Vitamins: Vitamins also called accessory food factors,are organic
substances, and quite different from carbohydrates, protein and lipids. These are normally available to the body from the diet we take,for the purpose to regulate energy transformation and metabolism.
Vitamins are effective in very small amounts, and none of these are formed in the body and must be obtained performed from animals or plant sources. However,the exceptions are there,for instance vitamin A is formed from its pre cursor carotene, vitamin D by the action of ultra-violet light on the skin. The bacteria in the intestine synthesized folic acid and vitamin K similarly rats can synthesize vitamin C and therefore do not develop scurvy.
Vitamins are different from each other in their chemical composition and function and have been synthesized or isolated from their plant or animal sources.
Vitamins are chemically unstable under adverse condition of heat, light and oxidation (especially in alkaline medium) strong acids and aging hence they lose their activity.
Nomenclature of Vitamin: vitamin e, a word derived from (Vital + Amine); and since all these substances were not amines, therefore Mecollum proposed terminology vitamin by dropping (e). From vitamine .
Organilly these substances were commonly known by letters of the alphabet such as Vitamin A,B,C,E,K
After understanding the composition and chemical structure of these vitamins their alphabet nomenclature is being replaced by their chemical names.
Properties of Vitamins:
• Vitamin are not available in human body but they obtain vitamin from diet.
• The chemical composition and vitamin are difference from each other.
• In the presence of heat, light and oxidation vitamin are chemically unstable.
• Vitamin requlates energy transformation and metabolism.
• Vitamin are isolated from plant and animals sources.
Classification of Vitamins:
Vitamins are classified Von the basis of their solubility.
Vitamin A: it is found in fats of milk , eggs,and liver fat. Fish liver oils specially, cod liver oil is the Cheif source of vitamin A Vitamins A is absent from vegetable oils and fats e.g olive oil, linked oil, Sunflower oil ground but oil. Margarine made from these oils supplemented vitamin A during its manufacture.
The main function of vitamin A is to form visual pigment. It’s transports nutrients across the cell membrane.
Vitamin D (Antirachitic): Chemically, vitamin D related to sterols. The active vitamin was proved to be calciferol which could be formed from its provitamin ergosterol, a plant sterol by the ultraviolet rays radiation. The provitamin in animals was shown to be fdehydrochlestrol, which upon irradiation give rise to vitamin D³ .
Daily requirement if vitamin D is 7.5 ug of calciferol. The main source of vitamin D are fish oil liver.
Vitamin E (Tocopherol) : like vitamin A and D vitamin E is soluble infant solvents and insoluble in water. It is resistant to heat upto 200°C but fairly easily oxidized and Destroyed by ultraviolet rays
Vitamin E is found in green leafy vegetables, oils and wheat grains. It is required for the maintenance of cell membrane. It maintains normal physiology of the muscular and vascular system. It’s deficiency causes fragility of red blood cells Haemolysis of R.B.C and Declines in respiration.
Vitamin K (Antihaemorrhagic Compound) :
The vitamin isolated from alfalfa and from putrefied fish meat is called Vitamin K .
Dietary requirements per day recommended 70_ 140 ug. This could be acquired from green vegetables.
It helps the synthesis of prothrombin and other blood clotting factors in liver. It’s deficiency causes the failure of blood clotting mechanism.
Vitamin B (Complex): a group of water soluble vitamins obtained from liver , yeast and other sources are found effective for growth, and appetite, reduce sugar content in diabetes, help in treatment of the virus infections and are collectively known as Vitamin B Complex.
The nutritionally important vitamins acquired by the body, through Virus sources of food are B1, B2, B6 niacin or nicotinic acid, vitamin B¹² Cyan- ocobaltamine)