Heart diseases: Grapes increase the nitric oxide levels in the blood, which prevents blood clots. Therefore, grapes are an effective way to reduce the chances of heart attacks. Additionally, the antioxidants present in grapes prevent the oxidation of LDL cholesterol, which blocks the blood vessels and is a main contributor to various coronary conditions. Grapes also have high numbers of flavonoids, which are what give grapes their color, but flavonoids are also very powerful antioxidants. The two main types in grapes are resveratrol and quercetin, and these two compounds negate the effects of free radicals that threaten the body and stimulate LDL cholesterol’s harmful effects on arteries. Also, these two antioxidant flavonoids act as a clean-up crew to reduce platelet clumping and filter toxins out of the blood