Health Benefits

Grapes contain beneficial compounds called flavonoids, which are phytonutrients that give the vibrant purple color to grapes, grape juice and red wine; the stronger the color, the higher the concentration of flavonoids.

These flavonoid compounds include quercitin, as well as a second flavonoid-type compound (falling into the chemical category of stilbenes)called resveratrol. Both compounds appear to decrease the risk of heart disease by:

• Reducing platelet clumping and harmful blood clots
• Protecting LDL cholesterol from the free radical damage that initiates LDL's artery-damaging actions

Grapes and products made from grapes, such as wine and grape juice, may protect the French from their high-fat diets. Diets high in saturated fats like butter and lard, and lifestyle habits like smoking are risk factors for heart disease. Yet, French people with these habits have a lower risk of heart attack than Americans do. One clue that may help explain this "French paradox" is their frequent consumption of grapes and red wines.

Protection Against Heart Disease

In a study in which blood samples were drawn from 20 healthy volunteers both before and after they drank grape juice, researchers found several beneficial effects from their juice consumption.

First, an increase occured in levels of nitric oxide, a compound produced in the body that helps reduce the formation of clots in blood vessels. Second, a decrease occurred in platelet aggregation, or blood clotting, by red blood cells. Lastly, researchers saw an increase in levels of alpha-tocopherol, an antioxidant compound that is a member of the vitamin E family, and this increase was accompanied by a 50% increase in plasma antioxidant activity.

These findings confirmed the benefits found in an earlier study, where researchers found not only an increase in blood antioxidant activity, but also discovered that grape juice protected LDL cholesterol from oxidation, a phenomenon that can turn LDL into an artery-damaging molecule. (Although LDL is often called the "bad" form of cholesterol, it is actually benign and only becomes harmful after it is damaged by free radicals or "oxidized."

Additionally, investigators have found that phenolic compounds in grape skins inhibit protein tyrosine kinases, a group of enzymes that play a key role in cell regulation. Compounds that inhibit these enzymes also suppress the production of a protein that causes blood vessels to constrict, thus reducing the flow of oxygen to the heart. This protein, called endothelin-1, is thought to be a key contributing agent in the development of heart disease.

A study published in the journal Hypertension sheds new insight on the mechanisms of action through which resveratrol inhibits the production of the potent blood vessel constrictor, endothelin-1 (ET-1). Resveratrol appears to work at the genetic level, preventing the strain-induced expression of a gene that directs the production of ET-1. Normally, ET-1 is synthesized by endothelial cells (the cells comprising the lining of blood vessel walls) in response to free radicals formed as a result of strain or stress. Resveratrol prevents the expression of ET-1, at least in part, by significantly lessening free radical formation, thus preventing the production of the agents that, in turn, activate the signaling pathways that control the creation of ET-1.

Resveratrol helps keep the heart muscle flexible and healthy

A team of researchers led by Gary Meszaros and Joshua Bomser at the Northeastern Ohio Universities College of Medicine has shown that resveratrol not only inhibits production of endothelin-1, but also directly affects heart muscle cells to maintain heart health. Their research, published in the American Journal of Physiology: Heart and Circulatory Physiology, shows that resveratrol inhibits angiotensin II, a hormone that is secreted in response to high blood pressure and heart failure.

Angiotensin II has a negative effect on heart health in that it signals cardiac fibroblasts, the family of heart muscle cells responsible for secreting collagen, to proliferate. The result is the production of excessive amounts of collagen, which causes the heart muscle to stiffen, reducing its ability to pump blood efficiently.

In addition to inhibiting angiotensin II, and therefore the proliferation of cardiac fibroblasts, resveratrol also prevented the cardiac fibroblasts that were already present from changing into myofibroblasts, the type of cardiac fibroblast that produces the most collagen.

The role of grapes' saponins in supporting heart health

Research presented at the 226th national meeting of the American Chemical Society provides yet another explanation for red wine's cardio-protective effects-phytonutrients that help lower cholesterol called saponins. A plant protective agent found in the grapes' waxy skin, which dissolves into the wine during its fermentation process, saponins are believed to bind to and prevent the absorption of cholesterol and are also known to settle down inflammation pathways, an effect that could have implications in not only heart disease, but cancer. The research team, led by Andrew Waterhouse, PhD, from the University of California, Davis, thinks that alcohol may make the saponins more soluble and thus more available in wine.

Currently, a hot research topic, saponins are glucose-based compounds, which are being found in an increasing number of foods including olive oil and soybeans. Waterhouse tested six varieties of California wines, four red and two white, to compare their saponin content, which varied among brands, but was found present in high concentrations in all the red wines tested. Red wines contained 3 to 10 times the amount of saponins found in white wines. The saponin content of red wine also showed a positive correlation with alcohol content, the stronger the wine, the more saponins. Among the red wines tested, red Zinfandel, which also had the highest level of alcohol-16%-contained the highest levels. Syrah came in second, followed by Pinot noir and Cabernet Sauvignon, which had a comparable amount. The white varieties tested, Sauvignon blanc and Chardonnay, contained much less.

"Average dietary saponin intake has been estimated at 15 mg, while one glass of red wine has a total saponin concentration of about half that, making red wine a significant dietary source," Waterhouse said.

Strokes occur when blood clots or an artery bursts in the brain, interrupting its blood supply. In the U.S., where every 45 seconds, someone will experience a stroke, according to the American Stroke Association, strokes are the leading cause of disability and the 3rd leading cause of death.

Resveratrol, a flavonoid found in grapes, red wine and peanuts, can improve blood flow in the brain by 30%, thus greatly reducing the risk of stroke, according to the results of an animal study published in the Journal of Agricultural and Food Chemistry.

Lead researcher Kwok Tung Lu hypothesized that resveratrol exerted this very beneficial effect by stimulating the production and/or release of nitric oxide (NO), a molecule made in the lining of blood vessels (the endothelium) that signals the surrounding muscle to relax, dilating the blood vessel and increasing blood flow.

In the animals that received resveratrol, the concentration of nitric oxide (NO) in the affected part of the brain was 25% higher than that seen not only in the ischemia-only group, but even in the control animals.

Pterostilbene, another antioxidant in grapes, may lower cholesterol

In addition to resveratrol and saponins, grapes contain yet another compound called pterostilbene (pronounced TARE-oh-STILL-bean), a powerful antioxidant that is already known to fight cancer and may also help lower cholesterol.

In a study using animal liver cells, scientists at the USDA Agricultural Research Service compared the cholesterol-lowering effects of pterostilbene to those of ciprofibrate, a lipid-lowering drug, and resveratrol, another antioxidant found in grapes with a chemical structure similar to pterostilbene that has been shown to help fight cancer and heart disease.

They based their comparison on each compound's ability to activate PPAR-alpha (short for peroxisome proliferator-activated receptor alpha). The PPARs are a family of receptors on cells all throughout the body that are involved in the absorption of compounds into cells for use in energy production. PPAR-alpha is crucial for the metabolism of lipids, including cholesterol.

Pterostilbene was as effective as ciprofibrate and outperformed resveratrol in activating PPAR-alpha. In addition to grapes, pterostilbene is found in berries of the Vaccinium genus such as cranberries and blueberries. The take away message: turn up your cholesterol burning machinery by eating more grapes, blueberries and cranberries.

 

 

Grape polyphenols lower key factors for coronary heart disease in women

More evidence shows grapes and grape juice, not just red wine, offer considerable cardiovascular benefits. Consuming a drink made from adding just 36 g (1.26 ounces) of a powder made from freeze-dried grapes to a glass of water daily for 4 weeks resulted in a wide variety of cardioprotective effects in 24 pre- and 20 postmenopausal women, shows a study published in the Journal of Nutrition.

• Blood levels of LDL cholesterol and apolipoproteins B and E dropped significantly. (These apolipoproteins are involved in the binding of LDL and VLDL cholesterol to blood vessel walls, one of the beginning steps in the development of atherosclerosis.)
• Triglycerides dropped 15 and 6% in pre- and postmenopausal women, respectively.
• Cholesterol ester transfer protein activity dropped 15%. (Inhibition of this protein has been shown to increase levels of HDL while decreasing LDL levels.)
• Levels of urinary F(2)-isoprostanes (a marker of free radical damage in the body) dropped significantly as did blood levels of TNF-alpha (tumor necrosis factor-alpha, which plays a major role in the inflammation process).

The rich mixture of phytonutrients found in grapes-which includes flavans, anthocyanins, quercetin, myricetin, kaempferol, as well as resveratrol-is thought to be responsible for these numerous protective effects on cholesterol metabolism, oxidative stress (free radical activity) and inflammation.

Wine Protective for Persons with Hypertension

If you have high blood pressure, a glass of wine with your evening meal may be a good idea, according to research published in the American Journal of Clinical Nutrition. In persons with high blood pressure, the risk of death from cardiovascular disease is much higher in northern Europe and the United States than in Mediterranean countries. When French researchers tested the hypothesis that drinking wine reduces the risk of hypertension-related death, they found that, in persons with hypertension, moderate regular wine drinking reduced the risk of death from all causes, not just coronary artery disease.

Grapes Provide Many of the Cardioprotective Benefits of Red Wine

While studies show red wine offers numerous protective benefits, grape juice also provides the majority of these effects without the risks of alcohol consumption, which, if excessive can lead to accidents, liver problems, higher blood pressure, heart arrhythmias-and alcoholism.

In addition, red wine causes migraines in some people and may bring on an attack of gout in others. Wine often contains added preservatives, colors and flavors, which are not listed on the label and may cause adverse reactions. Sulfur dioxide, for example, is an additive frequently found in red wine that can trigger an asthma attack in individuals sensitive to this chemical.

If consumed by pregnant women, any alcoholic beverage including wine, can cause fetal alcohol syndrome.

If you prefer not to consume alcoholic beverages, take heart-grapes may still provide many of the cardioprotective benefits attributed to red wine.

Resveratrol, which is concentrated in red wine but only appears in very small amounts in grapes, has been touted as the main agent responsible for the "French paradox," i.e., the health benefits associated with drinking red wine. But, Lawrence M. Szewczuk and Trevor M. Penning from the University of Pennsylvania, in a study published in the Journal of Natural Products, point out that other constituents found in far greater amounts in grapes as well as red wine, namely grapes' catechins and epicatechins, might be due the most credit.

One of the primary ways in which resveratrol is reported to have its cardioprotective effects is its ability to modify activity of cyclooxygenase enzymes. Two forms of cyclooxygenase (COX-1 and COX-2) have been closely studied in the research literature (often by drug companies developing new prescription medications). These cyclooxygenase enzymes have many roles in metabolism, including roles in triggering the body's inflammatory response. COX-2 appears to be the more important of these two enzyme forms when it comes to inflammatory response. Resveratrol appears to help block COX-2 activity indirectly, through changes in another system of messaging molecules called NF-kappaB and I-kappaB kinase. It also appears to directly block activity of COX-1. Unfortunately, the average wine drinker appears to absorb resveratrol in quantities too small to significantly lower cyclooxygenase activity. Catechins and epicatechins are present in much greater amounts in grapes as well as red wine, and smaller amounts of these compounds appear to be needed for reduction of cyclooxygenase activity.

To receive comparable benefits as those gained from drinking a glass of red wine, however, you need to drink more grape juice. A recent study found that six glasses of grape juice produced the same beneficial effect as two glasses of red wine in reducing platelet aggregation, the clumping that leads to blood clots, heart attacks and strokes.

Another option is to drink dealcoholized red wine. A study published in the American Journal of Clinical Nutrition suggests the alcohol-free alternative provides comparable cardioprotective benefit. In this six month study, female laboratory animals with an inbred susceptibility to develop cardiovascular disease were given a normal diet along with red, white or dealcoholized red wine to compare their effects on atherosclerosis development. Dealcoholized red wine provided effective protection comparable to that of either white or red wine, significantly decreasing the development of atherosclerosis. Researchers credit the polyphenolic compounds found in the wine, rather than alcohol, with these beneficial effects.

So, if you want to avoid alcohol and protect your heart, toast your health with at least three daily glasses of red or purple grape juice.

Resveratrol for Optimal Health

Recently, several studies have also identified resveratrol as an excellent candidate for use as a cancer-preventive agent in prostate, lung, liver and breast cancer. Resveratrol has demonstrated striking inhibitory effects on the cellular events involved in cancer initiation, promotion, and progression, and its safety in animal studies of cancer development resulting from exposure to chemical toxins is excellent.

One of the most exciting studies, published in the Journal of Applied Toxicology, suggested that resveratrol can provide protection against benzopyrene, a major environmental carcinogen involved in the development of lung cancer. Resveratrol works its protective magic by inhibiting a receptor on cells called the aryl hydrocarbon receptor (AhR) to which benzopyrene (and other carcinogens called polycyclic aromatic hydrocarbons) bind. The AhR turns on a whole battery of genes that is involved in carcinogenesis. In this study, significant DNA damage was found in laboratory animals exposed to benzopyrene, but when they were also given resveratrol, their DNA damage was less than half, plus, in those cells whose DNA was damaged, resveratrol also caused a significant rise in apoptosis (the self-destruction sequence the body uses to eliminate cancerous cells).Other studies suggest that resveratrol can also inhibit the growth of liver and breast cancer cells.

French scientists have discovered a potent anti-cancer agent, acutimissin A, in red wine that has been aged in oak barrels. A member of a class of polyphenols called ellagitannins, acutimissin A develops when a grape flavonoid called catechin combines with a phenol in oak called vescalagin. Discovered 16 years ago in the sawtooth oak, acutimissin A blocks the action of an important enzyme whose activity is essential to the development of cancerous cells. In preliminary tests, acutimissin A has been shown to be 250 times more potent than the clinical anti-cancer drug VP-16.

Promote Lung Health

Red, but not white wine, may offer protection against lung cancer, suggests a study published in Thorax by Professor Juan Barros-Dios and his team at the University of Santiago de Compostela, Spain, who reported the results of their hospital-based case-control study. While a daily glass of white wine was associated with a 20% increased risk of lung cancer, a daily glass of red wine lowered risk an average of 13%. No association was noted between lung cancer and the consumption of beer or spirits.

What might explain these different effects seen in individuals drinking red and white wine? Most likely, red wine's concentration of the phytonutrient, resveratrol. Another study published in the American Journal of Physiology: Lung, Cellular and Molecular Physiology found that resveratrol has a number of anti-inflammatory effects on human airway epithelial cells-the cells lining the lungs and nasal passages.

Resveratrol blocked the release in these epithelial cells of a number of inflammatory molecules including IL-8, inducible nitric oxide synthase and NF-kappaB, inhibiting the latter more effectively than the powerful glucocorticosteroid drug, dexamethasone.

Resveratrol's anti-inflammatory actions also inhibited the production of COX-2 in these epithelial cells. COX-2 is the pro-inflammatory compound whose production the non-steriodal anti-inflammatory drugs Vioxx and Celebrex were developed to prevent. While these drugs are now being pulled off the market due to the increased risk of heart attack and death associated with their use, resveratrol's anti-inflammatory actions pose no such risks.

In fact, the researchers concluded their report by saying, "This study demonstrates that resveratrol and quercetin have novel nonsteroidal anti-inflammatory activity that may have applications for the treatment of inflammatory diseases." Louise Donnelly, lead researcher in the study, was so impressed with resveratrol's broad anti-inflammatory effects that she has begun investigating its use in an aerosol spray to treat chronic obstructive pulmonary disease and asthma.

Grapes Enhance Women's Health

Red grape skins and seeds contain recently isolated compounds that a study published in Cancer Research has shown reduce the size of estrogen-dependent breast cancer tumors. In breast cancer, local estrogen production has been demonstrated to play a major role in promoting tumor growth. An enzyme called aromatase, which converts other hormone substrates (specifically, androgens) into estrogens, is present in greater amounts in breast cancer tissue compared to normal breast tissue and is thought to play a crucial role in breast cancer initiation and progression. Grape skins and seeds contain compounds called procyanidin B dimers that can inhibit aromatase, and in this study, were used to significantly reduce the size of mammary tumors in laboratory animals. Lead researcher, Shiuan Chen, of the City of Hope Cancer Center in Los Angeles, believes these phytonutrients in grape skins and seeds, while not as powerful as drugs used to inhibit aromatase (e.g., anastrozole, letrozole and exemestane), could play an important role as cancer preventive agents. If you drink wine, choose red. And next time you buy grapes, consider choosing red grapes with seeds.

Another Way Grapes Promote Optimal Health

Research published in Cancer Letters provides one reason why diets high in fruit help prevent cancer: raspberries, blackberries and muscadine grapes inhibit metalloproteinase enzymes. Although essential for the development and remodeling of tissues, if produced in abnormally high amounts, these enzymes play a significant role in cancer development by providing a mechanism for its invasion and spread.

Grapes' Resveratrol May Lower Risk of Alzheimer's Disease

Population studies indicate a link between moderate consumption of red wine and a lower incidence of Alzheimer's disease. A laboratory study published in the Journal of Biological Chemistry helps explain why.

Resveratrol, a naturally occurring polyphenol found mainly in grapes and red wine, greatly reduces the levels of amyloid-beta peptides (Abeta). Plaques containing Abeta are a hallmark finding in the brain tissue of patients with Alzheimer's disease.

In this study, cells treated with resveratrol had significantly lower levels of Abeta than untreated cells. Resveratrol lowers Abeta levels by promoting its rapid breakdown by proteasomes, protein-digesting "machines" inside our cells that dismantle a variety of proteins into short polypeptides and amino acids that can then be used to make new protein the cell needs.

Each human cell contains about 30,000 proteasomes, which mainly digest proteins made within the cell, such as enzymes and transcription factors, so their parts can be recycled to make new proteins.

Resveratrol-An Anti-Aging Agent

In recently published research, resveratrol has been identified as a potent activator of Sir2-an enzyme researchers have now discovered is responsible for the extension of life span seen in many species when placed on calorie restricted diets.

In the yeast Saccharomyces cerevisiae, not only does calorie restriction extend longevity through a pathway that requires the enzyme Sir2, but overproducing this enzyme can prolong the life of yeast even when grown under normal nutrient conditions. Similarly, in the evolutionarily more advanced worm Caenorhabditis elegans, increased expression of the worm's version of Sir2 has also been shown to extend lifespan.

The Sir2 enzyme belongs to a large family of molecules called sirtuins, found in virtually all life forms. In mammalian cells, sirtuins regulate cell maturation (differentiation) and programmed cell death (apoptosis).

Building on the knowledge that caloric restriction prolongs longevity through Sir2, researchers (Howitz et al.) searched for a small molecule that could activate this enzyme directly. They discovered two related compounds that stimulate Sir2 activity, both of which belong to the family of molecules called polyphenols-active compounds products by plants. Of all the polyphenols tested, resveratrol was the most potent by far. The researchers found that this compound prolonged the lifespan of yeast by approximately 70%, and that the extension of longevity was entirely dependent on resveratrol's activation of Sir2. Yeast strains deficient in this enzyme did not benefit from resveratrol treatment.

Could plant polyphenols such as resveratrol hold the secret of the elixir of youth sought by Ponce de Leon? Perhaps, but the research indicates that figuring out the way to apply their life extending effects will be complicated. At relatively low doses, resveratrol was found to stimulate sirtuin activity, but higher doses have had the opposite effect. While not an ideal characteristic for a pharmaceutical drug, this suggests that the appropriate dosage could be supplied by enjoying a daily glass of grape juice or red wine. More importantly, however, much more research must be done before we understand how sirtuins function in mammalian aging. Extending longevity in a yeast is a long way from life extension in higher organisms. Till scientists figure this out, a daily dose of resveratrol-rich grapes in all their delicious forms might add years to your life as well as delight to your years.

An Effective Anti-Microbial Agent

Researchers at Erciyes University, Turkey, have found that an agent made from grape pomace extract (grape seeds, skin and stems) is an effective anti-microbial agent. When tested against 14 bacteria including Escherichia coli and Staphylococcus aureus, the grape extract inhibited all the bacteria tested at extract concentrations of 2.5, 5, 10 and 20%, except for Y enterocolitica, which was not inhibited by the 2.5% concentration.

Red Wine Greatly Cuts Colorectal Cancer Risk, Reduces Risk of All-Causes of Mortality

Drinking at least three glasses of red wine a week could cut the risk of colorectal cancer by almost 70%, researchers reported at the 71st Annual Scientific Meeting of the American College of Gastroenterology in Las Vegas. Colorectal cancer accounts for 9% of new cancer cases every year worldwide, occurring primarily in the United States and Europe. Fortunately, if diagnosed early, it remains one of the most curable cancers.

Joseph Anderson and colleagues from the Stony Brook University in New York looked at the drinking habits of 360 red and white wine drinkers with similar lifestyles and found that, while white wine consumption had no association with colorectal cancer occurrence, regularly drinking red wine was linked to a 68% reduced risk of the cancer.

The active component in wine thought to be largely responsible is resveratrol, a natural anti-fungal that grapes-especially organically grown red grapes- produce under their skin. The concentration of resveratrol is significantly higher in red than white wine because the skins are removed earlier during white-wine production.

Nearly all dark red wines-merlot, cabernet, zinfandel, shiraz and pinot noir-contain resveratrol, although the amount in a bottle can range from 0.2 to 5.8 milligrams per litre, varying among types of grapes and growing seasons.

Also, grapes and wine are reported to contain more than 600 different phytonutrients, including many with antioxidant activity, so it's likely that a number of compounds in grapes, including resveratrol, work synergistically to protect against colorectal cancer.

In support of this hypothesis, a recent animal study by researchers from Tuft's University reported brain-protecting effects from Concord grape juice resulting from synergistic activity among grape polyphenols. "It may be that the whole is greater than the sum of its parts," wrote lead author of this study, Barbara Shukitt-Hale, in the journal Nutrition.

In other research-a meta-analysis of 34 studies involving over a million people published in the Archives of Internal Medicine-investigators at the Catholic University of Campobasso in Italy concluded that moderate drinking is associated with a reduction in all-cause mortality.

Although excessive alcohol consumption was shown to increase mortality, drinking 2 to 4 drinks per day was associated with a reduction in deaths from all causes in men. For women, the protective effect ended above 2 drinks per day.

It's been proposed that the protective effect of moderate drinking may be due to associated lifestyle factors, but lead author of this study, Di Castelnuovo noted, "We've carefully examined this aspect. Our data suggest that, even considering all main confounding factors (as dietary habits, physical activity or the health of people studied), a moderate consumption of alcoholic beverages keeps on showing a real positive effect."

The review also determined that the protective benefit of alcohol is greater for European than American men, which could be explained by the way in which alcohol is consumed: European men are likelier than Americans to drink wine and to enjoy it with a meal.

"The core of this study is not just about alcohol," Catholic University Research Laboratories director Giovanni de Gaetano stated. "It is also the way we drink that makes the difference: little amounts, preferably during meals, this appears to be the right way. This is another feature of the Mediterranean diet, where alcohol, wine above all, is the ideal partner of a dinner or lunch, but that's all: the rest of the day must be absolutely alcohol-free. The message carried by scientific studies like ours is simple: alcohol can be a respectful guest on our table, but it is good just when it goes with a healthy lifestyle, where moderation leads us toward a consumption inspired by quality not by quantity."

Recent Harvard research (the Northern Manhattan Study and the Cardiovascular Health Study) also suggest that moderation in alcohol consumption is key: lowest risk of stroke was seen in those who had one, or maybe two, drinks a day.

If you're inspired to try a daily glass of red wine as part of your healthy way of eating, you may want to look for red wine from southwestern France or Sardinia. Research published in Nature suggests that the protective polyphenols in red wine are present at higher concentrations in wines from southwestern France and Sardinia, where traditional production methods ensure these compounds are efficiently extracted during wine production.

In this study, researchers evaluated red wine samples from Australia (14), France (11), Greece (16), Italy (3), Spain (1), Sardinia (15), Argentina (33), Chile (9), Bolivia (5), Uruguay (4), and the USA (14 from California), along with various other wines from Southwest France, Georgia and South Africa.

They also looked at human aging patterns using data from the 1999 French census. The data showed six regions in Southwest and Central France with >25% higher level of men aged 75 or more, compared to the national average. Men living in Nuoro province in Sardinia also had higher longevity. (The analyses focused on men because they have been shown to benefit more than women from regular wine consumption.) Wines produced in areas of increased longevity (e.g., the Gers area of France and Nuoro province in Sardinia) were found to have 2-4-fold more polyphenol (oligomeric procyanidins or OPCs) content and biological activity than wines from other regions. These are areas where traditional wine making methods are still used, plus the Tannat grape used in these regions is also particularly high in OPCs.

Concord Grape Juice Ranked among the Highest in Antioxidant Activity

Not all fruit juices are the same. They differ markedly in the variety of phenolic compounds and antioxidant activity, according to Alan Crozier, Professor of Plant Biochemistry and Human Nutrition, who, with colleagues at the University of Glasgow, evaluated 13 commercially available popular juices.

Concord grapes came out on top with the highest and broadest range of polyphenols and the highest overall antioxidant capacity. (The main components in purple grape juice were flavan-3-ols, anthocyanins, and hydroxycinnamates, together accounting for 93% of the total phenolic content.)

Other top scorers were cloudy apple juice, cranberry juice and grapefruit juice.

Results for the red grape juice were said to be equal to those for a Beaujolais red wine. Interestingly, however, white grape juice, mainly containing hydroxycinnamates, had the lowest total phenolic content.

The products analyzed were: Spray Classic Cranberry; Welch's Purple Grape; Tesco Pure Pressed Red Grape; Pomegreat Pomegranate; Tesco Pure Apple (clear); Copella Apple (cloudy); Tesco Pure Grapefruit; Tesco Value Pure Orange (concentrate); Tropicana Pure Premium Smooth Orange (squeezed); Tropicana Pure Premium Tropical Fruit; Tesco Pure Pressed White Grape; Tesco Pure Pineapple; Del Monte Premium Tomato.

Dr. Crozier's findings come shortly after those of the Kame project, which indicated that long-term fruit juice consumption can provide protection against Alzheimer's disease (Dai et al., Am J Med), and suggest that, since each fruit juice contains its own array of protective phenols, drinking a variety may offer the best protection. Practical Tip: "The message is to mix these juices during the week. That way you will get all the compounds with anti-oxidant activity. If you drink only one juice you risk missing out on the compounds in the others," explained Crozier.

Description

Grapes are small round or oval berries that feature a semi-translucent flesh encased by a smooth skin. Some contain edible seeds, while others are seedless. Like blueberries, grapes are covered by a protective, whitish bloom.

Grapes that are eaten from the vine are called table grapes, as opposed to wine grapes (used in viniculture) or raisin grapes (used to make dried fruit). While there are thousands of varieties of grapes, only about 20 constitute the majority of table grapes consumed.

Color, size, taste and physical characteristics differ amongst the varieties. Grapes come in a variety of colors including green, amber, red, blue-black, and purple. In general, whole grapes have a slightly crunchy texture and a dry, sweet and tart taste.

There are three main species of grapes:

European grapes (Vitis vinifera):

Varieties include Thompson (seedless and amber-green in color), Emperor (seeded and purple in color) and Champagne/Black Corinth (tiny in size and purple in color). European varieties feature skins that adhere closely to their flesh.

North American grapes (Vitis labrusca and Vitis rotundifolia):

Varieties include Concord (blue-black in color and large in size), Delaware (pink-red in color with a tender skin) and Niagara (amber colored and less sweet than other varieties). North American varieties feature skins that more easily slip away from their flesh.

French hybrids:

These were developed from the vinifera grapes after the majority of grape varieties were destroyed in Europe in the 19th century.

History

Grapes have a long and abundant history. While they've grown wild since prehistoric times, evidence suggests they were cultivated in Asia as early as 5000 BC. The grape also played a role in numerous biblical stories, being referred to as the "fruit of the vine." Grapes were also pictured in hieroglyphics in ancient Egyptian burial tombs.

During the ancient Greek and Roman civilizations, grapes were revered for their use in winemaking. They were planted in the Rhine Valley in Germany, a place of notable wine production, in the 2nd century AD. Around this time, over 90 varieties of grapes were already known.

As European travelers explored the globe, they brought the grape with them. Grapes were first planted in the United States in the early 17th century at a Spanish mission in New Mexico. From there, they quickly spread to the central valley of California where climate, and absence of grape-preying insects, best supported their production.

In the late 19th century, almost all of the vinifera varieties of grapes in France were destroyed by an insect that was unintentionally brought from North America. Fortunately, agriculturists crossbred some of the vinifera variety with the American labrusca variety and were able to continue the cultivation of grapes in this region, one that is famous for its grapes and wine.

Today, as researchers continue to investigate the health-promoting polyphenolic compounds found in grapes, this fruit is gaining even more attention. Currently, Italy, France, Spain, the United States, Mexico and Chile are among the largest commercial producers of grapes.