Grape seed extract

About Grape seed extract

An extract of wine grape seeds standardised to proanthocyanidins — polyphenol polymers also found in pine bark, cocoa and berries. Not to be confused with grapefruit seed extract, a different and frequently adulterated product.

Grape seed extract has a moderate-sized trial literature focused on blood pressure and vascular measures, with pooled analyses reporting small reductions in systolic pressure. Most trials are short, several were funded by extract producers, and the proanthocyanidin content of retail products is inconsistently verified. Its antioxidant reputation rests heavily on test-tube assays that say little about what happens after digestion.

Sold as

Standardised extract capsule, Tablet, Combination antioxidant formulas

Standardised to

Commonly 90–95% proanthocyanidins or a stated OPC percentage — a product without this marker may not resemble what was studied.

Also known as

GSE, Oligomeric proanthocyanidins, OPC, Grape seed proanthocyanidin extract

What the research used

The amounts, forms and durations published trials of Grape seed extract actually administered.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

In the food catalogue

The whole-food form, where one exists. The evidence for a concentrated extract rarely transfers to the food, or the other way round — these are cross-links, not equivalents.