Blackberries are composed of more than 85 percent water along with a hefty dose of fiber, which makes them a great fruit to eat if you’re trying to lose weight, lower cholesterol, or manage type 2 diabetes. They are a good source of folate, a B vitamin that helps maintain healthy hair and may reduce the risk of cardiovascular disease and mood disorders. Additionally, blackberries are full of potent antioxidants that can help with arthritis, age-related memory loss, cataracts, and other eyesight problems.