Vitamin C, also called ascorbic acid, is a water-soluble substance that most animal can synthesize and is important in various bodily metabolic processes. Primates, including humans, and guinea pigs are, however, required to intake vitamin C as part of their diet in order to maintain good health.

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A human deficiency of vitamin C results in the disease known as scurvy, one of the oldest recognized nutritional disorders. Symptoms of scurvy include joint pain, bruising, skin lesions, softening of the gums, and weakness. Vitamin C occurs naturally in many foods and various others are fortified with the substance. Due to its solubility, however, vitamin C can easily leach out of vegetables and fruits cooked or stored in water.

Some accounts of illnesses that were most likely scurvy appear in ancient works and in accounts of the Crusades. The condition was most often associated, however, with sailors on long journeys and in 1753 a Scottish naval surgeon found that scurvy could be both cured and prevented by the consumption of citrus fruits. The British Royal Navy, enlightened by this knowledge, provided a daily ration of lime or lemon juice to all of its members beginning in 1795. The troops soon developed a nickname, and the term limeys is still frequently used to describe British sailors.