Four grape polyphenols—resveratrol, piceatannol, luteolin, and myricetin—demonstrate strikingly different effects on reproductive and adrenal hormone production. Resveratrol stimulates progesterone but inhibits estradiol in ovarian cells, while myricetin does the opposite. These compounds also show dose-dependent effects, with low resveratrol doses promoting cell growth but higher doses inhibiting it. The findings reveal a complex interplay where individual polyphenols can have contradictory effects on the same hormonal pathways. This challenges the oversimplified notion that all grape antioxidants provide uniform benefits. For adults interested in hormonal health, these results suggest caution with high-dose polyphenol supplements, particularly for those with reproductive concerns or hormone-sensitive conditions. The research exposes significant gaps in our understanding—no studies have examined luteolin's effects on certain reproductive cells, and combined polyphenol interactions remain unexplored. While promising for stress-related adrenal dysfunction, the conflicting hormonal effects indicate that grape polyphenols may require precision dosing rather than broad supplementation. This represents important foundational work, but the field needs human studies to translate these cellular findings into practical health guidance.