Mulberries are of th e best fruit sources of vitamin C and a regular cup serving provides 85% of the RDI for the vitamin. For comparison, this is the same amount of vitamin C that a medium-sized orange contains. Vitamin C is vital for our body because it has a crucial role in the growth, repair, and maintenance of our body's cells and functions. Furthermore, the vitamin is thought to have important antioxidant properties that may protect against oxidative stress and help to lower the risk of long-term disease.