Vitamins are essential food factors, which are required for the proper utilisation of the proximate principles of food like carbohydrates, lipids and proteins. They also serve the needs of growth, differentiation and maintenance of normal cellular functions.
Discovery of vitamins started from observation of deficiency manifestations, e.g. scurvy, rickets, beriberi etc. The vitamin theory was suggested independently by Hopkins in 1912 and Funk in 1913. The term “vitamine’ was coined from the words vital + amine, since the earlier identified one had amino groups. Later work showed that most of them did not contain amino groups, so the last letter ‘e’ was dropped in the modern tem of vitamin.
The vitamins are mainly classified into two:
- Fat soluble Vitamins: A, D, E and K.
- Water soluble vitamins are B complex and C
Fat Soluble vs Water Soluble Vitamins
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Characteristics
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Fat Soluble Vitamins
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Water soluble vitamins
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Major vitamins
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A, D, E and K
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B and C
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Solubility in fat
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Soluble
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Not soluble
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Water solubility
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Not soluble
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Soluble
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Absorption
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Along with lipids. Require bile salts
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Absorption is simple
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Carrier proteins
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Present
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No carrier proteins
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Excretion
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Not excreted
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Excreted
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Storage
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Stored in liver
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No appreciable storage
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Deficiency
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Manifests only when stores are depleted
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Manifests rapidly as there is no storage
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Treatment of deficiency
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Single large doses may prevent deficiency
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Regular dietary supply is required
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Toxicity
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Hypervitaminosis may result
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Unlikely, since excess is excreted
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