Just like humans, guinea pigs are unable to make their own Vitamin C. Guinea pigs therefore require a daily intake from their diet, otherwise supplementation is required. Vitamin C is essential for maintaining the health of skin, eyes, nervous system, muscles, bones and internal organ function. Adult guinea pigs should receive 20-50mg of Vitamin C per kilogram of body weight per day. In the case of illness, growth or pregnancy requirements increase to 100mg per kilogram per day. The table below will help you work out your guinea pig's daily Vitamin C intake.