Does a high dose of vitamin C—3 grams per day, for example—cause any side effects?
Few side effects occur even with large doses of vitamin C. However, one side effect of large doses of vitamin C (ascorbic acid) is a mild laxative effect. This can often be avoided by taking vitamin C in several smaller doses over the day. As a matter of fact, the body can use four 250 mg doses of vitamin C more efficiently than one single dose of 1,000 mg. The new Dietary Reference Intakes has set a Tolerable Upper Limit of 2,000 mg/day of vitamin C for all adults.
