Vitamins may be defined as potent organic compounds, which is found in foods in variable and a minute quantity, and must be supplied to the animal organisms from external sources, so that specific physiological functions, vital to life, may go on normally. They are neither oxidized to supply energy nor used to build structures.
Several centuries ago when Europeans first began to take long voyages by sea, manyof the sailors would come down with a mysterious disease, scurvy that seemed to affect the larger joints of the body. It was a peculiar form of arthritis, often associated with bleeding into the joints. The gums would also be affected, and the teeth would loosen and fall out. Patients would feel weak, tired and irritable, and would complain of soreness and aching in the muscles. But this strange disease always cleared up soon after the sailors reached land and began to eat fresh fruits and vegetables.
What was this secret substance in fruits and vegetables that prevented scurvy? No one knew for sure. But some wise doctor in the British navy prescribed a plentiful supply of limes and lemons for the sailors. The limes and lemons provided an adequate supply of vitamin C. thus scurvy, which we now know is due to a lack of vitamin C, was the first deficiency disease to be recognized and treated successfully.
During the nineteenth century another strange disease was recognized. Someone called the disease beriberi, a name still used by doctors today. It was this strange disease that led to the actual discovery of vitamins. A Dutch scientist, Eijkman, while working in Indonesia noted that this disease was more prevalent where people were crowded together. He suspected a deficiency in the diet of the poorer people.
Doctors all over the world were intensely interested as soon as these remarkable findings were discovered. This opened a whole new concept in the treatment of disease. Someone coined the word “vitamin”, and doctors soon began to discover other vitamins and their functions in the body.
Vitamin is not a food although it is usually present in the foods we eat. Nor it is a food supplement. Vitamins do not provide energy, nor do they build up worn out tissues. Still a man cannot live without vitamins. Many of the vitamins are needed in very small amounts, yet vitamins play a very important role in most chemical reactions within the body. Many of these cell reactions are carried on through enzymes, each different kind of enzyme being responsible for carrying on some particular chemical reaction within the body. Enzymes are made up of a combination of vitamins and minerals, all joined together in a highly complex fashion. If only one vitamin happens to be missing, that enzyme cannot be formed and some important function of the body cannot be carried out.
Where do vitamins come from? They are built up in plants and they are found in all fresh foods. However, some vitamins especially vitamin C, can be destroyed by excessive cooking. Drying or exposure to sun and wind may also destroy them. Other vitamins are not so easily destroyed. They will stand cooking and boiling without being changed. But many of these vitamins are water-soluble and are thrown away when the cooking water is drained off.
Vitamins work in various ways, and are often closely related to each other in their reactions within the body. Most vitamins do not occur alone. They are often found in pairs or groups.
The general characteristics of the vitamins are given below:
- The vitamins are widely distributed in nature both in animal and vegetable kingdoms. All vitamins are manufactured in plants. Almost all common articles of food contain more than one vitamin.
- Vitamins can perform their work in very small quantities. Hence, the total daily requirement is usually very small. The daily need of any vitamin for any individual is not a fixed quantity. It varies according to the rate of metabolism. In people undergoing heavy muscular work, in pregnancy, lactation, growing children, the vitamin requirement is high. Generally, a man doing ordinary work can obtain enough vitamins from his balanced mixed diet.
- Vitamins can be stored in the body to some extent, for example the fat-soluble vitamins are stored in the liver and subcutaneous tissue, vitamin C in adrenal cortex etc.
- Vitamins are partly destroyed and are partly excreted.
- Some vitamins are synthesized in the body. Some members of vitamin B complex are synthesized by microorganisms in the intestinal tract.
- Vitamins are not destroyed in the digestive process and are, therefore, absorbed as such. Hence all vitamins are effective when administered orally.
- Although they are essential for life, yet all vitamins are not required for all the species of animals. The physiological requirement is net with the synthesis of a particular vitamin in the organism.
- Some of vitamins are soluble in water and others are fat-soluble.
- Most of the vitamins have been artificially synthesized.
- Their mode of action is not clearly known. Some of them have been proved to act as coenzyme of other metabolic enzymes. Since the enzyme system of a tissue is specific in nature, it is quite reasonable that, a particular vitamin acts selectively upon one tissue. This helps us to explain why the deficiency of a particular vitamin specially affects some tissues and systems and leaves others more or less untouched.
Vitamins are divided into two groups:
- Fat-soluble vitamins, which includes vitamins A, D, E and K.
- Water soluble vitamins which includes vitamins of the B-group and vitamin C
Now if we were all perfectly healthy, and continued to eat the right food, we would probably remain strong and vigorous all the days. But most of us are not this fortunate. We have all inherited certain weaknesses, and none have perfect health. We must therefore be certain our diet contains all elements necessary for good health, and these include minerals and vitamins.
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vitamin H is now known as biotin (a b group vitamin) and vitamin P refers to a group of compounds known as bioflavanoids (not strictly speaking vitamins, but compounds important in maintaining health; also called flavanoids, a type of phytochemical)
If you have anemia you should take calcium away from meals so that you will absorb the iron.
Someone with hemochromatosis should not take vitamin c with meals because this boosts iron absorption.
Someone with anemia should take vitamin c with meals to boost iron absorption.
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