Can you over dose on Vitamin C?

I am dieting and have been craving sweets even though I normally don't eat many sweets so to curb the craving I have been eating Cutie brand Mandarin / tangalo type oranges. They are very small, healthier than normal sweets, and I am eating them for my snacks all the time. Is this bad for me? I am eating other heathy foods also so I am getting a pretty balanced diet but I just don't want to do harm to my body in the prosess of trying to get healthier. I need to lose 60 to 70 lbs and I have to bring down my high cholesterol a lot due to hereditary causes. If anyone has any real advice or knowledge on the subject I would appreciate any input I can get. Thanks in advance!