Short-term creatine supplementation does not reduce increased homocysteine concentration induced by acute exercise in humans

Changes in homocysteine and non-mercaptoalbumin levels after acute exercise: a crossover study

BACKGROUND

Acute exercise is one factor that increases blood homocysteine levels, and elevated homocysteine levels cause oxidative stress. Albumin, which is abundant in blood, is an antioxidant, and the redox state of albumin is used as an index of oxidative stress in blood. This study aimed to assess the effect of acute exercise on plasma homocysteine levels and the blood non-mercaptoalbumin/mercaptoalbumin ratio as an oxidative stress marker.

METHODS

This study used a crossover design with exercise and control conditions. Under exercise conditions, a bicycle ergometer was used to perform 40 min of transient constant-load exercise at 65% heart rate reserve. Under control conditions, participants rested for 40 min. Blood was collected before, 30 min after, and 90 min after exercise, and at the same time points under control conditions. Samples were analyzed for the homocysteine concentration and non-mercaptoalbumin/mercaptoalbumin ratio.

RESULTS

The results revealed that a 65% heart rate reserve and 40 min of acute exercise increased plasma homocysteine concentration and non-mercaptoalbumin ratio. In the intra-condition comparison, the plasma Hcy concentration was significantly increased at Post 30 min (+ 0.83 ± 0.70 µmol/L, P = 0.003) compared with that at Pre in the exercise condition. Furthermore, 90 min after exercise, the blood non-mercaptoalbumin ratio was significantly increased (+ 0.35 ± 0.71%, P = 0.030) compared to Pre.

CONCLUSION

These results indicate that the plasma Hcy concentration first increased, and then the non-mercaptoalbumin/mercaptoalbumin ratio increased as the elevated state was maintained. This study revealed that 65% heart rate reserve, 40 min of acute exercise increased plasma Hcy concentration and non-mercaptoalbumin ratio.

Creatine supplementation in the pediatric and adolescent athlete-- A literature review

Background

An increase in intra-muscular creatine through supplementation has been proposed as a strategy for improving muscle performance and recovery, with studies showing some benefit for adult athletes who rely on short, explosive movements. We reviewed and summarized the current literature on creatine supplementation in a pediatric and adolescent population.

Methods

The databases PubMed and EMBASE were queried to identity articles related to the use of creatine supplementation in a healthy pediatric and adolescent population according to the guidelines established by PRISMA. The abstracts of all articles were reviewed to determine relevancy, with those meeting the pre-defined criteria included in the final review.

Results

A combined total of 9393 articles were identified. Following application of filters and review of abstracts, 13 articles were found to meet criteria and were included in the final review. There was a total of 268 subjects across all studies, with mean age ranging from 11.5 to 18.2 years. More than 75% of the studies were randomized-controlled trials, and 85% involved either soccer players or swimmers. The overall quality of the studies was poor, and there were no consistent findings regarding creatine supplementation and improvements in athletic performance. No studies were designed to address the topic of safety.

Conclusions

There is a gap in the study of the safety and efficacy of creatine supplementation in adolescents. Additional studies are needed to evaluate the effects of alterations in muscle composition on the growth, development, and performance of the developing athlete. Orthopedic providers should counsel their pediatric and adolescent patients on the current limitations in trying to assess the true risk and benefit of creatine supplementation for the aspiring athlete.

Level of evidence

Review, III.

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.

Dietary supplementation of guanidinoacetic acid improves growth, biochemical parameters, antioxidant capacity and cytokine responses in Nile tilapia (Oreochromis niloticus)

A total of 180 unsexed Nile Tilapia fish (initial weight, 21 g) fed isonitrogenous (32%), isocaloric (3000 kcal/kg) diets containing different levels of guanidinoacetic acid (GAA) at levels of (GAA1, 0.06%, GAA2, 0.12%, GAA3, 0.18%); for 60 days. Results showed higher final body weight (FBW) and body weight gain (BWG) in groups supplemented with different levels of GAA. Specific growth rate (SGR) was the highest in groups supplemented with 0.12% and 0.18% GAA. Lipid % of whole-body composition was higher in all groups excluding GAA3 group. Serum creatine kinase (CK) activity, cholesterol, and creatinine levels showed a marked significant (P < 0.05) increase in all GAA supplemented groups compared to the control one. Triglycerides level demonstrated a higher elevation (P < 0.05) in both GAA2 and GAA3 supplemented groups. No significant observed in total protein, albumin, globulin, and A/G ratio. Lipid peroxidation marker (malondialdehyde/MDA) is markedly decreased along with a significant increase of superoxide dismutase (SOD), reduced glutathione (GSH), and nitric oxide (NO) levels in both GAA2 and GAA3 compared to other groups. Similarly, interleukin 1β (IL-1β) and tumor necrosis factor (TNF-α) gene expression levels were downregulated along with upregulation of transforming growth factor β1 (TGF-β1) at higher GAA levels, particularly at 0.18%. Our findings give important insights for the growth promoting, antioxidant and immunomodulatory effects of GAA supplemented diet particularly at level of 0.18%.

Effects of dietary supplementation with creatine on homocysteinemia and systemic microvascular endothelial function in individuals adhering to vegan diets

The incidence of cardiovascular diseases in vegetarian individuals is lower than that in the general population. Nevertheless, individuals who adhere to vegan diets have a higher prevalence of hyperhomocysteinemia with eventual adverse effects on vascular reactivity. Creatine supplementation (CrS) reduces plasma homocysteine levels and enhances vascular reactivity in the microcirculation. Thus, we investigated the effects of CrS on systemic microcirculation and homocysteine blood levels in strict vegan subjects. Forty-nine strict vegan subjects were allocated to the oral CrS (5 g micronized creatine monohydrate daily for three weeks; n = 31) and placebo (n = 18) groups. Laser speckle contrast imaging coupled with acetylcholine skin iontophoresis was used to evaluate cutaneous microvascular reactivity, and intravital video-microscopy was used to evaluate skin capillary density and reactivity before and after CrS. We demonstrated that CrS reduces the plasma levels of homocysteine and increases those of folic acid. After the CrS period, the homocysteine levels of all of the vegan subjects normalized. CrS also induced increases in baseline skin functional capillary density and endothelium-dependent capillary recruitment in both normo- (N-Hcy) and hyperhomocysteinemic (H-Hcy) individuals. CrS increased endothelium-dependent skin microvascular vasodilation in the H-Hcy vegan subjects but not in the N-Hcy vegan subjects. In conclusion, three weeks of oral CrS was sufficient to increase skin capillary density and recruitment and endothelium-dependent microvascular reactivity. CrS also resulted in plasma increases in folic acid levels and reductions in homocysteine levels among only the H-Hcy individuals.

Rehydration during exercise prevents the increase of homocysteine concentrations

This study aimed to assess the effect of rehydration during and after acute aerobic submaximal exercise on total homocysteine (tHcy) concentrations and related parameters in physically active adult males. Twenty trained males (29.4 ± 7.9 years old) completed four exercise tests: two without rehydration during exercise (NH1 and NH2), one with rehydration during exercise using water (H1) and one with rehydration during exercise using an isotonic sports drink (H2). After finishing the exercise tests, subjects followed a rehydration protocol for 2 h. Serum tHcy, vitamin B12, folate, creatine and creatinine were analysed before, after and at 2, 6 and 24 h after exercise. Data were analysed with and without correcting for haemoconcentration to assess the changes in tHcy related. The methylenetetrahydrofolate reductase (MTHFR) 677TT genotype was also analysed. THcy (uncorrected by haemoconcentration) increased significantly after exercise (P < 0.05) in the NH1 and NH2 tests [mean increase ± SD: 1.55 ± 0.33 (15.18%) and 1.76 ± 0.25 (17.69%) µmol/L, respectively], while no significant differences were found in the H1 and H2 tests [mean increase: 0.65 (6.29%) and 0.90 (8.69%) μmol/L, respectively]. The increase was partly due to haemoconcentration and partly due to the metabolism underlying acute exercise. THcy concentrations recovered to baseline after 24 h in all tests. In conclusion, adequate rehydration during acute aerobic exercise using either water or a sports drink maintains tHcy concentrations at baseline and for up to 2 h after exercise in physically active male adults and prevents further increases when compared to no rehydration.

Creatine Monohydrate and Guanidinoacetic Acid Supplementation Affects the Growth Performance, Meat Quality, and Creatine Metabolism of Finishing Pigs

This study aimed to investigate the effects of creatine monohydrate (CMH) and guanidinoacetic acid (GAA) supplementation on the growth performance, meat quality, and creatine metabolism of finishing pigs. The pigs were randomly allocated to three treatment groups: the control group, CMH group, and GAA group. In comparison to the control group, CMH treatment increased average daily feed intake and GAA treatment increased average daily feed intake and average daily gain of pigs. In addition, CMH and GAA treatment increased pH_45 min, myofibrillar protein solubility, and calpain 1 mRNA expression level and decreased the drip loss and shear force value in longissimus dorsi or semitendinosus muscle. Moreover, CMH and GAA supplementation increased the concentrations of creatine and phosphocreatine and the mRNA expressions of guanidinoacetate N-methyltransferase and creatine transporter in longissimus dorsi muscle, semitendinosus muscle, liver, or kidneys and decreased the mRNA expressions of arginine:glycine amidinotransferase in kidneys. In conclusion, CMH and GAA supplementation could improve the growth performance and meat quality and alter creatine metabolism of finishing pigs.

Acute exercise alters homocysteine plasma concentration in an intensity-dependent manner due increased methyl flux in liver of rats

PURPOSE

We aimed to determine the effects of different intensities of acute exercise on Hcy plasma levels, and the exercise-induced changes in Hcy liver metabolism.

METHOD

First, thirty-two Wistar rats were randomly submitted to an acute bout of swimming exercise carrying a load of 2% (n=8), 4% (n=8) and 6% (n=8) of their total body weight attached in their tail. Control rats remained rested (n=8). Blood samples were taken from tail vein for plasma S-containing amino acids determination before (Rest) and post, 1, 2, 3, 4, 6, and 10h after acute swimming exercise. Second, 56 exercised rats (4% loads) were euthanized before (Rest) and1, 2, 3, 4, 6, and 10h after acute swimming exercise. Blood and liver samples were collected for amino acids and keys genes involved in the Hcy metabolism assay.

RESULTS

Acute exercise increases (P<0.05) plasma Hcy concentration in an intensity-dependent manner (rest 7.7±0.8; 6% load 13.8±3.6; 4% load 12.2±2.9±and 2% load 10.1±2.6, μmol/L); this increase is transient and does not promote hyperhomocysteinemia (<15μmol/L).Exercise-induced increased plasma Hcywas accompanied by the decreased liver S-adenosylmethionine/S-adenosylhomocysteine ratio and elevated MAT1a mRNA content. Acute exercise also caused elevated mRNA of key enzymes of transsulfuration (CBS) and remethylation (BHMT and the MTRR).

CONCLUSION

Our data provided evidence that acute exercise increases plasma Hcy concentration due to the augmented requirement for methylated compounds that increases liver SAM consumption. Also, Hcy remethylation and transsulfuration are coordinately regulated to maintain methyl balance.

The effects of exercise training and acute exercise duration on plasma folate and vitamin B12

BACKGROUND/OBJECTIVES

Energy production and the rebuilding and repair of muscle tissue by physical activity require folate and vitamin B12 as a cofactor. Thus, this study investigated the effects of regular moderate exercise training and durations of acute aerobic exercise on plasma folate and vitamin B12 concentrations in moderate exercise trained rats.

MATERIALS/METHODS

Fifty rats underwent non-exercise training (NT, n = 25) and regular exercise training (ET, n = 25) for 5 weeks. The ET group performed moderate exercise on a treadmill for 30 min/day, 5 days/week. At the end of week 5, each group was subdivided into 4 groups: non-exercise and 3 exercise groups. The non-exercise group (E0) was sacrificed without exercising and the 3 exercise groups were sacrificed immediately after exercising on a treadmill for 0.5 h (E0.5), 1 h (E1), and 2 h (E2). Blood samples were collected and plasma folate and vitamin B12 were analyzed.

RESULTS

After exercise training, plasma folate level was significantly lower and vitamin B12 concentration was significantly higher in the ET group compared with the NT group (P < 0.05). No significant associations were observed between plasma folate and vitamin B12 concentrations. In both the NT and ET groups, plasma folate and vitamin B12 were not significantly changed by increasing duration of aerobic exercise. Plasma folate concentration of E0.5 was significantly lower in the ET group compared with that in the NT group. Significantly higher vitamin B12 concentrations were observed in the E0 and E0.5 groups of the ET group compared to those of the NT group.

CONCLUSION

Regular moderate exercise training decreased plasma folate and increased plasma vitamin B12 levels. However, no significant changes in plasma folate and vitamin B12 concentrations were observed by increasing duration of acute aerobic exercise.

Creatine affords protection against glutamate-induced nitrosative and oxidative stress

Creatine has been reported to exert beneficial effects in several neurodegenerative diseases in which glutamatergic excitotoxicity and oxidative stress play an etiological role. The purpose of this study was to investigate the protective effects of creatine, as compared to the N-Methyl-d-Aspartate (NMDA) receptor antagonist dizocilpine (MK-801), against glutamate or hydrogen peroxide (H2O2)-induced injury in human neuroblastoma SH-SY5Y cells. Exposure of cells to glutamate (60-80 mM) or H2O2 (200-300 μM) for 24 h decreased cellular viability and increased dichlorofluorescein (DCF) fluorescence (indicative of increased reactive oxygen species, ROS) and nitric oxide (NO) production (assessed by mono-nitrogen oxides, NOx, levels). Creatine (1-10 mM) or MK-801 (0.1-10 μM) reduced glutamate- and H2O2-induced toxicity. The protective effect of creatine against glutamate-induced toxicity involves its antioxidant effect, since creatine, similar to MK-801, prevented the increase on DCF fluorescence induced by glutamate or H2O2. Furthermore, creatine or MK-801 blocked glutamate- and H2O2-induced increases in NOx levels. In another set of experiments, the repeated, but not acute, administration of creatine (300 mg/kg, po) in mice prevented the decreases on cellular viability and mitochondrial membrane potential (assessed by tetramethylrhodamine ethyl ester, TMRE, probe) of hippocampal slices incubated with glutamate (10 mM). Creatine concentration-dependent decreased the amount of nitrite formed in the reaction of oxygen with NO produced from sodium nitroprusside solution, suggesting that its protective effect against glutamate or H2O2-induced toxicity might be due to its scavenger activity. Overall, the results suggest that creatine may be useful as adjuvant therapy for neurodegenerative disease treatments.

Low-Dose Creatine Supplementation Lowers Plasma Guanidinoacetate, but Not Plasma Homocysteine, in a Double-Blind, Randomized, Placebo-Controlled Trial

BACKGROUND

Creatine synthesis from guanidinoacetate consumes ~50% of s-adenosylmethionine (SAM)-derived methyl groups, accounting for an equivalent proportion of s-adenosylhomocysteine (SAH) and total homocysteine (tHcys) synthesis. Dietary creatine inhibits the synthesis of guanidinoacetate, thereby lowering plasma tHcys in rats.

OBJECTIVE

We tested the hypotheses that creatine supplementation lowers plasma guanidinoacetate, increases blood SAM, lowers blood SAH, and lowers plasma tHcys.

METHODS

Bangladeshi adults were randomly assigned to receive 1 of 4 treatments for 12 wk: placebo (n = 101), 3 g/d creatine (Cr; n = 101), 400 μg/d folic acid (FA; n = 153), or 3 g/d creatine plus 400 μg/d folic acid (Cr+FA; n = 103). The outcomes of plasma guanidinoacetate and tHcys, as well as whole blood SAM and SAH, were analyzed at baseline and week 12 by HPLC. Treatment effects of creatine supplementation were examined with the use of the group comparisons of Cr vs. placebo and Cr+FA vs. FA.

RESULTS

Plasma guanidinoacetate declined by 10.6% (95% CI: 4.9, 15.9) in the Cr group while increasing nonsignificantly in the placebo group (3.7%; 95% CI: -0.8, 8.5) (Pgroup difference = 0.0002). Similarly, plasma guanidinoacetate declined by 9.0% (95% CI: 3.4, 14.2) in the Cr+FA group while increasing in the FA group (7.0%; 95% CI: 2.0, 12.2) (Pgroup difference < 0.0001). Plasma tHcys declined by 23.4% (95% CI: 19.5, 27.1) and 21.0% (95% CI: 16.4, 25.2) in the FA and Cr+FA groups, respectively (Pgroup difference = 0.41), with no significant changes in the placebo or Cr groups (Pgroup difference = 0.35). A decrease in guanidinoacetate over time was associated with a decrease in tHcys over time in the Cr+FA group (β = 0.30; 95% CI: 0.17, 0.43; P < 0.0001).

CONCLUSIONS

Our findings indicate that whereas creatine supplementation downregulates endogenous creatine synthesis, this may not on average lower plasma tHcys in humans. However, tHcys did decrease in those participants who experienced a decline in plasma guanidinoacetate while receiving creatine plus folic acid supplementation. This trial was registered at clinicaltrials.gov as NCT01050556.

Effects of dietary creatine supplementation on systemic microvascular density and reactivity in healthy young adults

Background

Dietary creatine supplementation (CrS) is a practice commonly adopted by physically active individuals. However, the effects of CrS on systemic microvascular reactivity and density have never been reported. Additionally, CrS is able to influence blood levels of homocysteine, resulting in presumed effects on vascular endothelial function. Thus, we investigated the effects of CrS on the systemic microcirculation and on homocysteine levels in healthy young individuals.

Methods

This open-label study was performed on a group of 40 healthy male, moderately physically active subjects aged 27.7 ± 13.4 years who received one week of CrS at a dose of 20 g/day of commercially available micronized creatine monohydrate. Laser speckle contrast imaging was used in the evaluation of cutaneous microvascular reactivity, and intra-vital video microscopy was used to evaluate skin capillary density and reactivity, before and after CrS.

Results

CrS did not alter plasma levels of homocysteine, although CrS increased creatinine (p = 0.0001) and decreased uric acid (p = 0.0004) plasma levels. Significant changes in total cholesterol (p = 0.0486) and LDL-cholesterol (p = 0.0027) were also observed along with a reduction in plasma levels of T3 (p = 0.0074) and an increase in T4 levels (p = 0.0003). Skin functional capillary density (p = 0.0496) and capillary recruitment during post-occlusive reactive hyperemia (p = 0.0043) increased after CrS. Increases in cutaneous microvascular vasodilation induced by post-occlusive reactive hyperemia (p = 0.0078) were also observed.

Conclusions

Oral supplementation with creatine in healthy, moderately physically active young adults improves systemic endothelial-dependent microvascular reactivity and increases skin capillary density and recruitment. These effects are not concurrent with changes in plasma homocysteine levels.