Effects of curcumin supplementation on exercise-induced oxidative stress in humans

Curcumin analog WZ26 induces ROS and cell death via inhibition of STAT3 in cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive biliary epithelial tumor with limited therapeutic options and poor prognosis. Curcumin is a promising active natural compound with several anti-cancer properties, though its clinical uses remain hindered due to its poor bioavailability. We recently synthesized curcumin analogs with multifunctional pharmacological and bioactivities with enhanced bioavailability. Among these novel curcumin analogs, WZ26 is a representative molecule. However, the anti-tumor effect of WZ26 against CCA is unclear. In this study, we evaluated the anti-tumor effect of WZ26 in both CCA cells and CCA xenograft mouse model. The underlying molecular anti-cancer mechanism of WZ26 was also studied. Our results show that WZ26 significantly inhibited cell growth and induced mitochondrial apoptosis in CCA cell lines, leading to significant inhibition of tumor growth in xenograft tumor mouse model. Treatment of WZ26 increased reactive oxygen species (ROS) generation, subsequently decreased mitochondrial membrane potential and inhibited the phosphorylation of signal transducer and activator of transcription 3 (STAT3), thereby inducing G2/M cell cycle arrest and cell apoptosis. Pretreatment of N-acetyl cysteine (NAC), an antioxidant agent, could fully reverse the WZ26-induced ROS-mediated changes in CCA cells. Our findings provide experimental evidence that curcumin analog WZ26 could be a potential candidate against CCA via enhancing ROS induction and inhibition of STAT3 activation.

Role of Turmeric and Curcumin in Prevention and Treatment of Chronic Diseases: Lessons Learned from Clinical Trials

Turmeric (Curcuma longa) has been used for thousands of years for the prevention and treatment of various chronic diseases. Curcumin is just one of >200 ingredients in turmeric. Almost 7000 scientific papers on turmeric and almost 20,000 on curcumin have been published in PubMed. Scientific reports based on cell culture or animal studies are often not reproducible in humans. Therefore, human clinical trials are the best indicators for the prevention and treatment of a disease using a given agent/drug. Herein, we conducted an extensive literature survey on PubMed and Scopus following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The keywords "turmeric and clinical trials" and "curcumin and clinical trials" were considered for data mining. A total of 148 references were found to be relevant for the key term "turmeric and clinical trials", of which 70 were common in both PubMed and Scopus, 44 were unique to PubMed, and 34 were unique to Scopus. Similarly, for the search term "curcumin and clinical trials", 440 references were found to be relevant, of which 70 were unique to PubMed, 110 were unique to Scopus, and 260 were common to both databases. These studies show that the golden spice has enormous health and medicinal benefits for humans. This Review will extract and summarize the lessons learned about turmeric and curcumin in the prevention and treatment of chronic diseases based on clinical trials.

Curcumin Formulations for Better Bioavailability: What We Learned from Clinical Trials Thus Far?

Curcumin has been credited with a wide spectrum of pharmacological properties for the prevention and treatment of several chronic diseases such as arthritis, autoimmune diseases, cancer, cardiovascular diseases, diabetes, hemoglobinopathies, hypertension, infectious diseases, inflammation, metabolic syndrome, neurological diseases, obesity, and skin diseases. However, due to its weak solubility and bioavailability, it has limited potential as an oral medication. Numerous factors including low water solubility, poor intestinal permeability, instability at alkaline pH, and fast metabolism contribute to curcumin's limited oral bioavailability. In order to improve its oral bioavailability, different formulation techniques such as coadministration with piperine, incorporation into micelles, micro/nanoemulsions, nanoparticles, liposomes, solid dispersions, spray drying, and noncovalent complex formation with galactomannosides have been investigated with in vitro cell culture models, in vivo animal models, and humans. In the current study, we extensively reviewed clinical trials on various generations of curcumin formulations and their safety and efficacy in the treatment of many diseases. We also summarized the dose, duration, and mechanism of action of these formulations. We have also critically reviewed the advantages and limitations of each of these formulations compared to various placebo and/or available standard care therapies for these ailments. The highlighted integrative concept embodied in the development of next-generation formulations helps to minimize bioavailability and safety issues with least or no adverse side effects and the provisional new dimensions presented in this direction may add value in the prevention and cure of complex chronic diseases.

12-week curcumin supplementation may relieve postexercise muscle fatigue in adolescent athletes

Introduction

High-intensity exercise causes oxidative stress, muscle soreness, and muscle fatigue, leading to reduced exercise performance. Curcumin possesses antioxidative and anti-inflammatory properties and thus alleviates postexercise damage. Therefore, this study evaluated the effect of curcumin on athletes' postexercise recovery.

Methods

A non-randomized prospective cohort investigation was done. We recruited middle and high school athletes engaged in wrestling, soccer, and soft tennis. During the 12-week daily exercise training, the participants were assigned to receive curcumin supplementation (curcumin group) or not (control group). Body composition, exercise performance, inflammatory factors, muscle fatigue, and muscle soreness were recorded at the baseline and end of the study. We used the Mann-Whitney U test to compare the participants' demographics, such as age, height, weight, and training years. The Wilcoxon test was used to compare the differences between the groups before and after curcumin supplementation.

Results

Of 28 participants (21 men and 7 women, with a mean age of 17 years), 13 were in the curcumin group and 15 in the control group. A significant decrease in muscle fatigue and muscle soreness scores was observed in the curcumin group after 12 weeks. Moreover, a significant decrease in the 8-hydroxy-2 deoxyguanosine level and a significant increase in basic metabolic rate and fat-free mass were observed in the curcumin group.

Conclusion

Curcumin can reduce muscle fatigue and soreness after exercise, indicating its potential to alleviate postexercise damage. It could be considered to cooperate with nutritional supplements in regular training in adolescent athletes.

Effect of curcumin supplementation on exercise-induced muscle damage: a narrative review

Curcumin, a natural polyphenol extracted from turmeric, is a potent antioxidant and anti-inflammatory agent. In the past few decades, curcumin's ability to impact chronic inflammatory conditions such as metabolic syndrome, arthritis, and cancer has been widely researched, along with growing interest in understanding its role in exercise-induced muscle damage (EIMD). EIMD impacts individuals differently depending on the type (resistance exercise, high-intensity interval training, and running), intensity, and duration of the exercise. Exercise disrupts the muscles' ultrastructure, raises inflammatory cytokine levels, and can cause swelling in the affected limb, a reduction in range of motion (ROM), and a reduction in muscular force-producing capacity. This review focuses on the metabolism, pharmacokinetics of various brands of curcumin supplements, and the effect of curcumin supplementation on EIMD regarding muscle soreness, activity of creatine kinase (CK), and production of inflammatory markers. Curcumin supplementation in the dose range of 90-5000 mg/day can decrease the subjective perception of muscle pain intensity, increase antioxidant capacity, and reduce CK activity, which reduces muscle damage when consumed close to exercise. Consumption of curcumin also improves muscle performance and has an anti-inflammatory effect, downregulating the production of pro-inflammatory cytokines, including TNF-α, IL-6, and IL-8. Curcumin may also improve oxidative capacity without hampering training adaptations in untrained and recreationally active individuals. The optimal curcumin dose to ameliorate EIMD is challenging to assess as its effect depends on the curcumin concentration in the supplement and its bioavailability.

Nutritional Compounds to Improve Post-Exercise Recovery

The metabolic and mechanical stresses associated with muscle-fatiguing exercise result in perturbations to bodily tissues that lead to exercise-induced muscle damage (EIMD), a state of fatigue involving oxidative stress and inflammation that is accompanied by muscle weakness, pain and a reduced ability to perform subsequent training sessions or competitions. This review collates evidence from previous research on a wide range of nutritional compounds that have the potential to speed up post-exercise recovery. We show that of the numerous compounds investigated thus far, only two-tart cherry and omega-3 fatty acids-are supported by substantial research evidence. Further studies are required to clarify the potential effects of other compounds presented here, many of which have been used since ancient times to treat conditions associated with inflammation and disease.

Sirtuins in atherosclerosis: guardians of healthspan and therapeutic targets

Sirtuins are NAD⁺-dependent deacetylase and deacylase enzymes that control important cellular processes, including DNA damage repair, cellular metabolism, mitochondrial function and inflammation. Consequently, mammalian sirtuins are regarded as crucial regulators of cellular function and organism healthspan. Sirtuin activity and NAD⁺ levels decrease with age in many tissues, and reduced sirtuin expression is associated with several cardiovascular diseases. By contrast, increased sirtuin expression and activity slows disease progression and improves cardiovascular function in preclinical models and delays various features of cellular ageing. The potential cardiometabolic benefits of sirtuins have resulted in clinical trials with sirtuin-modulating agents; although expectations are high, these drugs have not yet been proven to improve healthspan. In this Review, we examine the role of sirtuins in atherosclerosis, summarize advances in the development of compounds that activate or inhibit sirtuin activity and critically evaluate the therapeutic potential of these agents.

The potential of Curcuma extract to alleviate muscle damage in amateur soccer players

Compounds with high bioactive are commonly used as a nutritional approach for accelerating muscle damage recovery after strenuous exercise. There are still inconsistent results of post-exercise antioxidant supplementation on the circulating muscle damage biomarker. This study aimed to examine the effect of post-exercise Curcuma extract supplementation in ice cream on muscle damage and inflammatory markers in amateur soccer players. Male amateur soccer athletes (aged 14 – 18 years) participated in a randomized double-blind placebo-controlled study under two conditions: control group (n = 10) and treatment group (n = 10). The treatment group was treated with Curcuma extract ice cream (250 mg/100 g) for 21 days. Blood samples were drawn before training, considered baseline, and 3 h after training on day 21. The level of creatine kinase, IL-6, haemoglobin (Hb), and lactic acid were quantified. There was a significant decrease in creatine kinase change in the treatment group compared to the control group (p <0.05). No change in IL-6 and Hb levels in the treatment group. Lactic acid decreased by 16.3% from baseline in the treatment group (p <0.05). Curcuma extract ice cream potentiates to ameliorate exercise-induced muscle damage.

Effects of Functional Phenolics Dietary Supplementation on Athletes' Performance and Recovery: A Review

In recent years, many efforts have been made to identify micronutrients or nutritional strategies capable of preventing, or at least, attenuating, exercise-induced muscle damage and oxidative stress, and improving athlete performance. The reason is that most exercises induce various changes in mitochondria and cellular cytosol that lead to the generation of reactive species and free radicals whose accumulation can be harmful to human health. Among them, supplementation with phenolic compounds seems to be a promising approach since their chemical structure, composed of catechol, pyrogallol, and methoxy groups, gives them remarkable health-promoting properties, such as the ability to suppress inflammatory processes, counteract oxidative damage, boost the immune system, and thus, reduce muscle soreness and accelerate recovery. Phenolic compounds have also already been shown to be effective in improving temporal performance and reducing psychological stress and fatigue. Therefore, the aim of this review is to summarize and discuss the current knowledge on the effects of dietary phenolics on physical performance and recovery in athletes and sports practitioners. Overall, the reports show that phenolics exert important benefits on exercise-induced muscle damage as well as play a biological/physiological role in improving physical performance.

Triplet-Energy Quenching Functions of Antioxidant Molecules

UV-like DNA damage is created in the dark by chemiexcitation, in which UV-activated enzymes generate reactive oxygen and nitrogen species that create a dioxetane on melanin. Thermal cleavage creates an electronically excited triplet-state carbonyl whose high energy transfers to DNA. Screening natural compounds for the ability to quench this energy identified polyenes, polyphenols, mycosporine-like amino acids, and related compounds better known as antioxidants. To eliminate false positives such as ROS and RNS scavengers, we then used the generator of triplet-state acetone, tetramethyl-1,2-dioxetane (TMD), to excite the triplet-energy reporter 9,10-dibromoanthracene-2-sulfonate (DBAS). Quenching measured as reduction in DBAS luminescence revealed three clusters of 50% inhibitory concentration, ~50 μM, 200–500 μM, and >600 μM, with the former including sorbate, ferulic acid, and resveratrol. Representative triplet-state quenchers prevented chemiexcitation-induced “dark” cyclobutane pyrimidine dimers (dCPD) in DNA and in UVA-irradiated melanocytes. We conclude that (i) the delocalized pi electron cloud that stabilizes the electron-donating activity of many common antioxidants allows the same molecule to prevent an electronically excited species from transferring its triplet-state energy to targets such as DNA and (ii) the most effective class of triplet-state quenchers appear to operate by energy diversion instead of electron donation and dissipate that energy by isomerization.

Curcumin: The Golden Nutraceutical on the Road to Cancer Prevention and Therapeutics. A Clinical Perspective

Cancer is considered as the major public health scourge of the 21st century. Although remarkable strides were made for developing targeted therapeutics, these therapies suffer from lack of efficacy, high cost, and debilitating side effects. Therefore, the search for safe, highly efficacious, and affordable therapies is paramount for establishing a treatment regimen for this deadly disease. Curcumin, a known natural, bioactive, polyphenol compound from the spice turmeric (Curcuma longa), has been well documented for its wide range of pharmacological and biological activities. A plethora of literature indicates its potency as an anti-inflammatory and anti-cancer agent. Curcumin exhibits anti-neoplastic attributes via regulating a wide array of biological cascades involved in mutagenesis, proliferation, apoptosis, oncogene expression, tumorigenesis, and metastasis. Curcumin has shown a wide range of pleiotropic anti-proliferative effect in multiple cancers and is a known inhibitor of varied oncogenic elements, including nuclear factor kappa B (NF-κB), c-myc, cyclin D1, Bcl-2, VEGF, COX-2, NOS, tumor necrosis factor alpha (TNF-α), interleukins, and MMP-9. Further, curcumin targets different growth factor receptors and cell adhesion molecules involved in tumor growth and progression, making it a most promising nutraceutical for cancer therapy. To date, curcumin-based therapeutics have completed more than 50 clinical trials for cancer. Although creative experimentation is still elucidating the immense potential of curcumin, systematic validation by proper randomized clinical trials warrant its transition from lab to bedside. Therefore, this review summarizes the outcome of diverse clinical trials of curcumin in various cancer types.

Dietary Supplementation for Attenuating Exercise-Induced Muscle Damage and Delayed-Onset Muscle Soreness in Humans

Dietary supplements are widely used as a nutritional strategy to improve and maintain performance and achieve faster recovery in sports and exercise. Exercise-induced muscle damage (EIMD) is caused by mechanical stress and subsequent inflammatory responses including reactive oxygen species and cytokine production. Therefore, dietary supplements with anti-inflammatory and antioxidant properties have the potential to prevent and reduce muscle damage and symptoms characterized by loss of muscle strength and delayed-onset muscle soreness (DOMS). However, only a few supplements are considered to be effective at present. This review focuses on the effects of dietary supplements derived from phytochemicals and listed in the International Olympic Committee consensus statement on muscle damage evaluated by blood myofiber damage markers, muscle soreness, performance, and inflammatory and oxidative stress markers. In this review, the effects of dietary supplements are also discussed in terms of study design (i.e., parallel and crossover studies), exercise model, and such subject characteristics as physical fitness level. Future perspectives and considerations for the use of dietary supplements to alleviate EIMD and DOMS are also discussed.

Recent Progress in Applicability of Exercise Immunology and Inflammation Research to Sports Nutrition

This article focuses on how nutrition may help prevent and/or assist with recovery from the harmful effects of strenuous acute exercise and physical training (decreased immunity, organ injury, inflammation, oxidative stress, and fatigue), with a focus on nutritional supplements. First, the effects of ketogenic diets on metabolism and inflammation are considered. Second, the effects of various supplements on immune function are discussed, including antioxidant defense modulators (vitamin C, sulforaphane, taheebo), and inflammation reducers (colostrum and hyperimmunized milk). Third, how 3-hydroxy-3-methyl butyrate monohydrate (HMB) may offset muscle damage is reviewed. Fourth and finally, the relationship between exercise, nutrition and COVID-19 infection is briefly mentioned. While additional verification of the safety and efficacy of these supplements is still necessary, current evidence suggests that these supplements have potential applications for health promotion and disease prevention among athletes and more diverse populations.

Current clinical developments in curcumin-based therapeutics for cancer and chronic diseases

The last decade has seen an unprecedented rise in the prevalence of chronic diseases worldwide. Different mono-targeted approaches have been devised to treat these multigenic diseases, still most of them suffer from limited success due to the off-target debilitating side effects and their inability to target multiple pathways. Hence a safe, efficacious, and multi-targeted approach is the need for the hour to circumvent these challenging chronic diseases. Curcumin, a natural compound extracted from the rhizomes of Curcuma longa, has been under intense scrutiny for its wide medicinal and biological properties. Curcumin is known to manifest antibacterial, antiinflammatory, antioxidant, antifungal, antineoplastic, antifungal, and proapoptotic effects. A plethora of literature has already established the immense promise of curcuminoids in the treatment and clinical management of various chronic diseases like cancer, cardiovascular, metabolic, neurological, inflammatory, and infectious diseases. To date, more than 230 clinical trials have opened investigations to understand the pharmacological aspects of curcumin in human systems. Still, further randomized clinical studies in different ethnic populations warrant its transition to a marketed drug. This review summarizes the results from different clinical trials of curcumin-based therapeutics in the prevention and treatment of various chronic diseases.

Nutritional considerations to counteract gastrointestinal permeability during exertional heat stress

Intestinal barrier integrity and function are compromised during exertional heat stress (EHS) potentially leading to consequences that range from minor gastrointestinal (GI) disturbances to fatal outcomes in exertional heat stroke or septic shock. This mini-review provides a concise discussion of nutritional interventions that may protect against intestinal permeability during EHS and suggests physiological mechanisms responsible for this protection. Although diverse nutritional interventions have been suggested to be protective against EHS-induced GI permeability, the ingestion of certain amino acids, carbohydrates, and fluid per se is potentially effective strategy, whereas evidence for various polyphenols and pre/probiotics is developing. Plausible physiological mechanisms of protection include increased blood flow, epithelial cell proliferation, upregulation of intracellular heat shock proteins, modulation of inflammatory signaling, alteration of the GI microbiota, and increased expression of tight junction (TJ) proteins. Further clinical research is needed to propose specific nutritional candidates and recommendations for their application to prevent intestinal barrier disruption and elucidate mechanisms during EHS.

Whether or Not the Effects of Curcuma longa Supplementation Are Associated with Physical Exercises in T1DM and T2DM: A Systematic Review

Diabetes mellitus is one of the most prevalent chronic diseases in the world; one of its main characteristics is chronic hyperglycemia. Pharmacotherapy and other alternatives such as regular exercise are among the therapeutic methods used to control this pathology and participate in glycemic control, as well as the ingestion of plant extracts with antioxidant effects. Among the different plants used for this purpose, curcumin has potential to be used to attenuate the hyperglycemic condition triggered by diabetes mellitus (DM). Some prior studies suggest that this plant has antioxidant and hypoglycemic potential. This review aims to evaluate the antioxidant and hypoglycemic potential of curcumin supplementation in Type 1 DM (T1DM) and Type 2 DM (T2DM). The search considered articles published between 2010 and 2019 in English and Portuguese, and a theoretical survey of relevant information was conducted in the main databases of scientific publications, including the Virtual Health Library and its indexed databases, PubMed, LILACS (Latin American and Caribbean Literature on Health Sciences-Health Information for Latin America and the Caribbean-BIREME/PAHO/WHO), and Scientific Electronic Library Online (SciELO). The associated use of turmeric and physical exercise has demonstrated antioxidant, anti-inflammatory, and hypoglycemic effects, suggesting that these could be used as potential therapeutic methods to improve the quality of life and survival of diabetic patients.

The regulatory role of dietary factors in skeletal muscle development, regeneration and function

Skeletal muscle plays a crucial role in motor function, respiration, and whole-body energy homeostasis. How to regulate the development and function of skeletal muscle has become a hot research topic for improving lifestyle and extending life span. Numerous transcription factors and nutritional factors have been clarified are closely associated with the regulation of skeletal muscle development, regeneration and function. In this article, the roles of different dietary factors including green tea, quercetin, curcumin (CUR), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and resveratrol (RES) in regulating skeletal muscle development, muscle mass, muscle function, and muscle recovery have been summarized and discussed. We also reviewed the potential regulatory molecular mechanism of these factors. Based on the current findings, dietary factors may be used as a potential therapeutic agent to treat skeletal muscle dysfunction as well as its related diseases.

Characterization and Modulation of Systemic Inflammatory Response to Exhaustive Exercise in Relation to Oxidative Stress

Exhaustive exercise induces systemic inflammatory responses, which are associated with exercise-induced tissue/organ damage, but the sources and triggers are not fully understood. Herein, the basics of inflammatory mediator cytokines and research findings on the effects of exercise on systemic inflammation are introduced. Subsequently, the association between inflammatory responses and tissue damage is examined in exercised and overloaded skeletal muscle and other internal organs. Furthermore, an overview of the interactions between oxidative stress and inflammatory mediator cytokines is provided. Particularly, the transcriptional regulation of redox signaling and pro-inflammatory cytokines is described, as the activation of the master regulatory factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is involved directly or indirectly in controlling pro-inflammatory genes and antioxidant enzymes expression, whilst nuclear factor-kappa B (NF-κB) regulates the pro-inflammatory gene expression. Additionally, preventive countermeasures against the pathogenesis along with the possibility of interventions such as direct and indirect antioxidants and anti-inflammatory agents are described. The aim of this review is to give an overview of studies on the systematic inflammatory responses to exercise, including our own group as well as others. Moreover, the challenges and future directions in understanding the role of exercise and functional foods in relation to inflammation and oxidative stress are discussed.

Deciphering the Role of Polyphenols in Sports Performance: From Nutritional Genomics to the Gut Microbiota toward Phytonutritional Epigenomics

The individual response to nutrients and non-nutrient molecules can be largely affected by three important biological layers. The gut microbiome can alter the bioavailability of nutrients and other substances, the genome can influence molecule kinetics and dynamics, while the epigenome can modulate or amplify the properties of the genome. Today the use of omic techniques and bioinformatics, allow the construction of individual multilayer networks and thus the identification of personalized strategies that have recently been considered in all medical fields, including sports medicine. The composition of each athlete’s microbiome influences sports performance both directly by acting on energy metabolism and indirectly through the modulation of nutrient or non-nutrient molecule availability that ultimately affects the individual epigenome and the genome. Among non-nutrient molecules polyphenols can potentiate physical performances through different epigenetic mechanisms. Polyphenols interact with the gut microbiota, undergoing extensive metabolism to produce bioactive molecules, which act on transcription factors involved in mitochondrial biogenesis, antioxidant systems, glucose and lipid homeostasis, and DNA repair. This review focuses on polyphenols effects in sports performance considering the individual microbiota, epigenomic asset, and the genomic characteristics of athletes to understand how their supplementation could potentially help to modulate muscle inflammation and improve recovery.

Influence of curcumin on performance and post-exercise recovery

Intense exercise, especially involving eccentric contractions, causes muscle damage concomitant with increased reactive oxygen species (ROS), which can lead to increased fatigue and decrements in physical performance. Additionally, inflammatory cytokines and advanced glycation end-products (AGEs) are produced as a result of eccentric exercise and may further lead to decreased exercise performance. Nutritional interventions may provide an avenue to respond to and reduce the symptoms associated with muscle damage. Of recent interest, curcumin, the main constituent in the spice turmeric, has been the focus of various studies considering post-exercise recovery. Curcumin has potent anti-oxidant and anti-inflammatory properties and can reduce the accumulation of AGEs. This review considers the current evidence for curcumin to impact muscle recovery following exercise to improve performance and the potential mechanisms of action. To date, clinical studies have considered the potential role of curcumin to reduce muscular damage following treadmill running (downhill and flat), conventional walking/running, cycling (acute and chronic), single-leg jumping (downhill), and eccentric muscular fitness exercises of the upper and lower body (single- and double-leg). Studies have been conducted in sedentary to highly active men and women, both young and old, with supplementation duration lasting from a single, acute dose to daily dosages for three months. Various curcumin-based interventions have improved self-perceived measures of pain and tenderness, reduced evidence of muscle damage, ameliorated inflammatory markers, increased markers of antioxidant capacity, diminished markers of oxidative stress, reduced markers of AGEs, and attenuated loss in mean power of single-leg sprints. However, these findings have not been consistently reported.

Effects of curcumin supplementation on sport and physical exercise: a systematic review

Curcumin is the main phenolic compound in turmeric. It has been investigated recently due to its numerous medicinal properties and health benefits. However, few studies assessed the effects of curcumin supplementation on physical activity practice. Therefore, the purpose of this review is to assess the available evidences with human beings about the potential effects of curcumin supplementation on sport and physical exercise. This systematic review was conducted within the period from January to February, 2019, following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) guidelines. The LILACS, Medline, SciELO and PubMed databases were used for the search, with no publication date limit. The following terms, with the respective Boolean operators, were searched: "curcumin" AND sports; "curcumin" AND exercise; curcumin AND "aerobic exercise"; "curcumin" AND "resistance exercise"; "curcumin" AND "endurance exercise"; "curcumin" AND "strength exercise". Eleven papers were selected for this review. Most of the studies displayed positive effects of the curcumin supplementation for athletes and physical exercise practitioners, and no side effects were reported. Participants supplemented with curcumin displayed reduced inflammation and oxidative stress, decreased pain and muscle damage, superior recovery and muscle performance, better psychological and physiological responses (thermal and cardiovascular) during training and improved gastrointestinal function. Curcumin supplementation appears to be safe and beneficial for sport and physical exercise in human beings. PROSPERO (CRD42019126763).

Curcumin reduces malondialdehyde and improves antioxidants in humans with diseased conditions: a comprehensive meta-analysis of randomized controlled trials

Objective: This systematic review and meta-analysis was conducted to collate the effects of curcumin on MDA and antioxidant markers in individuals with diseased conditions. In this study the research question was “does curcumin supplementation improves oxidative stress and antioxidant defense enzymes in human subjects compared to a group without curcumin supplementation?

Methods: This research included randomized controlled trials published in English in any year, in which intervention with curcumin was compared to either placebo, or standard of care or no intervention. Pubmed, Embase, Cochrane Central, Scopus and Google Scholar were searched. Meta-analysis was performed using RevMan (version 5.3), with standardized mean differences (SMD) and random-effects models.

Results: One hundred twenty-seven titles and abstracts were identified which 17 articles were included for final analysis. The number of participants ranged from 22 to 160 across the included studies. The duration of intervention, dose of curcumin and location of outcomes measurements varied across the studies. Curcumin significantly reduced MDA [SMD −0.46 (95% CI: −0.68 to −0.25)] and increased superoxide dismutase (SOD) [0.82 (0.27 to 1.38)], catalase [10.26 (0.92 to 19.61)], and glutathione peroxidase [8.90 (6.62 to 11.19)] when compared with control group. Subgroup analyses displayed that curcumin could significantly reduce MDA levels with or without use of piperine, however it could increase SOD level in presence of piperine.

Conclusions: These findings suggest that curcumin may be used as an adjunct therapy in individuals with oxidative stress. The administration of piperine with curcumin may enhance the efficacy of curcumin on antioxidant defense system.

Curcumin, Gut Microbiota, and Neuroprotection

Curcumin, a nontoxic, naturally occurring polyphenol, has been recently proposed for the management of neurodegenerative and neurological diseases. However, a discrepancy exists between the well-documented pharmacological activities that curcumin seems to possess in vivo and its poor aqueous solubility, bioavailability, and pharmacokinetic profiles that should limit any therapeutic effect. Thus, it is possible that curcumin could exert direct regulative effects primarily in the gastrointestinal tract, where high concentrations of curcumin are present after oral administration. Indeed, a new working hypothesis that could explain the neuroprotective role of curcumin despite its limited availability is that curcumin acts indirectly on the central nervous system by influencing the “microbiota–gut–brain axis”, a complex bidirectional system in which the microbiome and its composition represent a factor which preserves and determines brain “health”. Interestingly, curcumin and its metabolites might provide benefit by restoring dysbiosis of gut microbiome. Conversely, curcumin is subject to bacterial enzymatic modifications, forming pharmacologically more active metabolites than curcumin. These mutual interactions allow to keep proper individual physiologic functions and play a key role in neuroprotection.

Curcumin supplementation attenuates the decrease in endothelial function following eccentric exercise

[Purpose]

Eccentric exercise induces a decrease in vascular endothelial function. Curcumin, a major component of turmeric, has potent antioxidant and anti-inflammatory properties that are associated with vascular protective effects. The present study examined the effect of acute supplementation of curcumin on eccentric exercise-induced endothelial dysfunction in healthy young men.

[Methods]

Fourteen healthy sedentary young men (range, 21–29 years) were assigned to either the curcumin (n = 6) or placebo (n = 8) group. All subjects consumed either curcumin or placebo before exercise, and eccentric exercise of the elbow flexors was performed with their nondominant arm. Before and 60 min after exercise, brachial artery flow-mediated dilation (FMD), as an indicator of endothelial function, was measured in the non-exercised arm.

[Results]

Brachial artery FMD significantly decreased following eccentric exercise (p < 0.05) in the placebo group, but acute supplementation with curcumin before exercise nullified this change. The change in FMD before and after eccentric exercise between the placebo and curcumin groups was significantly different (p < 0.05).

[Conclusion]

The present study found that acute curcumin supplementation could attenuate the decrease in endothelial function, as measured by FMD, following eccentric exercise in healthy young men.

Chronic Inflammation as an Immunological Abnormality and Effectiveness of Exercise

Reduced levels of physical activity in people’s daily lives cause the development of metabolic syndromes or age-related disorders. Chronic inflammation is now understood to be an underlying pathological condition in which inflammatory cells such as neutrophils and monocyte/macrophages infiltrate into fat and other tissues and accumulate when people become obese due to overeating and/or physical inactivity. Pro-inflammatory mediators such as cytokines that are secreted in excess from inflammatory cells will not only lead to the development of arteriosclerosis when they chronically affect blood vessels but also bring tissue degeneration and/or dysfunction to various organs. Chronic inflammation is also involved in sarcopenia that brings hypofunction in the elderly, dementia, osteoporosis, or cancer and negatively affects many chronic diseases and people’s healthy life expectancy. In this paper, outlines of such studies are introduced in terms of homeostatic inflammation, which occurs chronically due to the innate immune system and its abnormalities, while focusing on the efficacy of exercise from aspects of immunology and oxidative stress. The preventative effects of functional food ingredients in combination with exercise are also introduced and described. The challenges and future directions in understanding the role of exercise in the control of chronic inflammation are discussed.

Nanobubbles Water Curcumin Extract Reduces Injury Risks on Drop Jumps in Women: A Pilot Study

Purpose

To verify the beneficial effects of Nanobubbles water curcumin extract (NCE) supplementation on health promotion and to demonstrate the application of NCE in reducing the risk of musculoskeletal injury.

Methods

In the current study, 12 females were randomly assigned to NCE (15g/day) and maltodextrin groups. Performance and related body composition were evaluated at 2 time points—presupplementation (pre-) and after 4 weeks of postsupplementation (post-). The posttest consists of a set of biochemical parameters for antifatigue activity and injury status evaluation.

Results

NCE group exhibited significantly lower levels of alanine aminotransferase (ALT), alkaline phosphatase (ALP), triglycerides (TG), and higher high-density lipoprotein (HDL) after a 4-week supplementation, compared with the placebo group. After a 15-minute session on the spinning bike, serum lactate and ammonia levels were decreased and glucose was economized in the NEC group. 4-week-NCE supplementation was also able to reduce the peak vertical ground reaction force (PVGRF) during drop jump. Therefore, the risk of musculoskeletal system in lower extremity could be reduced.

Conclusion

We demonstrate that 4-week-NCE supplementation can also be used in explosiveness exercise for better physiological adaptation. Thus, NCE has potential for use with nutrient supplements toward a variety of benefits for athletics.

Effects of Prolonged Dietary Curcumin Exposure on Skeletal Muscle Biochemical and Functional Responses of Aged Male Rats

Oxidative stress resulting from decreased antioxidant protection and increased reactive oxygen and nitrogen species (RONS) production may contribute to muscle mass loss and dysfunction during aging. Curcumin is a phenolic compound shown to upregulate antioxidant defenses and directly quench RONS in vivo. This study determined the impact of prolonged dietary curcumin exposure on muscle mass and function of aged rats. Thirty-two-month-old male F344xBN rats were provided a diet with or without 0.2% curcumin for 4 months. The groups included: ad libitum control (CON; n = 18); 0.2% curcumin (CUR; n = 18); and pair-fed (PAIR; n = 18) rats. CUR rats showed lower food intake compared to CON, making PAIR a suitable comparison group. CUR rats displayed larger plantaris mass and force production (vs. PAIR). Nuclear fraction levels of nuclear factor erythroid-2 related-factor-2 were greater, and oxidative macromolecule damage was lower in CUR (vs. PAIR). There were no significant differences in measures of antioxidant status between any of the groups. No difference in any measure was observed between CUR and CON rats. Thus, consumption of curcumin coupled with reduced food intake imparted beneficial effects on aged skeletal muscle. The benefit of curcumin on aging skeletal muscle should be explored further.

Montmorency cherry supplementation improves 15-km cycling time-trial performance

Aim

Montmorency cherries are rich in polyphenols that possess antioxidant, anti-inflammatory and vasoactive properties. We investigated whether 7-day Montmorency cherry powder supplementation improved cycling time-trial (TT) performance.

Methods

8 trained male cyclists (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot {V}{{\text{O}}_{2{\text{peak}}}}$$\end{document}V˙O2peak: 62.3 ± 10.1 ml kg⁻¹ min⁻¹) completed 10-min steady-state (SS) cycling at ~ 65% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot {V}{{\text{O}}_{2{\text{peak}}}}$$\end{document}V˙O2peak followed by a 15-km TT on two occasions. Participants consumed 6 pills per day (Montmorency cherry powder, MC; anthocyanin 257 mg day⁻¹ or dextrose powder, PL) for a 7-day period, 3 pills in the morning and evening. Capillary blood [lactate] was measured at baseline, post SS and post TT. Pulmonary gas exchange and tissue oxygenation index (TOI) of m. vastus lateralis via near-infrared spectroscopy, were measured throughout.

Results

TT completion time was 4.6 ± 2.9% faster following MC (1506 ± 86 s) supplementation compared to PL (1580 ± 102 s; P = 0.004). Blood [lactate] was significantly higher in MC after SS (PL: 4.4 ± 2.1 vs. MC: 6.7 ± 3.3 mM, P = 0.017) alongside an elevated baseline TOI (PL: 68.7 ± 2.1 vs. MC: 70.4 ± 2.3%, P = 0.018).

Discussion

Montmorency cherry supplementation improved 15-km cycling TT performance. This improvement in exercise performance was accompanied by enhanced muscle oxygenation suggesting that the vasoactive properties of the Montmorency cherry polyphenols may underpin the ergogenic effects.

Cytokine Response to Exercise and Its Modulation

Strenuous exercise induces such inflammatory responses as leukocytosis (neutrophilia) and symptoms as delayed-onset muscle soreness and swelling. However, the association between inflammatory mediator cytokines and oxidative stress is not fully delineated. Herein, in addition to basic background information on cytokines, research findings on exertional effects on cytokine release and the underlying mechanisms and triggers are introduced. Then, the associations among cytokine responses, oxidative stress, and tissue damage are described not only in overloaded skeletal muscle, but also in other internal organs. Furthermore, we introduce preventive countermeasures against the exhaustive exercise-induced pathogenesis together with the possibility of antioxidant interventions.

Short-term dietary curcumin supplementation reduces gastrointestinal barrier damage and physiological strain responses during exertional heat stress

Szymanski MC, Gillum TL, Gould LM, Morin DS, Kuennen MR. Short-term dietary curcumin supplementation reduces gastrointestinal barrier damage and physiological strain responses during exertional heat stress. J Appl Physiol 124: 330-340, 2018. First published September 21, 2017; doi: 10.1152/japplphysiol.00515.2017 .-This work investigated the effect of 3 days of 500 mg/day dietary curcumin supplementation on gastrointestinal barrier damage and systems-physiology responses to exertional heat stress in non-heat-acclimated humans. Eight participants ran (65% V̇o_2max) for 60 min in a Darwin chamber (37°C/25% relative humidity) two times (Curcumin/Placebo). Intestinal fatty acid-binding protein (I-FABP) and associated proinflammatory [monocyte chemoattractant protein-1, tumor necrosis factor-α (TNF-α), interleukin-6] and anti-inflammatory [interleukin-1 receptor antagonist (IL-1RA), interleukin-10 (IL-10)] cytokines were assayed from plasma collected before (Pre), after (Post) and 1 (1-Post) and 4 (4-Post) h after exercise. Core temperature and HR were measured throughout exercise; the physiological strain index (PSI) was calculated from these variables. Condition differences were determined with 2-way (condition × time) repeated-measures ANOVAs. The interaction of condition × time was significant ( P = 0.05) for I-FABP and IL-1RA. Post hoc analysis indicated I-FABP increased more from Pre to Post (87%) and 1-Post (33%) in Placebo than in Curcumin (58 and 18%, respectively). IL-1RA increased more from Pre to 1-Post in Placebo (153%) than in Curcumin (77%). TNF-α increased ( P = 0.01) from Pre to Post (19%) and 1-Post (24%) in Placebo but not in Curcumin ( P > 0.05). IL-10 increased ( P < 0.01) from Pre to Post (61%) and 1-Post (42%) in Placebo not in Curcumin ( P > 0.05). The PSI, which indicates exertional heatstroke risk, was also lower ( P < 0.01) in Curcumin than Placebo from 40 to 60 min of exercise. These data suggest 3 days curcumin supplementation may improve gastrointestinal function, associated cytokines, and systems-level physiology responses during exertional heat stress. This could help reduce exertional heatstroke risk in non-heat-acclimated individuals. NEW & NOTEWORTHY Exercise-heat stress increases gastrointestinal barrier damage and risk of exertional heatstroke. Over the past decade at least eight different dietary supplements have been tested for potential improvements in gastrointestinal barrier function and systems-level physiology responses during exercise-heat stress. None have been shown to protect against both insults simultaneously. In this report 3 days of 500 mg/day dietary curcumin supplementation are shown to improve gastrointestinal barrier function, associated cytokine responses, and systems-level physiology parameters. Further research is warranted.

Curcumin, the golden nutraceutical: multitargeting for multiple chronic diseases

Curcumin, a yellow pigment in the Indian spice Turmeric (Curcuma longa), which is chemically known as diferuloylmethane, was first isolated exactly two centuries ago in 1815 by two German Scientists, Vogel and Pelletier. However, according to the pubmed database, the first study on its biological activity as an antibacterial agent was published in 1949 in Nature and the first clinical trial was reported in The Lancet in 1937. Although the current database indicates almost 9000 publications on curcumin, until 1990 there were less than 100 papers published on this nutraceutical. At the molecular level, this multitargeted agent has been shown to exhibit anti-inflammatory activity through the suppression of numerous cell signalling pathways including NF-κB, STAT3, Nrf2, ROS and COX-2. Numerous studies have indicated that curcumin is a highly potent antimicrobial agent and has been shown to be active against various chronic diseases including various types of cancers, diabetes, obesity, cardiovascular, pulmonary, neurological and autoimmune diseases. Furthermore, this compound has also been shown to be synergistic with other nutraceuticals such as resveratrol, piperine, catechins, quercetin and genistein. To date, over 100 different clinical trials have been completed with curcumin, which clearly show its safety, tolerability and its effectiveness against various chronic diseases in humans. However, more clinical trials in different populations are necessary to prove its potential against different chronic diseases in humans. This review's primary focus is on lessons learnt about curcumin from clinical trials.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Curcumin and Boswellia serrata Modulate the Glyco-Oxidative Status and Lipo-Oxidation in Master Athletes

Background: Chronic intensive exercise is associated with a greater induction of oxidative stress and with an excess of endogenous advanced glycation end-products (AGEs). Curcumin can reduce the accumulation of AGEs in vitro and in animal models. We examined whether supplementation with curcumin and Boswellia serrata (BSE) gum resin for 3 months could affect plasma levels of markers of oxidative stress, inflammation, and glycation in healthy master cyclists. Methods. Forty-seven healthy male athletes were randomly assigned to Group 1, consisting of 22 subjects given a Mediterranean diet (MD) alone (MD group), and Group 2 consisted of 25 subjects given a MD plus curcumin and BSE (curcumin/BSE group). Interleukin-6 (IL-6), tumor necrosis factor-α (TNFα), high-sensitivity c-reactive protein (hs-CRP), total AGE, soluble receptor for AGE (sRAGE), malondialdehyde (MDA), plasma phospholipid fatty acid (PPFA) composition, and non-esterified fatty acids (NEFA) were tested at baseline and after 12 weeks. Results: sRAGE, NEFA, and MDA decreased significantly in both groups, while only the curcumin/BSE group showed a significant decline in total AGE. Only the changes in total AGE and MDA differed significantly between the curcumin/BSE and MD groups. Conclusions. Our data suggest a positive effect of supplementation with curcumin and BSE on glycoxidation and lipid peroxidation in chronically exercising master athletes.

Curcumin prevents muscle damage by regulating NF-κB and Nrf2 pathways and improves performance: an in vivo model

Purpose

Exercise (Ex) increases reactive oxygen species and impairs antioxidant defense systems. Recent data suggest that curcumin (CW) possesses peroxisome proliferator-activated receptor gamma activity and anti-inflammatory properties. Therefore, this study was designed to investigate the effects of CW supplementation on Ex performance, endurance, and changes in serum and muscle proteins in rats after exhaustive Ex.

Materials and methods

Twenty-eight (28) male Wistar rats (age: 8 weeks and body weight: 180±20 g) were divided into four treatment groups: 1) control (C; no Ex), 2) C + CW (no Ex + CW), 3) C + Ex, and 4) C + Ex + CW (Ex + CW). CW was administered as 100 mg/kg CurcuWin^®, providing 20 mg of curcuminoids daily for 6 weeks. A motor-driven rodent treadmill was used to carry out the Ex protocols. During a 5-day period, animals in chronic Ex groups were put through different regimens: day 1, 10 m/min for 10 minutes; day 2, 20 m/min for 10 minutes; day 3, 25 m/min for 10 minutes; day 4, 25 m/min for 20 minutes; and day 5, 25 m/min for 30 minutes. Animals were exercised at 25 m/min for 45 min/d for 5 d/wk for 6 weeks. Blood and muscle samples were analyzed for muscle markers, oxidative stress, and antioxidant markers.

Results

Lactate and muscle malondialdehyde levels decreased in the CW-treated groups (P<0.0001). However, activities of antioxidant enzyme levels increased in the CW-treated groups. Run to exhaustion (minutes) improved in the CW-treated groups. Muscle nuclear factor-κB (P<0.05) and heat shock protein 70 (P<0.05) levels were much lowered in the CW treated group followed by Ex group. In addition, muscle inhibitors of kappa B, peroxisome proliferator-activated receptor gamma coactivator 1-alpha, thioredoxin-1, sirtuin 1, nuclear factor (erythroid-derived 2)-like 2, and glucose transporter 4 protein levels in the Ex + CW group were higher than those in the control and Ex groups (P<0.05).

Conclusion

This study suggests that novel CW has the potential to help prevent muscle damage by regulating the nuclear factor-κB and nuclear factor (erythroid-derived 2)-like 2 pathways and improve the performance and nutritional values of CW.

Reduced inflammatory and muscle damage biomarkers following oral supplementation with bioavailable curcumin

Background

Exercise-Induced Muscle Damage (EIMD) and delayed onset muscle soreness (DOMS) impact subsequent training sessions and activities of daily living (ADL) even in active individuals. In sedentary or diseased individuals, EIMD and DOMS may be even more pronounced and present even in the absence of structured exercise.

Methods

The purpose of this study was to determine the effects of oral curcumin supplementation (Longvida® 400 mg/days) on muscle & ADL soreness, creatine kinase (CK), and inflammatory cytokines (TNF-α, IL-6, IL-8, IL-10) following EMID (eccentric-only dual-leg press exercise). Subjects (N = 28) were randomly assigned to either curcumin (400 mg/day) or placebo (rice flour) and supplemented 2 days before to 4 days after EMID. Blood samples were collected prior to (PRE), and 1, 2, 3, and 4 days after EIMD to measure CK and inflammatory cytokines. Data were analyzed by ANOVA with P < 0.05.

Results

Curcumin supplementation resulted in significantly smaller increases in CK (− 48%), TNF-α (− 25%), and IL-8 (− 21%) following EIMD compared to placebo. We observed no significant differences in IL-6, IL-10, or quadriceps muscle soreness between conditions for this sample size.

Conclusions

Collectively, the findings demonstrated that consumption of curcumin reduced biological inflammation, but not quadriceps muscle soreness, during recovery after EIMD. The observed improvements in biological inflammation may translate to faster recovery and improved functional capacity during subsequent exercise sessions.

General significance

These findings support the use of oral curcumin supplementation to reduce the symptoms of EIMD. The next logical step is to evaluate further the efficacy of an inflammatory clinical disease model.

•

Oral optimized curcumin supplementation reduced biological indices of muscle inflammation following exercise-induced muscle damage.

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Oral optimized curcumin supplementation did not significantly reduced subjective quadriceps muscle soreness for this sample size following exercise induced muscle damage.

•

These findings support the use of oral, optimized curcumin supplementation to reduce the biological symptoms associated with exercise induced muscle damage.

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The next logical step is to evaluated oral, optimized curcumin supplementation in an inflammatory clinical disease model.

Performance Enhancing Diets and the PRISE Protocol to Optimize Athletic Performance

The training regimens of modern-day athletes have evolved from the sole emphasis on a single fitness component (e.g., endurance athlete or resistance/strength athlete) to an integrative, multimode approach encompassing all four of the major fitness components: resistance (R), interval sprints (I), stretching (S), and endurance (E) training. Athletes rarely, if ever, focus their training on only one mode of exercise but instead routinely engage in a multimode training program. In addition, timed-daily protein (P) intake has become a hallmark for all athletes. Recent studies, including from our laboratory, have validated the effectiveness of this multimode paradigm (RISE) and protein-feeding regimen, which we have collectively termed PRISE. Unfortunately, sports nutrition recommendations and guidelines have lagged behind the PRISE integrative nutrition and training model and therefore limit an athletes' ability to succeed. Thus, it is the purpose of this review to provide a clearly defined roadmap linking specific performance enhancing diets (PEDs) with each PRISE component to facilitate optimal nourishment and ultimately optimal athletic performance.

Effect of curcumin supplementation on physiological fatigue and physical performance in mice

Curcumin (CCM) is a well-known phytocompound and food component found in the spice turmeric and has multifunctional bioactivities. However, few studies have examined its effects on exercise performance and physical fatigue. We aimed to evaluate the potential beneficial effects of CCM supplementation on fatigue and ergogenic function following physical challenge in mice. Male ICR mice were divided into four groups to receive vehicle or CCM (180 μg/mL) by oral gavage at 0, 12.3, 24.6, or 61.5 mL/kg/day for four weeks. Exercise performance and anti-fatigue function were evaluated after physical challenge by forelimb grip strength, exhaustive swimming time, and levels of physical fatigue-associated biomarkers serum lactate, ammonia, blood urea nitrogen (BUN), and glucose and tissue damage markers such as aspartate transaminase (AST), alanine transaminase (ALT), and creatine kinase (CK). CCM supplementation dose-dependently increased grip strength and endurance performance and significantly decreased lactate, ammonia, BUN, AST, ALT, and CK levels after physical challenge. Muscular glycogen content, an important energy source for exercise, was significantly increased. CCM supplementation had few subchronic toxic effects. CCM supplementation may have a wide spectrum of bioactivities for promoting health, improving exercise performance and preventing fatigue.

The effect of turmeric (Curcumin) supplementation on cytokine and inflammatory marker responses following 2 hours of endurance cycling

BACKGROUND

Endurance exercise induces IL-6 production from myocytes that is thought to impair intracellular defence mechanisms. Curcumin inhibits NF-κB and activator protein 1, responsible for cytokine transcription, in cell lines. The aim of this study was to investigate the effect of curcumin supplementation on the cytokine and stress responses following 2 h of cycling.

METHODS

Eleven male recreational athletes (35.5 ± 5.7 years; Wmax 275 ± 6 W; 87.2 ± 10.3 kg) consuming a low carbohydrate diet of 2.3 ± 0.2 g/kg/day underwent three double blind trials with curcumin supplementation, placebo supplementation, and no supplementation (control) to observe the response of serum interleukins (IL-6, IL1-RA, IL-10), cortisol, c-reactive protein (CRP), and subjective assessment of training stress. Exercise was set at 95% lactate threshold (54 ± 7% Wmax) to ensure that all athletes completed the trial protocol.

RESULTS

The trial protocol elicted a rise in IL-6 and IL1-RA, but not IL-10. The supplementation regimen failed to produce statistically significant results when compared to placebo and control. IL-6 serum concentrations one hour following exercise were (Median (IQR): 2.0 (1.8-3.6) Curcumin; 4.8 (2.1-7.3) Placebo; 3.5 (1.9-7.7) Control). Differences between supplementation and placebo failed to reach statistical significance (p = 0.18) with the median test. Repeated measures ANOVA time-trial interaction was at p = 0.06 between curcumin supplementation and placebo. A positive correlation (p = 0.02) between absolute exercise intensity and 1 h post-exercise for IL-6 concentration was observed. Participants reported "better than usual" scores in the subjective assessment of psychological stress when supplementing with curcumin, indicating that they felt less stressed during training days (p = 0.04) compared to placebo even though there was no difference in RPE during any of the training days or trials.

CONCLUSION

The limitations of the current regimen and trial involved a number of factors including sample size, mode of exercise, intensity of exercise, and dose of curcumin. Nevertheless these results provide insight for future studies with larger samples, and multiple curcumin dosages to investigate if different curcumin regimens can lead to statistically different interleukin levels when compared to a control and placebo.

Recent developments in delivery, bioavailability, absorption and metabolism of curcumin: the golden pigment from golden spice

Curcumin (diferuloylmethane) is a yellow pigment present in the spice turmeric (Curcuma longa) that has been associated with antioxidant, anti-inflammatory, anticancer, antiviral, and antibacterial activities as indicated by over 6,000 citations. In addition, over one hundred clinical studies have been carried out with curcumin. One of the major problems with curcumin is perceived to be the bioavailability. How curcumin should be delivered in vivo, how bioavailable is it, how well curcumin is absorbed and how it is metabolized, is the focus of this review. Various formulations of curcumin that are currently available are also discussed.