A vitamin is a vital substance. It is needed in very small quantity for growth and good health.They are vital body regulators.
It is a name given to a group of potent organic compounds which are not carbohydrates, proteins or fats in nature, are present in foods and are essential in small quantities for specific body functions of growth, maintenance and reproduction.
Characterstics of vitamins
- It is a vital organic dietary substance which is not a carbohydrate, protein , fat or mineral. It is required in a very small quantity to perform a particular metabolic function or to prevent an associated defeciency disease.
- It cannot be synthesised by the body and therefore must be supplied through the food (though there are few exceptions to this rule).
Classification of vitamins
Are classified according to their solubility in fat and water.
- Fat soluble vitamins are A,D,E,K
- Water soluble vitamins are B group vitamins and vitamin C
Provitamin (or a precursor) – is a substance which the human body can convert into the vitamin.For example-
- beta carotene – aprecursor of vitamin A called Provitamin A since our body can convert it into Vitamin A.
- Dehydrocholestrol and Ergosterol are precursors of Vitamin D