Dogs, cats produce their own vitamin C –

Dear Dr. Blonz: I have always wondered about the letters and numbers used to identify vitamins. Why do they skip some letters, and why are there so many different B’s? — S.Y., San Jose, California

Dear S.Y.: The word “vitamin” was coined in 1912 by Polish scientist Casimir Funk, who was searching for a cure for beriberi — a paralyzing disease that was common in regions where white rice was the main dietary staple.

Contemporary research had suggested that the rice husk and bran might contain a substance that could combat the dreaded disease. Funk identified the key compound — now called thiamin — and dubbed it a “vital amine.” This term was eventually shortened to “vitamin,” and came to signify an entire class of essential compounds that are needed by the body in trace amounts.

All vitamins can be found in food. They do not provide energy (calories) and they are all “organic,” in that they are constructed using the element of carbon. They perform specific metabolic functions in the cell, our basic unit of life, and they cannot be made by the body in amounts sufficient to meet its needs.

The absence of a vitamin from the diet can lead to a failure to thrive and the development of a deficiency disease, though the length of time it takes for problems to develop differs with each vitamin. It is interesting to note that not all animals require the same vitamins. Humans, for example, cannot manufacture their own vitamin C (ascorbic acid), which many animals can; this explains why our dogs and cats don’t need this vitamin like we do.

Back in 1913, scientists came up with a naming system that was based on two groupings: those that would dissolve in fat were called “fat-soluble A” vitamins, and those that would dissolve in water were referred to as “water-soluble B” vitamins. The naming then proceeded in order of discovery. Many times, a substance thought to be a vitamin was later determined not to be essential. When this happened, that letter ceased being used.

In some cases, the first letter of the compound’s function was used in its name. For example, vitamin K comes from the German “koagulation” (coagulation), or the clotting of blood — a process in which vitamin K plays a role.

The “B” vitamin, originally found in yeast, was originally thought to be only one compound. When it was later found that there were many different compounds, they were given the names vitamin B1, B2 and so forth. This is now referred to as the vitamin B complex.

At present, there is no universally accepted naming system, and letters have apparently lost some of their appeal. Some compounds are called by their chemical name, as opposed to a letter/number designation. Examples include biotin (vitamin B7) and folic acid/folate (vitamin B9).

• Ed Blonz, Ph.D., is a nutrition scientist and an assistant clinical professor at the University of California, San Francisco. Send questions to: “On Nutrition,” Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. For email, address questions to: Due to the volume of mail, personal replies cannot be provided.


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