Red and green European grapes have approximately 3 calories and less than 0.1 grams of fat per 0.2-ounce grape. Grapes also have no cholesterol or sodium and only 0.9 grams of carbohydrates.
Grapes contain less than 0.1 grams of protein, 0.5 milligrams of calcium, and 9.4 milligrams of potassium. A cup of fresh grapes provides 25 percent of the daily recommended value of vitamin K, 8 percent of vitamin B-2, and 21 percent of the daily value of copper. Experts believe that grapes provide a concentration of antioxidants that may help reduce the oxidation of fats and increase glutathione in blood levels.
Before eating grapes, rinse them with cold water to remove any pesticide residues and dirt. Grapes tend to spoil quickly and ferment at room temperature. They should be stored in the refrigerator.