The term "vitamin" is used to describe certain organic compounds that are needed by the body but that cannot be manufactured by the body. They mainly serve as catalysts for certain reactions in the body. If these catalysts are missing, as in a vitamin deficiency, normal body functions can break down amd make a person more susceptible to disease. The amounts of vitamins required are very small, perhaps hundredths of grams. Vitamins are mainly obtained from our foods, but there are some special cases. Vitamin K is manufactured in our bodies in certain bacteria in our intestines, and vitamin D is produced with the help of ultraviolet radiation on our skin.
Vitamins are classified as either fat-soluble (lipid soluble) or water-soluble. Vitamins A, D, E and K are lipid-soluble and accumulate within the fat stores of the body and within the liver. The lipid-soluble vitamins are often associated with toxicity when taken in large amounts.
Vitamin C and the B vitamins are water soluble. When water-soluble vitamins are taken in excess, they are readily excreted in the urine and not usually associated with toxicity. There is some storage of vitamins C and B in the liver.
The word vitamin comes from the word "vitamine" which was coined by researchers in 1912 to describe this recently discovered class of substances. At that time they were thought to be all amines which were essential to life. But not all of the vitamin are amines, so the "e" at the end was dropped to retain the now common term for these nutritional supplements.
Contributing author: Serena Baxter
Shipman and Wilson