In recent years, the C of this much-publicized vitamin has also stood for controversy. With Linus Pauling and others claiming that vitamin C has the potential to prevent and treat the common cold, flus, and cancer, all of which plague our society, concern has arisen in the medical establishment about these claims and the megadose requirements needed to achieve the hoped-for results. Some studies suggest that these claims have some validity; however, there is more personal testimony from avid users of ascorbic acid than there is irrefutable evidence. There has also been some recent research that disproves the claims about treatment and prevention of colds and cancer with vitamin C. However, in most cases, studies showing vitamin C to be ineffective used lower dosages than Dr. Pauling recommended. Overall, vitamin C research is heavily weighted to the positive side for its use in the treatment of many conditions, including the common cold.

C also stands for citrus, where this vitamin is found. It could also stand for collagen, the protein "cement" that is formed with ascorbic acid as a required cofactor. Many foods contain vitamin C, and many important functions are mediated by it as well.

Vitamin C is a weak acid and is stable in weak acids. Alkalis, such as baking soda, however, destroy ascorbic acid. It is also easily oxidized in air and sensitive to heat and light. Since it is contained in the watery part of fruits and vegetables, it is easily lost during cooking in water. Loss is minimized when vegetables such as broccoli or Brussels sprouts are cooked over water in a double boiler instead of directly in water. The mineral copper, in the water or in the cookware, diminishes vitamin C content of foods.

Ascorbic acid was not isolated from lemons until 1932, though the scourge of scurvy, the vitamin C deficiency disease, has been present for thousands of years. It was first written about circa 1500 B.C. and then described by Aristotle in 450 B.C. as a syndrome characterized by lack of energy, gum inflammation, tooth decay, and bleeding problems. In the 1700s, high percentages of sailors with the British navy and other fleets died from scurvy, until James Lind discovered that the juice of lemons could cure and also prevent this devastating and deadly disease. The ships then carried British West Indies limes for the sailors to consume daily to maintain health, and thus these sailors became known as "limeys." Other cultures of the world discovered their own sources of vitamin C. Powdered rose hips, acerola cherries, or spruce needles were consumed regularly, usually as teas, to prevent the scurvy disease.

In earlier times, humans consumed large amounts of vitamin C in their fresh and wholesome native diet, as apes (another species that does not make vitamin C) still do. Most other animals, except guinea pigs, produce ascorbic acid in the liver from glucose, and in relative amounts much higher than we get from our diets today. For this reason, Dr. Pauling and others feel that our bodies need somewhere between 2,000 and 9,000 mg. of vitamin C daily. These amounts seem a little high to me, given the basic food values of vitamin C. Some authorities feel we need 600–1,200 mg. daily based on extrapolations from the historical herbivore, early-human diet. These levels can be obtained today by eating sufficient fresh food; a diet that includes foods with high levels of vitamin C can provide several grams or more per day.