Across 3 studies, 1 reported a small beneficial effect of grape seed extract (GSE) on reducing cardiac output, while 2 found neutral, non-significant results. The median study duration was only 7 days, and limited evidence suggests a potential benefit specifically in obese males, though the overall effect is small and inconsistent.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. All studies used grape seed extract, but doses were not reported, limiting dose-response interpretation.
There were no differences on the CO … between placebo and GSE treatments
GSE supplementation significantly decreased CO in only obese group.
Q was decreased at rest and across all workloads, but there were no significant differences (7.5 ± 0.4 L/min vs. 7.1 ± 0.4 L/min; 20.4 ± 1.2 L/min vs. 19.6 ± 0.9 L/min; 26.3 ± 1.1 L/min vs. 25.5 ± 1.6 L/min, respectively).