Erythorbic acid, formerly known as isoascorbic acid and -araboascorbic acid, is a stereoisomer of ascorbic acid (vitamin C). It is a vegetable-derived food additive produced from sucrose. It is denoted by E number E315, and is widely used as an antioxidant in processed foods.
Clinical trials have been conducted to investigate aspects of the nutritional value of erythorbic acid. One such trial investigated the effects of erythorbic acid on vitamin C metabolism in young women; no effect on vitamin C uptake or clearance from the body was found. A later study found that erythorbic acid is a potent enhancer of nonheme-iron absorption.
Since the U.S. Food and Drug Administration banned the use of sulfites as a preservative in foods intended to be eaten fresh (such as salad bar ingredients), the use of erythorbic acid as a food preservative has increased. It is also used as a preservative in cured meats and frozen vegetables.