Turmeric

Turmeric reached Europe as an imported spice and dyestuff. It appears in an Assyrian herbal of around 600 BCE and is described by Dioscorides ^{31,35Reference 31Bone K · 2013Principles and Practice of PhytotherapyReference 35Swahn JO · 1991The Lore of Spices: Their History and Uses Around the World}.

Modern Western practice uses it chiefly as an anti-inflammatory, especially for the digestive tract. It is given for chronic inflammatory conditions such as irritable bowel syndrome, endometriosis and interstitial cystitis, and alongside cancer treatment. Practitioners use a 1:2 liquid extract or a standardised curcuminoid extract, often combined with black pepper.

In Ayurveda the dried rhizome is used above all as an anti-inflammatory ^{33Reference 33Ammon HP · 1991Pharmacology of Curcuma longa}.

Internally it is classed as a stomachic and a tonic. It is given to purify the blood, improve digestion, and treat fevers, skin conditions and vomiting in pregnancy ^{31Reference 31Bone K · 2013Principles and Practice of Phytotherapy}.

Externally it is used for conjunctivitis, skin infection, sprains, arthritis, haemorrhoids, wounds and eczema, and cosmetically to reduce hair growth ^{31Reference 31Bone K · 2013Principles and Practice of Phytotherapy}.

Turmeric is also a daily food, cooked into fat, and the internal and external remedies use the same powdered rhizome.

Chinese medicine takes two drugs from this plant and treats them as separate entries in the materia medica ^{32Reference 32Hempen CH · 2009A Materia Medica for Chinese Medicine: Plants, Minerals, and Animal Products. (pp}.

Jiang Huang is the rhizome: pungent, bitter and warm, entering the Spleen, Stomach and Liver channels ^{32Reference 32Hempen CH · 2009A Materia Medica for Chinese Medicine: Plants, Minerals, and Animal Products. (pp}. It regulates and moves blood and Qi, descends Qi, dispels wind-damp, breaks blood stasis and relieves pain. It is used for chest and abdominal pain and distension, frozen shoulder, and amenorrhoea from blood stasis ^{31,32Reference 31Bone K · 2013Principles and Practice of PhytotherapyReference 32Hempen CH · 2009A Materia Medica for Chinese Medicine: Plants, Minerals, and Animal Products. (pp}. It is decocted for twenty minutes at 3–10 g, and it is not given in deficiency patterns without signs of blood or Qi stagnation ^{32Reference 32Hempen CH · 2009A Materia Medica for Chinese Medicine: Plants, Minerals, and Animal Products. (pp}.

Yu Jin is the tuberous root: pungent, bitter and aromatic, but cold rather than warm, and entering the Heart, Lung and Liver channels ^{32Reference 32Hempen CH · 2009A Materia Medica for Chinese Medicine: Plants, Minerals, and Animal Products. (pp}. It moves blood and Qi in the same way, and it also cools heat, cools the blood and drains damp-heat. It takes the same indications when the pattern is a hot one, jaundice among them ^{31,32Reference 31Bone K · 2013Principles and Practice of PhytotherapyReference 32Hempen CH · 2009A Materia Medica for Chinese Medicine: Plants, Minerals, and Animal Products. (pp}. The dose and decoction are the same, and it is contraindicated in yin deficiency after blood loss ^{32Reference 32Hempen CH · 2009A Materia Medica for Chinese Medicine: Plants, Minerals, and Animal Products. (pp}.

Both drugs are contraindicated in pregnancy ^{32Reference 32Hempen CH · 2009A Materia Medica for Chinese Medicine: Plants, Minerals, and Animal Products. (pp}.

A 2024 meta-analysis of meta-analyses pooled 11 prior ones and found curcumin reduced pain on the visual analogue scale and improved WOMAC pain, function and stiffness in knee osteoarthritis ^{3Reference 3Bideshki MV et al. · 2024Meta-analysisThe efficacy of curcumin in relieving osteoarthritis: a meta-analysis of meta-analysesView study →}.

An underlying review of 15 RCTs (1,621 participants) found curcumin and Curcuma longa extract lowered pain and improved function against placebo, with adverse-event rates comparable to placebo and lower than NSAIDs, and recommended a course of more than 12 weeks ^{2Reference 2Zeng L et al. · 2021Meta-analysisThe efficacy and safety of Curcuma longa extract and curcumin supplements on osteoarthritis — systematic review and meta-analysis of randomized controlled trialsView study →}.

A multicentre non-inferiority RCT in 367 people found 1,500 mg a day of a standardised Curcuma domestica extract (an older name for C. longa ^{39Reference 39Wu et al. · 2000Curcuma longa Linnaeus — species description and distribution — floraView study →}) as effective as 1,200 mg a day of ibuprofen over 4 weeks, with fewer gastrointestinal complaints ^{4Reference 4Kuptniratsaikul V et al. · 2014RCTEfficacy and safety of Curcuma domestica extracts compared with ibuprofen in patients with knee osteoarthritis: a multicenter randomized controlled studyView study →}.

A 2025 Bayesian network meta-analysis placed curcumin among the effective, well-tolerated options for function ^{26Reference 26Zhang Y et al. · 2025Meta-analysisComparative Effectiveness of Nutritional Supplements in the Treatment of Knee Osteoarthritis — a systematic review and Bayesian network meta-analysis of randomized controlled trialsView study →}.

Gap: trials use varied standardized extracts and doses, follow-up is mostly ≤12 weeks, and heterogeneity between studies is high — long-term structural (not just symptomatic) benefit is unproven.

A GRADE-assessed dose-response meta-analysis of 66 RCTs found turmeric/curcumin reduced C-reactive protein (−0.58 mg/L), TNF-α (−3.48 pg/mL) and IL-6 (−1.31 pg/mL), with no change in IL-1β ^{5Reference 5Dehzad MJ et al. · 2023Meta-analysisAntioxidant and anti-inflammatory effects of curcumin/turmeric supplementation in adults: a GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trialsView study →}.

A dedicated CRP meta-analysis confirmed reductions in both CRP and hs-CRP. The effect on hs-CRP was significant in trials at 1,000 mg a day or less and in those lasting 10 weeks or less ^{6Reference 6Gorabi AM et al. · 2022Meta-analysisEffect of curcumin on C-reactive protein as a biomarker of systemic inflammation: an updated meta-analysis of randomized controlled trialsView study →}.

In the 103-RCT overview, CRP was one of only four outcomes rated high certainty ^{1Reference 1Jafari A et al. · 2024Meta-analysisCurcumin on Human Health: A Comprehensive Systematic Review and Meta-Analysis of 103 Randomized Controlled TrialsView study →}.

In cell studies curcumin inhibits arachidonic-acid metabolism and suppresses TNF-induced NF-κB signalling.

These are circulating-biomarker changes. Whether the magnitude translates into symptom or hard-outcome benefit outside arthritis is largely untested, and between-study heterogeneity is substantial.

In a 9-month double-blind RCT in 240 adults with prediabetes, 16.4% of the placebo group progressed to type 2 diabetes against none on curcumin. The curcumin group also had better β-cell function and lower insulin resistance ^{7Reference 7Chuengsamarn S et al. · 2012RCTCurcumin extract for prevention of type 2 diabetes — randomized, double-blind, placebo-controlled trialView study →}.

A 2024 meta-analysis of 18 RCTs (1,382 patients with T2DM) found curcumin lowered fasting glucose by ~11.5 mg/dL and HbA1c by ~0.54% ^{8Reference 8Mokgalaboni K et al. · 2024RCTCurcumin Attenuates Hyperglycemia and Inflammation in Type 2 Diabetes Mellitus: Quantitative Analysis of Randomized Controlled TrialsView study →}.

Fasting blood sugar was rated high certainty in the 103-RCT overview ^{1Reference 1Jafari A et al. · 2024Meta-analysisCurcumin on Human Health: A Comprehensive Systematic Review and Meta-Analysis of 103 Randomized Controlled TrialsView study →}.

An earlier glycaemic meta-analysis, Poolsup 2019, has been retracted ^{38Reference 38PLOS ONE Editors · 2020Meta-analysisRetraction: Effects of curcumin on glycemic control and lipid profile in prediabetes and type 2 diabetes mellitus: a systematic review and meta-analysis (Poolsup N, Suksomboon N, Kurnianta PDM, Deawjaroen K, 2019)View study →}.

Gap: effect sizes are modest and formulation-dependent; curcumin is an adjunct, not a replacement for glucose-lowering therapy, and the prevention finding rests on a single (if large) trial.

The 66-RCT GRADE meta-analysis found turmeric/curcumin significantly raised total antioxidant capacity, reduced malondialdehyde (a lipid-peroxidation marker) and increased superoxide dismutase activity ^{5Reference 5Dehzad MJ et al. · 2023Meta-analysisAntioxidant and anti-inflammatory effects of curcumin/turmeric supplementation in adults: a GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trialsView study →}.

A separate 15-RCT meta-analysis similarly reported reduced MDA and hs-CRP, though effects on TNF-α and SOD were not significant there ^{27Reference 27Tabrizi R et al. · 2019Meta-analysisThe effects of curcumin-containing supplements on biomarkers of inflammation and oxidative stress: a systematic review and meta-analysis of randomized controlled trialsView study →}.

In cell studies the curcuminoids reduce lipid peroxidation and activate the Nrf2/ARE cytoprotective pathway.

The endpoints are surrogate oxidative-stress markers with high heterogeneity, and no durable clinical benefit has been isolated from the antioxidant effect specifically.

A GRADE-assessed dose-response meta-analysis of 64 RCTs found turmeric/curcumin produced statistically significant but small improvements in total cholesterol (−3.99 mg/dL), triglycerides (−6.69 mg/dL), LDL-C (−4.89 mg/dL) and HDL-C (+1.80 mg/dL), with no effect on apolipoproteins A or B ^{9Reference 9Dehzad MJ et al. · 2023Meta-analysisEffects of curcumin/turmeric supplementation on lipid profile: a GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trialsView study →}.

In metabolic syndrome, curcumin taken with piperine, which raises curcumin absorption ^{18Reference 18Shoba G et al. · 1998Clinical trialInfluence of piperine on the pharmacokinetics of curcumin in animals and human volunteersView study →}, lowered total cholesterol and LDL-C but not triglycerides ^{28Reference 28Hosseini H et al. · 2023Meta-analysisA systematic review and meta-analysis of randomized controlled trials investigating the effect of the curcumin and piperine combination on lipid profile in patients with metabolic syndromeView study →}.

Gap: the authors graded the certainty low to very low; the absolute changes are small, heterogeneity is high, and trials did not standardize potency, purity or co-ingestion with food.

As an adjunct to standard 5-ASA therapy in mild-to-moderate ulcerative colitis, a meta-analysis of 3 RCTs (142 patients) found curcumin plus mesalamine markedly increased the odds of clinical remission versus mesalamine alone (pooled OR 6.78) ^{11Reference 11Iqbal U et al. · 2018Meta-analysisUse of Curcumin in Achieving Clinical and Endoscopic Remission in Ulcerative Colitis: a systematic review and meta-analysis of randomized controlled trialsView study →}.

In a 2024 double-blind RCT in 42 patients with active UC, a curcumin–QingDai (indigo) combination at 3 g a day met the trial’s main week-8 outcome in 43% of patients, against 8% on placebo ^{12Reference 12Ben-Horin S et al. · 2024RCTCurcumin-QingDai Combination for Patients With Active Ulcerative Colitis: a randomized, double-blinded, placebo-controlled trialView study →}.

Gap: trials are few and small, formulations differ, and the QingDai combination raises its own safety questions (indigo has been linked to pulmonary hypertension) — curcumin is adjunctive, not a mesalamine substitute.

A meta-analysis of 6 RCTs (377 patients) found curcumin significantly reduced depressive symptoms versus placebo (Hamilton Rating Scale SMD −0.34), with anti-anxiety benefit in 3 trials and no reported adverse events ^{10Reference 10Ng QX et al. · 2017Meta-analysisClinical Use of Curcumin in Depression: a meta-analysis of clinical trialsView study →}. Later meta-reviews of psychiatric phytoceuticals echo a modest antidepressant effect, generally as an adjunct to standard antidepressants ^{29Reference 29Sarris J et al. · 2021Meta-analysisPlant-based Medicines (Phytoceuticals) in the Treatment of Psychiatric Disorders: a meta-review of meta-analyses of randomized controlled trialsView study →}.

The trials are short (4–8 weeks) and small, several used adjunctive designs, and the pooled effect is modest; long-term and monotherapy efficacy are unestablished.

A meta-analysis of 4 RCTs (229 patients) found curcumin lowered LDL-C, triglycerides, fasting glucose, HOMA-IR, weight and AST versus placebo in non-alcoholic fatty liver disease ^{13Reference 13Wei Z et al. · 2019Meta-analysisThe effects of curcumin on the metabolic parameters of non-alcoholic fatty liver disease: a meta-analysis of randomized controlled trialsView study →}.

In a 24-week double-blind RCT in 80 people, 500 mg a day of curcumin reduced hepatic fat content, alongside changes in gut-microbiota-dependent bile-acid metabolism and TGR5/GLP-1 signalling ^{14Reference 14Chen Y et al et al. · 2024RCTCurcumin supplementation alleviates hepatic fat content associated with modulation of gut microbiota-dependent bile acid metabolism in NAFL — randomized controlled trialView study →}.

Broader polyphenol systematic reviews consistently place turmeric/curcumin among the agents that lower liver enzymes and improve the metabolic profile in NAFLD ^{30Reference 30Ranneh Y et al. · 2024Systematic reviewPolyphenol Intervention Ameliorates Non-Alcoholic Fatty Liver Disease: an updated comprehensive systematic reviewView study →}.

The RCTs are small and short, imaging-confirmed steatosis reduction comes from limited trials, and histological fibrosis benefit is untested.

A systematic review and meta-analysis of six studies with 539 patients found curcumin supplementation improved disease activity in rheumatoid arthritis. DAS28, ESR, and tender and swollen joint counts all fell against controls ^{15Reference 15Kou H et al. · 2023Meta-analysisEffect of curcumin on rheumatoid arthritis: a systematic review and meta-analysisView study →}.

The trials are few and small with wide confidence intervals, and the authors call for large RCTs.

An 18-month double-blind, placebo-controlled RCT in 40 adults without dementia tested a bioavailable curcumin (Theracurmin, 90 mg twice daily). It found significant improvements in memory and attention against placebo, with FDDNP-PET imaging suggesting less amyloid and tau build-up in the amygdala and hypothalamus ^{16Reference 16Small GW et al. · 2018RCTMemory and Brain Amyloid and Tau Effects of a Bioavailable Form of Curcumin in Non-Demented Adults: a double-blind, placebo-controlled 18-month randomized controlled trialView study →}.

Gap: a single small trial of one proprietary formulation; the imaging findings are exploratory, and no larger replication or clinical-endpoint (dementia incidence) trial exists.

Preclinical work on curcumin is extensive. It acts on many carcinogenic pathways in cell and animal studies, and is discussed as a candidate chemopreventive agent for colorectal cancer ^{17Reference 17Patel VB et al. · 2010In vitroColorectal cancer: chemopreventive role of curcumin and resveratrol — review of mechanisms (in vitro and animal model evidence)View study →}. Synthetic curcumin analogues have been designed as candidate anti-prostate-cancer agents ^{37Reference 37Lin L et al. · 2006Antitumor agents 250: design and synthesis of new curcumin analogues as potential anti-prostate cancer agents}.

Human work to date is early-phase. A dose-escalation study of Theracurmin alongside gemcitabine-based chemotherapy in pancreatic or biliary tract cancer established tolerability and measurable plasma curcumin, but was not designed to show efficacy ^{23Reference 23Kanai M et al. · 2013A phase I study investigating the safety and pharmacokinetics of highly bioavailable curcumin (Theracurmin) in cancer patients on gemcitabine-based chemotherapyView study →}.

Gap: there is no phase III (or even robust phase II efficacy) trial showing curcumin changes cancer outcomes; low systemic bioavailability is a fundamental obstacle, and all current human data are safety/pharmacokinetic rather than outcome trials.

Liver. An Italian series described seven cases of acute hepatitis in Tuscany, all after high-dose, high-bioavailability curcumin products. A review of the literature found 23 more cases. Most people were also taking at least one other medicine, and most recovered after stopping ^{20Reference 20Lombardi N et al. · 2021Systematic reviewAcute liver injury following turmeric use in Tuscany: case series and systematic reviewView study →}.

Gallbladder. Because curcumin can stimulate bile flow, concentrated products should be used cautiously by people with bile-duct obstruction or active gallstones.

Anticoagulant and antiplatelet drugs. In a clinical study, 10 days of a curcumin phytosome (Meriva) did not change bleeding time in people taking aspirin, ticlopidine or clopidogrel, or INR in people taking warfarin or dabigatran ^{19Reference 19Hu S et al. · 2018Curcumin phytosome (Meriva) does not alter the antiplatelet or anticoagulant effect of common agents — clinical non-interaction studyView study →}. Care is still sensible around surgery.

Drug metabolism. Curcumin inhibits CYP3A4 in laboratory tests, but this has not carried over to people. In healthy volunteers, a curcumin–piperine extract did not change blood levels of midazolam, flurbiprofen or paracetamol, the test drugs for CYP3A, CYP2C9 and the conjugating enzymes ^{42Reference 42Volak LP et al. · 2013Effect of a herbal extract containing curcumin and piperine on midazolam, flurbiprofen and paracetamol (acetaminophen) pharmacokinetics in healthy volunteersView study →}.

Two weeks of curcumin at 1 g a day did slow CYP1A2 in healthy men, by about 29%, so drugs cleared by that enzyme may reach somewhat higher levels ^{43Reference 43Chen Y et al. · 2010Plant polyphenol curcumin significantly affects CYP1A2 and CYP2A6 activity in healthy, male Chinese volunteersView study →}.

Curcumin also blocks the drug transporter BCRP. In healthy volunteers, a 2 g dose roughly tripled blood levels of sulfasalazine, a drug carried by that transporter ^{44Reference 44Kusuhara H et al. · 2012AnimalPharmacokinetic interaction study of sulphasalazine in healthy subjects and the impact of curcumin as an in vivo inhibitor of BCRPView study →}. Studies of the P-glycoprotein substrate talinolol have given conflicting results.

Animal toxicity. The oral LD50 of a petroleum-ether extract is about 12.2 g/kg in rats, and repeated high-dose and long-term animal studies have found low toxicity ^{31Reference 31Bone K · 2013Principles and Practice of Phytotherapy}.