Dietary Creatine Supplementation Research Articles

Creatine in giant grouper (Epinephelus lanceolatus): Insights into biosynthesis and transporter genes molecular characterization, regulation and impact on muscle metabolism

Creatine is synthesized from glycine, arginine, and methionine with the catalysis of glycine amidinotransferase (GATM) and guanidinoacetate N-methyltransferase (GAMT), playing a crucial role in regulating the cellular metabolism and whole-body energy balance. However, information regarding the molecular characteristics of GATM and GAMT is limited in fish species. In this study, GATM and GAMT cDNA were cloned from giant grouper (Epinephelus lanceolatus). The cloned cDNA sequence of GATM was 1503 bp encoding a 421 aa containing conserved regions of amidinotransferase superfamily. GAMT cDNA was 892 bp encoding a 235 aa containing conserved regions of S-adenosylmethionine-dependent methyltransferases superfamily. The phylogenetic tree indicated that GATM and GAMT were clustered distinctly into teleost and featured common function domains and homology with teleost proteins, but they were distinct from the terrestrial clusters. The mRNA transcripts of GATM and GAMT were detectable mainly in muscle tissue. Additionally, as the creatine synthesis limited enzyme, GATM gene and protein expression were both significantly regulated by supplement of dietary creatine (P < 0.05). Metabolomics analysis showed that dietary creatine significantly affected skeletal muscle nutrients and energy metabolism. Meanwhile, inclusion of dietary creatine led to a significant inhibition of AMPK phosphorylation. What is more, we also recorded that cytochrome oxidase (cox) and mitochondrial fission factor (mff) gene expression were remarkable up-regulated by dietary creatine supplementation. In summary, the results obtained from the present study would help us better understand the creatine synthesis pathway in fish species. We also demonstrated that creatine plays a significant role in fish muscle metabolism.

Dietary creatine and guanidinoacetic acid supplementation have limited effects on hybrid striped bass.

The effects of dietary supplementation of creatine and guanidinoacetic acid (GDA) have been studied to a limited extent in various fish species including red drum (Sciaenops ocellatus) and hybrid striped bass (HBS) (Morone saxatilis x M. chrysops). However, in HSB, there is a need to better understand the impact of creatine and GDA supplementation at elevated salinity which may be encountered by this euryhaline fish. Therefore, two separate feeding trials were conducted at a salinity ranging from 15 to 20g/L with juvenile HSB for 9 and 8weeks to evaluate the effects of dietary creatine and GDA. In each trial, four diets were formulated with either singular additions of creatine at 2% of dry weight, GDA at 1% of dry weight, or a combination of both. Fish grew adequately in both feeding trials but no significant (P > 0.05) effects of supplemental creatine or GDA were observed on weight gain, feed efficiency, survival, hepatosomatic index (HSI), intraperitoneal fat (IPF ratio), or protein conversion efficiency (PCE). However, fish fed diets supplemented with creatine had significantly (P < 0.05) increased ash and reduced lipid deposition in whole-body tissues in the first feeding trial. Supplemental creatine also resulted in significantly higher muscle yield in the second trial, but no other effects on growth performance or body composition were observed. The addition of GDA to the diet had little effect except for significantly increasing the creatine content in the liver of fish in both feeding trials due to its role as a precursor and a catalyst for synthesis of creatine within the body. Based on the results of these two trials, supplemental creatine and GDA had rather limited effects on HSB cultured in moderately saline water.

Effects of dietary creatine levels on the growth, muscle energy metabolism and meat quality of spotted seabass (Lateolabrax maculatus) fed low-fishmeal diets

The study was performed to evaluate the effects of dietary creatine (CR) levels on the growth, muscle energy metabolism and meat quality of spotted seabass (Lateolabrax maculatus) fed low-fishmeal diets. The experimental diets were formulated with 15% fishmeal, and contained five creatine levels of 0.03%, 0.07%, 0.12%, 0.21% and 0.39%. Spotted seabass (initial body weight: 4.38 ± 0.06 g) were randomly allocated into 15 tanks (20 fish per tank) and fed twice daily for 8 weeks. With increasing dietary CR levels, the final body weight (FBW) and weight gain (WG) significantly increased, and the peak occurred in the 0.21% group. Second-order polynomial regression analysis showed that the optimum CR supplementation level based on WG was 0.25% for spotted seabass. With the increase in dietary CR levels, anaerobic glycolysis (the activities of lactic dehydrogenase and pyruvate kinase) in fish muscle was significantly reduced. The energy reserve (the content of ATP and activity of creatine kinase) was significantly increased to promote the pH value at 48 h postmortem with increasing CR levels. Water holding capacity increased as dietary CR levels increasing from 0.03% to 0.39%. The mRNA expression of myog, myod, myf5, mef2c, mstn, capn1 and capn2 was upregulated, but the mRNA expression of cast was downregulated with increasing CR levels from 0.03% to 0.39%. In conclusion, dietary CR supplementation promoted the growth performance of spotted seabass fed low-fishmeal diets, and the optimum creatine level was 0.25%. Dietary CR supplementation increased energy reserve and deceased anaerobic glycolysis at 48 h postmortem and enhanced meat quality.

Role of creatine supplementation on the myofiber characteristics and muscle protein synthesis of grass carp (Ctenopharyngodon idellus).

To assess the role of dietary creatine on myofiber characteristics and protein synthesis in muscle, we fed grass carp (Ctenopharyngodon idellus, initial body weight: 88.47 ± 1.44 g) creatine-supplemented diets (1.84, 5.91, 8.48, and 15.44 g/kg diet) for 8 weeks. Creatine supplementation did not affect growth performance, but significantly increased creatine contents in muscle and liver. At 8.48 g/kg, creatine decreased the activities of alanine transaminase and aspartate aminotransferase in serum, and improved hardness and chewiness of muscle due to shorter myofiber mean diameter, higher myofiber density and the frequencies of the diameters of class I and III and collagen content, longer sarcomere length, and upregulated mRNA levels of slow myosin heavy chains. Creatine supplementation upregulated the mRNA expressions of myogenic regulatory factors. The 8.48 g/kg creatine-supplemented diet significantly increased the contents of protein, total amino acids (AAs), essential AAs, and free flavor AAs in muscle, the protein levels of insulin-like growth factor I, myogenic differentiation antigen, and peroxisome proliferator-activated receptor-γ coactlvator-1α in muscle, and stimulated the phosphorylation of target of rapamycin (TOR) pathway in muscle. In summary, 8.48 mg/kg creatine improved fish health and skeletal muscle growth, and increased hardness and protein synthesis in muscle of grass carp by affecting myofiber characteristics and the TOR signaling pathway. A second-order regression model revealed that the optimal dietary creatine supplementation of grass carp ranges between 8.48 and 12.04 g/kg.

Effects of dietary creatine on juvenile hybrid striped bass in low‐salinity and brackish waters

AbstractA 12‐week, two‐part feeding trial was conducted to evaluate the potential benefits of creatine supplementation in the diet of hybrid striped bass (HSB) under different water salinity and osmoregulatory conditions. A basal diet was formulated to contain 40% crude protein, contributed equally by menhaden fishmeal and soy protein concentrate, and 10% lipid. Three isonitrogenous experimental diets were prepared by supplementing 1, 2, and 4% creatine to the basal diet replacing cellulose and adjusting a 50/50 aspartate/glutamate premix. During the first 7 weeks, salinity of the recirculating system was maintained at 3 g/L (low salinity), then, for an additional 5 weeks, switched to 15 g/L (brackish water). No discernable differences in weight gain, feed efficiency, or survival of HSB were observed during the low‐salinity phase. However, significant improvements in weight gain were exhibited by fish fed diets supplemented with 2 and 4% creatine compared to those fed basal and 1% creatine diets during the brackish water phase. Muscle creatine levels significantly increased with dietary creatine supplementation during both culture phases. The positive effects of dietary creatine supplementation on HSB appeared to be due to increased energetic demands of the brackish water environment.

Creatine supplementation does not alter proliferation or doxorubicin sensitivity of mammary carcinoma cells

Objectives Doxorubicin (DOX) is an effective chemotherapy drug used to treat breast cancer, but its use is limited by detrimental side effects such as cardiotoxicity and skeletal muscle atrophy. Supplementation with creatine has been shown to protect cardiac and skeletal muscle cells from the cytotoxic effects of DOX. One concern with dietary creatine supplementation in cancer patients, however, is the possible protection of cancer cells from therapeutic DOX toxicity. Thus, we investigated the effects of in vitro creatine supplementation on proliferation and survival of DOX-treated MAT-BIII rat mammary carcinoma cells. Methods MATB-III cells were seeded in triplicate at 15,000 cells/well in a 96-well microplate for an eight day incubation in one of six treatments: no treatment, 5 µM DOX, 2 mM creatine, 2 mM creatine + 5 µM DOX, 20 mM creatine, 20 mM creatine + 5 µM DOX. Media and treatments were refreshed every 48 hours. An MTT assay was run on day 8 to assess remaining cell number in each well. The results represent an average from three time separated experiments with differences between treatments identified using a two-way ANOVA (IBM SPSS 27). Significance was at the α=0.05 level. Results As expected, the number of MAT-BIII cells was significantly reduced (P < 0.001) after DOX treatment consistent with impaired proliferation or cytotoxicity. Neither low nor high-dose creatine exposure altered the number of cells or the suppressive effects of DOX as no creatine x DOX interaction was identified (P > 0.05). Conclusion DOX decreased proliferation of MAT-BIII mammary carcinoma cells indicating this cell line is sensitive to the effects of this chemotherapy drug. There was no indication that creatine influenced proliferation or DOX sensitivity of the mammary carcinoma cells. The absence of an effect in this experiment suggests that creatine could be supplemented to alleviate the adverse side effects of DOX treatment in human breast cancer patients. Future research aims to elucidate further the possible interactions between DOX and creatine in cancer cell metabolism.

Creatine Metabolism in Female Reproduction, Pregnancy and Newborn Health.

Creatine metabolism is an important component of cellular energy homeostasis. Via the creatine kinase circuit, creatine derived from our diet or synthesized endogenously provides spatial and temporal maintenance of intracellular adenosine triphosphate (ATP) production; this is particularly important for cells with high or fluctuating energy demands. The use of this circuit by tissues within the female reproductive system, as well as the placenta and the developing fetus during pregnancy is apparent throughout the literature, with some studies linking perturbations in creatine metabolism to reduced fertility and poor pregnancy outcomes. Maternal dietary creatine supplementation during pregnancy as a safeguard against hypoxia-induced perinatal injury, particularly that of the brain, has also been widely studied in pre-clinical in vitro and small animal models. However, there is still no consensus on whether creatine is essential for successful reproduction. This review consolidates the available literature on creatine metabolism in female reproduction, pregnancy and the early neonatal period. Creatine metabolism is discussed in relation to cellular bioenergetics and de novo synthesis, as well as the potential to use dietary creatine in a reproductive setting. We highlight the apparent knowledge gaps and the research “road forward” to understand, and then utilize, creatine to improve reproductive health and perinatal outcomes.

Effects of dietary creatine supplementation on kidney and striated skeletal muscles of rats submitted to ischemia and reperfusion of hind limbs.

ABSTRACTPurposeTo evaluate the effect of creatine supplementation in the diet of rats subjected to ischemia and reperfusion of hind limbs.MethodsEighteen male Wistar rats were randomized to receive dietary creatine supplementation (G1) or no supplementation (G2), before being subjected to 4 h of ischemia followed by 4 h of reperfusion. In addition, 10 rats (G3) underwent the same surgical procedure, without ischemia, but with supplementation. After reperfusion, kidney and musculature were evaluated for histological damage and serum levels of alanine aminotransferase, urea and creatinine were obtained.ResultsThe urea dosage showed significant differences between the groups (averages G1 = 155.1; G2 = 211.27; G3 = 160.42). Histological analysis found significant differences between G1 and G2 (but not between G1 and G3) in renal myoglobin cylinders and vacuolar degeneration variables and in hypereosinophilia and karyopyknosis variables in muscle fibers. There were no significant differences in the other variables studied.ConclusionsCreatine supplementation was related to fewer histological lesions, as well as lower levels of plasma urea, which may suggest a protective effect against lesions caused by ischemia and reperfusion of posterior paws muscles in Wistar rats.

No evidence for brown adipose tissue activation after creatine supplementation in adult vegetarians.

Creatine availability in adipose tissue has been shown to have profound effects on thermogenesis and energy balance in mice. However, whether dietary creatine supplementation affects brown adipose tissue (BAT) activation in humans is unclear. In the present study, we report the results of a double-blind, randomized, placebo-controlled, cross-over trial (NCT04086381) in which 14 young, healthy, vegetarian adults, who are characterized by low creatine levels, received 20 g of creatine monohydrate per day or placebo. Participants were eligible if they met the following criteria: male or female, white, aged 18-30 years, consuming a vegetarian diet (≥6 months) and body mass index 20-25 kg m-2. BAT activation after acute cold exposure was determined by calculating standard uptake values (SUVs) acquired by [18F]fluorodeoxyglucose positron emission tomography-magnetic resonance imaging. BAT volume (-31.32 (19.32) SUV (95% confidence interval (CI) -73.06, 10.42; P = 0.129)), SUVmean (-0.34 (0.29) SUV (95% CI -0.97, 0.28; P = 0.254)) and SUVmax (-2.49 (2.64) SUV (95% CI -8.20, 3.21; P = 0.362)) following acute cold exposure were similar between placebo and creatine supplementation. No side effects of creatine supplementation were reported; one participant experienced bowel complaints during placebo, which resolved without intervention. Our data show that creatine monohydrate supplementation in young, healthy, lean, vegetarian adults does not enhance BAT activation after acute cold exposure.

The Evolving Applications of Creatine Supplementation: Could Creatine Improve Vascular Health?

Creatine is a naturally occurring compound, functioning in conjunction with creatine kinase to play a quintessential role in both cellular energy provision and intracellular energy shuttling. An extensive body of literature solidifies the plethora of ergogenic benefits gained following dietary creatine supplementation; however, recent findings have further indicated a potential therapeutic role for creatine in several pathologies such as myopathies, neurodegenerative disorders, metabolic disturbances, chronic kidney disease and inflammatory diseases. Furthermore, creatine has been found to exhibit non-energy-related properties, such as serving as a potential antioxidant and anti-inflammatory. Despite the therapeutic success of creatine supplementation in varying clinical populations, there is scarce information regarding the potential application of creatine for combatting the current leading cause of mortality, cardiovascular disease (CVD). Taking into consideration the broad ergogenic and non-energy-related actions of creatine, we hypothesize that creatine supplementation may be a potential therapeutic strategy for improving vascular health in at-risk populations such as older adults or those with CVD. With an extensive literature search, we have found only four clinical studies that have investigated the direct effect of creatine on vascular health and function. In this review, we aim to give a short background on the pleiotropic applications of creatine, and to then summarize the current literature surrounding creatine and vascular health. Furthermore, we discuss the varying mechanisms by which creatine could benefit vascular health and function, such as the impact of creatine supplementation upon inflammation and oxidative stress.

Pilot Study: The Effect of Acute 5-Day Creatine Supplementation on Macrovascular Endothelial Function in Older Adults

Abstract Objectives Cardiovascular disease (CVD) remains the leading cause of mortality in the United States, and aging is a primary risk factor for CVD events. Dietary creatine supplementation has been used to alleviate age-related health deteriorations, and has been shown to reduce sarcopenia, improve cognition and decrease reactive oxygen species in older adults. There is scarce information, however, regarding the use of creatine to improve vascular function. Therefore, the primary aim of this pilot study was to determine the effect of creatine on vascular function in older adults. Methods Four older adults (66 ± 8.3 years) participated in this pilot study, with four young adults (27 ± 2.9 years) serving as a comparator. Participants reported for their baseline visit, and completed basic anthropometrics and resting hemodynamic testing. Brachial artery flow mediated dilation (FMD) was used to assess macrovascular endothelial function following 5-minutes of occlusion. Resting and peak brachial artery diameters were assessed using edge detection software, and FMD % change (FMD%) was determined utilizing the following equation: [(peak diameter – baseline diameter)/baseline diameter] * 100. Participants were then given creatine monohydrate to consume over the following 5 days (4 × 5 g/day), before returning to repeat all assessments. A two-way ANOVA statistical analysis was performed using SPSS software, and significance was accepted at P ≤ 0.05. Results No statistically significant changes were seen in FMD%. However, mean delta (Δ) change for groups did show a greater improvement in FMD% in old vs. young (Δ2.44 ± 1.78% vs. −.82 ± 3.09%) and estimated marginal means of FMD showed a positive change in FMD% in older adults but not in younger. Furthermore, 100% of older adults showed improvement following creatine, whereas only 50% of young adults showed (minimal) improvement. Conclusions Although there were no significant changes identified, this may be due to the small sample size not being sufficient to detect an interaction effect. The improvements seen for each older adult could still be considered physiologically significant for vascular health, and future study of additional participants may result in significant benefits and expand the use of creatine to improve vascular health. Funding Sources No grants or Funding Sources were used for this pilot study.

Dietary Creatine Supplementation Does Not Alter Trabecular Bone Morphology in Male and Female Rats

BackgroundSupplementation with dietary creatine has been reported to improve markers of bone structure in animals and humans. Trabecular bone is one of two types of bone responsible for strength and structural support in the body. It serves to support areas that experience mechanical stress. The purpose of this study was to investigate the effect of varying doses of dietary creatine on the trabecular bone morphology of male and female rats.Methods32 Sprague‐Dawley rats (16 male, 16 female) were randomized into one of four groups: 0g/L, 2.5g/L, 5g/L, or 10g/L of creatine monohydrate (CM) in drinking water with 1% sucrose (for palatability). Dietary interventions began at 12 weeks and lasted for 8 weeks. Ex vivo scanning and analysis was conducted on the proximal region of left femurs using micro‐computed tomography (mCT). Standard measures of trabecular bone morphology were measured at the proximal femur: trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), percent bone volume (BV/TV), connectivity (Conn) and connectivity density (Conn.Dn).ResultsThere were no significant differences in Tb.Th, Tb.Sp, Tb.N, BV/TV, Conn, or Conn.Dn between creatine dose groups for males or females. Males had greater Tb.Th than females (p&lt;0.01). Greater Tb.Sp was also observed in males as compared to females (p&lt;0.01). Females demonstrated significantly higher BV/TV (p&lt;0.01) as well as a greater Tb.N (p&lt;0.01) than males. Conn was significantly different between sexes (p&lt;0.05) with a higher value in females compared to males. Conn.Dn was also significantly higher in females (p&lt;0.01) compared to males.ConclusionsEight weeks of different dietary intakes of creatine does not appear to have an effect on proximal femur Tb.Th, Tb.Sp, Tb.N, BV/TV, Conn, or Conn.Dn. However, differences in sex were observed for each dependent variable which is suggestive of a difference in the trabecular structure between males and females.Support or Funding InformationSupported by NSERC (Canada).

Acceptability of dietary or nutritional supplementation in pregnancy (ADONS) – Exploring the consumer's perspective on introducing creatine monohydrate as a pregnancy supplement

BackgroundPre-clinical studies suggest maternal dietary creatine supplementation during pregnancy could protect babies against hypoxic intrapartum events, however creatine has not been used as a supplement in pregnancy. The aim of this study was to explore pregnant women and healthcare professional's general knowledge, behaviours, and attitudes toward nutritional supplements, and their thoughts on introducing creatine as a pregnancy supplement. MethodsPregnant women (n = 42) and partners (n = 23), attending a tertiary care pregnancy service in Melbourne, Australia, participated in focus groups or semi-structured interviews. Health professionals (n = 100), completed a semi-structured online survey. Descriptive data were analyzed using SPSS 25.0 and qualitative data was managed using NVivo 22.0. ResultsUse of branded nutritional supplements in pregnancy was commonplace and acceptable. All primary healthcare respondents discussed supplements with their patients at first consultation. Supplements consumed corresponded closely to those recommended. Women had good general awareness of commonly recommended nutritional supplements, however, were less aware of the rationale for supplement use. This aligned with health professional's perceptions. Women would consider taking creatine if recommended by their health professional. Health professionals would require detailed safety, beneficence, and efficacy information before recommending creatine supplementation. They would also be more likely to recommend a new supplement in higher-risk pregnancies, where benefits may outweigh any perceived side-effects. ConclusionThere is high acceptance of current recommended nutritional supplements in pregnancy. Implementing creatine as a new supplement will require substantive empirical evidence and changes to clinical guidelines. Public awareness and education would also be essential to consumer acceptability of creatine.

Evaluation of dietary creatine and guanidinoacetic acid supplementation in juvenile red drumSciaenops ocellatus

Two separate comparative feeding trials were conducted to evaluate if supplemental dietary guanidinoacetic acid (GDA), either singly or in combination with creatine, could enhance growth performance of red drum. The basal diet for both trials was formulated with practical ingredients but was not supplemented with creatine or GDA. For the experimental diets, creatine (0 or 20 g/kg) and GDA (0, 5 or 10 g/kg) were added to the basal diet in a 2 × 3 factorial arrangement for trial 1. Another 2 × 3 experimental design was adopted in trial 2 to further evaluate creatine (0 or 20 g/kg) and GDA (0, 10 or 20 g/kg) supplementation. Each diet was fed to juvenile red drum in either quadruplicate (trial 1) or triplicate (trial 2) aquaria twice daily for a total of 8 weeks. After each feeding trial, fish were sampled for body condition indices and whole‐body composition analysis, as well as determination of plasma, liver and muscle creatine concentrations. In trial 1, dietary creatine supplementation alone significantly (p < .05) improved weight gain and feed efficiency of red drum. An interaction between creatine and GDA was seen in whole‐body protein and lipid in the two trials. In trial 1, the highest levels of whole‐body protein and lipid were observed in fish fed 10 g GDA/kg, and in trial 2, supplementation of the diet with 10 g GDA/kg increased muscle protein and muscle lipid although there was a trending decline in fish fed the 20 g/kg GDA‐supplemented diet. In both trials of the present study, dietary GDA significantly (p < .05) enhanced liver creatine content. Dietary creatine also significantly (p < .05) enhanced plasma and muscle creatine content of red drum. Based on the results of this study, creatine was effective in enhancing weight gain and feed efficiency of red drum as seen in previous studies; however, GDA was not effective in influencing growth performance but limited synthesis of creatine from dietary GDA was apparent.

Effects of the Anticancer Drug Doxorubicin and Dietary Creatine Supplementation on Myogenic Regulatory Factor Expression

The purpose of this study was to explore the acute effects of doxorubicin (Dox) treatment on myogenic regulatory factor (MRF) expression and determine the impact that creatine monohydrate (Cr) feeding prior to Dox treatment has on the MRF response. Male Sprague‐Dawley rats were randomly assigned to one of three feeding groups: rodent chow supplemented with 2% Cr for four weeks (Cr1), rodent chow supplemented with 4% Cr for one week followed rodent chow supplemented with 2% Cr for three weeks (Cr2), or standard rodent chow for four weeks (Con). After four weeks, animals in each feeding intervention received a 15 mg/kg bolus Dox i.p. injection or a 0.9% bolus saline i.p. injection as a placebo (Sal). One day after injections, animals were anesthetized, and the extensor digitorum longus (EDL) muscles were excised. Expression of the primary MRFs Myf5 and MyoD and the secondary MRFs myogenin and Mrf4 were then quantified with Western blotting. Creatine feeding promoted an upregulation in Myf5 and MyoD (significant diet effect p=0.022 and p=0.017, respectively), and this upregulation was more profound with MyoD expression in Cr2. Significant diet effects were also observed with myogenin (p=0.0011) and Mrf4 (p&lt;0.001) with Cr1 and Cr2 expressing higher levels of myogenin than Con+Sal (p&lt;0.05) and Cr2 expressing higher levels of Mrf4 than Con+Sal and Con+Dox (p&lt;0.05). In conclusion, Cr feeding prior to Dox treatment increased MRF expression suggesting that Cr may enhance signaling for skeletal muscle repair and regeneration following Dox treatment thereby attenuating muscle damage.Support or Funding InformationDavid S. Hydock, PhD was supported by a Pilot and Exploratory Projects in Palliative Care of Cancer Patients and Their Families, PEP‐17‐193‐01 ‐ PCSM, from the American Cancer Society.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Dietary creatine requirement of red drum (Sciaenops ocellatus) and effects of water salinity on responses to creatine supplementation

Creatine is a multifunctional organic acid necessary for various physiological processes and is commonly supplemented to improve muscle growth and performance of humans. However, the effects of supplemented creatine in the diets of fishes is unclear. Thus, two feeding trials were conducted to examine the performance of juvenile red drum fed diets supplemented with creatine. The first feeding trial was conducted for 7 weeks, to determine the optimal dietary supplementation of creatine for red drum at low (5 ppt) salinity. Red drum is a euryhaline species and potential benefits of creatine may include enhanced energy utilization during osmoregulation. Therefore, the second trial was a two-part, 12-week, feeding trial. During the first 7 weeks, salinity was maintained at 3 ppt (low salinity), then, for an additional 5 weeks, maintained at 15 ppt (moderate salinity). The basal diet for both feeding trials was formulated to contain 40% crude protein, contributed equally by menhaden fishmeal and soy protein concentrate, and 10% lipid. For trial 1, five experimental diets were derived from the basal diet by supplementing creatine at 0.5, 1, 1.5, 2, or 4% by weight at the expense of cellulose. The diets for trial 1 were adjusted with a 50/50 blend of aspartate and glutamate to maintain the diets isonitrogenous. For trial 2, the same basal diet and one supplemented with creatine at 2% were prepared with the creatine-supplemented diet adjusted with a 50/50 blend of aspartate and glutamate on an equal-weight basis. In trial 1, significant (P ≤ .05) positive trends were observed in weight gain, feed efficiency, and survivability of fish fed the diets supplemented with creatine. Broken-line regression analysis indicated creatine supplementation at 1.98% of diet provided optimal weight gain of red drum. In trial 2, there was a trending increase in percent weight gain and feed efficiency of fish fed the creatine supplemented diet during the moderate salinity portion of the trial, resulting in significant improvements over the 12-week period. Results from these study confirm that red drum benefit from dietary creatine supplementation in practical diets.

Dietary Creatine Supplementation in Gilthead Seabream (Sparus aurata) Increases Dorsal Muscle Area and the Expression of myod1 and capn1 Genes.

Creatine (Cr) is an amino acid derivative with an important role in the cell as energy buffer that has been largely used as dietary supplement to increase muscle strength and lean body mass in healthy individuals and athletes. However, studies in fish are scarce. The aim of this work is to determine whether dietary Cr supplementation affects muscle growth in gilthead seabream (Sparus aurata) juveniles. Fish were fed ad libitum for 69 days with diets containing three increasing levels of creatine monohydrate (2, 5, and 8%) that were compared with a non-supplemented control (CTRL) diet. At the end of the trial, the fast-twist skeletal muscle growth dynamics (muscle cellularity) and the expression of muscle-related genes were evaluated. There was a general trend for Cr-fed fish to be larger and longer than those fed the CTRL, but no significant differences in daily growth index (DGI) were registered among dietary treatments. The dorsal cross-sectional muscle area (DMA) of fish fed Cr 5 and Cr 8% was significantly larger than that of fish fed CTRL. The groups supplemented with Cr systematically had a higher relative number of both small-sized (≤20 μm) and large-sized fibers (≥120 μm). Dorsal total fibers number was highest in fish fed 5% Cr. In fish supplemented with 5% Cr, the relative expression of myogenic differentiation 1 (myod1) increased almost four times compared to those fed the CTRL diet. The relative expression of calpain 3 (capn3) was highest in fish fed diets with 2% Cr supplementation, but did not differ significantly from those fed the CTRL or Cr 5%. The myod1 gene expression had a positive and significant correlation with that of capn1, capns1a, and capn3 expression. These results suggest that the observed modulation of gene expression was not enough to produce a significant alteration in muscle phenotype under the tested conditions, as a non-significant increase in muscle fiber diameter and higher total number of fiber was observed, but still resulted in increased DMA. Additional studies may be required in order to better clarify the effect of dietary Cr supplementation in fish, possibly in conjunction with induced resistance training.

Dietary Creatine Supplementation in Gilthead Seabream (Sparus aurata): Comparative Proteomics Analysis on Fish Allergens, Muscle Quality, and Liver.

The quality of fish flesh depends on the skeletal muscle's energetic state and delaying energy depletion through diets supplementation could contribute to the preservation of muscle's quality traits and modulation of fish allergens. Food allergies represent a serious public health problem worldwide with fish being one of the top eight more allergenic foods. Parvalbumins, have been identified as the main fish allergen. In this study, we attempted to produce a low allergenic farmed fish with improved muscle quality in controlled artificial conditions by supplementing a commercial fish diet with different creatine percentages. The supplementation of fish diets with specific nutrients, aimed at reducing the expression of parvalbumin, can be considered of higher interest and beneficial in terms of food safety and human health. The effects of these supplemented diets on fish growth, physiological stress, fish muscle status, and parvalbumin modulation were investigated. Data from zootechnical parameters were used to evaluate fish growth, food conversion ratios and hepatosomatic index. Physiological stress responses were assessed by measuring cortisol releases and muscle quality analyzed by rigor mortis and pH. Parvalbumin, creatine, and glycogen concentrations in muscle were also determined. Comparative proteomics was used to look into changes in muscle and liver tissues at protein level. Our results suggest that the supplementation of commercial fish diets with creatine does not affect farmed fish productivity parameters, or either muscle quality. Additionally, the effect of higher concentrations of creatine supplementation revealed a minor influence in fish physiological welfare. Differences at the proteome level were detected among fish fed with different diets. Differential muscle proteins expression was identified as tropomyosins, beta enolase, and creatine kinase among others, whether in liver several proteins involved in the immune system, cellular processes, stress, and inflammation response were modulated. Regarding parvalbumin modulation, the tested creatine percentages added to the commercial diet had also no effect in the expression of this protein. The use of proteomics tools showed to be sensitive to infer about changes of the underlying molecular mechanisms regarding fish responses to external stimulus, providing a holistic and unbiased view on fish allergens and muscle quality.

Changing to a vegetarian diet reduces the body creatine pool in omnivorous women, but appears not to affect carnitine and carnosine homeostasis: a randomised trial.

Balanced vegetarian diets are popular, although they are nearly absent in creatine and carnosine and contain considerably less carnitine than non-vegetarian diets. Few longitudinal intervention studies investigating the effect of a vegetarian diet on the availability of these compounds currently exist. We aimed to investigate the effect of transiently switching omnivores onto a vegetarian diet for 6 months on muscle and plasma creatine, carnitine and carnosine homeostasis. In a 6-month intervention, forty omnivorous women were ascribed to three groups: continued omnivorous diet (control, n 10), vegetarian diet without supplementation (Veg+Pla, n 15) and vegetarian diet combined with daily β-alanine (0·8-0·4 g/d) and creatine supplementation (1 g creatine monohydrate/d) (Veg+Suppl, n 15). Before (0 months; 0M), after 3 months (3M) and 6 months (6M), a fasted venous blood sample and 24-h urine was collected, and muscle carnosine content was determined by proton magnetic resonance spectroscopy (1H-MRS). Muscle biopsies were obtained at 0M and 3M. Plasma creatine and muscle total creatine content declined from 0M to 3M in Veg+Pla (P=0·013 and P=0·009, respectively), whereas plasma creatine increased from 0M in Veg+Suppl (P=0·004). None of the carnitine-related compounds in plasma or muscle showed a significant time×group interaction effect. 1H-MRS-determined muscle carnosine content was unchanged over 6M in control and Veg+Pla, but increased in Veg+Suppl in soleus (P<0·001) and gastrocnemius (P=0·001) muscle. To conclude, the body creatine pool declined over a 3-month vegetarian diet in omnivorous women, which was ameliorated when accompanied by low-dose dietary creatine supplementation. Carnitine and carnosine homeostasis was unaffected by a 3- or 6-month vegetarian diet, respectively.

Dietary creatine supplementation lowers hepatic triacylglycerol by increasing lipoprotein secretion in rats fed high-fat diet

Recent studies have shown that dietary creatine supplementation can prevent lipid accumulation in the liver. Creatine is a small molecule that plays a large role in energy metabolism, but since the enzyme creatine kinase is not present in the liver, the classical role in energy metabolism does not hold in this tissue. Fat accumulation in the liver can lead to the development of nonalcoholic fatty liver disease (NAFLD), a progressive disease that is prevalent in humans. We have previously reported that creatine can directly influence lipid metabolism in cell culture to promote lipid secretion and oxidation. Our goal in the current study was to determine whether similar mechanisms that occur in cell culture were present in vivo. We also sought to determine whether dietary creatine supplementation could be effective in reversing steatosis. Sprague–Dawley rats were fed a high-fat diet or a high-fat diet supplemented with creatine for 5 weeks. We found that rats supplemented with creatine had significantly improved rates of lipoprotein secretion and alterations in mitochondrial function that were consistent with greater oxidative capacity. We also find that introducing creatine into a high-fat diet halted hepatic lipid accumulation in rats with fatty liver. Our results support our previous report that liver cells in culture with creatine secrete and oxidize more oleic acid, demonstrating that dietary creatine can effectively change hepatic lipid metabolism by increasing lipoprotein secretion and oxidation in vivo. Our data suggest that creatine might be an effective therapy for NAFLD.