Turmeric (Turmeric, Latin: Curcuma longa) is a plant from the ginger family, which is native to Southeast Asia. Turmeric is also the orange-yellow powder from the rhizomes (rhizomes) of the plant. In India, this powder is consumed as a spice in large quantities, but is also used for dyeing [34]. Turmeric contains between 2 and 9% curcuminoids. The main ingredient is curcumin, other representatives are e.g. demethoxycurcumin and bisdemethoxycurcumin [8]. It is assumed that the widespread consumption of turmeric contributes to the lower incidence of colorectal and prostate carcinomas as well as Alzheimer's disease in India, compared to Western industrialized countries (overview in [34]). Positive effects of curcumin on chronic inflammatory bowel diseases are mentioned in an English [21] and a German [18] gastroenterological guideline, without a concrete therapy recommendation being derived from it.
The MMI Pharmindex lists about 200 preparations with turmeric, either as a monosubstance or in combination with other plant substances such as black pepper, frankincense, nasturtium and basil. The majority are offered as non-pharmacy food supplements, with at least 50 additional homeopathic preparations.
Chemical and pharmacological composition
Curcumin is a naturally occurring compound from the group of diarylheptanoids. Two o-methoxyphenol residues are connected to each other via an unsaturated C7 chain containing a 1,3-diketone unit. The compound can be counted among the substance group of plant polyphenols (source: Wikipedia and [9]).
A special feature of curcumin is its poor bioavailability, so that healthy volunteers do not achieve measurable serum concentrations up to a daily dose of 8 grams [22]. At doses of up to 12 grams, curcumin can be detected in plasma in glucuroned or sulfated form [35]. Measurements of the plasma levels of patients with various tumor diseases and Alzheimer's disease came to inconsistent results, so that a poor and inconsistent bioavailability of the substance must be assumed (overview in [34]). For this reason, research is being carried out on several carrier systems that are intended to improve the absorption of curcumin. These include natural substances such as piperine, an alkaloid from black pepper, as well as essential oils from the turmeric plant itself. Other approaches deal with micronized turmeric powder and embedding it in hydrophilic nanoparticles, which increase absorption by up to 27 times. (Overview in [34]). The use of detergents to produce micelles even increased the absorption of curcumin by a factor of 185 [31].
Effects in vitro and in animal models
In vitro, curcumin exhibits immunomodulating, anti-inflammatory and antioxidant effects. In the area of T cell function, these include the down-regulation of IL-17, interferon alpha, NF-kB and adhesion molecules (overview in [29]). The antioxidant effect is apparently based on the inhibition of cyclooxygenases and lipoxygenases and inducible NO synthetase (overview in [25]). Curcumin interferes with the Janus kinase and mTOR systems and induces apoptosis of mutated cells in vitro [27], an indication of an antiproliferative effect that could be important for neoplastic diseases.
In the animal model, curcumin reduced paw swelling, CRP levels, and levels of proinflammatory cytokines in rat adjuvant arthritis, with the comparison group taking ibuprofen showing a stronger effect [3]. In the rat staphylococcal cell-wall model, arthritis could not be prevented by intraperitoneal and oral administration of highly purified curcumin, but it could be significantly attenuated over the course of the disease [11]. Further work on adjuvant-induced and collagen-induced arthritis showed the reduction of cartilage-destroying enzymes, prostaglandins, and the inhibition of pannus formation and synovial hyperplasia for both native curcumin and curcumin in nanoparticles. Curcumin was comparably potent as naproxen, indomethazine, MTX, and rapamycin (overview in [34]).
A literature search on the keywords "turmeric" and "arthritis" yielded 159 citations for studies on humans (as of 24.6.2025). Of these, 28 appeared as "clinical trials", 12 as meta-analyses. Under "curcumin" and "arthritis", 296 citations were listed, of which 39 were clinical trials, 17 as meta-analyses. Under "curcumin" and "autoimmune disease", 192 results were listed ("clinical trial" 18, meta-analysis 9). The corresponding figures for "turmeric" and "autoimmune disease" were 85, 4 and 6, respectively.
Osteoarthritis
The majority of studies on turmeric were conducted on osteoarthritis patients, mainly on patients with knee osteoarthritis. Many studies took place in India [15, 17, 19, 24, 26, 32, 33] or Thailand [20, 28, 30]. Curcumin was used as a pure extract or in formulations aimed at improving bioavailability [4, 13, 26, 32, 33]. It was also used in combination with other substances, e.g. frankincense (Boswellia serrata) [4, 12, 17], boswellia and myrobalans (Terminalia chebula) [15] or sleeping berry (Withania somnifera), boswellia and zinc [19]. The comparison groups took either placebo [12, 13, 15, 19, 26], ibuprofen [20, 30], diclofenac [28], celecoxib [17], paracetamol [33] or glucosamine sulfate [16, 24]. A stronger effect than placebo [12, 13, 26], equivalence to NSAIDs [20], paracetamol [33] or standard treatment [4] was reported. In one study, the combination of turmeric longa extract and diclofenac only tended to be more effective than diclofenac alone [28], while a combination of turmeric and turmeric oil significantly enhanced the effect of diclofenac [32].
A meta-analysis of 15 randomized controlled osteoarthritis studies with a total of 1621 patients attested that Curcuma longa extract and curcumin had a positive effect on the visual analogue scale for pain and the WOMAC scores for pain, function and stiffness. The tolerability of the substances was in the placebo range. A significant risk of bias was found in 3 of the 15 studies with regard to their blinding [38].
The (no longer up-to-date) German S3 guideline on hip osteoarthritis from 2019 mentions positive studies on turmeric in degenerative joint diseases, but considers the studies to be insufficient for a recommendation1.
Rheumatoid arthritis
For RA, a three-arm, double-blind study with curcumin in a formulation with increased bioavailability has been published. 12 patients each received 250 or 500 mg of curcumin in a mixture with turmeric oil and water-soluble turmeric extracts. The results showed a highly significant decrease in DAS28 after 90 days, which at 53% and 66% respectively would significantly exceed the effect of biologic or JAK inhibitor therapy, while no improvement occurred in the placebo group [2]. However, the study reveals weaknesses that call into question the plausibility of the data. Unusually, almost two-thirds of the study participants were men. Although the authors stated that the groups were comparable at the start of the study, the placebo group had a significantly lower baseline DAS28 than the verum groups. A complete lack of response in a placebo group is not typical for RA studies. The decrease in erythrocyte sedimentation rate from values between 175 and 181 to 21 in the verum group and to 127 in the placebo group (without information from a unit) is just as incomprehensible as the massive drop in rheumatoid factor in the relatively short study period. There is no information on concomitant therapy, especially steroids.
A second, single-blind pilot study on three groups of 15 patients each compared a therapy with 2x500mg curcumin (in a formulation with increased bioavailability) with 2x50mg diclofenac and a combination of both preparations over a therapy period of 8 weeks [6]. Curcumin was described as more effective compared to diclofenac and caused fewer side effects. In this study, too, the response rates in the curcumin monotherapy group with an ACR 20, 50 and 70 response of 93%, 73% and 33% respectively went well above the level known from biologics, and the number of swollen joints fell from 12 to less than 1. Steroid therapy is not reported, and the authors did not address possible limitations of their data. A systematic literature review attested to a high risk of bias in both studies [23].
In another randomized study, 65 patients were treated with either placebo or curcumin as nanomicelles. After 12 weeks, there were no significant differences in DAS28 between the two groups, despite a tendency to decrease more strongly in the verum group [14]. Signals regarding adverse effects before curcumin were not found in any of the three RA studies mentioned.
Other indications
A systematic literature review with meta-analysis of various forms of arthritis [37] mentioned a small, placebo-controlled study on 12 patients with ankylosing spondylitis who received nanocurmin and 12 patients who received placebo. The main reports were on the influence on biochemical markers such as interleukin 6 and 10 as well as on the expression of T-cell surface markers [1]. Two small studies on juvenile idiopathic arthritis found significant improvements with curcumin compared to placebo, but these studies are only available as abstracts. A tendency to reduce uric acid levels with curcumin did not reach statistical significance [5].
A review on autoimmune diseases published by the same group of authors using the same methodology described positive effects in 9 studies on ulcerative colitis. However, 2 studies on Crohn's disease concluded inconsistently. Two studies on psoriasis vulgaris reported improvements in the skin score (PASI). For SLE, the data situation was assessed as insufficient [36].
1 1 register.awmf.org/assets/guidelines/033-001l_S2k_Koxarthrose_2019-07_1-abgelaufen.pdf
Curcumin is available as a dietary supplement in numerous preparations in Germany. So far, there is no pharmacologically clearly defined, tested and approved drug based on turmeric on the German market.
The European Food Safety Authority (EFSA) recommends a quantum of 3mg per kg body weight as an acceptable daily intake (ADI) of turmeric as a food additive E100 [10]. The data on native curcumin to date show that in studies daily doses of up to 8g showed no relevant side effects (overview in [37]). Curcumin in the form of nanoparticles showed no relevant acute, chronic or genotoxicity even in high doses of [7].
A statement by the Federal Office of Consumer Protection and the BfArM1 on curcumin products with improved bioavailability states that turmeric preparations could be classified as a traditional herbal medicinal product if a reference is made to certain diseases. The statement goes on to state: "For classification as a non-traditional medicinal product, evidence of efficacy and safety would have to be provided; however, there is currently insufficient clinical evidence that the intake of the new preparations can lead to a pharmacological effect on target structures that goes beyond the normal digestive physiological effect. Although there are a large number of clinical trials, they either have significant deficiencies in the study design, have been discontinued prematurely or have not yet led to any reliable results as pilot studies. A classification of curcumin-containing products as functional medicinal products is therefore not considered sensible." With regard to tolerability, it goes on to say: “For the toxicological assessment, it should be noted that the ADI for conventional curcumin cannot be transferred to curcumin with improved bioavailability without further study data, as it must be assumed that the systemic exposure responsible for the toxic effects to the substance itself or to relevant metabolites could be significantly increased with the intake of curcumin with improved bioavailability.”
1www.bvl.bund.de/SharedDocs/Downloads/01_Lebensmittel/expertenkommission/Stellungnahme_Curcumin.pdf
Despite numerous indications of anti-inflammatory, antioxidant and immunomodulating properties of curcumin in vitro and in animal models, the data situation is not sufficient to recommend the use of curcumin or curcumin preparations with improved bioavailability in inflammatory joint diseases or autoimmune diseases. A tested and approved herbal medicinal product based on curcumin is not offered in Germany.
Patients with degenerative joint diseases who consume turmeric as a dietary supplement at their own request with the expectation of positive effects on their symptoms do not have to be advised against its use. Natural turmeric as a spice is considered a useful component of a plant-based, anti-inflammatory diet.
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Last updated: March 11, 2026