INTRODUCTION
Vitamins are organic compounds that are consumed in the diet. Most vitamins are required in small quantities and serve specific cellular functions. The word ‘Vitamin’ comes from Latin, in which “Vita” means life and “amine” means containing basic or amine nitrogen. Previously, vitamins were considered as substances just to prevent or treat deficiency states. The research in recent years has unfolded their role in many other body functions. For example, beta-carotenes, vitamin C, vitamin E are known to have antioxidant properties that prevent many degenerative disorders of adult life, like coronary artery disease (CAD), diabetes, etc. The role of periconceptional folic acid in the prevention of neural tube defect (NTD) and possibly other malformations, is the greatest discovery of this century. This has opened a new exciting field for prevention of malformation by the simple method of food supplementation.
The role of folic acid in the prevention of CAD, strokes and malignancies by correcting homocysteine metabolism has given a hope for the prevention of diseases in adults. Folic acid supplementation during pregnancy in reducing low birth weight (LBW) is of great public health importance.
The observation that vitamin A prevents morbidity and mortality in measles, acute respiratory tract infection (ARI), chronic diarrhea and has its role in the reduction of human immunodeficiency virus (HIV) transmission from mother to fetus, are the exciting contributions of studies on vitamins. Vitamin E once known only as an agent against “antifertility” is now known to have a lot of other benefits like, prevention of retinopathy of prematurity, intraventricular hemorrhage (IVH) of prematurity, bronchopulmonary dysplasia (BPD) of preterms, hemolytic anemia of preterms, myopathies, neuromuscular disorders and thrombosis.2
HISTORY OF VITAMINS
Tragedy of Modern Medicine
Too much zeal for the new and contempt for the old
Putting knowledge before wisdom
Putting science before art
Putting cleverness before common sense
Making cure of the disease more grevious than endurance of the disease
Treating patients as cases!!
“One swears by wholemeal bread, one by sour milk; vegetarianism is the only road to salvation of some, others insist not only on vegetables alone, but on eating those raw. At one time the only thing that matters is calories; at another time they are crazy about vitamins or about roughage. The scientific truth may be put quite briefly; eat moderately, having an ordinary mixed diet and don't worry.”
—Sir Robert Hutchison (1871–1960)
The experiences of eighteenth century explorers and the British navy that fresh fruits could cure scurvy is an important milestone in the discovery of vitamins.
The fact that such components of nutrition existed was not recognized long ago until a phase came in the science of nutrition, where it gained recognition on a global scale. It has now been agreed as a fact that, the existence of dietary factors of the nature of vitamins, was documented and came from the school of Professor Bunge at Basel.
In the year 1881, Lunin, one of the workers in that school, fed mice with an artificial component of the separate constituents of milk. He found out that after being fed with this mixture, the animals failed to survive even though proteins, fats, carbohydrates and salts were present in the mixture. It was concluded that this mixture must contain besides these three principal ingredients, another key ingredient essential for life.
History of Vitamins During the Five Periods
The history of vitamins can be divided into five periods
First Period
Healing of diseases associated with vitamin deficiency, through consumption of specific foods that help cure diseases. For example, treating night blindness with liver.
Second Period
This period was focused to induce a deficiency disease in animals. For example, ability to produce beriberi. Hopkins conceptualized finally that, “small amounts of accessory growth factors” are necessary for growth and life and the Polish-American Scientist Casimir Funk coined the term “vitamine” in 1912.
Third Period
This period was mainly concerned with the discovery, structure and synthesis of all the vitamins and ended with the synthesis of vitamin B12 in 1972. Many researchers were awarded Nobel prizes in recognition of their feats.
Fourth Period
The fourth phase was mainly concerned with the establishment of dietary requirements and commercial production of vitamins. It was during this period that most of the B-complex vitamins were identified as coenzymes. The first successful industrial effort happened during this period with the commercial synthesis of vitamin C by Reichstein in 1933.
Fifth Period
The hallmark of this period is the report stating the cholesterol lowering effect of niacin in 1955. This period is also known for the discovery of many new biochemical functions of vitamins.4
Milestones in the Discovery of Vitamins
Some of the important milestones in the discovery of vitamins are recorded in the following points and subsequent two tables (Table 1.1 and 1.2).
1910–1920
Mendel distinguished two types of vitamins based on their solubilities and named them fat-soluble A and water-soluble B.
1920
The terminal alphabet ‘e’ from the word “vitamine” was dropped and the vitamins were named as vitamin A and vitamin B. Anti-scurvy factor was named as vitamin C. Anti-rickets factor was named as vitamin D. Anti-hemorrhagic factor of chicks in 1935 by Henrik Dam, was later named vitamin K.
There are many gaps present in between the alphabetical and numerical naming of the vitamins, which clearly indicate that there were many nutritional factors that were initially thought to be vitamins but were later found out to be other factors. This confusion arose due to similarities between those factors and vitamins. After the isolation of each vitamin, they were given names according to the chemical compound and the class to which they belonged. The last vitamin to be discovered was vitamin B12 in 1948.
“But further, no animal can live upon a mixture of pure protein, fat and carbohydrate and even when the necessary inorganic material is carefully supplied, the animal still cannot flourish. The animal body is adjusted to live either upon plant tissues or the tissues of other animals and these contain countless substances other than proteins, carbohydrates and fats… In diseases such as rickets and particularly in scurvy, we have had for long years knowledge of a dietetic factor; but though we know how to benefit these conditions empirically, the real errors in the diet are to this day quite obscure. They are, however, certainly of the kind which comprises these minimal qualitative factors that I am considering.”
—Sir Frederick Gowland Hopkins
(20th June 1861 to 16th May 1947)
|
CLASSIFICATION
Vitamins are classified according to their solubility and their role in various metabolism. A practical way of classifying them is based on their solubility. The following table 1.3 lists the classification of vitamins.
|
CONCLUSION
Vitamins, as the Latin derivation of the name implies, are essential for maintenance of adequate health and life. They are diverse organic substances provided in small quantities in the diet and are found in a variety of chemical forms and structures. Vitamins have assorted essential biochemical roles in contributing towards maintenance of health and have unique therapeutic places in the treatment of related disorders.
The further section deals in detail with the individual vitamins, their history, biochemical and physiological aspects, recommended dietary allowances, deficiency states and toxicity if any, associated with them.