Scurvy disorders, unusual eating habits, alcoholism, and old people who live alone. Other risk factors include intestinal malabsorption and dialysis. Humans and certain other animals require vitamin C in their diets to make the building blocks for collagen. Diagnosis typically is based on physical signs, X-rays, and improvement after treatment. Treatment is with vitamin C supplements taken by mouth. Improvement often begins in a few days with complete recovery in a few weeks. Sources of vitamin C in the diet include citrus fruit and a number of vegetables such as tomatoes and potatoes. Cooking often decreases vitamin C in foods. Scurvy
Vitamin A Approximately 250,000–500,000 children in developing countries become blind each year owing to vitamin A deficiency, with the highest prevalence in Southeast Asia and Africa. Vitamin A deficiency is "the leading cause of preventable childhood blindness," according to UNICEF. It also increases the risk of death from common childhood conditions such as diarrhea. UNICEF regards addressing vitamin A deficiency as critical to reducing child mortality, the fourth of the United Nations' Millennium Development Goals. Vitamin A deficiency can occur as either a primary or a secondary deficiency. A primary vitamin A deficiency occurs among children and adults who do not consume