Crunchy, sweet and juicy, green seedless grapes satisfy a multitude of cravings, which may be why everyone like them so much. With 104 calories per 1-cup serving, green grapes make a healthy and natural low-calorie snack. The 1-cup serving of green grapes fills you up and satisfies hunger, which helps keep overall calories and ultimately weight under control. Grapes contain a substance called resveratrol, which is a natural compound that protects the fruit from environmental stress, fungal infections and ultraviolet radiation. Resveratrol also works to protect human health. As an antioxidant, it may protect your cells from free-radical damage and lower your risk of heart disease by preventing blood clots and reducing inflammation. The resveratrol in green seedless grapes may also prevent the growth of cancer cells. Green seedless grapes can help you meet your vitamins A, C and K needs. One cup of grapes provides 100 international units of vitamin A, 4.8 milligrams of vitamin C and 22 micro grams of vitamin K. Vitamin A helps your body fight off infection by boosting your immune system. Vitamin C is important for healthy gums and muscles and also helps wounds to heal. And finally, vitamin K is essential for blood clotting.