# Clinical Potential of Curcuma longa Linn. as Nutraceutical/Dietary Supplement for Metabolic Syndrome: Systematic Review and Meta-Analysis of Randomized Controlled Trials

## TL;DR

This review finds that Curcuma longa (turmeric) can help improve blood sugar, cholesterol, and inflammation in people with metabolic syndrome and related conditions.

## Contribution

The study provides a comprehensive meta-analysis of randomized trials on the clinical efficacy of Curcuma longa for metabolic syndrome.

## Key findings

- Curcumin reduced fasting blood sugar and HbA1c in type 2 diabetes patients.
- It improved lipid profiles by lowering triglycerides and LDL while raising HDL and antioxidant capacity.
- Curcuma longa also reduced inflammatory markers like CRP, TNF-α, and IL-6.

## Abstract

Metabolic syndrome (MetS) and its associated conditions, namely, type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease (NAFLD), obesity, and polycystic ovary syndrome (PCOS) are characterized by insulin resistance, dyslipidemia, and low-grade inflammation. Curcumin, a polyphenolic compound derived from Curcuma longa Linn., exhibits pleiotropic metabolic and anti-inflammatory properties and has thus been evaluated as a nutraceutical intervention for these conditions, but findings remain inconsistent. This systematic review and meta-analysis evaluated the clinical efficacy of Curcuma longa supplementation on anthropometric, glycemic, lipid, inflammatory, and oxidative stress parameters in adults with MetS or related disorders. A comprehensive search of databases (PubMed, Scopus, AMED, LILACS, and Google Scholar) identified 104 eligible randomized controlled trials (RCTs). The included trials primarily assessed standardized oral turmeric/curcumin supplements and bioavailability-enhanced formulations rather than whole culinary turmeric. Pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were computed using random-effects models. Subgroup analyses were conducted by disease category, dose, and formulation. Risk of bias was assessed using the Cochrane RoB 2 tool. Curcumin supplementation significantly reduced fasting blood sugar (SMD = −0.54, 95% CI −0.72 to −0.36) and HbA1c (SMD = −0.41, 95% CI −0.60 to −0.23) in T2DM; decreased triglycerides (SMD = −0.48; 95% CI: −0.70 to −0.25), and LDL cholesterol (SMD = −0.39; 95% CI: −0.59 to −0.18) while elevating HDL cholesterol (SMD = 0.45; 95% CI: 0.25 to 0.65) and total antioxidant capacity (SMD = 0.73; 95% CI: 0.51 to 0.94). Curcuma longa also attenuated systemic inflammation, lowering C-reactive protein (SMD = −0.62; 95% CI: −0.81 to −0.43), TNF-α (SMD = −0.57; 95% CI: −0.80 to −0.34), and IL-6 (SMD = −0.50; 95% CI: −0.70 to −0.29). Heterogeneity was moderate-to-high, reflecting some differences in the formulation, dosage, and duration. Collectively, these findings affirm that Curcuma longa exerts measurable, clinically relevant improvements on glycemic regulation, lipid metabolism, and inflammatory−oxidative balance, supporting its role as a nutraceutical adjunct in metabolic health management, while its bioavailability-enhanced formulations show superior efficacy. Larger, long-term, multicenter RCTs are warranted to confirm durability, optimal dosing, and safety.