Short answer: Grape Seed Extract is rich in OPCs that protect the collagen structure of blood vessels, while Horse Chestnut's active compound escin reduces capillary permeability.
Why these two ingredients address genuinely different parts of vascular health
Grape Seed Extract's role centers on structural blood vessel strength, while Horse Chestnut's role centers specifically on preventing fluid leakage — two complementary, not overlapping, mechanisms.
Why pairing a structural ingredient with a permeability-focused one makes sense
Supporting stronger circulation and reducing fluid leakage together address both the blood-flow and bloating angles of the formula's broader claim.
💡 Worth knowing: rich in OPCs is a specific, checkable claim — worth understanding this compound class directly rather than a vague "antioxidant" description.