Effect of Green tea (Camellia sinensis) Supplementation on liver enzymes: A Systematic Review of Clinical Trials
Effect of Green tea (Camellia sinensis) Supplementation on liver enzymes: A Systematic Review of Clinical Trials
Amirfaham Rezaee,1Sina beshkooh,2,*Hedieh Molaei,3
1. Department of Nutrition, Science and Research Branch, Islamic Azad University, Tehran, Iran 2. Department of Nutrition, Science and Research Branch, Islamic Azad University, Tehran, Iran 3. Department of Nutrition, Science and Research Branch, Islamic Azad University, Tehran, Iran
Introduction: Green tea, which is derived from the leaves of *Camellia sinensis*, is widely known for its health benefits, such as its antioxidant and anti-inflammatory properties. It has been suggested that consuming green tea may have a positive impact on liver function by affecting certain liver enzymes, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT). Elevated levels of these liver enzymes are often indicative of liver damage or dysfunction. Despite the increasing interest in this topic, the precise effect of green tea on liver enzymes is still unclear. This systematic review seeks to assess the existing clinical evidence regarding the effect of green tea on liver enzymes.
Methods: A comprehensive search was conducted using PubMed, Google Scholar, Scopus, and Medline databases. The search focused on randomized controlled trials (RCTs) examining the effects of green tea on liver enzymes in human subjects. Keywords used included "green tea," "liver enzymes," "ALT," "AST," "ALP," "GGT," and "RCT." Studies were screened based on inclusion criteria, including human clinical trials, green tea intervention, and reported liver enzyme outcomes. A total of 10 RCTs were identified and included in the review. Data from these studies were extracted, and a qualitative synthesis was performed.
Results: Among the 10 RCTs included in the review, eight studies reported a statistically significant beneficial effect of green tea on liver enzyme levels. These studies demonstrated reductions in ALT, AST, and GGT levels, suggesting a hepatoprotective effect of green tea. The potential mechanisms discussed include green tea's antioxidant properties, which may reduce oxidative stress in the liver, and its ability to modulate inflammatory responses. In contrast, two studies found no significant impact of green tea on liver enzymes. These studies reported that green tea did not result in any substantial changes in liver function markers compared to placebo. Possible explanations for the lack of effect in these studies include differences in study populations, green tea dosages, and study durations.
Conclusion: The majority of RCTs reviewed in this systematic analysis suggest that green tea may have beneficial effects on liver enzyme levels, supporting its role as a potential hepatoprotective agent. However, the presence of conflicting results in a minority of studies highlights the need for further research, particularly to clarify the dose-response relationship and to identify subpopulations that may benefit most from green tea consumption. Future studies should aim to standardize green tea formulations and dosages to allow for more consistent comparisons across trials.