Vitamins
vitamins are essentially substances made by plant and by lower forms of life such as bacteria; in a few cases, vitamins can also be created by animals or the human body
a vitamin is called a cofactor or coenzyme; some enzymes needs such cofactors for their biochemical functionality; a cofactor is a substance that helps chemical reactions occur
a vitamin is a nutrient required in small amounts for normal body function. With few exceptions, vitamins are not made in the body and must be supplied from an outside source. Even in those circumstances where vitamins are made in the body, the process generally involves an important ingredient from outside the body, such as the bacteria normally found in our intestines. These bacteria are part of the normal flora that find their way into our body and reside within each of us
there is a specific set of symptoms or a specific disease associated with a deficiency of each vitamin, and it can be corrected by taking the appropriate amount of that vitamin
There are two categories of vitamins, those that dissolve in water, and those that dissolve in lipids
the water soluble vitamins are B1 (thiamin), B2 (riboflavin), B3 (niacin or nicotonic acid), B5 (pantothenic acid), B6 (pyridoxine), B12 (cyanocobalamine), C (ascorbic acid), biotin, and folic acid
these vitamins can be easily absorbed directly through the gastrointestinal tract into the bloodstream
most water-soluble vitamins are not stored in large quantities for long periods of time
once a certain reserve level, the threshold or saturation level, is reached, much of the excess water-soluble vitamin is eliminated from the body via the urine
the major fat soluble vitamins are A, D, E, and K
these vitamins are oily substances that require the addition of bile acids, the body´s natural emulsifying agents, to be dissolved in the intestinal contents and then absorbed into the bloodstream
some fat-soluble vitamins, however, can be purchased in a "water-soluble" form; these products consist of vitamin that has been mixed with an emulsifying agent and can be absorbed without the assistance of bile acids
once absorbed, the fat-soluble vitamins migrate to their storage sites in body fat; when they are needed in the body, special carrier proteins take the vitamins from their storage areas to where they are needed
excessive amounts of some fat-soluble vitamins can be retained in the body and result in unpleasant or even hazardous symptoms