Turmeric

Authors:

Jyoti Mehta, Shivkanya Fuloria

Findings:

This comprehensive review synthesizes traditional uses and scientific evidence for *Curcuma longa* (turmeric) and its main active constituent, curcumin, detailing their broad pharmacological activities including antioxidant, anti-inflammatory, neuroprotective, anticancer, hepatoprotective, cardioprotective, immunomodulatory, antimicrobial, and antidepressant properties. While highlighting promising preclinical data and extensive traditional use, the review underscores the current 'lack of supportive evidence especially from clinical trials on the adjunct use of C. longa and curcumin.' It also discusses challenges such as curcumin's low bioavailability and efforts to overcome this, like nanoformulations, calling for further preclinical and clinical investigations.

Participants:

This review covers studies involving a wide range of participants: human subjects (including healthy individuals and patients with various conditions such as diabetes, irritable bowel syndrome, inflammatory bowel disease, cancer, depression, kidney transplants, periodontitis, end-stage renal disease, and overweight individuals), various animal models (mice, rats, guinea pigs, zebrafish, chicks, rabbits), and in vitro systems (including diverse cell lines like human cancer cells, immune cells, endothelial cells, hepatocytes, and microbial strains like bacteria and fungi).

Dosage:

The review cites various dosages from numerous studies, for example: oral intake of 500 mg/day curcumin for a week for cardiovascular effects; 480 mg of curcumin and 20 mg of quercetin per capsule for kidney transplant patients; consumption of 6 g of *C. longa* in a study on postprandial glucose; administration of *C. longa* extract at a dose of 200 mg/kg in rats for neuroprotection; an oral dosage of 500 mg of curcumin with 5 mg of piperine for tropical pancreatitis; 600 milligrams of curcumin five times a day for 12 weeks for peptic ulcers. Clinical trials referenced in the text (e.g., via figures or tables) report curcumin doses up to 8-12 g/day (e.g., 'Up to 8 g/day for 3 months' from Cheng et al., 2001; 'Up to 12 g' from Vareed et al., 2008).

Study Quality Assessment:

This is a review article published in Frontiers in Pharmacology (2022), a peer-reviewed journal. It synthesizes information from various sources, citing preclinical studies (in vitro, in vivo animal models), and clinical studies (human trials, including randomized controlled trials like a 'randomized, multicenter, double-blind, placebo-controlled trial' by Hanai et al., 2006, pilot studies, and other human trials). The review itself explicitly states a 'lack of supportive evidence especially from clinical trials on the adjunct use of C. longa and curcumin,' prompting further research. The article includes author contributions, funding information ('funded by the Deanship of Scientific Research through Research Group (Small) (project number RGP.1/330/42) of the King Khalid University'), and a conflict of interest statement ('The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The handling editor declared a past co-authorship with one of the authors MS.'). The article was also 'Edited by' and 'Reviewed by' named individuals.

All Effects:

Authors:

Euan MacLennan, Marion Mackonochie, Simon Mills, Vivien Rolfe

Findings:

This meta-review of 65 systematic reviews found moderate quality evidence supporting the use of turmeric/curcumin for relieving pain and improving physical function in osteoarthritis. There was low quality evidence for its use in metabolic syndrome, inflammatory conditions, and other diseases. The data from the systematic reviews suggested that whole turmeric and bioavailability-enhanced preparations may be useful for different conditions. Turmeric was reported as safe and well tolerated.

Participants:

The meta-review analyzed systematic reviews (SRs) of studies on humans with various health conditions (covering 20 disease topics) who used oral turmeric products.

Dosage:

The SR data suggested that whole turmeric and bioavailability-enhanced preparations may be useful for different conditions; specific dosages or regimens are not detailed in the provided abstract.

Study Quality Assessment:

This is a meta-review of 65 systematic reviews (SRs). The SRs included evaluated the use of oral turmeric products versus a placebo or standard care. Two reviewers screened the SRs for inclusion, extracted, and analyzed the data. Review quality was assessed by R-AMSTAR, and the quality of evidence was expressed according to GRADE. The review was registered on PROSPERO (CRD42018115813). A declaration of competing interest states that all four authors work for Pukka Herbs Ltd., a company that sells turmeric products, but the paper is a broad review of turmeric and does not reference their specific products.

All Effects:

Authors:

Javad Sharifi-Rad

Findings:

This review provides an in-depth discussion on the bioactive effects and safety profiles of turmeric and its major compound curcumin for various applications, including food, pharmaceutical, biotechnological, and medicinal. It highlights curcumin's antioxidant, anti-inflammatory, neuroprotective, anticancer, hepatoprotective, and cardioprotective effects, while also addressing its bioavailability, bioefficacy, safety features, side effects, quality parameters, and strategies to overcome limitations like instability and low bioavailability.

Participants:

The review synthesizes information from studies involving in vitro models (e.g., various human cancer cell lines like MCF-7, HNSCC, Patu8988, PANC1, BxPC3, HCT116, SW480, human lung cancer cells, mouse prostate cancer cells TRAMP-C1; primary hippocampus neurons), animal models (e.g., rats, mice including specific strains like Sprague–Dawley, Wistar, Tg2576, nude BALB/c, Swiss albino rats), and human participants (healthy volunteers and patients in clinical trials, e.g., 25 patients with high risk of cancer or pre-malignant lesions, patients with advanced pancreatic cancers, subjects in dose escalation studies).

Dosage:

The review compiles dosage information from various studies. For nutritional purposes in food, curcumin is applied at 5-500 mg/kg. Animal studies report a wide range of doses (e.g., in rats: 5-300 mg/kg b.w. daily, single doses like 200 mg/kg, or 100 mg/kg P.V.; in mice: 150 mg/kg/day for 4 weeks, 160-5000 mg/mL for 6 months). In vitro studies use concentrations typically in µM (e.g., 2.5-50 µM) or µg/mL ranges. Human clinical trials and safety studies mention doses from 1.125 mg/day up to 12 g/day (e.g., 0.45-3.6 g/day for 1-4 months; up to 8 g/day for 3 months found safe, but >8g/day could be intolerable). The Acceptable Daily Intake (ADI) for curcumin was established by JECFA as 0-3 mg/kg b.w.

Study Quality Assessment:

This is a review article published in 'Frontiers in Pharmacology', an open-access journal (CC BY license), and peer-reviewed (reviewers mentioned as Ren-You Gan and Michal Glensk). It synthesizes evidence from numerous preclinical (in vitro, in vivo animal models) and clinical studies (including phase I clinical trials, randomized double-blind placebo-controlled trials). The review discusses limitations such as curcumin's low bioavailability and instability, and notes the need for more extensive, high-quality clinical trials. Funding sources (CONICYT PIA/APOYO CCTE AFB170007, FCT-Portugal, NORTE2020) are acknowledged, and a conflict of interest statement is provided, noting employment of two authors by Aromatic Plant Research Center and declaring no other commercial/financial conflicts for the remaining authors.

All Effects:

Findings:

Curcumin, a component of turmeric, possesses antioxidant and anti-inflammatory properties. Its antioxidant action is considered vital against chronic pathological complications such as cancer, atherosclerosis, and neurodegenerative diseases by combating free-radical-mediated damage. The anti-inflammatory effect of curcumin is likely mediated through its ability to inhibit cyclooxygenase-2 (COX-2), lipoxygenase (LOX), and inducible nitric oxide synthase (iNOS), and it is anticipated to exert chemopreventive effects on carcinogenesis.

Study Quality Assessment:

Publication type: Review

All Effects:

Findings:

This systematic review of 12 studies found that curcumin supplementation leads to statistically significant improvements in cognitive performance (particularly working memory) and serum biomarkers in adults aged 18 and older. These benefits were observed across diverse groups, including non-demented healthy adults, those with metabolic disorders, pre-existing cognitive decline, mood disorders, and chemotherapy-induced cognitive impairment. The review notes that effects are dose-specific, often require bioavailable curcumin formulations, and that gastrointestinal side effects can occur.

Participants:

Systematic review of studies involving adults 18 years and older, both with and without neurocognitive disorders. Specific populations from included studies comprised: non-demented healthy adults, adults at risk of or with metabolic disorders (e.g., obesity, pre-diabetes), adults with pre-existing cognitive impairment or dementia, adults with major depressive disorder, and adults with chemotherapy-induced cognitive impairment.

Dosage:

The systematic review analyzed studies using varied curcumin dosages and formulations. Examples include: 80 mg/day lipidated curcumin extract, 400 mg/day Longvida® (containing 80 mg curcumin), 1500 mg/day Biocurcuma™, 90 mg Theracurmin® twice daily, 160 mg/day curcumin, 1g turmeric, 180 mg/day curcumin, 400 mg CurQfen® (CGM) twice daily, 2 g/day or 4 g/day Curcumin C3 Complex®, 500 mg curcumin twice daily, and 240-400 mg curcumin extract intermittently. The review highlights that therapeutic effects are dose-dependent and emphasizes the importance of using bioavailable forms of curcumin.

Study Quality Assessment:

Systematic review following Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Searched PubMed, Science Direct, Google Scholar, Cochrane Library, and Multidisciplinary Digital Publishing Institute (MDPI). Screened 1,284 studies, ultimately including 12 studies (11 randomized controlled trials (RCTs) and 1 cohort study) published within the last 20 years. Quality assessment was performed using the revised Cochrane Risk-of-Bias tool (RoB2) for RCTs and the Newcastle-Ottawa Scale for cohort studies. Study limitations mentioned include variable population characteristics across studies and few trials employing intention-to-treat analysis.

All Effects: