A reference work, not a recommendation to use: this profile describes mechanism and evidence and does not replace medical advice. The claims come from marketing and forums and are tested here, not endorsed.

Claims checked

  • Relieves joint pain and inflammation

    Small benefit

    Recovery & healing · Patients: knee osteoarthritis · Human, randomised

    A review of eleven meta-analyses finds better pain and function scores [14]; the best-known RCT shows 9.1 mm less pain on the 100-mm scale with no effect on joint inflammation on MRI, co-funded by a company [15].

  • Lowers inflammatory markers and blood lipids in healthy people

    No benefit

    Heart & blood vessels · healthy (slightly elevated cholesterol and CRP) · Human, randomised small studiesEvery study behind this level and result had fewer than 100 participants. Small studies report larger effects on average than large ones, so the result is less certain.

    In a placebo-controlled crossover study with 42 participants, blood lipids, inflammatory markers, and glucose values remained unchanged despite measurable curcuminoids in the blood [13]; further studies in healthy people were not examined here.

  • Better mental performance

    Mixed results

    Cognition & focus · healthy (cognitive aging; individual populations not examined) · Human, randomised

    Meta-analysis of ten human studies (531 participants): no overall effect, benefits in subgroups for working memory and processing speed; adverse events more frequent than with placebo [16].

small studies: Every study behind this level and result had fewer than 100 participants. Small studies report larger effects on average than large ones, so the result is less certain.

Mechanism of action

Evidence map: Curcumin

Each line stands for a published finding; line style and color show where it comes from. The filter hides weaker evidence levels. Sources: see references.

Curcumin makes up up to about 5% of the turmeric root. A medicinal chemistry review classifies it as a PAINS (pan-assay interference compound) and IMPS (invalid metabolic panacea): it binds covalently to thiol groups of proteins (Michael acceptor), forms metal complexes, is redox-active, fluoresces in the measurement range of many cell assays, decomposes in aqueous solution, and from 10 to 20 µM forms colloidal aggregates that inhibit enzymes nonspecifically; with detergent, the inhibition of several enzymes largely disappeared [1]. The many targets described in cell experiments (e.g., NF-κB, COX-2) are therefore not evidence of an effect. The authors put the oral bioavailability at below 1% and found no successful double-blind, placebo-controlled trial up to 2017 [1].

The human pharmacokinetic data confirm this. In a dose escalation with 24 healthy people, curcumin was detectable in serum only at the two highest, very high single doses and only in small amounts in two people [2]. In 12 healthy people, only one person had measurable free curcumin at any time point, whereas all had glucuronides and sulfates (ratio 1.92 : 1; modeled half-life of the conjugates 6.8 hours) [3]. In cancer patients, curcumin and its conjugates in plasma were in the range of 10 nmol/l [4], that is, about three orders of magnitude below the concentrations of typical cell experiments. The causes are low water solubility and rapid glucuronidation and sulfation in the intestinal wall and liver [1][3][5].

Piperine from black pepper inhibits glucuronidation. In the 1998 study that advertising usually refers to, curcumin alone was barely or not at all detectable in serum; with piperine, bioavailability rose by 2000% [5]. The increase starts from a baseline near zero, the sample size is not stated in the abstract, and clearly higher levels appeared only 0.25 to 1 hour after administration. In addition, in cell and microsome experiments, piperine inhibits CYP3A4 and P-glycoprotein [6]. Newer formulations raised the area under the curve of total curcuminoids in small crossover studies: a lecithin complex (phytosome) about 29-fold, with only phase 2 metabolites detectable and the concentrations remaining below those needed for anti-inflammatory targets [7]; liquid micelles 185-fold in 23 healthy people, more strongly in women than in men [8]; a colloidal nanoparticle preparation 27-fold in a manufacturer’s study [9]. In a comparison of four products, a formulation with turmeric oil (turmerones) reached only 1.3 times, the phytosome 7.9 times, and a carrier matrix 45.9 times; the study was funded by the manufacturer of the carrier matrix [10]. The same research group later found 39 times for a γ-cyclodextrin formulation, this time funded by its manufacturer [11].

Almost all of these comparisons enzymatically cleave the conjugates before measurement and thus report total curcumin; how much free curcumin arrives in the blood remains open, and the factors are not comparable because of different comparison products and analytes [10][11][12]. This criticism, too, comes from authors with consulting contracts in the industry [12]. Whether more curcumin in the blood means more effect is questionable: micellar curcumin reached 49 nmol/l in fasting plasma but, in 42 people with slightly elevated cholesterol and CRP, changed neither blood lipids nor inflammatory or glucose values compared with placebo [13]. Clinically, a review of eleven meta-analyses summarizes better pain and function scores in knee osteoarthritis [14]; in the best-known single study, knee pain fell by 9.1 mm on the 100-mm scale compared with placebo, joint inflammation on MRI did not change, and a company co-funded the study [15]. For cognition, a meta-analysis of ten human studies with 531 participants found no overall effect [16]. Rarely, turmeric products cause liver injury, sometimes severe, that is closely linked to the tissue type HLA-B*35:01 [17].

Targets

TargetTypeActionKey dataEvidence
Thiol groups of proteins (Michael addition)OtherBindingcovalent, nonspecific Laboratory[1]
Enzymes in biochemical assays (including AmpC β-lactamase, malate dehydrogenase)EnzymeInhibitorIC50 9–12 µM, with detergent > 30 µM; critical aggregation concentration 10–20 µM (apparent inhibition by aggregates) Laboratory[1]
Prostaglandin E2 formation in blood leukocytes (ex vivo)Signaling pathwayInhibitor−62% and −57% inducible PGE2 (highest level, cancer patients) Human, non-randomised[4]

Effect profile

Which signaling systems the compound affects according to current data. ↑ enhanced, ↓ dampened, ≈ modulated, ○ no effect; dots = evidence level.

  • Dopamineno data
  • Noradrenalineno data
  • Serotoninno data
  • Acetylcholineno data
  • Glutamate · AMPAno data
  • Glutamate · NMDAno data
  • GABAno data
  • Histamineno data
  • Orexinno data
  • Adenosineno data
  • Opioidsno data
  • Melatoninno data
  • Neurotrophinsno data
  • Blood flowno data
  • Nitric oxideno data
  • Energy metabolismno data
  • Insulin · glucoseno effect · Glucose metabolism unchanged under highly bioavailable micellar curcumin (one RCT)[13]
  • Inflammation · oxidativeunclear · PGE2 formation reduced ex vivo (nonrandomized); no effect on inflammatory markers at slightly elevated CRP (RCT); small pain effect in knee osteoarthritis[4][13][14]
  • Stress axisno data
  • Testosterone axisno data
  • Endocannabinoidsno data
  • Autophagy · senescenceno data
  • Immune systemno data
  • Lipid metabolismno data
  • Coagulation · fibrinolysisno data
  • Methylationno data

Routes of administration and bioavailability

How much of a compound reaches the blood or target tissue depends on the route into the body and on the dosage form. All routes of administration explained

  • Oral (swallowed) · Turmeric or curcumin powder (unformulated)

    < 1% (estimate); free curcumin in the blood usually not detectable

    Even after very high single doses, hardly any curcumin in serum [2]; in the blood almost exclusively glucuronides and sulfates [3]; plasma levels in the range of 10 nmol/l [4].[1]

    Human, non-randomised

  • Oral (swallowed) · with piperine

    +2000% compared with curcumin alone (one small study, 1998)

    Piperine inhibits glucuronidation; the increase starts from nearly unmeasurable baseline values and was visible mainly in the first hour [5]. Piperine additionally inhibits CYP3A4 and P-glycoprotein (laboratory) [6].

    Human, non-randomised

  • Oral (swallowed) · Phytosome (lecithin complex)

    ≈ 29-fold (total curcuminoids) or 7.9-fold in another study

    Only phase 2 metabolites detectable, mainly demethoxycurcumin increased; concentrations below those needed for anti-inflammatory targets [7]. In a comparison by another group, only 7.9-fold [10].

    Human, randomised

  • Oral (swallowed) · liquid micelles

    ≈ 185-fold (total curcuminoids, 23 healthy people)

    Randomized crossover study; 277-fold in women, 114-fold in men [8]. Despite measurable levels (49 nmol/l fasting), no effect on blood lipids and inflammatory markers [13].

    Human, randomised

  • Oral (swallowed) · Nanoparticles (colloidal dispersion)

    ≈ 27-fold (manufacturer’s study)

    Area under the curve in humans 27-fold compared with curcumin powder; first author employed by the manufacturer [9].

    Human, non-randomised

  • Oral (swallowed) · Carrier matrix or γ-cyclodextrin

    ≈ 46-fold and 39-fold (total curcuminoids, 12 people each)

    Two crossover studies by the same research group, each funded by the manufacturer of the winning formulation; measured after enzymatic cleavage of the conjugates [10][11].[10][11]

    Human, randomised

  • Oral (swallowed) · with turmeric oil (turmerones)

    ≈ 1.3-fold (total curcuminoids, 12 people)

    In the only direct comparison found here, hardly better than unformulated curcumin [10].

    Human, randomised

Human studies

  • Knee osteoarthritis with joint effusion

    RCT, double-blind, placebo-controlled · Patients: symptomatic knee osteoarthritis with effusion · n = 70 · 12 weeks

    Measured: Knee pain (VAS), effusion volume on MRI

    Result: Pain −9.1 mm compared with placebo (95% CI −17.8 to −0.4); effusion unchanged.[15]

    Human, randomised

  • Umbrella meta-analysis, osteoarthritis

    Meta-analysis of 11 meta-analyses of randomized trials · Patients: knee osteoarthritis

    Measured: VAS, WOMAC

    Result: Significant improvement in pain, function, and stiffness.[14]

    Human, randomised

  • Micellar curcumin in slightly elevated blood lipids

    RCT, double-blind, placebo-controlled, crossover · healthy (slightly elevated cholesterol and CRP) · n = 42 · 2 × 6 weeks

    Measured: Blood lipids, inflammatory, glucose, and liver markers

    Result: Curcuminoids in plasma 49 nmol/l, no differences from placebo.[13]

    Human, randomised

  • Meta-analysis, cognition

    systematic review and meta-analysis (animal and human studies) · healthy (cognitive aging) · n = 531

    Measured: global cognition, subdomains

    Result: No overall effect (SMD 0.14; 95% CI −0.78 to 1.07); working memory SMD 1.01, processing speed SMD 0.37; more adverse events.[16]

    Human, randomised

  • Micelles and micronized powder, pharmacokinetics

    randomized, crossover · healthy · n = 23 · Single doses, 24 hours of measurement

    Measured: Area under the curve of total curcuminoids

    Result: Micelles 185-fold, micronized 9-fold compared with powder; women absorbed more.[8]

    Human, randomised

  • Conjugates in serum

    Pharmacokinetics, randomized allocation to two dose levels · healthy · n = 12 · Single dose, 72 hours of measurement

    Measured: free curcumin, glucuronide, sulfate

    Result: Free curcumin measurable in only one person, conjugates in all.[3]

    Human, non-randomised

  • Dose escalation

    open-label dose escalation · healthy · n = 24 · Single doses

    Measured: Tolerability, curcumin in serum

    Result: Hardly any curcumin in serum; 7 of 24 with mild complaints not dependent on dose.[2]

    Human, non-randomised

  • Comparison of four formulations

    randomized, double-blind, crossover · healthy · n = 12 · Single doses

    Measured: Total curcuminoids after enzymatic cleavage

    Result: Turmerone formulation 1.3-fold, phytosome 7.9-fold, carrier matrix 45.9-fold; funded by the manufacturer of the carrier matrix.[10]

    Human, randomised

Risks and warnings

  • Liver injury

    Ten cases in the US Drug-Induced Liver Injury Network, mostly hepatocellular, five hospitalized, one death from acute liver failure; seven of those affected carried HLA-B*35:01; three of seven products examined also contained piperine [17].

    Human, non-randomised

  • Piperine additive and drug metabolism

    In the laboratory, piperine inhibits CYP3A4 and P-glycoprotein (Ki 36–77 µM) and could thereby raise levels of other drugs [6].

    Laboratory

  • Adverse events

    In a meta-analysis, adverse events occurred more often with curcumin than with placebo [16]; in a dose escalation, 7 of 24 healthy people had mild complaints [2].

    Human, randomised

Interactions

  • Drugs that are metabolized or transported via CYP3A4 or P-glycoprotein (for products with piperine): Inhibition of both systems by piperine in Caco-2 cells and human liver microsomes [6]; clinical significance for curcumin products not studied.

Fact check: common claims

  • partly supported

    “With black pepper, curcumin is absorbed 2000% better”

    The figure comes from a small study from 1998 in which curcumin alone was barely measurable [5]; the factor is therefore unstable and has not been independently confirmed for free curcumin. Three of seven products in liver injury cases contained piperine [17].

  • partly supported

    “New formulations are up to 185 times more bioavailable and therefore work better”

    Higher total curcuminoids in the blood have been shown [7][8][9][10][11], but mostly after enzymatic cleavage, so free curcumin remains unknown [12], and often in manufacturer-funded studies [10][11]. A highly bioavailable micellar form had no effect on blood lipids and inflammation in one RCT [13].

  • not supported

    “Curcumin inhibits NF-κB, COX-2, and dozens of other targets and therefore works against many diseases”

    Curcumin shows all the typical interference effects of PAINS compounds, and many laboratory findings are probably artifacts [1]; the concentrations reached in the blood are in the nanomolar range [4][13].

  • not supported

    “Turmeric oil with turmerones markedly improves absorption”

    In the only direct comparison in humans found here, the turmerone formulation reached only 1.3 times that of unformulated curcumin [10].

  • refuted

    “Turmeric is a spice and therefore completely harmless”

    Turmeric products can rarely cause severe, sometimes fatal liver injury, more often with HLA-B*35:01 [17].

Pharmacokinetics

Absorption
Very low; free curcumin in the blood usually below the detection limit, estimated oral bioavailability below 1% [1][2][3].
Half-life
Modeled half-life of the conjugates 6.8 hours (human) [3].
Metabolism
Rapid glucuronidation and sulfation in the intestinal wall and liver; glucuronide to sulfate 1.92 : 1, no mixed conjugates [3][5].
Entry into the brain
Not verified in humans.

Legal status

Germany
Not verified.
EU
Re-evaluated by EFSA as a food additive (colorant E 100) [18]; status as a food supplement not checked.
USA
Not verified.

Related compounds

Berberinesame class

Open questions

  • How much free, unconjugated curcumin do the various formulations deliver to the blood, measured independently of manufacturers?
  • Do the glucuronides and sulfates themselves act, or are they cleaved back in tissue?
  • Can the small pain effect in knee osteoarthritis be confirmed in large, independently funded studies?
  • Does the risk of liver injury rise with more bioavailable or piperine-containing products?

References

  1. Nelson KM, Dahlin JL, Bisson J, Graham J, Pauli GF, Walters MA. The essential medicinal chemistry of curcumin. J Med Chem. 2017;60(5):1620–37. doi:10.1021/acs.jmedchem.6b00975 · PubMed
  2. Lao CD, Ruffin MT 4th, Normolle D, Heath DD, Murray SI, Bailey JM, et al. Dose escalation of a curcuminoid formulation. BMC Complement Altern Med. 2006;6:10. doi:10.1186/1472-6882-6-10 · PubMed
  3. Vareed SK, Kakarala M, Ruffin MT, Crowell JA, Normolle DP, Djuric Z, et al. Pharmacokinetics of curcumin conjugate metabolites in healthy human subjects. Cancer Epidemiol Biomarkers Prev. 2008;17(6):1411–7. doi:10.1158/1055-9965.EPI-07-2693 · PubMed
  4. Sharma RA, Euden SA, Platton SL, Cooke DN, Shafayat A, Hewitt HR, et al. Phase I clinical trial of oral curcumin: biomarkers of systemic activity and compliance. Clin Cancer Res. 2004;10(20):6847–54. doi:10.1158/1078-0432.CCR-04-0744 · PubMed
  5. Shoba G, Joy D, Joseph T, Majeed M, Rajendran R, Srinivas PS. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med. 1998;64(4):353–6. doi:10.1055/s-2006-957450 · PubMed
  6. Bhardwaj RK, Glaeser H, Becquemont L, Klotz U, Gupta SK, Fromm MF. Piperine, a major constituent of black pepper, inhibits human P-glycoprotein and CYP3A4. J Pharmacol Exp Ther. 2002;302(2):645–50. doi:10.1124/jpet.102.034728 · PubMed
  7. Cuomo J, Appendino G, Dern AS, Schneider E, McKinnon TP, Brown MJ, et al. Comparative absorption of a standardized curcuminoid mixture and its lecithin formulation. J Nat Prod. 2011;74(4):664–9. doi:10.1021/np1007262 · PubMed
  8. Schiborr C, Kocher A, Behnam D, Jandasek J, Toelstede S, Frank J. The oral bioavailability of curcumin from micronized powder and liquid micelles is significantly increased in healthy humans and differs between sexes. Mol Nutr Food Res. 2014;58(3):516–27. doi:10.1002/mnfr.201300724 · PubMed
  9. Sasaki H, Sunagawa Y, Takahashi K, Imaizumi A, Fukuda H, Hashimoto T, et al. Innovative preparation of curcumin for improved oral bioavailability. Biol Pharm Bull. 2011;34(5):660–5. doi:10.1248/bpb.34.660 · PubMed
  10. Jäger R, Lowery RP, Calvanese AV, Joy JM, Purpura M, Wilson JM. Comparative absorption of curcumin formulations. Nutr J. 2014;13:11. doi:10.1186/1475-2891-13-11 · PubMed
  11. Purpura M, Lowery RP, Wilson JM, Mannan H, Münch G, Razmovski-Naumovski V. Analysis of different innovative formulations of curcumin for improved relative oral bioavailability in human subjects. Eur J Nutr. 2018;57(3):929–38. doi:10.1007/s00394-016-1376-9 · PubMed
  12. Stohs SJ, Chen CYO, Preuss HG, Ray SD, Bucci LR, Ji J, et al. The fallacy of enzymatic hydrolysis for the determination of bioactive curcumin in plasma samples as an indication of bioavailability: a comparative study. BMC Complement Altern Med. 2019;19(1):293. doi:10.1186/s12906-019-2699-x · PubMed
  13. Kocher A, Bohnert L, Schiborr C, Frank J. Highly bioavailable micellar curcuminoids accumulate in blood, are safe and do not reduce blood lipids and inflammation markers in moderately hyperlipidemic individuals. Mol Nutr Food Res. 2016;60(7):1555–63. doi:10.1002/mnfr.201501034 · PubMed
  14. Bideshki MV, Jourabchi-Ghadim N, Radkhah N, Behzadi M, Asemani S, Jamilian P, et al. The efficacy of curcumin in relieving osteoarthritis: a meta-analysis of meta-analyses. Phytother Res. 2024;38(6):2875–91. doi:10.1002/ptr.8153 · PubMed
  15. Wang Z, Jones G, Winzenberg T, Cai G, Laslett LL, Aitken D, et al. Effectiveness of Curcuma longa extract for the treatment of symptoms and effusion-synovitis of knee osteoarthritis: a randomized trial. Ann Intern Med. 2020;173(11):861–9. doi:10.7326/M20-0990 · PubMed
  16. Yu L, Li N, Li B, Ye KX, Guo J, Shan J, et al. Targeting cognitive aging with curcumin supplementation: a systematic review and meta-analysis. J Prev Alzheimers Dis. 2025;12(8):100248. doi:10.1016/j.tjpad.2025.100248 · PubMed
  17. Halegoua-DeMarzio D, Navarro V, Ahmad J, Avula B, Barnhart H, Barritt AS, et al. Liver injury associated with turmeric – a growing problem: ten cases from the Drug-Induced Liver Injury Network [DILIN]. Am J Med. 2023;136(2):200–6. doi:10.1016/j.amjmed.2022.09.026 · PubMed
  18. EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). Scientific opinion on the re-evaluation of curcumin (E 100) as a food additive. EFSA J. 2010;8(9):1679. doi:10.2903/j.efsa.2010.1679
How this profile was checked

Last reviewed: 2026-10-23. All sources with a DOI or PMID were resolved automatically via Crossref or doi.org and PubMed.

Translated from the German profile (version of 2026-10-23); translation checked on 2026-10-26.

Checked

  • All abstracts read via PubMed; DOIs and PMIDs reconciled via PubMed esummary; EFSA opinion [18] via Crossref (title and bibliography only).
  • Full text Nelson 2017 (PMC5346970): PAINS/IMPS, critical aggregation concentration 10–20 µM, IC50 shift with Triton X-100, solubility, F < 1%, no successful placebo-controlled trial [1].
  • From the abstracts: 24 healthy people, curcumin measurable in only two people at the highest levels, 7/24 mild complaints [2]; free curcumin in 1 of 12, glucuronide : sulfate 1.92 : 1, t1/2 6.77 h [3]; 10 nmol/l, PGE2 −62%/−57% [4]; +2000% with piperine [5]; Ki 36–77 µM CYP3A4 [6]; 29-fold, only phase 2 metabolites [7]; 185-fold, women 277, men 114, n = 23 [8]; 27-fold, Theravalues [9]; 49 nmol/l, n = 42, no effects [13]; 11 meta-analyses [14]; n = 70, −9.1 mm, funding including Natural Remedies [15]; 10 studies, 531 participants, SMD 0.14 [16]; 10 cases, HLA-B*35:01, 3/7 with piperine [17].
  • In the full text (PMC3918227, PMC5861163): 12 evaluable participants each, enzymatic cleavage with glucuronidase/sulfatase, funding by OmniActive [10] and Wacker Chemie [11], respectively; conflicts of interest in [12] according to the abstract (consulting Boston Biopharm, employment Stratum Nutrition).
  • ClinicalTrials.gov: 415 entries for “curcumin” (October 23, 2026).
  • Precision flags (m004; rules guideline of October 26, 2026; participant numbers, direction, and funding checked on October 26, 2026 via PubMed efetch against the abstract, COI statement, and affiliations): “Lowers inflammatory markers and blood lipids in healthy people”: “kleine_studien” – [13] 42.

Not verified

  • Sample size and design of the human part of the piperine study [5] (full text not freely accessible); whether a coauthor is connected to a piperine manufacturer not checked.
  • Funding and conflicts of interest of [7] and [8] (no free full text); in [7], the correspondence address is from a supplement manufacturer.
  • Whether the formulation studies [8][9] measured free or total curcumin (the abstract of [8] mentions total curcuminoids).
  • Content of the EFSA opinion [18] (page not reachable); only the fact of the re-evaluation as E 100 is cited.
  • Legal status in Germany and the USA.

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