What are vitamins?
Vitamins are substances which, in small amounts, are necessary to sustain life. They must be obtained from food as they are either not made in the body at all, or are not made in sufficient quantities for growth, vitality and well-being. Lack of a particular vitamin or mineral can lead to incomplete metabolism, fatigue and other health problems; and in severe cases, to deficiency disease. A deficiency of a particular vitamin causes disease symptoms which can only be cured by that vitamin.
Vitamins are chemically unrelated substances and all are organic. Organic substances are those that contain carbon and come from materials that are living, such as plants and animals, or that were once living, for example petroleum or coal. It is impossible to sustain life without all the essential vitamins.
What vitamins do?
Vitamins have many functions and influence the health of nearly every organ in the body. Their combination with other substances such as minerals, proteins and enzymes brings about certain chemical reactions. Individual vitamins have specific functions which vary widely and can overlap. They are involved in growth, the ability to produce healthy offspring and the maintenance of health. They play a role in metabolism, enabling the body to use other essential nutrients such as carbohydrates, fats, proteins and minerals. Vitamins are important for a normal appetite, in digestion, mental alertness and resistance to bacterial infections.
In addition to their basic roles in metabolism, some vitamins have specific preventive and therapeutic effects when taken in larger amounts. For example, niacin can be used to lower cholesterol and vitamin B6 can be used to treat premenstrual syndrome. Large doses of vitamins may slow, or even reverse many diseases previously thought an inevitable part of aging; such as cancer, heart disease, osteoporosis, impaired immunity, nerve degeneration and other chronic health problems. Many experts consider that taking larger doses of some vitamins is necessary for optimum health.
Vitamins are not substitutes for food. They cannot be assimilated without taking in food. They have no energy value of their own and are not components of body structures.
Where does the word vitamin come from?
In 1912, a Polish biochemist called Casimir Funk suggested that disease might be caused by a lack of something in the diet and cured by adding it. He thought this substance was necessary for life (vita) and contained nitrogen (amine) thus ‘vitamine’. Later research showed that few of these substances contained nitrogen so the final ‘e’ was dropped giving us the word ‘vitamin’.
How were vitamins discovered?
Diseases such as scurvy, rickets and pellagra have been known for centuries. It is only this century that the vitamins necessary for preventing them have been identified and isolated. Vitamins were originally discovered through animal experiments. Scientists fed animals diets known to cause certain diseases in man and then treated those animals with the nutrient missing from the diet. If the nutrient was found to cure or prevent the disease, it was identified as a vitamin.
How many vitamins are there?
In the USA the following are officially listed as vitamins: vitamin A; vitamin C; vitamin D; vitamin E; vitamin K; and the B vitamin complex containing: vitamin B1 (thiamin), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B6 (pyridoxine), folic acid, vitamin B12 (cobalamin), biotin and pantothenic acid.
There are other substances whose vitamin status has not been established. Some researchers consider these to be vitamins but this is not generally accepted. Such substances include choline, inositol, para-aminobenzoic acid (PABA) and coenzyme Q10.
Vitamins are usually divided into two categories: fat soluble and water soluble. Vitamins A, D, E and K are fat soluble. They require an adequate supply of minerals and fats to be absorbed in the digestive system and are stored in the liver. The remaining vitamins are water soluble with any excess being excreted in the urine. These need to be replenished frequently.
How do vitamins and minerals work?
In order to be effective, vitamins and minerals work with the other nutrients found in food. They are known as micronutrients because they are required in very small quantities. Macronutrients, which include oxygen, water, carbohydrates, proteins and fats are needed in large quantities.