Protecting Cardiovascular Health with Whole Grape ExtractSeptember 2007
By Julius G. Goepp, MD
Scientists continue to uncover a wealth of impressive nutrients contained in the red grape. The latest findings indicate that full spectrum grape extract can help support cardiac health by maintaining youthful endothelial function, regulating platelet aggregation, and reducing inflammation.
This article explores how whole grape constituents can have a profound impact on your longevity.
An ever growing body of evidence shows that components of red grapes can have powerful effects on vascular health, reducing platelet aggregation and lipid peroxidation while improving endothelial function.1-4 The ability of red grape constituents to fight inflammation is opening new doors in treatment of chronic age-related disorders, including both the prevention and treatment of cancer.5,6
Nowhere are the “blessings of the grape” so evident as in prevention of cardiovascular disease.3 While many factors—ranging from vitamin K deficiency to elevated glucose levels—contribute to cardiovascular risk, perhaps one of the most insidious triggers is inflammation.
When inflammation is present, oxidant stress damages blood vessel walls and oxidizes low-density lipoproteins (LDL). These processes cause immune system cells to release inflammatory mediators called cytokines, which in their own turn produce changes in the walls of blood vessels, eventually resulting in accumulation of diseased tissue known as plaques. The same cascade causes platelets, the tiny cell-like fragments responsible for blood clotting, to cluster together (aggregate) excessively, increasing the risk of clot formation that can produce ischemic heart attacks and strokes.
In just the past decade, striking new findings have been made on how components of red grapes (including both skin and seeds) affect vascular health, ranging from increasing vital nitric oxide (critical in maintaining endothelial function) to protecting against heart muscle damage.7
Preventing Lipid Peroxidation
Cardiovascular disease involves a cascade of aberrant biological processes, but one area of interest even amongst the medical establishment is LDL oxidation. LDL transports lipids (fats) from the digestive system to tissues. Comprising both lipid and proteins, LDL particles are particularly vulnerable to the effects of oxygen free radicals. The process, known as lipid peroxidation, is a powerful stimulant of inflammation in blood vessels, eventually leading to plaque formation.
Scientists are therefore keenly interested in finding ways to reduce lipid peroxidation by lowering LDL levels directly and by reducing the rate at which these molecules become damaged by reactive oxygen species. Many of the antioxidant molecules in grapes work to reduce that LDL lipid peroxidation process.8,9
The components of red grapes prevent the consequences of oxidant damage in a large number of human tissue models far better than vitamins C, E, and beta-carotene. This protection has been credited with preventing medication-induced liver and kidney damage, heart muscle damage following heart attack, and inducing programmed cell death (apoptosis) in a variety of human cancer cells.8,9
One of the most detailed human studies of grape seed extract and oxidative stress in humans comes from a group of Italian researchers. In a study published in 2002, human volunteers consumed a lipid-rich meal, either with or without 300 mg of a proanthocyanidin-rich grape seed extract.10 The researchers measured the quantity of oxidized fats circulating in the bloodstream following the meals. The unsupplemented group had a 1.5-fold increase in circulating oxidized fats after the meal, compared with those who took the extract. The researchers concluded that even a single dose of grape seed extract can minimize after-meal oxidant stress, both by decreasing oxidants and by increasing the blood’s own antioxidant capacity. Grape seed extract provides the overall effect of reducing the deadly load of oxidized fats that can trigger atherosclerosis.
When British researchers gave grape seed extract to healthy volunteers, they found further evidence of the critical role of grape polyphenols.11 Twenty young volunteers took 300 mg of grape seed extract or placebo daily for five days. Serum antioxidant activity increased by more than 11% after just five days in those using grape seed extract.
Evidence suggests that red grape extracts, which are rich in polyphenols such as resveratrol, are especially beneficial. When Israeli researchers gave either red or white wine to a group of healthy men for two weeks, they found that lipid peroxidation in plasma dropped by 20% in those who consumed red wine. Men who consumed white wine did not see the same benefit.12
By now there’s simply no question about the remarkable ability of red grape polyphenols to markedly reduce lipid peroxidation (and other cardiovascular risk factors).13-19 That’s a fantastic benefit by itself, but even more impressive when we look at the downstream effects of cutting down on those toxic molecules.
Maintaining Healthy Endothelial Function
Blood vessel lining cells (endothelial cells) are charged with the critical tasks of maintaining muscle tone and smoothness of arterial walls, thereby controlling blood pressure and the propensity for plaques to form and platelets to congregate.20 It’s becoming increasingly clear that reducing lipid peroxidation-induced damage to delicate endothelial cells is an important way to maintain vascular health.21 There are several mechanisms at work here, including the production of the important signaling molecules nitric oxide and endothelin-1, both of which are beneficially affected by grape seed polyphenols.22,23 Clinical studies are showing powerful effects of grape seed extracts on important measures of vascular health.
Sadly, smokers provide researchers with ample opportunities to study the impact of oxidative stress on endothelial function. In a basic but powerful demonstration of how red grape components can battle even the worst oxidant-induced endothelial damage, Greek researchers tested flow-mediated dilation (a measure of endothelial cell-mediated blood vessel relaxation) following either a cigarette alone, or a cigarette along with either red wine or alcohol-free red wine.24 Flow-mediated dilation decreased significantly (a bad sign) after smoking alone, but remained at baseline when the cigarette was accompanied by either red grape beverage. This simple result demonstrates the power of grape polyphenols to preserve vascular function, even in the face of severe oxidant stress.
Of course, a high-fat diet is another major cardiovascular risk factor. Chilean scientists studied endothelial function as measured by flow-mediated dilation in a group of healthy volunteers who consumed either a control diet rich in fruits and vegetables, or a high fat diet, for 30 days with red wine and again after 30 days without wine.25 Flow-mediated dilation adversely decreased in the high-fat group compared with the control group when no wine was consumed. However, when both dietary groups drank a glass of red wine each day, there was no adverse decrease. It appears, then, that red wine or its constituents (remember that red wine includes many grape seed-derived compounds) can dramatically reduce the impact of bad lifestyle choices that increase cardiovascular risks.
But it’s not just smokers or high- fat consumers who can receive the vascular health benefits of red grapes and their extracts. Swedish scientists measured flow-mediated dilation in 12 healthy subjects less than 40 years old who had no known cardiovascular risk factors, following consumption of red wine with or without alcohol.26 The red wine caused the arteries to dilate, increasing blood flow (many people experience a “flush” with red wine). But even the alcohol-free version significantly increased flow-mediated dilation, which is the important measure of endothelial function. The researchers concluded that the antioxidant properties of the red grape protect against cardiovascular disease by promoting healthy endothelial function. The next natural step would be to examine the effects of a pure red grape extract.
Greek scientists recently did just that, conducting a controlled study of red grape extract alone among 30 men with coronary artery disease.27 The men received either a grape polyphenol extract (600 mg) dissolved in water, or pure water as a placebo. Flow-mediated dilation increased (a positive finding) in the men who took the extract, both compared with their own values at baseline and compared with the placebo group. These scientists point out that “polyphenolic compounds from red grapes acutely improve endothelial function in patients with coronary heart disease.”
Another group of researchers examined the effects of red wine on measures of blood vessel health.28 Red wine dramatically decreased major inflammatory markers and molecules that can cause blood cells to stick to vessel walls, such as C-reactive protein and monocyte-and endothelial-adhesion molecules. This study demonstrates the ability of red grape-derived polyphenols to protect blood vessel linings, a key component of a healthy cardiovascular system.
Numerous additional studies have now established the powerful ability of the red grape and its seed-derived polyphenols to improve health and prevent disease by protecting blood vessel linings and preserving their vital natural functions.29-3