Vitamin C is the most commonly taken dietary
supplement taken by Americans. As a single-ingre-
dient supplement, it is available as tablets, capsules,
and powder. It is found in multivitamin and antiox-
idant supplements. It is also combined with minerals
such ascalcium(e.g. Ester-C) to make it less acidic
and thus less irritating to the stomach in large doses.
Vitamin C can be made synthetically or derived from
corn or palm oil (ascorbyl palmate). There is little
evidence that one form is more effective than another.
Vitamin C is added to some skin creams, throat loz-
enges, energy drinks, and energy bars, and to some
processed foods. In 2007, the two largest American
soft drink manufacturers announced that they were
going to produce carbonated drinks fortified with
vitamins and minerals, including vitamin C.
Vitamin C deficiency produces a disease called
scurvy. From the earliest times, scurvy was a problem
for sailors on long voyages where there was no way to
store fresh fruits and vegetables. In 1746, a doctor in
the British navy proved that eating lemons and
oranges could prevent scurvy among sailors. Early
Spanish explorers planted orange trees in Florida
and the Caribbean so that they would have a source
of oranges to prevent scurvy on their long voyages
back to Europe. Today scurvy occurs infrequently.
As little as 10 mg per day of vitamin C can prevent
the disease. People with alcoholism, elderly individu-
als on extremely restricted diets, and malnourished
infants in developing countries are at higher risk for
developing scurvy. Symptoms include fatigue, easy
bruising, excessive bleeding, hair loss, sore gums,
tooth loss, and joint pain. Left untreated, death can
occur, usually through sudden cardiac attack. Smok-
ing increases the body’s need for vitamin C, but is not,
by itself, a cause of scurvy.
Sources of vitamin C
People need a continuous supply of vitamin C
from their diet because of the role it plays in many
metabolic processes. Vitamin C is found in many
foods. Good natural sources of vitamin C include
citrus fruits and their juices, papaya, red bell peppers,
broccoli, and tomatoes.
Vitamin C is unstable and is lost when food is
exposed to air, temperature changes, and water.
About one-quarter of the vitamin C content of vegeta-
bles is lost by brief boiling, steaming, or freezing and
thawing. Canning fruits and vegetables reduces their
vitamin C content by about one-third, as does longer
cooking at higher temperatures. However, both the
American Cancer Society and the American Heart
Association recommend that people meet their vitamin
C (and many other vitamin requirements) through a
healthy diet that includes eating a minimum of 5 serv-
ings of fruits and vegetables daily.
The following list gives the approximate vitamin
C content for some common foods:
orange, 1 medium: 70 mg
orange juice, 3/4 cup (6 ounces): 75 mg
grapefruit, 1/2 medium: 44 mg
grapefruit juice, 3/4 cup (6 ounces): 60 mg
strawberries, 1 cup: 82 mg
papaya, 1: 94 mg
tomato, 1 medium: 23 mg
red bell pepper, 1/2 cup raw: 141 mg
broccoli, steamed, 1/2 cup: 62 mg
cauliflower, boiled, 1/2 cup: 27 mg
potato, 1 medium, baked: 26 mgControversial health claims for vitamin C
Controversy about vitamin C centers on its use-
fulness in preventing or treating disease when taken in
very large quantities as a dietary supplement. Most of
these claims have not been substantiated by well-
designed, well-controlled studies. Many are still
being investigated in government-sponsored clinical
trials. Individuals interested in participating in a clin-
ical trial at no charge can find a list of open trials at
http://www.clinicaltrials.gov.
COLDS.Nobel prize-winning chemist Linus Paul-
ing popularized the idea that large doses (1,000 mg or
more) of vitamin C daily, will prevent, shorten the
duration, or reduce the severity of symptoms of the
common cold. More than 30 trials have compared
colds in people taking up to 2,000 mg of vitamin C
daily and those taking a placebo (pill with no nutri-
tional value). These studies found no difference in the
number or severity of colds in the two groups, with one
exception. Skiers, marathon runners, and soldiers train-
ing in Arctic conditions who took vitamin C supple-
ments had 50% fewer colds than people who took no
extra vitamin C. All the people who benefited from
taking vitamin C supplements were putting their bodies
under extreme stress. It appears that for elite athletes
and others under physical stress,dietary supplements
of vitamin C may be of value in preventing colds.
CANCER.Cancer is thought to arise because of dam-
age to cells caused by free radicals. Health claims that
vitamin C prevents cancer are based on its antioxidant
properties. Many studies have shown that people who eat
adietlowinfatsandhighinfreshfruitsandvegetables
have a lower risk of developingcancer, especially cancerVitamin C