This study evaluated 13 different dietary polyphenol supplements, alone or in combination.

The following polyphenols showed the strongest effects:

Tea catechins were the most effective for reducing ALT and AST and for increasing HDL-C.
Naringenin worked best for reducing triglycerides and total cholesterol.
Quercetin demonstrated the strongest effect for reducing TNF-alpha.
Dihydromyricetin (a flavonoid compound primarily found in the Japanese raisin tree)^[1] was the most effective for lowering fasting blood glucose.

The quality of the evidence varied widely, with 25 studies having a low risk of bias, 20 having some concern, and 9 having a high risk.

Can polyphenols improve liver function in people with NAFLD? Original paper