence metabolism. © 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Although mechanical loading is essential for maintaining bone health and combating osteoporosis, its practical application is limited to a large extent by the high variability in bone mechanoresponsiveness. Here, we found that gut microbial depletion promoted a significant reduction in skeletal adaptation to mechanical loading. Among experimental mice, we observed differences between those with high and low responses to exercise with respect to the gut microbial composition, in which the differential abundance of Lachnospiraceae contributed to the differences in bone mechanoresponsiveness. Microbial production of L-citrulline and its conversion into L-arginine were identified as key regulators of bone mechanoadaptation, and administration of these metabolites enhanced bone mechanoresponsiveness in normal, aged, and ovariectomized mice. Mechanistically, L-arginine-mediated enhancement of bone mechanoadaptation was primarily attributable to the activation of a nitric-oxide-calcium positive feedback loop in osteocytes. This study identifies a promising anti-osteoporotic strategy for maximizing mechanical loading-induced skeletal benefits via the microbiota-metabolite axis.

Hypertension and arterial stiffness are significant factors contributing to cardiovascular disease. L-citrulline, a nitric oxide precursor, has been proposed as a nutritional, non-pharmacological blood pressure-lowering intervention. This study aimed to investigate the impact of L-citrulline on central and peripheral blood pressure, pulse wave reflection, and central arterial stiffness at rest and during an isometric knee extension exercise protocol. Twelve older males received 6 g of L-citrulline or a placebo for six days using a double-blind crossover design. Blood hemodynamics parameters (i.e., aortic and brachial systolic and diastolic blood pressure, mean arterial pressure, pulse pressure, heart rate), pulse wave reflection (i.e., augmented pressure, augmentation index, forward/backward wave pressure), and arterial stiffness (i.e., carotid-femoral pulse wave velocity) were measured at baseline, post-supplementation, and during isometric exercise. No significant effects of L-citrulline supplementation were observed at rest or during exercise on blood pressure, pulse wave reflection, or arterial stiffness. Both central and peripheral blood pressure were increased during the exercise, which is consistent with isometric contractions. The results of the present study do not support any blood pressure-lowering effect of short-term L-citrulline at rest or during low-intensity isometric exercise compared to the pre-exercise values in older males.

Postmenopausal women have augmented pressure wave responses to low-intensity isometric handgrip exercise (IHG) due to an overactive metaboreflex (postexercise muscle ischaemia, PEMI), contributing to increased aortic systolic blood pressure (SBP). Menopause-associated endothelial dysfunction via arginine (ARG) and nitric oxide deficiency may contribute to exaggerated exercise SBP responses. L-Citrulline supplementation (CIT) is an ARG precursor that decreases SBP, pulse pressure (PP) and pressure wave responses to cold exposure in older adults. We investigated the effects of CIT on aortic SBP, PP, and pressure of forward (Pf) and backward (Pb) waves during IHG and PEMI in twenty-two postmenopausal women. Participants were randomised to CIT (10 g/d) or placebo (PL) for 4 weeks. Aortic haemodynamics were assessed via applanation tonometry at rest, 2 min of IHG at 30 % of maximal strength, and 3 min of PEMI. Responses were analysed as change (Δ) from rest to IHG and PEMI at 0 and 4 weeks. CIT attenuated ΔSBP (−9 ± 2 v. −1 ± 1 mmHg, P = 0·006), ΔPP (−5 ± 2 v. 0 ± 1 mmHg, P = 0·03), ΔPf (−6 ± 2 v. −1 ± 1 mmHg, P = 0·01) and ΔPb (−3 ± 1 v. 0 ± 1 mmHg, P = 0·02) responses to PEMI v. PL. The ΔPP during PEMI was correlated with ΔPf (r = 0·743, P < 0·001) and ΔPb (r = 0·724, P < 0·001). Citrulline supplementation attenuates the increase in aortic pulsatile load induced by muscle metaboreflex activation via reductions in forward and backward pressure wave amplitudes in postmenopausal women.

L-citrulline serves as a nitric oxide precursor with the potential to increase blood flow and improve resistance exercise performance, yet more research is needed to examine its ergogenic potential. To examine the effect of L-citrulline supplementation on resistance exercise performance, muscle oxygenation, and the subjective perception of effort, energy, focus, fatigue, and muscle pump, eighteen resistance-trained men (n = 11) and women (n = 7) (21.4 ± 1.8 years; 172.3 ± 7.5 cm; 76.9 ± 10.8 kg) were randomly assigned for supplementation with 8 g of L-citrulline (CIT) or a placebo (PL) in a cross-over fashion one hour prior to testing. Participants completed an isometric mid-thigh pull test (IMTP), a ballistic bench press protocol [two sets of two repetitions at 75% 1-repetition maximum (1 RM) with maximum ballistic intent], and a strength-endurance bench press protocol [five repetition-maximum sets at 75% 1RM]. Barbell velocity and power were measured via a linear position transducer during the ballistic protocol, while the repetitions completed, volume load and muscle oxygenation were quantified during the strength-endurance protocol. Subjective measures were assessed at the baseline and immediately pre- and post-exercise. Repeated measures of the analysis of variance and Bayesian equivalents revealed no significant interactions, providing evidence favoring the null hypothesis (BF10 < 1) for IMTP (PL 497.5 ± 133.6 vs. CIT 492.5 ± 129.4 N), barbell velocity, and power, and repetitions completed (PL 36.7 ± 7.2 vs. CIT 36.9 ± 8.1 repetitions). There were also no significant interactions for muscle oxygenation parameters or subjective measures except perceived fatigue. Women reported greater fatigue across all time points compared to men (~1.88 au, p = 0.045, BF10 = 0.2). The results indicate that a single 8 g dose of L-citrulline did not enhance isometric force production, muscle endurance, or muscle oxygenation parameters during the protocol implemented in this study.

Grape seed extract (GSE) or L-citrulline supplement has been known to increase nitric oxide (NO) bioavailability and enhance endothelial-mediated vasodilation. Accordingly, to examine the additive benefits of combination of the two supplementations on hemodynamic responses to dynamic exercise, young, healthy males were recruited for this study. Effects of 7 days of 1) GSE + L-citrulline, 2) GSE, 3) L-citrulline, and 4) placebo supplementation on systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), cardiac output, total vascular conductance (TVC), and oxygen (O2) consumption were examined at rest and during cycling exercise. Compared with placebo, GSE, L-citrulline, and combined supplementations did not reduce SBP, DBP, and MAP, while cardiac output (placebo; 23.6 ± 1.3 L/min, GSE; 25.7 ± 1.1 L/min; L-citrulline, 25.2 ± 1.2 L/min; GSE + L-citrulline; 25.3 ± 0.9 L/min) and TVC (placebo; 234.7 ± 11.3 ml/min/mmHg, GSE; 258.3 ± 10.6 ml/min/mmHg; L-citrulline, 255.2 ± 10.6 ml/min/mmHg; GSE + L-citrulline; 260.4 ± 8.9 ml/min/mmHg) were increased at only the 80% workload (p < 0.05). Compared with placebo and L-citrulline, GSE and combined supplementations had a reduction in VO2 across workloads (p < 0.05). However, there was no additive benefits on these variables. We conclude that supplementation with GSE, L-citrulline, and combined supplementations increased cardiac output due partially to decreased vascular resistance. Our findings suggest that GSE may act as an ergogenic aid that can improve O2 delivery to exercising muscles.

A pre-workout supplement's (PWS; 200 mg caffeine, 3.3 g creatine monohydrate, 3.2 g β-alanine, 6 g citrulline malate and 5 g branched chained amino acid (BCAA) per dose) acute effects on the alactic (jumping, sprinting, agility), lactic (Running-Based Anaerobic Sprint Test, RAST) and aerobic performance (Yo-Yo Intermittent Recovery Test Level 1, Yo-Yo IRL1 VO2max) of well-trained basketball players was investigated in this double-blind placebo-controlled study. Thirty players (age 18-31 years, height 166-195 cm, weight 70.2-116.7 kg, body fat 10.6-26.4%) were allocated to pre-workout (PWS, n = 15) or placebo (PL, n = 15) groups. Half of the participants in each group performed the evaluations without PWS or PL, while the rest consumed PWS or PL 30 min before the assessments (1st trial) and vice versa (2nd trial). Significant improvements in counter-movement jump (CMJ) (PWS: 4.3 ± 2.1%; PL: 1.2 ± 1.0%), agility (PWS: -2.9 ± 1.8%; PL: 1.8 ± 1.7%), RAST average (PWS: 18.3 ± 9.1%; PL: -2.2 ± 2.0%), minimum power (PWS: 13.7 ± 8.9%; PL: -7.5 ± 5.9%), and fatigue index (PWS: -25.0 ± 0.9%; PL: -4.6 ± 0.6%) were observed in the PWS group vs. the PL group (p < 0.05). No differences were found regarding sprinting, aerobic performance, and blood lactate concentrations. Thus, although players' alactic and lactic anaerobic performance could be improved, peak power, sprinting and aerobic performance are not.

BACKGROUND: Citrulline is a popular dietary supplement, primarily thought to exert ergogenic effects on exercise performance through the enhancement of nitric oxide (NO) synthesis and ammonia buffering. However, recent findings surrounding citrulline's effect on endurance performance have been inconsistent. A systematic review and meta-analysis of the relevant literature have yet to be undertaken. AIM: To determine if acute ingestion of citrulline has an ergogenic effect on endurance performance in young healthy adults. METHODS: A systematic search of three databases was undertaken to find peer-reviewed randomized controlled trials (RCTs) published in English investigating the effects of citrulline supplementation on endurance performance in young healthy adults. Two independent investigators completed a three-phased screening procedure against pre-determined eligibility criteria. Included studies evaluated loading or bolus dosage regimes of citrulline in participants aged 18 or over that were at least recreationally active. Outcome measures focused on time-to-completion (TTC) or time-to-exhaustion (TTE) in continuous submaximal intensity exercise. Cochrane's Risk of Bias 2 (RoB 2) tool was used to assess the risk of bias in individual studies. Meta-analysis was conducted using a fixed-effects model to pool the weighted estimate of standardized mean differences (SMD) across studies. A chi-squared test assessed heterogeneity between studies. This review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: Nine studies (n = 158 participants) met the eligibility criteria; five reported TTE outcomes (I2 = 0%, χ2 = 0.37, df = 4, P = 0.99) and four reported TTC outcomes (I2 = 0%, χ2 = 0.46, df = 3, P = 0.93), both with a low between-study heterogeneity. The results of the meta-analyses showed no significant difference in the endurance performance measures, TTE (pooled SMD = 0.03 [-0.27, 0.33]) and TTC (pooled SMD = -0.07 [-0.50, 0.15]), after acute ingestion of citrulline supplementation or a control in young healthy adults. DISCUSSION: The current evidence suggests no signif