MegaNatural ® Gold Grapeseed Extract: In Vitro Antioxidant and In Vivo Human Supplementation Studies

Abstract

Epidemiological studies have produced solid evidence that consumption of fruits results in a reduction of cancer and cardiovascular disease. Red wine has been hypothesized to reduce the risk of heart disease as a result of its antioxidant, endothelial relaxation, and antiplatelet aggregation mechanisms. We investigated a commercial California wine grapeseed extract, MegaNatural^® Gold, and compared it to grapes, grape juice, red wine, other grapeseed extracts, and commercial extracts with respect to antioxidant activity, using an oxidation-reduction colorimetric assay. The quality of the antioxidants was determined with the use of an in vitro model of heart disease, a dose-response inhibition of low-density lipoprotein oxidation. MegaNatural^® Gold had a superior quantity/quality antioxidant index compared with all other samples tested. In nine subjects given 600 mg of MegaNatural^® Gold, the plasma antioxidant activity as measured by the RANDOX assay was significantly increased by 12% after both 1 and 2 hours. This was equivalent to drinking 300 ml of red wine or consuming 1,250 mg of vitamin C, as found in a previous study. We then determined the dose-response human plasma bioavailability of one of the polyphenols in MegaNatural^® Gold (epicatechin) in nine human subjects after giving 200 and 300 mg of the product. The in vivo antioxidant activity was also measured. The higher dose was much more effective. A long-term human supplementation study with 2 × 300 mg/day of MegaNatural^® Gold was then done on 17 (9 normal and 8 hypercholesterolemic) subjects. Plasma cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol concentrations were significantly decreased in the subjects with high cholesterol. Triglycerides were significantly increased in the high-cholesterol subjects but were still in the normal range after supplementation. Plasma antioxidant capacity was significantly improved in the high-cholesterol subjects. There was no change in plasma lipids or antioxidant capacity in the normal subjects.