Health Benefits of Grapes
Extremely delicious sweet-n-sour juiciness and versatility to act as snacks as well as a part of salads have made grapes immensely popular all over the world.
These small oval or round berries are attractive to look at too with their smooth skin encasing semi-translucent flesh. Some varieties have edible seeds, while others are seedless.
Grapes are categorized as table grapes that are eaten as is or used in recipes, raisin grapes that are used to make dried fruit and wine grapes that are used in viniculture.
These extremely tasty fruits have now been proven to be extremely healthy too. Several phytonutrients present in them are believed to help in longevity.
Although table, raisin and wine grapes belong to the same family (Vitaceae) and genus (Vitis) of the plant, around 60 different species of this plant exist and within them there are virtually thousands of grape varieties (for example, in Italy, over 1,000 varieties of wine grapes occur in hillside vineyards).
Table grapes are usually larger in size, tend to be seedless and have comparatively thin skins. Wine grapes are typically smaller in size, consist of seeds and have thicker skins (this thicker skin provides the wine with a richer flavor). There are a variety of colors in grapes.
While black, red and green are the most common in the US, there are also colors like blue black, purple, pink, amber/yellow and crimson.
A lot of people assume that seedless varieties of grapes are produced by genetic modification by agricultural researchers.
However, although certainly there is a lot of research going on to find genetically modified grapes and such genetically engineered (GE) grapes have been found, they are rarely sold in the marketplace.
Some seedless grape varieties are produced by natural mutations and they can be commercially produced. Some other seedless varieties are produced when pollination is withheld.
Still others are produced by grafting or crossbreeding. None of these techniques involve any direct manipulation of the genetic material of the grape plant.
Purchasing a certified organic version is one of the best ways to avoid genetically modified grape varieties.
Although there are many reasons of why one should buy organically produced grapes, avoiding GE grapes is not among them, because even if one purchases conventionally grown grapes, he is unlikely to get GE grapes.
Grapes Health Benefits
Loaded with Phytonutrients
While a single variety of grapes may not contain all the phytonutrients, as a group, grapes have been found to provide mankind with this wide array of nutrients.
- Flavonoids: Isorhamnetin, Myricetin, Kaempferol, Quercetin
- Flavanols: Viniferones, Procyanidins, Proanthocyanidins, Catechins, Epicatechins
- Stilbenes: Resveratrol, Pterostilbene, Piceatannol
- Carotenoids: Zeaxanthin, Lutein, Beta-carotene
- Phenolic Acids: Gallic acid, Ferulic acid, Coumaric acid, Caffeic acid
Besides the above-mentioned phytonutrients, grapes have also been found to contain the antioxidant and hormone melatonin and unique oligopeptides that have antibacterial and other health-giving properties.
Great for Diabetes
Grapes have long been known as a low glycemic index (GI) food, having GI values ranging from 43 to 53. However, having a low GI value doesn’t necessarily offer benefits for blood sugar. Recent research has shown that the low GI value of grapes has blood sugar benefits. Intake of grape extracts, juices and individual phytonutrients in grapes have now been associated with better blood sugar balance, increased insulin sensitivity and better insulin regulation.
Resveratrol in grapes has been found to increase insulin sensitivity due to which body’s ability to use glucose is increased which in turn lowers blood sugar levels.
Resveratrol has also been found to increase the number of glucose receptors on cell membrane which reduces blood sugar.
Beneficial in Diabetic Neuropathy and Retinopathy
According to some studies, resveratrol in grapes may protect against diabetic neuropathy, which adversely affect nerve function. According to scientists, this may be because of the neuroprotective effects of resveratrol.
As per animal studies, resveratrol may also protect against retinopathy which can adversely affect vision.
Diabetic neuropathy and retinopathy both arise when diabetes is poorly managed.
Many of the phytonutrients in grapes are believed to play an important role in longevity, the major among them being resveratrol which is a stilbene phytonutrient found mostly in skins, but also in flesh and seeds of grapes. This compound has been found to increase manifestation of three genes, PBEFs, Fox0s and SirT1s, all associated to longevity. It’s interesting to note that some researchers have found a parallel between stimulation of these longevity genes by resveratrol and that by calorie-restricted diets.
The research on aging and longevity says that one’s longevity is related to his ability to get optimal nutrition for the fewest possible number of calories and the more one can reduce his calories while being optimally nourished, the better are his chances of healthy aging and longevity.
There is a surprising amount of antioxidants in grapes. Ranging from usual antioxidants like vitamin C and manganese to rare stilbenes like resveratrol to hormone melatonin, there are hundreds of antioxidants in grapes. It should be noted that the highest concentration of these antioxidants is found in the seeds and skin of grapes, but not in the fleshy part. In general, the flesh contains around 1/20th to 1/100th of the total antioxidant concentration of the seed or skin.
Following are the benefits of antioxidants in grapes found by various researches:
- Reduction in oxidation of fat (lipid peroxidation)
- Reduction in the levels of oxygen reactive molecules in blood
- Reduction in biomarkers of oxidative stress
- Increase in blood levels of glutathione and also in the ratio of reduced-to-oxidized glutathione (an important measure of antioxidant capacity)
- Help in preventing certain oxygen-related enzymes including xanthine oxidase and catalase from getting overactive.
- Protection of cell membranes from free radicals
Besides a super-strong antioxidant benefits, grapes also offer equally strong anti-inflammatory support. Grapes have been found to reduce the risk of excessive and undesired inflammation in various ways. Several pro-inflammatory messaging molecules, such as tumor necrosis factor alpha (TNF-alpha), interleukin 1-beta (IL-1B) and interleukin 6 (IL-6), can get their activity levels retarded by grape intake. Chances of overproduction of pro-inflammatory enzymes like cyclooxygenase 1 and 2 (COX-1 and COX-2) are also reduced after intake of grape ingredients.
Beneficial for Heart
Cardiovascular benefits provided by grapes and their components are probably the most impressive of all grape health benefits. Some researchers have regarded the consumption of grapes in the form of red wine as “French Paradox”. The heart health of French people despite their high intake of saturated fat is known as French Paradox.
French people are found to have much lower levels of heart disease than expected and the reason is supposed to be the antioxidant and anti-inflammatory support provided by red wine (which is made from red grapes).
Here are the cardio benefits found by studies on grapes and their components:
- Better regulation of total cholesterol
- Better regulation of blood pressure
- Reduced LDL oxidation
- Reduced LDL cholesterol levels
- Increased levels of glutathione in the blood
- Better inflammatory regulation in the blood
- Less clumping together of platelet cells
- Reduced chances of adhesion of cells to the blood vessel walls
- Reduced levels of reactive oxygen molecules in the blood
- Improved release of nitric oxide from endothelial lining of blood vessel walls when vasodilation is required
It’s also indicated by animal studies that resveratrol and quercetin in grapes may decrease the risk of atherosclerosis and protect against damage resulting from LDL or “bad” cholesterol. It should be noted that these studies mostly used flavonoids in doses far higher than those normally consumed by humans.
The polyphenol stilbene, resveratrol, in grapes are considered to have lipid-lowering, anti-inflammatory and antioxidant properties that lower the risk of cardiovascular disease by reducing the risk of irregular heart rhythms and blood pressure, and preventing platelet buildup.
Grapes also contain fiber and potassium, both promote heart health. A higher intake of potassium has been linked to preservation of bone mineral density, protection against muscle loss and a reduced risk of stroke.
Several animal and human studies suggest that grapes may offer some important cognitive advantages. For example, intake of grape extracts has been found to be likely to prevent excessive accumulation of reactive oxygen species (ROS) (and beta-amyloid protein in the hippocampus region) in the brain in animals. Intake of grape extracts has also been found to reduce synthesis of pro-inflammatory messaging molecules in the brain (including TNF-alpha, IL-1B and IL-6). Various studies have shown that intake of grapes elevates mood, increases speed of memory-related skills and improves growth and blood flow in brain. Resveratrol is useful to treat Alzheimer’s disease. Red grapes can also fight against neurodegenerative diseases.
Grapes are a natural protector against cancer due to their antioxidant and anti-inflammatory properties, chronic oxidative stress as well as chronic inflammation can be major causative factors of cancer. The risk of cell cancer is increased if cells are damaged by oxidative stress (damage to cell structure and function by overly reactive oxygen-containing molecules). Grapes, by providing rich supplies of antioxidant and anti-inflammatory nutrients, can help avoid this dangerous combination.
When it comes to cancer, research on grapes and its components has focused on three main types of cancer – colon cancer, breast cancer and prostate cancer.
In case of colon cancer, research has focused on grape flavonoids and anthocyanins (This tendency of research may mean that dark purple, black and red grapes could be better choices for the prevention of colon cancer than green grapes; however, there is no definite conclusion). Another interesting point regarding grapes and colon cancer prevention is that a lot of research has been done on GADF, a type of grape antioxidant fiber.
Although GADF is a proprietary product that may sooner or later become available on the market as a dietary supplement, the concept that grape fiber combined with grape antioxidants can make one’s colon healthy makes sense. Fiber is essential for a healthy colon and grapes offer around 1gm of fiber in every 60 calories. Antioxidants are also essential and grapes have a strong antioxidant profile.
Thus grapes may provide a strong protection against colon cancer with this excellent combination of fiber and antioxidants.
Regarding breast cancer, the research has focused on stilbenes (particularly resveratrol), proanthocyanidins and catechins.
In case of prostate cancer, the most focus of research is on stilbenes (including resveratrol).
It’s suggested in laboratory studies that resveratrol in grapes may decelerate or prevent the growth of tumors in liver, stomach, lymph, breast and colon, and leukemia and skin cancer.
Since grapes consist of water and fiber, they can help people stay hydrated, regularize bowel movements and thereby reduce constipation.
Red grapes have been found to reduce uric acid due to which workload on kidneys is reduced.
A study found that mice fed with diet containing grapes showed reduced signs of damage to retina and improvement in retinal function than in mice that were not fed grapes.
In another study, resveratrol was seen to protect retinal cells in the human eye from UV A light. This may reduce the risk of developing AMD (age-related macular degeneration).
Another study has found that resveratrol may also protect against cataract, diabetic eye disease and glaucoma.
Moreover, zeaxanthin and lutein in grapes have been found to help protect eyes from damage from blue light.
Grapes contain calcium, phosphorous, magnesium, manganese, potassium and vitamin K which are necessary for bone health. Resveratrol in grapes also improves bone density as shown by studies on rats, though human studies are not available.
Since grapes are rich in antioxidants, they help protect the skin from toxin damage and pollution. They are also helpful in repair of collagen.
Several of the phytonutrients in grapes have been found to have anti-microbial properties. However, it’s not yet known exactly how the anti-microbial ingredients in grapes work.
Although research in this area is in its early stages, researchers have started to speculate about the potential role of these antimicrobial ingredients to prevent problems like food-borne disease. The antiviral properties of grapes have been found to protect against herpes simplex virus and polio virus.
Nutritional Profile of Grapes
Nutritional profile of the grapes varies depending on the variety, growing area and conditions, etc. On average 1 cup (151gm) of fresh grapes contains:
|- Carbohydrates: 27.33gm (12% DRI/DV)
- Protein: 1.09gm (2% DRI/DV)
- Fat: 0.24gm (0% DRI/DV)
- Dietary Fiber: 1.36gm (5% DRI/DV)
- Calories: 104.19 (6% DRI/DV)
- Vitamin A: 99.66 IU (1% DRI/DV)
- Vitamin B1: 0.10mg (8% DRI/DV)
- Vitamin B2: 0.11mg (8% DRI/DV)
- Vitamin B3: 0.28mg (2% DRI/DV)
- Biotin: 0.45mcg (2% DRI/DV)
- Choline: 8.46mg (2% DRI/DV)
- Folate: 3.02mcg (1% DRI/DV)
- Pantothenic Acid: 0.08mg (2% DRI/DV)
- Vitamin C: 4.83mg (6% DRI/DV)
- Vitamin E: 0.43 IU (2% DRI/DV)
|- Vitamin K: 22.05mcg (25% DRI/DV)
- Zinc: 0.11mg (1% DRI/DV)
- Boron: 694.60mcg
- Copper: 0.19mg (21% DRI/DV)
- Chromium: 0.30mcg (1% DRI/DV)
- Calcium: 15.10mg (2% DRI/DV)
- Iodine: 1.51mcg (1% DRI/DV)
- Iron: 0.54mg (3% DRI/DV)
- Manganese: 0.11mg (5% DRI/DV)
- Magnesium: 10.57mg (3% DRI/DV)
- Potassium: 288.41mg (6% DRI/DV)
- Phosphorus: 30.20mg (4% DRI/DV)
- Sodium: 3.02mg (0% DRI/DV)
- Selenium: 0.15mcg (0% DRI/DV)
Raisins are grapes that are dried using either the heat of the sun or an artificial heat of oven. Some of the most popular raisin varieties are Monukka, Malaga, Zante Currant, Sultana, Thompson seedless and Muscat.
Although raisins can be one of the healthiest foods, they cannot replace grapes because drying out of grapes not only reduces water content in the fruit but also increase the concentration of sugar and calories. The heating process also makes grapes lose their nutrient density. Each ounce of raisins offers four times more sugar and calories of that present in an ounce of grapes, but not any more nutrients.
However, raisins can definitely be healthful snacks, and addition to salads, cereals and other foods. Eating them in moderation is good; but one should remember that one quarter cup of raisins contain more than 100 calories and glycemic index level of raisins is medium rather than low. On the contrary, one full cup of grapes offer the same number of calories but with a low glycemic index.
Risk Factors of Grapes
- As per the 2014 issue of the Shopper’s Guide to Pesticides by the Environmental Working Group, conventionally grown grapes are one of the most problematic fruits in terms of pesticide residues. As per new evidence, pesticide residues can be avoided by buying certified organic grapes.
- People with heart disease are commonly prescribed beta-blockers which can cause potassium levels to increase in blood. Therefore foods high in potassium, such as grapes, should be eaten in moderation by people on beta-blockers.
- People who are on blood-thinning medications, such as Coumadin or Warfarin, should talk to their doctor before eating large amounts of grapes, because resveratrol may increase the anticoagulant action of these medications, same as vitamin K.
- Consuming excessive amount of potassium can also be dangerous to those whose kidneys are not working properly. If the excess potassium in the blood is not removed by the kidneys, it can be fatal.
- Although red wine is considered good for heart health, it should be consumed in moderation. Women are recommended to drink not more than one drink a day, while men should not drink more than two.
Long Story Short: if you have your own garden, plant few grape vines - they can be rather decorative plants, they can provide you with a nice shade and when time comes, they fruit great looking and tasty fruits with many health benefits.