The effect of Green green tea consumption on body mass index, lipoprotein, liver enzymes, and liver cancer: An updated systemic review incorporating a meta-analysis

Introduction Green tea is related to the reduction of liver enzymes, lipoprotein, and body mass index. However, some reports related green tea to the risk of developing liver cancer, but their outcomes were conflicting. Hence, the present study aimed to determine the relationship between green tea intake and lipoprotein, liver enzymes, body mass index, and liver cancer.Methods A systematic literature search up to January 2022 was performed and 22 studies with a total of 169599 subjects participated in the studies with 97316 subjects of them used green tea intake. Odds ratio (OR) or standardized mean difference (MD) with 95% confidence intervals (CIs) was calculated to evaluate the relationship between green tea intake and lipoprotein, liver enzymes, body mass index, and liver cancer using the dichotomous or the contentious method with a random effect model.Results Green tea intake significantly lowered the risk of developing liver cancer (OR, 0.85; 95% CI, 0.74 to 0.97, p = 0.02), and body mass index (MD, −0.69; 95% CI, −0.95to −0.42, p < 0.001) compared to no green tea intake. Also, there was a significant lowering effect of green tea intake on liver enzymes including alanine aminotransferase (MD, −0.65; 95% CI, −0.92 to −0.38, p < 0.001), and aspartate aminotransferase (MD, −0.77; 95% CI, −1.40 to −0.14, p = 0.02) compared to no green tea intake. There was also a significant lowering effect of green tea intake on lipoprotein including triglycerides (MD, −0.70; 95% CI, −1.35 to −0.04, p = 0.04), total cholesterol (MD, −0.39; 95% CI, −0.74 to −0.04, p = 0.03) and law-density lipoprotein (MD, −0.44; 95% CI, −0.69- −0.19, p < 0.001) compared to no green tea intake. However, no significant different was found between green tea intake and no green tea intake on high-density lipoprotein (MD, 0.16; 95% CI, −0.11 to 0.44, p = 0.24).Conclusions Based on this meta-analysis, green tea intake had a significant lowering effect on the risk of developing liver cancer and had a significantly improving effect on body mass index, liver enzymes, and lipoprotein compared to no green tea intake. These results suggest that green tea may be added to the daily dietary program to improve cardiovascular status with no possible risk of liver cancer. It even may have a protecting effect against liver cancer in the usual daily number of cups.