Blueberries are definitely one of the most over-hyped of foods and have been subject to all manner of claims, which suggest that by all accounts they should be able to make us fly! A lot of what you hear is exaggerated, but blueberries are nevertheless nutritious little treats.
Heart & circulation
Blueberries are high in the antioxidant compounds anthocyanidins. These are the compounds that give them their deep-purple colour, and have been shown to cause relaxation of blood vessels, protect blood vessel walls against damage, and even reduce cholesterol slightly.
Some of the antioxidants in blueberries have been clinically tested in various scenarios, and have shown potential benefit in cases of macular degeneration (loss of vision in the centre of the visual field) and cataracts. They are not a cure, but may help with prevention.