January 2015

Grape Seed Extract Products Might Contain Peanut Skin

A new study suggests that many grape seed extract products are adulterated, and might contain peanut skin extract.

Grape leaves, sap, seed, and fruit have purportedly been used medicinally since the time of the ancient Greeks. Grape seed is used for diabetes complications such as neuropathy or retinopathy, improving wound healing, aging skin, preventing dental cavities, cancer prevention, age-related macular degeneration (ARMD), poor night vision, liver cirrhosis, allergic rhinitis, and prevention of collagen breakdown.

In a new study, researchers analyzed 21 commercial grape seed extract products to identify the major compounds present in these products. The authors were particularly interested in the potential presence of peanut skin extract and pine bark extract, as both contain similar flavanols.

The researchers found that the overall quality of grape seed extract products on the market is very low. Of the 21 tested products, six samples were composed of almost entirely peanut skin extract and contained no detectable grape seed extract. Five other samples contained very low levels of flavanols.

The authors concluded that there appears to be widespread adulteration in grape seed extract commercial products, particularly with peanut skin extract, which raises concerns for those with allergies.

For information about grape seed, please visit Natural Standard’s Food, Herbs & Supplements Database.


  1. Natural Standard: The Authority on Integrative Medicine.
  2. Villani TS, Reichert W, Ferruzzi MG, et al. Chemical investigation of commercial grape seed derived products to assess quality and detect adulteration. Food Chem. 2015 Mar 1;170:271-80.

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