Across 4 studies, all reported beneficial effects on reducing triglyceride levels, with effect sizes ranging from small to moderate. The median study duration was 72 days, suggesting effects typically observed at 8-12 weeks. Most evidence comes from clinical populations with NAFLD or obesity, with doses of grape seed extract (the primary form studied) ranging from 300–520 mg/day.
Caveats: Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). All studies used grape seed extract rather than whole red grape or other forms, so results may not generalize to other preparations. Evidence base is small (only 4 studies) — conclusions should be considered preliminary.
Flavonoids intervention significantly decreased ... triglycerides (TG)
insulin, HOMA-IR, TC, TG, LDL-c, ALT, AST, AST/ALT, SBP, DBP and MAP decreased and QUICKi and HDL-c increased significantly (p-value for all < 0.05)
VAI, AIP, total cholesterol and triglyceride significantly decreased in the GSE group compared with the baseline (p = .04, .02, .01, and .02, respectively).
triglycerides (WMD: -6.55; 95% CI: -9.28, -3.83)