Wednesday, April 8, 2020

Vitamin : Definition, Characteristics, Types of Vitamins & Antivitamin and Provitamin

Vitamin : Definition, Characteristics, Types of Vitamins & Antivitamin and Provitam

Vitamin : Definition, Characteristics, Types of Vitamins & Antivitamin and Provitamin
Vitamin


From the results of different examinations performed worldwide in the Nineteenth Century, it is proven that some human diseases as Night Blindness, Scurvey and Beri-Beri caused by deficiency of some important nutrients other than Carbohydrates, Proteins and Fats. Then the concept of Vitamin comes in form.

The term Vitamin is derived from the word Vitamine, which was first coined in 1912 by scientist Casimir Funk. He isolated a complex of micronutrients from Brown Rice and he assumed that it may contain an 'Amine' group. The letter "e" at the end of  the word "vitamine" was later removed, when it was realized that every vitamins need not be nitrogen-containing amines. Later, all the vitamins were discovered (identified) between 1913 and 1948.

Definition of Vitamin :

Vitamins are non-caloric organic micro-nutrients and a vital compound or substance that an organism requires in diet in small quantities (from few micro-grams to few milligrams) for
  • Normal growth
  • Development
  • Metabolism
  • Physiological function &
  • Optimal health of body.
Vitamins cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through proper diet.

Characteristics of Vitamins :

  1. Most of the vitamins are synthesized in the plant body and few vitamins are synthesized in animals. As vitamins are natural components of foods, there are some vitamins in very small amounts in every food we take.
  2. They are essential for normal physiologic functions like growth, metabolism, reproduction, etc.
  3. Each vitamin has a specific function to perform and deficiency of any particular vitamin may lead to specific deficiency disease.
  4. When vitamins are absent in the regular diet, they will cause a specific deficiency in our body.
  5. Most vitamins act as co-enzymes with enzymes in metabolism.
  6. We need vitamins in small quantities in diet as vitamins work well in low concentration.
  7. Vitamins are partially wasted after being used in metabolism and excreted from the body.
  8. A small amount of vitamins may store in our body. Generally fat soluble vitamins are stored in the liver and lower layer of the skin and vitamin C is in the adrinal cortex.
  9. Vitamins are essential for life, but not all vitamins are needed for all kind of animals or organisms.
  10. Some vitamins are water soluble (Vitamin C and Vitamin B complex) and some vitamin are fat soluble (Vitamin A, Vitamin D, Vitamin E, Vitamin K).


Types of Vitamins :

In humans, 13 different vitamins are required in diet. On the basis of their solubility, vitamins have been classified into two main groups, i.e. (1) Water soluble vitamins (include 9 vitamins), (2) Fat soluble vitamins (include 4 vitamins).

Water Soluble Vitamins :

The vitamins which are soluble in water and insoluble in fat are called Water Soluble Vitamins. Water soluble vitamins, which include all Eight of the vitamin B complex (Thiamine, Riboflavin, Niacin, Folic acid, Pyridoxine, Pantothenic acid, Biotin and Cyanocobalamin) and vitamin C. These do not stay in the body for long because the body cannot store them. Because of their water solubility, the water soluble vitamins if ingested in excess amounts are readily excreted in urine and produce no toxicity.

Fat Soluble Vitamins :

The vitamins that are insoluble in water but soluble in fat (or ethers, Chloroform, alcohol etc.), are called Fat Soluble Vitamins. These types of Vitamins are usually found in the fat content in foods. Sources of these may also be found in vegetable oils, nut, egg yolk, fish oil, whole grains and deep green leafy vegetables. These are easily stored in the fatty tissues of the body and liver. Stored vitamins can act as reserves for months. Also, these vitamins are absorbed through the intestinal tract with the help of fats, or lipids. These include 04 vitamines –
  • Vitamin A (Retinol, Retinal/Retinaldehyde & Retinoic acid)
  • Vitamin D (Calciferol),
  • Vitamin K (Phylloquinone & Menaquinone)
  • Vitamin E (Tocopherols)



  • Definition of Antivitamin :


Antivitamins are the Organic compounds that have the same chemical composition as some vitamins, but counteract the essential effects of vitamins or prevents a vitamin from exerting it's typical biological effects or decrease the metabolic action of a vitamin.
For example,

  1. Ascorbic acid oxidase, an enzyme found in fruits and vegetables, has antivitamine properties and can oxidize ascorbic acid (Vitamin C). Hence, fresh juices lose 50% of the vitamin in less than 1 h.R
  2. Raw fish contains thiaminase, which has antivitamin properties and destroys the vitamin.
  3. It is also known that tannins found in plants destroy Thiamin. 
  4. Avidin, a heat-sensitive compound found in egg white also an antivitamin and forms a complex with biotin.

  • Definition of Provitamin : 

A provitamin is a substance that are inactive in pro form and activate once they are inside the body and it may be converted to a vitamin within the body under some organisms.
For example,

  1. β-Caroten is a pro-vitamin of vitamin A (retinal) . Two molecules of beta-carotene is required to form one molecule of retinal
  2. Ergosterol is a provitamin of Vitamin D. In exposure to ultraviolet (UV) light, it causes a chemical reaction that produces vitamin D. 
  3. Menadione is a synthetic provitamin of Vitamin K.



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