Introduction
Nonalcoholic fatty liver disease (NAFLD) is a chronic liver condition characterized by excessive fat accumulation in liver cells. It can progress to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and even liver cancer. NAFLD affects approximately 25.2% of the global population and is closely associated with metabolic syndromes such as obesity, dyslipidemia, insulin resistance, and type 2 diabetes mellitus. Currently, there are no approved pharmacological treatments for NAFLD or NASH, highlighting the urgent need for effective therapies.
Section 1: Silymarin and Its Potential Benefits
Silymarin, an extract from milk thistle (Silybum marianum), is known for its hepatoprotective properties. It contains several antioxidant compounds, including silibinin A and B, and the flavonoid taxifolin. Silymarin has demonstrated antioxidant, anti-inflammatory, and antifibrotic effects, making it a promising candidate for NAFLD treatment.
Studies suggest that silymarin can improve liver enzyme levels and hepatic steatosis in NAFLD patients. However, a systematic evaluation of its efficacy is lacking. This meta-analysis aims to assess the effects of silymarin on energy metabolism, liver injury, liver histology, and anthropometric parameters in NAFLD patients.
Section 2: Materials and Methods
This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and was registered with PROSPERO. Relevant studies were retrieved from databases including PubMed, Embase, the Cochrane Library, Web of Science, clinicaltrials.gov, and China National Knowledge Infrastructure.
Search terms related to «silymarin» and «nonalcoholic fatty liver disease» were used. Studies were selected based on eligibility criteria, including randomized controlled trials (RCTs) involving NAFLD patients treated with silymarin or silymarin complex. Data were analyzed using RevMan 5.3, and heterogeneity was assessed using the Cochran’s Q test (I2 statistic).
Section 3: Results
A total of 26 RCTs involving 2,375 patients were included. Silymarin administration significantly reduced levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), fasting insulin (FI), and homeostatic model assessment of insulin resistance (HOMA-IR). It also increased high-density lipoprotein cholesterol (HDL-C) levels. Additionally, silymarin attenuated liver injury, as indicated by decreased levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The fatty liver index and fatty liver score were also reduced, and liver histology showed improved hepatic steatosis.
Subsection: Energy Metabolism
Silymarin significantly decreased TC, TG, and LDL-C levels while increasing HDL-C levels in NAFLD patients. It also showed potential in lowering fasting blood glucose (FBG) and HOMA-IR, although these results were not statistically significant.
Subgroup analysis revealed that silymarin alone was more effective than silymarin complex in reducing TC and increasing HDL-C levels. The duration of treatment also influenced the efficacy, with 12-24 weeks being the most common and effective duration.
Subsection: Liver Injury
Silymarin significantly reduced ALT and AST levels, indicating its protective effect on the liver. Elevated ALT and AST levels are biomarkers for liver injury and are associated with NAFLD progression.
Subsection: Liver Histology
Silymarin improved liver histology by reducing the fatty liver index and fatty liver score and improving hepatic steatosis grade. These findings suggest that silymarin can protect the liver from oxidative stress, inflammation, and fibrosis.
Section 4: Discussion
This meta-analysis demonstrates that silymarin can regulate energy metabolism, attenuate liver damage, and improve liver histology in NAFLD patients. However, the study has limitations, including variations in silymarin types, doses, and lifestyle management among the included RCTs. Further studies with standardized methodologies are needed to confirm these findings.
Conclusion
Silymarin shows promise as a treatment for NAFLD by improving energy metabolism, reducing liver injury, and enhancing liver histology. Despite the limitations of this study, silymarin’s potential benefits warrant further investigation in well-designed clinical trials.
References
- Younossi ZM, Golabi P, de Avila L, et al. The global epidemiology of NAFLD and NASH in patients with type 2 diabetes: a systematic review and meta-analysis. 2019;71(4):793-801.
- Eslam M, Sarin SK, Wong VW-S, et al. The Asian Pacific Association for the Study of the Liver clinical practice guidelines for the diagnosis and management of metabolic associated fatty liver disease. 2020;14:889-919.
- Brunt EM. Pathology of nonalcoholic fatty liver disease. 2010;7(4):195-203.
- Vanni E, Bugianesi E, Kotronen A, et al. From the metabolic syndrome to NAFLD or vice versa? 2010;42(5):320-30.
- Golabi P, Sayiner M, Fazel Y, et al. Current complications and challenges in nonalcoholic steatohepatitis screening and diagnosis. Expert Rev Gastroenterol Hepatol 2016;10(1):63-71.