Orange juice concentrate starts as sweet orange juice, then the water is removed. What is left is a dry, shelf-stable powder. The powder holds onto natural flavonoids and vitamin C, though heat from dehydration can lower some delicate nutrients. It supplies the same nutritional profile as liquid juice but in an easier-to-store form.
People stir the powder into water to make a drink, mix it into smoothies, or use it as a flavoring in food. Others take it just for the vitamin C and the antioxidant compounds that oranges naturally contain. It travels well and works when fresh oranges are not around.
Anyone with a citrus allergy, acid reflux, or diabetes should be careful. Stick to sensible amounts.