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." During the ancient Greek and Roman civilizations, grapes were revered for their use in wine making. 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. Even though grapes are known to have grown wild on many continents - including Europe, Asia, Africa, and North America - travel and exploration (together with a cultural fondness for this food and its wines) led to transport of native grapes across the world. For example, as European travelers explored the globe, they brought native European ("old World") grapes with them. For the best tasting grapes with high concentrations of antioxidants select those that are fully ripe. Fully ripened grapes are plump and free from wrinkles. They should be intact, firmly attached to a healthy looking stem, and not leaking juice. The area around the attachment should have the same color as the rest of the grape. One way to help predict the sweetness of grapes is by their color: green grapes are medium sweet, red grapes are very sweet, and blue-black grapes are the least sweet. Green grapes should have a slight yellowish hue, red grapes should be mostly red, while purple and blue-black grapes should be deep and rich in color.
Since grapes tend to spoil and ferment at room temperature, they should always be stored in the refrigerator. Loosely wrap unwashed grapes in a paper towel and place them in an airtight container or plastic bag. This way, they'll keep fresh in the refrigerator for up to 5 days. While freezing detracts from some of their flavor, frozen grapes are a wonderful snack and particularly intriguing to children. To freeze grapes, wash and pat them dry, then arrange in a single layer on a cookie sheet and place in freezer. (Patting the grapes dry is important, because excess moisture can cause the grapes to stick together and become one large frozen fruit clump.) Once frozen, transfer grapes to a heavy plastic bag and return them to the freezer. Grapes should be washed under cold running water right before consuming or using in a recipe. After washing, either drain the grapes in a colander or gently pat them dry. If you are not going to consume the whole bunch at one time, use scissors to separate small clusters of grapes from the stem instead of removing individual grapes. This will help keep the remaining grapes fresher by preventing the stem from drying out.
HEALTH BENEFITS: The wealth of antioxidant nutrients in grapes is somewhat startling! In addition to providing us with conventional antioxidant nutrient like vitamin C and manganese, grapes are filled with antioxidant and the total number of different antioxidant nutrients in grapes runs well into the hundreds. (Even the hormone melatonin has been identified in grapes and is known to act as an antioxidant provided by this food.) It's important to note that the seed and the skin contain the richest concentration of antioxidants. As a general rule, the flesh of the grape contains approximately 1/20th-1/100th of the total antioxidant capacity of the seed or the skin. The greater concentration of antioxidants in the skin and seed of grapes does not mean that we don't benefit from eating the whole grape, including the flesh! But it does mean that we need to treat grape studies as a whole as most likely reflecting stronger short-term antioxidant benefits that would be associated with short-term intake of whole grapes. Research on antioxidant benefits provided by grapes or grape components includes the following findings. Grapes and grape components can:
Reduce swelling: Along with their strong antioxidant support, grapes provide us with equally strong anti-inflammatory benefits. Grapes have been determined to lower our risk of excessive and unwanted inflammation in a variety of ways. Many pro-inflammatory messaging molecules can have their activity level reduced by grape intake. These molecules include interleukin 6 interleukin 1-beta and tumor necrosis factor alpha. Overproduction of the pro-inflammatory enzymes cyclo-oxygenase 1 and 2 is also less likely following intake of grape components.
For Heart: No body system is better situated to reap the benefit of antioxidants and anti-inflammatory molecules in grapes than the cardiovascular system. All cells in our blood need protection from potential oxygen damage (especially in our arteries where oxygen concentration in our blood is especially high). Our blood vessel linings also need strong antioxidant support. Chronic inflammation in our cardiovascular system is also a primary concern for many types of cardiovascular disease, and optimal regulation of inflammatory system activity is especially important in lowering our risk of atherosclerosis and other conditions. The list of cardio benefits provided by grapes and grape components is perhaps the most impressive of all grape benefits. It's also one of the reasons that consumption of grapes in the form of red wine has been regarded by some researchers as a key for understanding "the French Paradox." The French Paradox refers to research observations about heart health in the French population in relationship to their saturated fat intake. Despite eating fairly large amounts of saturated fat in their overall diet, the French population as a whole has been observed to have much lower levels of heart disease than would be expected with high saturated fat intake. One of the reasons might be the anti-inflammatory (and antioxidant) support provided to their cardiovascular system on a regular basis by red wine. The idea that red wine (from red grapes) could help explain the French Paradox is just one more reason for us to consider grapes as a great addition to a heart healthy diet. All of the following cardio benefits have been demonstrated in research studies on grapes and grape components:
For Diabetes: Have long been classified as a low glycemic index (GI) food, with GI values ranging between 43-53. In the case of grapes, recent studies have also shown that the low GI value of grapes is a good indicator of this fruit's blood sugar benefits. Studies have now connected grape intake to better blood sugar balance, better insulin regulation, and increased insulin sensitivity.
Anti-Aging: Several grape phytonutrients may play a role in longevity and may provide us with anti-aging benefits. Best-studied in this area of health benefits is resveratrol (a stilbene phytonutrient presently mostly in grape skins, but also in grape seeds and grape flesh). Resveratrol has recently been shown to increase expression of three genes all related to longevity. (These three genes are SirT1s, Fox0s, and PBEFs.) Interestingly, some researchers have shown a parallel between activation of these longevity genes by resveratrol and activation by calorie-restricted diets. (In aging and longevity research, our ability to get optimal nutrition for the fewest possible amount of calories is related to our longevity, and the more we can decrease our calories while staying optimally nourished, the better our chances of healthy aging and longevity.)
Cognitive Benefits: Several recent studies on grape extract intake by animals, as well as grape juice intake by humans, suggest that grapes may provide us with some important cognitive benefits. For example, daily consumption of Concord grape juice in a 1-2 cup amount over a period of several months has been shown to improve the scores of study participants on the California Verbal Learning Test. Other studies on animals have shown that excessive accumulation of reactive oxygen species (ROS) in the brain can be prevented with intake of grape extracts, as can excessive accumulation of beta-amyloid protein in the hippocampus region of the brain. Synthesis of pro-inflammatory messaging molecules in the brain has also been shown to be reduced by intake of grape extracts. While large-scale human studies are needed to confirm these potential benefits.
Anti-Microbial: Numerous grape phytonutrients have been shown to have anti-microbial properties. These phytonutrients range from common flavonoids like quercetin to less common stilbenes like piceatannol and resveratrol. Recent studies have determined that grapes may also contain unique sets of oligopeptides (short protein-like molecules) that have anti-microbial properties. Exactly how we benefit from these anti-microbial substances in grapes is not yet known. But researchers have begun to speculate about their possible role in helping us prevent microbe-related problems like food-borne illness.
Anti-Cancer: The antioxidant and anti-inflammatory properties of grapes make them a natural for protection against cancer because chronic oxidative stress and chronic inflammation can be key factors in the development of cancer. If our cells get overwhelmed by oxidative stress (damage to cell structure and cell function by overly reactive oxygen-containing molecules) and chronic excessive inflammation, our risk of cell cancer is increased. By providing us with rich supplies of antioxidant and anti-inflammatory nutrients, grapes can help us avoid this dangerous combination of chronic oxidative stress and chronic inflammation. Research on grapes, grape components and cancer has focused on three cancer types: breast cancer, colon cancer, and prostate cancer. In the case of breast cancer, the grape phytonutrients receiving the most research attention have been the catechins, proanthocyanidins, and stilbenes (especially resveratrol). For colon cancer, more research attention has been focused on grape flavonoids and grape anthocyanins. (This research tendency may mean that dark purple, red, and black grapes could end up being better choices for colon cancer prevention than green grapes, even though the jury is still out in this area.) One interesting development in the research on grapes and colon cancer prevention has involved studies on GADF( grape antioxidant dietary fiber). Fiber is greatly needed for a healthy colon, and grapes provide us with approximately 1 gram of fiber in every 60 calories. Antioxidants are also needed, and grapes come through strong in the antioxidant category. This antioxidant-plus-fiber combination may be one of the reasons that colon cancer prevention has jumped out in health research on grapes.
Raisins are made from grapes: Raisins are made from dehydrating grapes in a process that either involves the heat of the sun or a mechanical process of oven drying. Among the most popular types of raisins are Sultana, Malaga, Monukka, Zante Currant, Muscat, and Thompson seedless. While raisins can be a good addition to a Healthiest Way of Eating, it's important not to see them as a substitute for grapes. That's because dehydration not only reduces the grapes' water content but also increases their concentration of sugar and calories. With these changes, the grapes lose their nutrient richness: in every ounce of raisins, you end up getting four times the amount of sugar and calories that you would be getting in an ounce of grapes, even though you aren't getting any more vitamins and minerals. Additionally, even though raisins are made from grapes, it's not possible to generalize the health benefits shown in research studies on grapes and their components to raisins. That said, raisins can make a healthful contribution to snacks, cereals, salads, and other recipes. Eating them in moderation is best, given that one-quarter cup contains over 100 calories and the glycemic index rating for raisins is medium rather than low.
Dr Chander Shekhars Sharma
Associate professor, Deptt. Medicine,
Dayanand Ayurvedic College, Jalandhar.