Probably the first
disease to be recognized as being caused by a nutritional deficiency
was scurvy, when it was found that certain foods could prevent the disease.
Scurvy was described by the Egyptians and Creeks, but it was Bachstrom
in Leiden in 1734 who maintained that it was due to a lack of fresh
vegetables in the diet. In 1795, the British Admiralty adopted James
Lind's recommendations for citrus fruit to prevent seaboard scuny and,
thereafter, British sailors were nicknamed 'limeys'.
In scurvy, the
connective tissues of the body are defective; the tissues are fragile,
and bleeding occurs into the skin, from the gums and into deeper tissues.
Wound healing is also poor. Changes in brain and nerve function occur,
with mood and personality changes. Muscle weakness and proneness to
infection may occur. Our bodies' ability to detoxify certain chemicals
may also be reduced in scurvy. It seems likely that there may be lesser
degrees of vitamin C deficiency than the extreme of scurvy.
Vitamin C (or ascorbic
acid, as it is also called) can be lost from foods because of its water
solubility, and sensitivity to heat, air or oxygen. The addition of
alkalis, such as bicarbonate of soda, and the use of copper cookware
can also destroy it.
People at risk
from vitamin C deficiency include those who avoid fruit and vegetables,
those with poor cooking practices (see
Figure 31 and Processing
Food - Cooking),
the elderly, alcohol abusers and cigarette smokers.
about vitamin C intake were first concerned with the prevention of scurvy.
Recommended intakes of about 30 milligrams per day do not usually 'saturate'
the body tissues with vitamin C and, indeed, this may not be necessary.
But to saturate body tissues, no more than 100 to 130 milligrams per
day are required. With intakes above this, our bodies adapt by increasing
breakdown of vitamin C or excreting it in the urine. From a mixed diet
it would be difficult to have more than about 400 to 500 milligrams
of vitamin C per day.
It has been suggested
that daily intakes of vitamin C in excess of 500 milligrams may be of
benefit. There is some evidence that amounts of this kind may reduce
the symptoms of the common cold. This raises the question of non-nutritional
or drug-like properties of the vitamin. The possible adverse effects
must also be considered. These include:'rebound scurvy', which may occur
if you are coming off high-dosage vitamin C; increased excretion of
oxalic acid in the urine which may lead to 'stones' in the urinary tract;
an increased absorption of iron in those susceptible to iron overload;
increased absorption of toxic metals, such as mercury; and interactions
with certain medications, for example warfarin, aspirin, antidepressants
and the contraceptive pill.
dietary intake of vitamin C:
Pregnancy (2nd and 3rd