Vitamin C - Ascorbic Acid
Vitamin C (Ascorbic Acid) is a water
soluble, white crystalline material that is stable in dry form. Much ascorbic
acid is lost in cooking, but the loss can be reduced by cooking quickly in
small amounts of water, or steaming foods with the pot covered tightly.
Preservation is also accomplished via quick freezing.
Vitamin C has many functions: it can
function as a coenzyme or as a cofactor in the body. It appears to be necessary
for the normal function of cellular units and subcellular structures. In
metabolism, vitamin C functions to accept and donate hydrogen. Vitamin C also
plays an important role in the synthesis of neurotransmitters, compounds which
allow nerve impulse transmission between nerve axons.
Production of collagen, a protein
substance in fibrous tissue, depends on ascorbic acid. Vitamin C maintains
capillary integrity through the production of an intercellular cement
substance. This function promotes the healing of wounds, fractures, bruises,
some hemorrhages, and bleeding gums. Additionally, it reduces susceptibility to
Vitamin C helps to facilitate the
absorption of iron and calcium, and it is essential for the utilization of
Humans absorb vitamin C in the upper part
of the intestine. This is accomplished by simple diffusion, a sodium-dependent
active transport mechanism. When megadoses are taken (1.5 to 3.0 grams) the
absorption is only 36 to 49%. At intakes of 12 grams, only 16% is absorbed.
Unabsorbed vitamin C continues into the lower bowel and causes watery stools or
Intakes of vitamin C above 100 mg do not
result in an increase of ascorbic acid levels. Immediately after ingesting
vitamin C, the serum level is temporarily elevated. The level subsides when the
excess is picked up by the tissues that store it, or is excreted. The highest
concentration of stored vitamin C is in the adrenal gland; however, the liver
stores the largest amount of the vitamin in the body.
Vitamin C is excreted in the urine after
enough is resorbed in the kidneys to maintain a plasma level of 1.2 to 1.4
milligrams per 100 milliliters.
Vitamin C plays a vital role in the
formation of collagen by catalyzing chemical changes that allow lysine and
proline to bind together as collagen subunits, adding structural stability to
the "complete" collagen fibers.
Vitamin C is important and necessary for
the synthesis of the neurotransmitters, norepinephrine and serotonin. It
catalyzes the conversion of dopamine to norepinephrine and the conversion of
tryptophan to serotonin.
Vitamin C has recently been the subject of
controversy. Popular literature suggests that large doses (one gram or more)
may prevent or cure the common cold or influenza. Scientists are presently
conducting studies to establish the validity of this claim.
One study demonstrated that vitamin C
reduced the severity of cold symptoms. A subsequent study indicated that the
result of decreasing symptoms was the result of an increased dosage at the
onset of illness and was not due to an increased daily dosage during
non-illness. Contradictory findings in a study of children indicated a
decreased severity of symptoms with the administration of one to two grams per
day. It is important to note that these contradictory results may be due to
differences in the vitamin C status at the beginning of the studies.
Vitamin C supplementation is beneficial
for patients suffering from scurvy and its symptoms. Recommended dosages for
these patients are 100 mg three times per day, with the alleviation of symptoms
usually apparent in five days.
Vitamin C deficiency is not common.
Populations subject to vitamin C deficiency are alcoholics, people who consume
a diet devoid of fruits and vegetables, elderly individuals on a limited diet,
severely ill individuals under chronic stress, and infants fed exclusively
Deficiency symptoms may appear the first
month following deprivation, when the serum level has been reduced to 0.2
mg/dl. Scurvy is caused by severe vitamin C deficiency, with symptoms
including: anemia, weakness, poor appetite and growth, tenderness to touch,
swollen and inflamed gums, loosened teeth, swollen wrist and ankle joints, and
shortness of breath. Furthermore it may be observed that wounds fail to heal or
previous wounds break down, and that infections develop easily in bleeding
areas of the gum and skin. These effects are attributed to problems with
collagen formation. It is also hypothesized that vitamin C is involved in the
blood clotting mechanism.
Psychiatric symptoms of vitamin C
deficiency include depression, hysteria, and hypochondriacal symptoms.
Smoking acts as an antagonist to vitamin
C. Less vitamin C is available in smokers for utilization and storage, and
smokers need twice the amount of vitamin C as the nonsmoker to show a
comparable blood level.
Massive doses of vitamin C have been
implicated in "rebound scurvy," when the conditions occurs after the cessation
of administration of these massive doses. It has been hypothesized that this is
due to a high rate of vitamin C catabolism as an adaptation to hypersaturation.
After reducing the vitamin C intake, the catabolism does not return to normal
levels and this produces a vitamin C deficiency state.
Excess vitamin C excreted in the urine
produces a false positive test for glucose. Excess vitamin C has also been
implicated in the formation of orate and oxalate stones. However, current
evidence suggests that large doses (nine grams per day) produce only a small
increase in urinary oxalate.
- RDA for adult males: 60 mg
- RDA for adult females: 60 mg
- RDA for children 7 to 10 years: 45 mg
- RDA for infants: 35 mg
- RDA for pregnant and lactating women: 95 mg
The Nobel prize winners: Albert Szent
Georgi and Linus Pauling, both of whom spent many years researching this
vitamin, recommend a daily intake of at least 2 grams, and have seen no toxic
side effects at much higher doses, with many benefits. Any writings on the
subject by either man is very much worth reading and consideration.
- Beet Greens
- Cabbage (raw)
- Chicory Greens
- Collard Greens
- Citrus Fruits
- Turnip Greens
- Dandelion Greens
- Hot Chili Peppers
- Mustard Greens
- Cutaneous Hemorrhages
- Improper Bone Development
- Weakened Cartilages
- Poor Collagen Production
- Muscle Degeneration
- Stunted Growth
- Susceptibility to Infection