Grape Polyphenols Exert a Cardioprotective Effect in Pre- and Postmenopausal Women by Lowering Plasma Lipids and Reducing Oxidative Stress

To evaluate the effects of grape polyphenols on plasma lipids, inflammatory cytokines, and oxidative stress, 24 pre- and 20 postmenopausal women were randomly assigned to consume 36 g of a lyophilized grape powder (LGP) or a placebo for 4 wk. The LGP consisted of 92% carbohydrate and was rich in flavans, anthocyanins, quercetin, myricetin, kaempferol, and resveratrol. After a 3-wk washout period, subjects were assigned to the alternate treatment for an additional 4 wk. The placebo consisted of an equal ratio of fructose and dextrose and was similar in appearance and energy content (554 kJ) to LGP. Plasma triglyceride concentrations were reduced by 15 and 6% in pre- and postmenopausal women, respectively (P < 0.01) after LGP supplementation. In addition, plasma LDL cholesterol and apolipoproteins B and E were lower due to LGP treatment (P < 0.05). Further, cholesterol ester transfer protein activity was decreased by [approximately]15% with intake of LGP (P < 0.05). In contrast to these beneficial effects on plasma lipids, LDL oxidation was not modified by LGP treatment. However, whole-body oxidative stress as measured by urinary F₂-isoprostanes was significantly reduced after LGP supplementation. LGP also decreased the levels of plasma tumor necrosis factor-[alpha], which plays a major role in the inflammation process. Through alterations in lipoprotein metabolism, oxidative stress, and inflammatory markers, LGP intake beneficially affected key risk factors for coronary heart disease in both pre- and postmenopausal women.