Function:
Vitamin C, also called ascorbic acid, is known to be essential
for the synthesis of collagen (a protein important in the
formation of healthy skin, tendons, bones, supportive tissues
and in wound healing), maintenance of the integrity of blood
vessels, metabolism of certain amino acids, and the formation
of hormones.
Vitamin
C plays a significant role in the body as an antioxidant.
Antioxidants help neutralize potentially damaging byproducts
of the body's metabolism. These byproducts are sometimes
called free radicals. Because they react so easily with
other molecules, they often interfere with the normal operation
of cells and cause damage.
Although
a huge amount of research has been done concerning claims
of prevention of a variety of chronic ailments including
cardiovascular disease, diabetes, Alzheimer's, and various
forms of cancer, The Institute of Medicine has been unable
to conclude that antioxidants such as vitamin C can be shown
to be beneficial. They state; "After a comprehensive review
of the scientific evidence, our panel concluded that too
little is known at present to provide a definitive answer.
Too
few studies have tested the effects of these dietary antioxidants
in human subjects, and in some cases, where such human testing
has been done, the results are contradictory.
Although
a large number of population studies reveal a link between
a diet rich in foods containing antioxidants, such as fruits
and vegetables, and a lower incidence of certain chronic
diseases, we cannot conclude at this time that the antioxidants
are the reason. Other nutrients or factors could be at play."
Recommended
Dietary Allowance:
For
women 75 mg per day and 90 mg for men.
Because
smokers are more likely to experience higher levels of oxidative
stress and cellular damage, they need more vitamin C. An
extra 35 mg each day is recommended for smokers.
Deficiency:
Its absence it causes a disease called scurvy characterized
by weakness, swollen joints, inflamed and bleeding gums,
hemorrhages in the tissues, impaired wound healing and ultimately
death.
Sources:
Among
foods containing vitamin C are citrus fruits, strawberries,
broccoli, potatoes, peppers, and leafy green vegetables.
Toxicity
and UL:
Some
people have taken high doses (1 to 10 grams) for long periods
of time without severe side effects, and it is the belief
of some advocates that very high levels are warranted. Reviews
of high vitamin C intake have indicated low toxicity.
Some
recent studies suggest a pro-oxidant (the opposite of antioxidant)
effect of large doses of vitamin C.
The
Institute cites a number of possible side effects but diarrhea
was found to be the most common resulting in setting the
UL at 2,000 mg per day.
