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.
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.