Ascorbic acid (vitamin C) is used as a dietary supplement when the amount of ascorbic acid in the diet is not enough. People most at risk for ascorbic acid deficiency are those with a limited variety of food in their diet, or who have intestinal malabsorption problems from cancer or kidney disease.
Ascorbic acid (vitamin C) is used to prevent or treat low levels of vitamin C in people who do not get enough of the vitamin from their diets. Most people who eat a normal diet do not need extra ascorbic acid. Low levels of vitamin C can result in a condition called scurvy.