A new curcuma extract (flexofytol®) in osteoarthritis: results from a belgian real-life experience

Recent updates on clinical developments of curcumin and its derivatives

Curcumin, a natural polyphenol, derived from Curcuma longa L. is extensively studied by various researchers across the globe and has established its immense potential in the management of several disorders at clinical level. The underlying mechanism of curcumin involves regulation of various molecular targets, namely, inflammatory cytokines, transcription factor, apoptotic genes, growth factors, oxidative stress biomarkers, and protein kinases. In clinical trials, curcumin as an adjuvant has significantly boost-up the efficacy of many proven drugs in the management of arthritis, neurodegenerative disorder, oral infection, and gastrointestinal disorders. Moreover, clinical studies have suggested curcumin as an appropriate candidate for the prevention and/or management of various cancers via regulation of signaling molecules including NF-kB, cytokines, C-reactive protein, prostaglandin E2, Nrf2, HO-1, ALT, AST, kinases, and blood profiles. This article highlights plethora of clinical trials that have been conducted on curcumin and its derivatives in the management of several ailments. Besides, it provides recent updates to the investigators for conducting future research to fulfill the current gaps to expedite the curcumin utility in clinical subjects bearing different pathological states.

Curcuma as an anti-inflammatory component in treating osteoarthritis

Osteoarthritis (OA) is nowadays the most common musculoskeletal progressive condition. In recent decades, incidence and prevalence of OA have increased significantly. It is estimated that the prevalence of OA among adults older than 60 is 12%, affecting about 240 million people globally. The cause has not been fully elucidated, and therefore, there is no cure at the moment. It is a multifactorial degenerative disease with an inflammatory component mediated by numerous proinflammatory and anti-inflammatory cytokines, chemokines, and growth factors. OA is not yet fully understood; therefore, therapeutic interventions are aimed primarily at reducing symptoms and slowing the progression of joint destruction. Of the therapeutic options available, the most often prescribed are nonsteroidal antirheumatic drugs, which have numerous side effects. Therefore, a need for a safe, effective substance is differentiated, which will be used in adjuvant treatment, but also in disease prevention, and which will comparatively have no or fewer side effects. One such substance is curcumin, a hydrophobic polyphenol that forms the active component of the rhizome of the Curcuma longa plant. Several studies have shown its potent antioxidant and anti-inflammatory effect, non-toxicity, and safety at high daily doses. In addition to blocking chondrocyte apoptosis, curcumin also blocks the expression of cyclooxygenase, prostaglandin E-2 and proinflammatory cytokines in chondrocytes, potentially alleviating symptomatic diseases. Although there are significant variations in quality, methodology, and research results conducted on curcumin efficiency in OA treatment, curcumin is primarily recommended as systematic short-term and medium-term adjuvant therapy that reduces inflammatory biochemical factors. Reducing inflammation leads to better pain regulation and improved joint function, significantly reducing standard prescribed doses of drugs. The most researched daily doses of curcumin intake are 1000-2000 mg/day, which would also be the doses that most of the authors recommend. Further research is needed to determine the preventive role of curcumin in the pathogenesis of OA, the effects of long-term usage of curcumin in preventive purposes and treatment of osteoarthritis, as well as to determine optimal therapeutic dosages.

Curcumin promotes microglial M2 polarization and suppresses chronic constriction: Injury-induced neuropathic pain in a rat model of peripheral neuropathy

OBJECTIVES

Glia (i.e., astrocyte and microglia) activation in the central nervous system plays a critical role in developing neuropathic pain. Microglia can be activated into proinflammatory (M1) and anti-inflammatory (M2) phenotypes. Switching microglial polarization from M1 to M2 phenotypes represents a novel therapeutic strategy for neuropathic pain. Curcumin has been widely used for its anti-inflammatory and immunomodulatory effects. This study investigated effects of curcumin on astrocyte activation and microglia polarization in the cuneate nucleus (CN) and development of neuropathic pain behavior after chronic constriction injury (CCI) of the median nerve.

METHODS

Rats were fed with curcumin once daily at a dose of 40, 80, or 120 mg/kg 30 min before and until 7 d after median nerve CCI. Subsequently, mechanical allodynia and thermal hyperalgesia were evaluated using von Frey filaments and plantar tests, respectively. The levels of astrocyte marker, monoclonal glial fibrillary acidic protein; microglia marker, ionized calcium-binding adapter molecule 1; M1 marker, CD86; and M2 marker, CD206 in the cuneate nucleus were determined. Enzyme-linked immunosorbent assay was applied to measure cytokine concentrations.

RESULTS

Curcumin administration dose-dependently reduced mechanical allodynia and thermal hyperalgesia and decreased monoclonal glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 immunoreactivity in the ipsilateral cuneate nucleus after CCI. On ultrastructural observation, curcumin treatment was associated with fewer features of activated astrocytes and microglia. Furthermore, CCI rats given curcumin exhibited a decline in CD86 immunoreactivity and proinflammatory cytokine levels but an increase in CD206 immunoreactivity and release of anti-inflammatory cytokines.

CONCLUSIONS

In our findings, curcumin switches microglial phenotypes from M1 to M2 by suppressing astrocytic activation, reducing proinflammatory cytokine release, promoting anti-inflammatory cytokine production, and contributing to relief of neuropathic pain.

Analgesic effect of curcumin topical formulation in knee osteoarthritis patients: a clinical trial

OBJECTIVES

The aim of this study was to recognize the efficacy and safety of curcumin ointment on patients with knee osteoarthritis (OA) compare to diclofenac as standard medication.

METHODS

The topical effects of curcumin (10%) and diclofenac (1%) ointments were assessed through the visual analog scale (VAS) and Western Ontario and McMaster Universities Arthritis (WOMAC) index after three times a day administration for two weeks in 60 patients.

RESULTS

Desirable effects compared to the pre-treatment period were observed after two weeks of continuous treatment. Based on our results, VAS and WOMAC index were altered after treatment significantly (p<0.0001).

CONCLUSIONS

Two-week use of curcumin ointment could ameliorate the pain, stiffness and function disability in patients with OA.

The Oral Administration of Highly-Bioavailable Curcumin for One Year Has Clinical and Chondro-Protective Effects: A Randomized, Double-Blinded, Placebo-Controlled Prospective Study

Purpose

The purpose of this study was to determine the clinical and chondroprotective efficacy and safety of orally administered Theracurmin in patients who underwent mosaicplasty for knee chondral or osteochondral diseases over 12 months of treatment.

Methods

We enrolled 50 patients, older than 20 years of age, who underwent mosaicplasty for their knee joint diseases. Theracurmin at 180 mg of curcumin per day or placebo was administered orally every day for 12 months. Because 7 patients dropped out of the study, 43 patients were examined; they included 14 men and 29 women and 24 right and 19 left knees. The mean operative age was 59.5 years (range, 24-84 years). We evaluated the Japanese Orthopaedic Association knee osteoarthritis score (JOA), visual analog scale (VAS), and Japanese Knee Osteoarthritis Measure (JKOM) as clinical symptoms; T2 mapping values using magnetic resonance imaging as an indication of the chondroprotective effect; and blood concentration of curcumin at 0, 3, 6, and 12 months after the operations. We performed intraoperative acoustic evaluation of articular cartilage as a measure of chondroprotective effect during the operations and second-look arthroscopy.

Results

The JOA, VAS and JKOM at 3, 6, and 12 months were significantly better than those during the preoperative period. However, the values of JOA, VAS and JKOM and T2 mapping were not significantly different between the Theracurmin and placebo groups. The blood concentration of curcumin in the Theracurmin group was significantly higher than that in the placebo group at 3, 6, and 12 months after the operations. Cartilage stiffness and surface roughness were significantly better in the Theracurmin group than in the placebo group at second-look arthroscopy.

Conclusions

The oral administration of Theracurmin for 1 year demonstrated significantly better chondroprotective effects and no worse clinical effects and adverse events than the placebo.

Level of Evidence

Level I, double-blinded, placebo-controlled, prospective study.

Quality of Evidence Supporting the Role of Curcuma Longa Extract/Curcumin for the Treatment of Osteoarthritis: An Overview of Systematic Reviews

Background

Well known for its good anti-inflammatory effect, curcuma longa extract (CLE)/curcumin (C) has a potential effect on osteoarthritis (OA), and a large number of researchers have completed several systematic reviews/meta-analyses (SRs/MAs) in this research area. However, the methodological and evidentiary quality of these SRs/MAs need to be further evaluated, and whether these findings provide reliable evidence for clinicians remains controversial.

Methods

Two researchers collected data from seven databases for SRs/MAs that are about randomized controlled trials (RCTs) on CLE/C for OA. Assessment was made for the SRs/MAs included in this article by means of the Assessment System for Evaluating Methodological Quality 2 (AMSTAR-2), the Risk of Bias in Systematic (ROBIS) scale, the list of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system.

Results

Nine published SRs/MAs were included in our study. According to the results of the AMSTAR-2 assessment, only one SR/MA was assessed as high quality. According to the ROBIS evaluation results, only 2 SRs/MAs have a low risk of bias. According to the results of the PRISMA checklist assessment, only 2 SRs/MAs studies fully reported the checklist, while other studies had reporting flaws. According to GRADE, a total of 59 effect sizes extracted from the included SRs/MAs were evaluated, among which no effect size was rated as high.

Conclusions

CLE/C may be an effective and safe complementary treatment for OA. However, further standard SRs/MAs and RCTs are needed to provide an evidence-based medical rationale for this.

Effectiveness of Curcuma longa extract versus placebo for the treatment of knee osteoarthritis: A systematic review and meta-analysis of randomized controlled trials

The aim of this systematic review was to evaluate the efficacy and safety of all types of Curcuma longa extract versus placebo for knee osteoarthritis (OA) treatment. The research was conducted by using the databases of PubMed, Embase, Scopus, and Cochrane Library through April 2021. Randomized controlled trials (RCTs) that compared the effect of Curcuma longa extract with placebo for patients with knee OA were considered eligible. The pooled results were expressed as mean differences or relative risks with 95% confidence intervals. A total of 10 RCTs with 783 patients were eligible for this meta-analysis. The pooled analysis showed that Curcuma longa extract was associated with significantly better pain relief and functional improvement compared with placebo for knee OA. Moreover, the smallest effect sizes of VAS for pain and WOMAC total score exceeded the minimum clinically important differences (MCIDs). Current evidence indicates that, compared with placebo, Curcuma longa extract has more benefit in pain relief and functional improvement for symptomatic knee OA. However, considering the potential heterogeneity in the included studies, more future high-quality RCTs with large sample sizes are necessary to confirm the benefits of Curcuma longa extract on knee OA.

Herbal Medicine for Pain Management: Efficacy and Drug Interactions

Complementary and alternative medicines such as herbal medicines are not currently part of the conventional medical system. As the popularity of and global market for herbal medicine grows among all age groups, with supporting scientific data and clinical trials, specific alternative treatments such as herbal medicine can be reclassified as a practice of conventional medicine. One of the most common conditions for which adults use herbal medicine is pain. However, herbal medicines carry safety concerns and may impact the efficacy of conventional therapies. Unfortunately, mechanisms of action are poorly understood, and their use is unregulated and often underreported to medical professionals. This review aims to compile common and available herbal medicines which can be used as an alternative to or in combination with conventional pain management approaches. Efficacy and safety are assessed through clinical studies on pain relief. Ensuing herb–drug interactions such as cytochrome modulation, additive and synergistic effects, and contraindications are discussed. While self-management has been recognized as part of the overall treatment strategy for patients suffering from chronic pain, it is important for practitioners to be able to also optimize and integrate herbal medicine and, if warranted, other complementary and alternative medicines into their care.

Clusters of Responders and Predictive Factors for Response to Supplementation with Boswellia, Turmeric, and Red Algae Extracts in Painful Knee Osteoarthritis: A Prospective Observational Study Using an Arsenal of Patient-Centered Measures

Purpose

This observational study evaluated a combination of boswellia, turmeric, and red algae extracts in patients with knee osteoarthritis (KOA). Given the growing interest in patient-centered care in osteoarthritis, effects were assessed by an arsenal of patient-reported outcome measures (PROMs): Patient Acceptable Symptom Scale (PASS), Minimal Clinically Important Improvement (MCII), Patient Global Impression of Change (PGIC), and Lequesne algofunctional index (LAFI). Patients also completed a list of 17 items on pain quality.

Patients and Methods

Patients with painful unilateral or bilateral KOA had to take 1-4 capsules per day of a dietary supplement containing boswellia, turmeric, and red algae extracts for 90 days. Patients completed PROMs on Days 0 (baseline), 10, 20, 30, 60, and/or 90.

Results

A total of 118 patients [female: 69.5%; age: 62.9 (9.5) years, mean (SD)] were included in the study and took at least one capsule. Mean (SD) follow-up duration was 100.7 (54.9) days. Pain relief was maximal on Day 90: 64.5% of patients were responders (positive PASS); 68.8% and 58.4% had MCII and PGIC scores indicating positive effect (score ≥3) or global improvement (score ≥5); 73.3% (versus 47.5% at baseline) were mildly/moderately disabled (LAFI score <8); 55.2% had meaningful decrease (-30%) in pain intensity (VAS), 35.1% (versus 59.2% at baseline) took analgesics as supplementary treatment. Median time to the first PASS change was 34 days. Pain intensity (VAS), as well as two pain characteristics (ie, "Stabbing pain" and "Widespread pain"), were independent factors associated with non-response on Day 30. Four clusters of responders were isolated according to pain characteristics, with one cluster exhibiting a higher responder rate.

Conclusion

The results of this preliminary study suggest that the combination of boswellia, turmeric, and red algae extracts tested could improve KOA patients. Beyond these results, this study showed the importance of PROMs and specific pain qualitative descriptors for the accurate evaluation of dietary supplement approaches in painful conditions.

The effect of oral curcumin supplementation on health-related quality of life: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

With an aging society, a multitude of physical, mental, and emotional challenges are being faced both in the general population and by those with chronic disorders. An enhanced understanding of 'quality of life' could be considered a major criterion for improved clinical care. We performed a meta-analysis to examine the effect of oral curcumin on improving the health-related quality of life (HRQOL).

METHODS

A systematic search was performed through PubMed, Clarivate Web of Science, Scopus, and Embase up to February 2020 using relevant keywords. Trials that met the inclusion criteria were included in this study. We applied the standardized mean difference (SMD) in a random-effects model to analyze the impact of combined trials. Additionally, we used the Cochrane Risk Bias Tool to evaluate any potential risks of bias.

RESULTS

A total of 10 studies were considered eligible and included in the meta-analysis. We found an overall significant effect of oral curcumin supplementation on improved HRQOL (SMD: 2.46, 95% CI: 1.30, 3.63; I2=97.4). In the subgroup analysis, curcumin showed significantly favorable effects on HRQOL in trials with a short duration of curcumin intervention (<5 months) and those that used curcumin formulations with high bioavailability.

CONCLUSION

Oral curcumin has a strong positive impact on HRQOL. Our analysis supports the use of an improved-bioavailability formulation of curcumin to improve HRQOL. However, given the heterogeneity among the studies included in this review, additional evidence from well-designed, large, and long-term trials is still required.

Supplementation Effect of a Combination of Olive (Olea europea L.) Leaf and Fruit Extracts in the Clinical Management of Hypertension and Metabolic Syndrome

BACKGROUND

The role of herbal products in the prevention of cardiovascular disease requires supporting evidence. This open pilot study assessed the effect of 2-month supplementation of a combination of olive leaf and fruit extracts (Tensiofytol^®, Tilman SA, Baillonville, Belgium) in the clinical management of hypertension and metabolic syndrome (MetS).

METHODS

A total of 663 (pre)-hypertensive patients were enrolled by general practitioners and supplemented for two months with Tensiofytol^®, two capsules per day (100 mg/d of oleuropein and 20 mg/d of hydroxytyrosol). Systolic and diastolic blood pressures (SBP/DBP) were measured before and after treatment. Markers of MetS, high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), fasting blood glucose (FG) and waist circumference (WC), were also examined.

RESULTS

Significant reductions (p < 0.0001) in SBP/DBP (13 ± 10/7.1 ± 6.6 mmHg) were observed and similarly in pre-diabetic and diabetic patients. Improvements in SBP/DPB were independent of age and gender but greater for elevated baseline SBP/DBP. Tensiofytol^® supplementation also significantly improved markers of MetS, with a decrease of TG (11%), WC (1.4%) and FG (4.8%) and an increase of HDL-C (5.3%). Minor side effects were reported in 3.2% patients.

CONCLUSIONS

This real-life, observational, non-controlled, non-randomized pilot study shows that supplementation of a combination of olive leaf and fruit extracts may be used efficiently and safely in reducing hypertension and MetS markers.

Curcumin Diglutaric Acid, a Prodrug of Curcumin Reduces Pain Hypersensitivity in Chronic Constriction Injury of Sciatic Nerve Induced-Neuropathy in Mice

The drug treatment for neuropathic pain remains a challenge due to poor efficacy and patient satisfaction. Curcumin has been reported to alleviate neuropathic pain, but its clinical application is hindered by its low solubility and poor oral bioavailability. Curcumin diglutaric acid (CurDG) is a curcumin prodrug with improved water solubility and in vivo antinociceptive effects. In this study, we investigated the anti-inflammatory mechanisms underlying the analgesic effect of CurDG in the chronic constriction injury (CCI)-induced neuropathy mouse model. Repeated oral administration of CurDG at a low dose equivalent to 25 mg/kg/day produced a significant analgesic effect in this model, both anti-allodynic activity and anti-hyperalgesic activity appearing at day 3 and persisting until day 14 post-CCI surgery (p < 0.001) while having no significant effect on the motor performance. Moreover, the repeated administration of CurDG diminished the increased levels of the pro-inflammatory cytokines: TNF-α and IL-6 in the sciatic nerve and the spinal cord at the lowest tested dose (equimolar to 25 mg/kg curcumin). This study provided pre-clinical evidence to substantiate the potential of pursuing the development of CurDG as an analgesic agent for the treatment of neuropathic pain.

The Efficacy and Safety of Highly-Bioavailable Curcumin for Treating Knee Osteoarthritis: A 6-Month Open-Labeled Prospective Study

Background

We previously developed a surface-controlled water-dispersible form of curcumin that we called Theracurmin^®. The area under the blood concentration-time curve (AUC) of Theracurmin in humans was 27-fold higher than that of curcumin powder. Previously, we reported on the anti-inflammatory effects of Theracurmin for knee osteoarthritis.

Hypothesis/Purpose

We determined the clinical effects of orally administered Theracurmin in patients with knee osteoarthritis over a 6-month period.

Study Design

Open prospective study.

Methods

Fifty patients Kellgren-Lawrence grade II, III, or IV knee osteoarthritis who were above 40 years old were enrolled in this clinical study. Theracurmin containing 180 mg/day of curcumin was administered orally every day for 6 months. To monitor for adverse events, blood biochemistry analyses were performed before and after 6 months of each intervention. The patients' knee symptoms were evaluated at 0, 1, 2, 3, 4, 5, and 6 months based on the Japanese Knee Osteoarthritis Measure, the knee pain visual analog scale, and the knee scoring system of the Japanese Orthopedic Association.

Results

Five cases dropped out during the study, but no cases dropped out because of major problems. No major side effects were observed with Theracurmin treatment, including the blood biochemistry analysis results. The effective group included 34 cases (75.6%), while the not-effective group included 11 cases.

Conclusion

This study demonstrates the safety and good efficacy of Theracurmin for various types of knee osteoarthritis. Theracurmin shows great potential for the treatment of human knee osteoarthritis.

Bio-optimized Curcuma longa extract is efficient on knee osteoarthritis pain: a double-blind multicenter randomized placebo controlled three-arm study

Objectives

Comparison of two doses of bio-optimized Curcuma longa extract (BCL) in the management of symptomatic knee osteoarthritis (OA).

Methods

A prospective, randomized, 3-month, double-blind, multicenter, three-group, placebo-controlled trial assessing Patient Global Assessment of Disease Activity (PGADA) and serum sColl2-1, a biomarker of cartilage degradation, as co-primary endpoints. Pain on visual analog scale (VAS), Knee injury and Osteoarthritis Outcome Score (KOOS), and paracetamol/non-steroidal anti-inflammatory drug (NSAID) consumption were used as secondary endpoints.

Results

One hundred fifty patients with knee OA were followed for 90 days. Low and high doses of BCL showed a greater decrease of PGADA than placebo. Analysis of sColl2-1 showed in the placebo and BCL low-dose groups, but not in the BCL high-dose group, a transient but non-significant increase of sColl2-1 between T0 and T1. Thereafter, in all groups, sColl2-1 decreased between T1 and T3 (all p < 0.01), but no difference between the groups was found. Pain reduction at day 90 in the low- and high-dose BCL groups (− 29.5 mm and − 36.5 mm) was higher than that in the placebo (− 8 mm; p = 0.018). The global KOOS significantly decreased overtime, but changes were comparable across treatment arms. The ratio of patients with adverse events (AE) related to the product was similar in the placebo and treatment groups, but the number of AE linked to the product was higher in the high-dose BCL group compared to the placebo (p = 0.012).

Conclusions

BCL appeared safe and well-tolerated with no evidence of severe adverse effects. Efficacy analysis suggested positive trends for measurements of PGADA and serum levels of an OA biomarker and showed a rapid and significant decrease of pain in knee OA (Trial registration: ISRCTN, ISRCTN12345678. Registered 21 September 2016—retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT02909621?term=osteoarthritis+curcumin&rank=5—Evaluation of FLEXOFYTOL® Versus PLACEBO (COPRA) NCT02909621).

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1960-5) contains supplementary material, which is available to authorized users.

Role of curcumin in the management of pathological pain

BACKGROUND

Pathological pain conditions can be triggered after peripheral nerve injury and/or inflammation. It is a major clinical problem that is poorly treated with available therapeutics. Curcumin is a phenolic compound derived from Curcuma longa, being widely used for its antioxidant, anti-inflammatory and immunomodulatory effects.

PURPOSE

This review systematically summarized updated information on the traditional uses of curcumin in order to explore antinociceptive effects in pathological pain and evaluate future therapeutic opportunities clinically. Moreover, some structure-activity relationships would greatly enrich the opportunity of finding new and promising lead compounds and promote the reasonable development of curcumin.

METHODS

PubMed were searched and the literature from the year 1976 to January 2018 was retrieved using keywords pain and curcumin.

RESULTS

This review systematically summarized updated information on the traditional uses, chemical constituents and bioactivities of curcumin, and highlights the recent development of the mechanisms of curcumin in the pathological pain by sciatic nerve injury, spinal cord injury, diabetic neuropathy, alcoholic neuropathy, chemotherapy induced peripheral neuroinflammtion, complete Freund's adjuvant (CFA) injection or carrageenan injection. Importantly, the clinical studies provide a compelling justification for its use as a dietary adjunct for pain relief. And we also present multiple approaches to improve bioavailability of curcumin for the treatment of pathological pain.

CONCLUSION

This review focuses on pre-clinical and clinical studies in the treatment of pathological pain. Although the mechanisms of pain mitigating effects are not very clear, there is compelling evidence proved that curcumin plays an essential role. However, further high-quality clinical studies should be undertaken to establish the clinical effectiveness of curcumin in patients suffering from pathological pain. Potential methods of increase the water solubility and bioavailability of curcumin still need to be studied. These approaches will help in establishing it as remedy for pathological pain.

Curcumin in turmeric: Basic and clinical evidence for a potential role in analgesia

WHAT IS KNOWN AND OBJECTIVE

Current analgesic pharmacotherapy-opioids, non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen (paracetamol) and related drugs-is effective for acute pain, but their use is limited by adverse effects on the renal, hepatic, cardiovascular or gastrointestinal systems, or they have potential for abuse. Therefore, alternative options are desired. Compounds used in traditional medicine might offer such alternatives, but the evidence must be based on pharmacologic properties and on clinical trial data. This review summarizes the evidence for one of these: the analgesic properties of turmeric and other curcumins.

METHODS

The PubMed database and other sources were searched using keywords related to turmeric, curcumin, antinociception and analgesia. Primary sources and reviews of preclinical and clinical studies were identified, assessed and summarized. Bibliographies within these sources provided additional information.

RESULTS

Turmeric has consistently been demonstrated to produce analgesic and anti-inflammatory effects in animal models and in clinical trials, and appears to have less serious adverse effects than many current analgesics.

WHAT IS NEW AND CONCLUSIONS

Turmeric (curcumin) appears to be a possible candidate for consideration for use as a stand-alone analgesic, or in analgesic combinations as part of opioid-, NSAID- or paracetamol (acetaminophen)-sparing strategies.

Effects of curcumin consumption on human chronic diseases: A narrative review of the most recent clinical data

Numerous clinical trials have investigated the potential beneficial effects of curcumin supplementation against several human chronic diseases. Up to now, it has been claimed that curcumin consumption may exert beneficial effects against several chronic diseases by promoting human health and preventing diseases. In this aspect, the present review aims to critically collect and in-depth summarize the most recent, well-designed clinical studies evaluating the potential beneficial effects of curcumin consumption on human health promotion and disease prevention. According to recent and well-designed clinical studies, curcumin consumption may benefit against obesity, metabolic syndrome, and diabetes. Moreover, curcumin consumption seems to exert a positive effect on people suffering from various types of cancer, fatty liver disease, depression, arthritis, skin diseases, gut inflammation, and symptoms of premenstrual syndrome. Due to the strong heterogeneity among the clinical studies concerning the exact effective curcumin dose and formulation, as well as the recommended treatment duration for each chronic disease, no precise and definitive conclusions could be drawn. Further large-scale prospective studies are strongly recommended, being well-designed as far as follow-up times, dosage, formulation, and duration of curcumin supplementation are concerned. Moreover, potential confounders in each specific chronic disease should carefully be taken into account in future studies.

Curcumin-mediated regulation of intestinal barrier function: The mechanism underlying its beneficial effects

Curcumin has anti-inflammatory, anti-oxidant and anti-proliferative properties established largely by in vitro studies. Accordingly, oral administration of curcumin beneficially modulates many diseases including diabetes, fatty-liver disease, atherosclerosis, arthritis, cancer and neurological disorders such as depression, Alzheimer's or Parkinson's disease. However, limited bioavailability and inability to detect curcumin in circulation or target tissues has hindered the validation of a causal role. We established curcumin-mediated decrease in the release of gut bacteria-derived lipopolysaccharide (LPS) into circulation by maintaining the integrity of the intestinal barrier function as the mechanism underlying the attenuation of metabolic diseases (diabetes, atherosclerosis, kidney disease) by curcumin supplementation precluding the need for curcumin absorption. In view of the causative role of circulating LPS and resulting chronic inflammation in the development of diseases listed above, this review summarizes the mechanism by which curcumin affects the several layers of the intestinal barrier and, despite negligible absorption, can beneficially modulate these diseases.

Curcumin and normal functioning of joints: evaluation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006

Following an application from Suomen Terveysravinto Oy, submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Finland, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to curcumin and normal functioning of joints. The food that is proposed as the subject of the health claim is curcumin. The Panel considers that curcumin is sufficiently characterised. The claimed effect proposed by the applicant is 'normal functioning of joints by reducing the biomarkers of inflammation'. The target population proposed by the applicant is the general population. Upon a request from EFSA to clarify whether the claimed effect is related to the normal function of joints or rather to the reduction of inflammation, the applicant did not address this issue in the reply. The Panel assumes that the claimed effect refers to the maintenance of joint function. The Panel considers that maintenance of joint function is a beneficial physiological effect. The Panel considers that no conclusions can be drawn from 15 human intervention studies conducted in patients with osteoarthritis or rheumatoid arthritis and from one study in obese subjects on serum cytokines for the scientific substantiation of the claim. In the absence of evidence for an effect of curcumin on the normal function of joints in humans, the results of the human studies on curcumin pharmacokinetics, safety and mechanistic studies, the animal studies and the in vitro studies submitted by the applicant cannot be used as a source of data for the scientific substantiation of the claim. The Panel concludes that a cause and effect relationship has not been established between the consumption of curcumin and maintenance of joint function.

Efficacy of Turmeric Extracts and Curcumin for Alleviating the Symptoms of Joint Arthritis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Although turmeric and its curcumin-enriched extracts have been used for treating arthritis, no systematic review and meta-analysis of randomized clinical trials (RCTs) have been conducted to evaluate the strength of the research. We systemically evaluated all RCTs of turmeric extracts and curcumin for treating arthritis symptoms to elucidate the efficacy of curcuma for alleviating the symptoms of arthritis. Literature searches were conducted using 12 electronic databases, including PubMed, Embase, Cochrane Library, Korean databases, Chinese medical databases, and Indian scientific database. Search terms used were “turmeric,” “curcuma,” “curcumin,” “arthritis,” and “osteoarthritis.” A pain visual analogue score (PVAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used for the major outcomes of arthritis. Initial searches yielded 29 articles, of which 8 met specific selection criteria. Three among the included RCTs reported reduction of PVAS (mean difference: −2.04 [−2.85, −1.24]) with turmeric/curcumin in comparison with placebo (P < .00001), whereas meta-analysis of four studies showed a decrease of WOMAC with turmeric/curcumin treatment (mean difference: −15.36 [−26.9, −3.77]; P = .009). Furthermore, there was no significant mean difference in PVAS between turmeric/curcumin and pain medicine in meta-analysis of five studies. Eight RCTs included in the review exhibited low to moderate risk of bias. There was no publication bias in the meta-analysis. In conclusion, these RCTs provide scientific evidence that supports the efficacy of turmeric extract (about 1000 mg/day of curcumin) in the treatment of arthritis. However, the total number of RCTs included in the analysis, the total sample size, and the methodological quality of the primary studies were not sufficient to draw definitive conclusions. Thus, more rigorous and larger studies are needed to confirm the therapeutic efficacy of turmeric for arthritis.

Curcumin: An effective adjunct in patients with statin-associated muscle symptoms?

In spite of the unequivocal efficacy of statins in reducing primary and secondary cardiovascular events, the use of these drugs in a considerable number of patients is limited because of statin intolerance, mainly statin-associated muscle symptoms (SAMS). SAMS encompass a broad spectrum of clinical presentations, including mild muscular aching and other types of myalgias, myopathy with the significant elevation of creatine kinase, and the rare but life-threatening rhabdomyolysis. Among several pathophysiologic mechanisms of SAMS, mitochondrial dysfunction is thought to be one of the main one. Curcumin is the polyphenolic ingredient of Curcuma longa L., which has various pharmacological properties against a vast range of diseases. Curcumin has several mechanisms of actions relevant to the treatment of SAMS. These effects include the capacity to prevent and reduce delayed onset muscle soreness by blocking the nuclear factor inflammatory pathway, attenuation of muscular atrophy, enhancement of muscle fibre regeneration following injury, and analgesic and antioxidant effects. Curcumin can also increase the levels of cyclic adenosine monophosphate, which leads to an increase in the number of mitochondrial DNA duplicates in skeletal muscle cells. Finally, owing to its essential lipid-modifying properties, curcumin might serve as an adjunct to statin therapy in patients with SAMS, allowing for effective lowering of low-density lipoprotein cholesterol and possibly for statin dose reduction. Owing to the paucity of effective treatments, and the safety of curcumin in clinical practice, proof-of-concept trials are recommended to assess the potential benefit of this phytochemical in the treatment of SAMS.

Reflections about Osteoarthritis and Curcuma longa

Osteoarthritis (OA) is a chronic inflammatory degenerative process that affects joints such as the hands, hips, shoulders, feet, spine, and especially knees in millions of people worldwide. Some authors have shown that Curcuma longa components may exhibit benefic effects in the treatment of degenerative diseases as OA. This plant belongs to the family Zingiberaceae and it is popularly known as turmeric or saffron. This review intended to perform a retrospective search to identify studies involving humans and animal models. This review was based on articles linking OA and C. longa. Databases as Medline, Science Direct, and Lilacs were consulted and a retrospective search was carried out in order to identify studies involving humans and animal models. The curcuminoids from C. longa exhibit actions at different locations in the pathogenesis of OA once it may play an important role as anti-inflammatory, down-regulating enzymes as phospholipase A2, cyclooxygenase-2, and lipoxygenases, and reducing tumor necrosis factor-alpha-and interleukins such as interleukin-1β (IL-1β), IL-6, and IL-8. They also act as inducer of apoptosis in synoviocytes, decreasing the inflammation process and may also reduce the synthesis of reactive oxygen species. For these reasons, new pharmaceutical technology and pharmacological studies should be proposed to determine the dose, the best delivery vehicle, pharmaceutical formulation and route of administration of this plant so its use as an adjunct in the treatment of OA may become a reality in clinical practice.

The spice for joint inflammation: anti-inflammatory role of curcumin in treating osteoarthritis

Osteoarthritis is a degenerative disease of the joint affecting aging populations worldwide. It has an underlying inflammatory cause, which contributes to the loss of chondrocytes, leading to diminished cartilage layer at the affected joints. Compounds with anti-inflammatory properties are potential treatment agents for osteoarthritis. Curcumin derived from Curcuma species is an anti-inflammatory compound as such. This review aims to summarize the antiosteoarthritic effects of curcumin derived from clinical and preclinical studies. Many clinical trials have been conducted to determine the effectiveness of curcumin in osteoarthritic patients. Extracts of Curcuma species, curcuminoids and enhanced curcumin, were used in these studies. Patients with osteoarthritis showed improvement in pain, physical function, and quality of life after taking curcumin. They also reported reduced concomitant usage of analgesics and side effects during treatment. In vitro studies demonstrated that curcumin could prevent the apoptosis of chondrocytes, suppress the release of proteoglycans and metal metalloproteases and expression of cyclooxygenase, prostaglandin E-2, and inflammatory cytokines in chondrocytes. These were achieved by blocking the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) system in the chondrocytes, by preventing the activation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha, phosphorylation, and translocation of the p65 subunit of NF-κB complexes into the nucleus. In conclusion, curcumin is a potential candidate for the treatment of osteoarthritis. More well-planned randomized control trials and enhanced curcumin formulation are required to justify the use of curcumin in treating osteoarthritis.

Efficacy of Curcuma for Treatment of Osteoarthritis

The objective of this review is to identify, summarize, and evaluate clinical trials to determine the efficacy of curcuma in the treatment of osteoarthritis. A literature search for interventional studies assessing efficacy of curcuma was performed, resulting in 8 clinical trials. Studies have investigated the effect of curcuma on pain, stiffness, and functionality in patients with knee osteoarthritis. Curcuma-containing products consistently demonstrated statistically significant improvement in osteoarthritis-related endpoints compared with placebo, with one exception. When compared with active control, curcuma-containing products were similar to nonsteroidal anti-inflammatory drugs, and potentially to glucosamine. While statistical significant differences in outcomes were reported in a majority of studies, the small magnitude of effect and presence of major study limitations hinder application of these results. Further rigorous studies are needed prior to recommending curcuma as an effective alternative therapy for knee osteoarthritis.

Benefits of antioxidant supplements for knee osteoarthritis: rationale and reality

Arthritis causes disability due to pain and inflammation in joints. There are many forms of arthritis, one of which is osteoarthritis whose prevalence increases with age. It occurs in various joints including hip, knee and hand with knee osteoarthritis being more prevalent. There is no cure for it. The management strategies include exercise, glucosamine plus chondroitin sulfate and NSAIDs. In vitro and animal studies provide a rationale for the use of antioxidant supplements for its management. This review assesses the reality of the benefits of antioxidant supplements in the management of knee osteoarthritis. Several difficulties were encountered in examining this issue: poorly conducted studies, a lack of uniformity in disease definition and diagnosis, and muddling of conclusions from attempts to isolate the efficacious molecules. The antioxidant supplements with most evidence for benefit for pain relief and function in knee osteoarthritis were based on curcumin and avocado-soya bean unsaponifiables. Boswellia and some herbs used in Ayurvedic and Chinese medicine may also be useful. The benefits of cuisines with the appropriate antioxidants should be assessed because they may be more economical and easier to incorporate into the lifestyle.

Analgesic Efficacy and Safety of Curcuminoids in Clinical Practice: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Curcuminoids are natural products with potent anti-inflammatory and antioxidant properties. There have been a number of reports on the analgesic effects of curcuminoids in clinical trials, yet data have not been fully conclusive.

OBJECTIVES

To provide the highest level of evidence on the efficacy of curcuminoids in patients with painful conditions through meta-analysis of data from randomized controlled trials (RCTs).

METHODS

A systematic review and meta-analysis was conducted using data reported by RCTs. The primary efficacy measure was pain intensity or algofunctional status. Treatment effect was summarized with standardized mean difference (SMD) calculated from differences in means of pain measures between treatment and control groups using a random-effects model.

RESULTS

A total of eight RCTs met our inclusion criteria that included 606 randomized patients. Curcuminoids were found to significantly reduce pain (SMD: -0.57, 95% CI: -1.11 to -0.03, P = 0.04). This pain-relieving effect was found to be independent of administered dose and duration of treatment with curcuminoids, and was free from publication bias. Curcuminoids were safe and well tolerated in all evaluated RCTs.

CONCLUSION

Curcuminoids supplements may be a safe and effective strategy to improve pain severity, by warranting further rigorously conducted studies to define the long-term efficacy and safety.