What are the health benefits of grapes?
The ways to consume grapes are endless - from red, green and purple grapes to seedless grapes, grape jelly, grape jam and grape juice. And don't forget wine and raisins! This popular fruit's history goes back as far as 8,000 years, when grape vines were first cultivated in what is now the Middle East.
It may surprise you to hear that the humble grape is actually considered to be a berry. Seventy-two million tons of these berries are grown each year worldwide, with most of them being used to produce wine - 7.2 trillion gallons of wine per year, to be exact.7
The portability, texture, flavor and variety of grapes have made them a popular finger food in countries all over the world. The potential health benefits of consuming grapes are numerous, with past studies associating them with prevention of cancer, heart disease, high blood pressure and constipation.
This MNT Knowledge Center feature is part of a collection of articles on the health benefits of popular foods. It provides a nutritional breakdown of grapes and an in-depth look at their possible health benefits, how to incorporate more grapes into your diet, as well as some potential health risks associated with their consumption.
Nutritional breakdown of grapes
The average serving size for grapes is about one cup, or 32 grapes. As a useful measure, you can use the size of your fist to estimate the proper portion size for grapes.
One cup of red or green grapes contains 104 calories, 1.09 grams of protein, 0.24 grams of fat, 1.4 grams of fiber, 4.8 milligrams of vitamin C, 10 micrograms of vitamin A, 288 milligrams of potassium, 0.54 milligrams of iron and 3 micrograms of folate.3
Grapes are high in water content and good for hydration. High water-content fruits and vegetables are nutrient dense, meaning they provide a large amount of essential nutrients while containing few calories. Grapes contain 70 milliliters of fluid per cup.2
Grapes are high in antioxidants important for eye health such as lutein and zeaxanthin, and red grapes contain the phytochemical resveratrol in their skins, the antioxidant synonymous with wine known to lend protection from several chronic diseases and conditions. Grapes also boast the power of the flavonoids myricetin and quercetin which help the body to counter-act harmful free radical formation.
Possible health benefits of consuming grapes
Consuming fruits and vegetables of all kinds has long been associated with a reduced risk of heart disease, diabetes, cancer and other conditions. Many studies have shown that increasing consumption of plant foods like grapes decreases the risk of obesity and overall mortality. Grapes also have some special components that make them even more essential to our health, giving them "super food" status and reducing the risk of the following conditions:
Cancer: Grapes contain powerful antioxidants known as polyphenols, which may slow or prevent many types of cancer, including esophageal, lung, mouth, pharynx, endometrial, pancreatic, prostate and colon.1
The resveratrol found in red wine famous for heart health is a type of polyphenol found in the skins of red grapes.
Heart Disease: The flavonoid quercetin is a natural anti-inflammatory that appears to reduce the risk of atherosclerosis and protect against the damage caused by low-density lipoprotein (LDL) cholesterol in animal studies. Quercetin may have the additional bonus of anti-cancer effects; however more studies are needed using human subjects before these results can be confirmed.6
The high polyphenol content in grapes may also reduce the risk of cardiovascular disease (CVD) by preventing platelet build-up and reducing blood pressure via anti-inflammatory mechanisms.
The fiber and potassium in grapes also support heart health. An increase in potassium intake along with a decrease in sodium intake is the most important dietary change that a person can make to reduce their risk of cardiovascular disease, according to Mark Houston, MD, MS, an associate clinical professor of medicine at Vanderbilt Medical School and director of the Hypertension Institute at St Thomas Hospital in Tennessee.5
In one study, those who consumed 4069 mg of potassium per day had a 49% lower risk of death from ischemic heart disease compared with those who consumed less potassium (about 1000 mg per day).5
High potassium intakes are also associated with a reduced risk of stroke, protection against loss of muscle mass, preservation of bone mineral density and reduction in the formation of kidney stones.5
High Blood Pressure: As noted above, potassium has many benefits for the body. It may be that a low potassium intake is just as big of a risk factor in developing high blood pressure as a high sodium intake.4 Because of their high potassium content, grapes are recommended to those with high blood pressure to help negate the effects of sodium in the body.
According to the National Health and Nutrition Examination Survey, fewer than 2% of US adults meet the daily 4700 mg recommendation for potassium.5
Also of note, a high potassium intake is associated with a 20% decreased risk of dying from all causes.5
Constipation: Eating foods that are high in water content like grapes, watermelon and cantaloupe can help to keep you hydrated and your bowel movements regular. Grapes also contain fiber, which is essential for minimizing constipation.
Allergies: Because of the anti-inflammatory effects of quercetin, consuming grapes may help to alleviate symptoms of allergies including runny nose, watery eyes and hives. There have been no human studies done to prove this theory.6
Diabetic neuropathy and retinopathy: A few studies have shown promise that resveratrol can protect against diabetic neuropathy and retinopathy, conditions caused by poorly controlled diabetes where vision is severely affected. One study in which diabetic rats were treated with resveratrol for two weeks found that it reduced the effects of neural changes and damage associated with diabetic neuropathy.
Researchers have also found resveratrol to be beneficial for treating Alzheimer's disease, relieving hot flashes and mood swings associated with menopause and improving blood glucose control, however large studies using human subjects are still needed to confirm these findings.
Incorporating more grapes into your diet
The Environmental Working Group produces a list each year of fruits and vegetables with the highest levels of pesticide residue, known as the Dirty Dozen. Grapes are high on the list of produce that the EWG suggests that you buy in the organic version to ensure a lower risk of pesticide exposure.
Grapes are available year round. Select grapes that are tight to the touch and free of wrinkles. Grapes are best stored in the refrigerator and should be washed before eaten.
The best way to consume grapes is fresh right out of your hand! Most grape jellies/spreads, juices and wine have added sugars, which tack on additional calories.
Here are some handy tips to incorporate more grapes into your diet:
- Slice grapes in half and add them to your chicken salad.
- Make your own fruit cocktail with fresh fruit and include grapes, pineapple, sliced peaches and strawberries. Drizzle a small amount of honey on top of the fruit mixture for an extra sweet treat.
- Freeze grapes and eat them as a snack or dessert on a hot day.
- Have a quick 100-calorie snack with 1 cup of fresh grapes.
Risks and precautions
Beta-blockers, a type of medication most commonly prescribed for heart disease, can cause potassium levels to increase in the blood. High potassium foods such as bananas should be consumed in moderation when taking beta-blockers.
Consuming too much potassium can be harmful for those whose kidneys are not fully functional. If your kidneys are unable to remove excess potassium from the blood, it could be fatal.When drinking wine to reap it's health benefits drink no more than one drink per day for women or two drinks per day for men.
Recent developments on grapes from MNT news
New research presented at the Experimental Biology conference in San Diego, California, suggests that regular grape consumption may help alleviate pain associated with symptomatic osteoarthritis of the knee, and improve joint flexibility and overall mobility. Researchers attribute these potential benefits to the polyphenols found in grapes.
In an analysis of 446 compounds for their ability to boost the innate immune system in humans, researchers in the Linus Pauling Institute at Oregon State University discovered just two that stood out from the crowd - the resveratrol found in red grapes and a compound called pterostilbene from blueberries.
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