Understanding Key Vitamins and Minerals

The Fat Soluble Vitamins · Vitamin A · Vitamin D · Vitamin E · Vitamin K The Water Soluble Vitamins · The B-Group Vitamins · Thiamine - Vitamin B1 · Riboflavin-Vitamin B2 · Pantothenic Acid - Vitamin B3 · Biotin - Vitamin B4 · Nicotinic Acid (Niacin) - Vitamin B5 · Pyridoxine - Vitamin B6 · Cyanocobalamin - Vitamin B12 · Ascorbic Acid - Vitamin C

Vitamins are organic substances that the body requires in small amounts for metabolism but is unable to make for itself, at least in sufficient quantities.  Vitamins generally are unrelated chemically and differ in their physiological actions.

The role of many vitamins is to help make possible the processes by which other nutrients are digested, absorbed and metabolised or built into body structures.

As the vitamins were discovered they were first identified with a letter, but once their chemical structure was clearly known they were given specific names.

However, there are certain advantages in using some of the letters as labels. Many vitamins, such as vitamins A, D, K, E B12, Folic Acid, each consist of several closely related compounds with similar physiological properties.

The Vitamin B complex group are grouped together because although they are chemically unrelated they often occur together in the same foods.  Some vitamins occur in foods as precursors or provitamins, but once inside the body these are changed into one or more active forms.

The vitamins fall naturally into two classes - the fat soluble vitamins A, E, D and K - which generally occur together in such foods as fish oils and plant oils.  Like lipids, once these vitamins have been absorbed from the GI tract they are not easily excreted.  Instead they are stored in the liver, fatty tissues and fat cells.

Excesses, especially of vitamin A, D and K can reach toxic levels.  The fat-soluble vitamins can be inadvertently lost from the digestive tract with undigested fat, any disease that produces fat malabsorption (liver disease) can create deficiencies.  The use of mineral oils (which the body cannot absorb) as laxatives can promote the extra excretion of the fat-soluble vitamins.  Some weight loss products such as Chitosan may also deplete these essential vitamins.

The other class of vitamins are the water-soluble vitamins - B and C.  Being water-soluble, they are relatively easily excreted from the body if taken in megadoses.  It is recommended that foods rich in water-soluble vitamins be eaten daily, together with appropriate supplementation, if required.