This meta-analysis of seven studies—one focusing on SLE and six on RA—found no significant effect of curcumin or Curcuma longa extract on DAS-28, ESR, or CRP levels. Substantial heterogeneity was observed across outcomes, necessitating the use of random-effects models. Sensitivity analyses using a leave-one-out approach confirmed the robustness of the overall findings. Due to the limited sample size, subgroup analyses by disease type, dosage, and formulation could not be thoroughly conducted; however, these factors likely contribute to the observed heterogeneity and warrant further investigation. In summary, this meta-analysis provides the most up-to-date, disease-specific synthesis of curcumin’s effects, integrating recent RCTs to clarify key inflammatory outcomes and thereby strengthen the evidence base for clinical practice and future research.

Recent meta-analyses have examined curcumin in autoimmune diseases with inconsistent results. For example, Ebrahimzadeh et al. [25] and Kou et al. [26] reported significant improvements in inflammatory biomarkers in rheumatoid arthritis, whereas Zeng et al. [27] and Marton et al. [28] found limited or disease-specific benefits. In contrast, our study uniquely focused on rheumatoid arthritis and systemic lupus erythematosus with updated randomized controlled trials up to 2025, demonstrating inconsistent effects across key biomarkers (DAS-28, ESR, and CRP). These findings provide a disease-specific synthesis that refines the current evidence base and highlights the need for standardized, high-quality trials.

Inflammatory states have been implicated as an important mechanism of action in many diseases ranging from cardiovascular disease (CVD) to diabetes, to autoimmune conditions such as SLE and RA [29]. Current drug treatments for many of these conditions can have minimal effectiveness in a large number of patients, as well as side effects that can become intolerable. As a result, there is growing interest in exploring natural compounds such as curcumin (including Curcuma longa extract) as potential supplementary therapies to enhance disease management and reduce inflammatory burden.

Curcumin is one of the most studied natural compounds, and studies have indicated that it may have promise as a treatment or adjuvant treatment for many conditions such as inflammatory diseases [29], various malignancies [30], slowing of the aging process [31], weight loss [32], and diabetes mellitus [33]. However, despite the breadth of research, there is still no clear consensus regarding its clinical effectiveness across these indications.

Meta-analyses and systematic reviews performed over the past 5 years examining the effectiveness of curcumin on various conditions have provided inconsistent results. In a study published in 2021, Ebrahimzadeh et al. [25] performed a systematic review and meta-analysis of the effects of curcumin supplementation on inflammatory biomarkers in patients with RA and ulcerative colitis (UC). Six studies were included in their analysis, and they reported that curcumin supplementation of 250–1500 mg/day over 8–12 weeks was associated with significant decreases in CRP level and ESR in patients with RA and UC. Published in 2022, Zeng et al. [27] performed a systematic review and meta-analysis of 31 RCTs that examined the effectiveness of curcumin and Curcuma longa extract for the treatment of 10 different autoimmune diseases. The overall results showed that curcumin and Curcuma longa extract exhibited effectiveness in the treatment of psoriasis, UC, and RA. On the other hand, neither compound was effective for the treatment of oral lichen planus, and there was insufficient data in the studies to perform a meta-analysis with respect to the effect on Takayasu arteritis, SLE, multiple sclerosis, ankylosing spondylitis, Behcet’s disease, or Crohn’s disease.

In another study published in 2022, Marton et al. [28] performed a systematic review examining the effectiveness of curcumin in the treatment of autoimmune and inflammatory diseases. The authors reported that curcumin was effective for reducing symptoms and/or inducing remission in IBD, OA, SLE, psoriasis, and sclerosis. Notably, curcumin had effects equal to those of ibuprofen and diclofenac without the common adverse effects reported by patients. A meta-analysis published in 2023 specifically examined the effects of curcumin for the treatment of RA [26]. Six studies with a total of 539 patients with RA were included in the analysis. The results showed that curcumin supplementation resulted in significant changes of ESR, DAS-28, swollen joint count, and tender joint count compared to control patients.

Expanding beyond autoimmune conditions, broader evidence has also been synthesized to evaluate curcumin’s impact on general health-related outcomes. A review published in 2024 performed by Jafari et al. [34] examined the effects of curcumin on “human health” by performing a systematic review and meta-analysis of 103 RCTs. There were 42 outcomes reported in the 103 RCTs, and the total number of patients was 7,216. Overall, 55% of the outcomes had statistically significant effect sizes, and the credibility of evidence was rated high for fasting blood sugar, CRP, high-density lipoprotein (HDL), and weight. The credibility of evidence was rated as moderate for outcomes of waist circumference, hip circumference, and BMI. For other outcome measures the quality of evidence was rated as low or very low.

An important consideration of our study, as well as most studies examining the effects of natural compounds on human diseases, in the substantial heterogeneity across outcomes and studies. The heterogeneity limits the strength of pooled estimates and warrants careful interpretation of the results. There are many sources of the heterogeneity such as variations in curcumin formulations used indifferent studies (e.g., bioavailability-enhanced formulations, standardized extracts), which can the pharmacokinetics and clinical response. Dosage and treatment duration also varied considerably in the studies included in our meta-analysis, with curcumin dosages ranging from low to high and intervention periods ranging from 8 to 12 weeks. Differences in study populations can also influence the results: in our study, after applying the selection criteria, only 1 of the included studies was of SLE patients, the others were studies of patients with RA. In addition, there was inconsistent reporting of baseline disease activity or inflammatory marker levels among the studies included.

While curcumin and Curcuma longa extract appear to be safe and are biologically plausible as adjunct therapies for autoimmune and inflammatory conditions, current clinical evidence does not support their reliable impact on inflammatory biomarkers in RA or SLE. Future RCTs should standardize curcumin formulations, optimize dosing strategies, and include longer follow-up durations. Efforts to stratify patients by disease subtype and baseline inflammatory burden may also help identify subgroups more likely to benefit.

This meta-analysis provides a timely and focused synthesis of current evidence on the effects of curcumin and Curcuma longa extract on inflammatory biomarkers in patients with RA and SLE. Despite its strengths, several limitations should be noted. The small number of included trials (n = 7), with only one addressing SLE, limits the generalizability of findings—particularly to the SLE population. Significant heterogeneity across studies likely stems from variations in study design, formulations, dosages, treatment durations, and baseline disease activity. However, as the overall number of included studies was small, we were unable to perform reliable subgroup analyses—particularly those stratified by dosage and duration—which would have provided additional insights. This underscores the need for future stratified pooled analyses once more original studies become available. Additionally, while one study [18] appeared to influence pooled estimates, sensitivity analyses confirmed the overall robustness of results. Inconsistent biomarker measurement methods and the lack of standardized outcome reporting further challenged data synthesis. Although interleukins (e.g., IL-6, IL-1β) and TNF-α are key inflammatory mediators in autoimmune diseases, they were insufficiently reported among the included trials (only one reported IL-6 and none reported TNF-α). Therefore, a pooled meta-analysis of these cytokines was not feasible. Future studies should standardize biomarker reporting to allow for broader synthesis. Further, the generally short trial durations may not have captured the full therapeutic potential of these interventions. Although no significant benefits were observed for DAS-28, ESR, or CRP, these null findings are valuable in refining clinical expectations and reducing publication bias. Finally, although interleukins and TNF-α are important inflammatory markers that would be expected as outcome measures in studies of curcumin and autoimmune diseases, they were insufficiently reported among the included trials, making a pooled analysis infeasible.