http://ods.od.nih.gov/factsheets/VitaminC-QuickFacts/
This document also available in Spanish
Office of Dietary Supplements, National Institutes of Health
Vitamin C, also known as ascorbic acid, is a water-soluble nutrient found in citrus fruits, and in many other fruits and vegetables. In the body, it acts as an antioxidant. In addition, vitamin C improves the absorption of iron from plant-based foods and helps the immune system work properly to protect the body from disease.