Vitamin C is generally regarded as safe in amounts obtained from foods. Vitamin C supplements are also generally regarded as safe for most individuals in recommended amounts. Although there are rarely side effects, including nausea, heartburn, abdominal cramps, and headache, no harmful effects on bones or joints have been proven. In healthy individuals, it appears that megadoses of up to 1,000 mg/day of vitamin C are well tolerated and not associated with any adverse effects. The best food sources of vitamin C are citrus fruits, berries, melons, tomatoes, potatoes, green peppers, and leafy green vegetables. As for orange juice, at 75 mg of vitamin C per 6-ounce glass, one glass would fulfill your recommended daily allowance (RDA), but you can enjoy several glasses a day without exceeding the safe limit.