Vitamin C
In most animals, ascorbic acid ( vitamin
C ) can be synthesized from glucose. However, humans, and
the guinea pig are unable to synthesize it.. The enzyme
that catalyzes this reaction (L-gluconolactone oxidase)
is defective in humans. Thus the need for vitamin C in
the diet is the result of an inborn error in carbohydrate
metabolism.
Structure of Vitamin C
The recommended daily allowance for
vitamin C
Vitamin
C content of various food items
The vitamin is present in milk
and some meats (kidney, liver, fish) and
is widely distributed in fruits and vegetables.
A portion is lost after prolonged storage of unprocessed
fruits and vegetables (e.g., potatoes), but it is
partially preserved ( half or greater) by most means of
food processing (boiling, steaming, pressure cooking,
preserving jams and jellies, freezing, dehydration, and
canning).
As a consequence, the recommended daily allowances can be
met with even a modest intake of fruits and vegetables.
Utilization of the vitamin is increased
during pregnancy and lactation and in thyrotoxicosis, and
absorption is decreased in diarrheal states and in
achlorhydria.
Vitamin C
Deficiency
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