Concentrated red grape juice exerts antioxidant, hypolipidemic, and antiinflammatory effects in both hemodialysis patients and healthy subjects.
American Journal of Clinical Nutrition. 2006 July;84(1):252-62
Hemodialysis often results in vascular complications caused by dyslipidemia, increased oxidative stress and inflammation. The aim of this study was to determine the effect of intake of concentrated red grape juice on lipoprotein profile, antioxidant capacity, low density lipprotein oxidation and inflammatory biomarkers. The study involded 26 patients receiving hemodialysis and 15 healthy volunteers. Both groups consumed daily 100 ml red grape juice concentrate during a period of 14 days. The researchers also measured the bioavailability of red grape juice polyphenols in the healthy volunteers. They found that the maximum plasma concentration of quercetin was achieved after 3 hours after grape juice intake, indicating that the phytochemical is quickly assorbed. The researchers found that red grape juice consumption increased HDL cholesterol (=good cholesterol) and the antioxidant capacity of plasma and reduced LDL cholesterol (=bad cholesterol) and the oxidation of low density lipoproteins. They also found that red grape juice intake by the hemodialysis patients lowered an inflammatory biomarker associated with cardiovascular disease risk. The study concluded that consumption of red grape juice could lower the risk of cardiovascular disease by improving lipoprotein profile, reducing inflammation and oxidized low density lipoproteins.
Protective effects of grape seed proanthocyanidins against oxidative stress induced by lipopolysaccharides of periodontopathogens.
Journal of Periodontology. 2006 August;77(8):1371-9
Macrophages are blood cells which destroy invaders. In this process the macrophages release chemicals, such as reactive oxygen species and reactive nitrogen species, aimed at destroying the intruders. However these chemicals create oxidative stress resulting in damage to tissue. The aim of this study was to investigate if grape seed proanthocyanidins, gallic acid and epigallocatechin-3-gallate have antioxidant capacities and have an influence on the production of oxygen species and reactive nitrogen species. They also investigated the influence of these phytochemicals on the production of inducible nitric oxide synthase by macrophages. The macrophages were stimulated with lipopolysaccharides from periodontal pathogens. The researchers found that grape seed decreased nitric oxide, reactive oxygen species and inducible nitric oxide synthase. Gallic acid mainly inhibited nitric oxide production whereas epigallocatechin-3-gallate inhibited the production of nitric oxide, reactive oxygen species and inducible nitric oxide synthase. They concluded that grape seed proanthocyanidins have potent antioxidant properties and might be used to prevent periodontal diseases.
Protective Effect of Grape Seed Polyphenols against High Glucose-Induced Oxidative Stress.
Bioscience, Biotechnology and Biochemistry. 2006 September 7
The aim of this in-vitro study was to determine if grape seed polyphenols could be used to treat diabetes mellitus and to determine the optimal degree of polymerization. Epithelial cells were subjected to high concentrations of glucose and to oxidative stress from reactive oxygen species and nitric oxide. The researchers found that the oligomers of grape seed polyphenols showed the strongest protective effect against high glucose-induced oxidative stress.
In vivo antioxidant activity of procyanidin-rich extracts from grape seed and pine (Pinus maritima) bark in rats.
International Journal for Vitamin and Nutrition Research. 2006 January;76(1):22-7
Studies have shown that grape extracts rich in procyanidins have potential antioxidant activity. There is not much evidence that these extract also work in-vivo. The aim of this study was to evaluate the effect of procyanidin-rich extracts of grape seed and pine bark extract on oxidative stress in rats. The rats were fed with the extract over a longer period or only received a single dose. The antioxidant effect was determined with the ferric-reducing antioxidant power method and measurement of thiobarbituric acid-reactive substances in the plasma. The researchers found that the administration of the extracts during a period of 8 weeks significantly increased the antioxidant capacity in plasma. After the administration of a single dose of the procyanidin-rich extracts the antioxidant capacity of the serum also increased. The grape seed extract had a stringer antioxidant effect than the pine bark extracts. The study concluded that procyanidin-rich extracts have antioxidant effect in-vivo.
The grape component resveratrol interferes with the function of chemoattractant receptors on phagocytic leukocytes.
Cellular and Molecular Immunology. 2004 February;1(1):50-6
Previous studies have shown that resveratrol, a main phytochemical of grape seeds has anti-inflammatory and antioxidant activities. The aim of this study was to determine the effect of resveratrol on G protein-coupled receptors, which play an important role in inflammation and immune responses. The researchers found that resveratrol inhibited the function of the receptors and this may explain the anti-inflammatory properties of resveratrol.