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| Proper name |
Ascorbic acid |
| Category |
Vitamin |
| Functions |
Connective tissue - Collagen and elastin formation are dependent on vitamin
C. Collagen and elastin are the building material of bone matrix, cartilage,
tendons, ligaments, dentin, skin, capillary walls and other forms of connective
tissue. Collagen is the most abundant protein in the human body, accounting
for 25-30% of total body protein. Antioxidant - Vitamin C donates hydrogen
ions to neutralize free radicals. Vitamin C is water soluble and is present
in all body fluids and tissues. It is especially important in protecting
the brain against the aging effects of free radicals. Vitamin C also helps
to regenerate the antioxidant capacity of vitamin E. Hormones - Assists
in the synthesis of carnatine and many peptide hormones; serotonin, thyroxine,
norepinephrine as well as corticosteroids and receptors for the neurotransmitter,
acetylcholine. Blood - Assists in the formation of hemoglobin by aiding
the absorption of iron and separating iron from ferritin so that the iron
is available to be incorporated in hemoglobin. Anti-infection - Vitamin
C stimulates the production of interferons, proteins that protect cells
from viral attack. Vitamin C has been used effectively to treat the common
cold, herbes, viral hepatitis, poliovirus, etc. Meta-analysis of 14 placebo
controlled studies on the common cold show vitamin C reduces the severity
of symptoms and reduces the duration of colds by 35%. Vitamin C increases
the production of white blood cells (neutraphils, lymphocytes and natural
killer cells) as well as the production of antibodies IgA, IgG and IgM.
Stress and healing - Vitamin C assists in synthesis of adrenal hormones
needed to cope with stress; adrenalin, noradrenalin, cortisol and histamine.
These hormones assist in coping with fever, illness, burns and exposure
to cold, radiation, high altitude, radiation exposure, fractures and wounds.
Allergies and asthma - Vitamin C inhibits the release and enhances degradation
of histamine, thus having an anti-histamine effect. Vitamin C also inhibits
phosphodiesterase (similar to the action of some asthma medications). Cardiovascular
- Vitamin C increases HDL (the "good" cholesterol) while decreasing LDL
(the "bad" cholesterol) and total cholesterol by converting them to bile
acids for excretion. It decreases lipoprotein(a), a factor in the production
of atherosclerotic plaque. Vitamin C also dissolves atherosclerotic plaques
by forming water soluble compounds that can be excreted (exchanges sodium
for calcium in the plaque to form two water-soluble compounds). Cancer
prevention - Plasma vitamin C levels are inversely correlated with gastrointestinal
and cervical cancers. Vitamin C reduces cervical dysplasia and is claimed
to inhibit bladder cancer. Vitamin C prevents the formation of nitrosamines
(a tumor inducing factor found in meats) and other free radicals. Vitamin
C protects tissue integrity by maintaining normal collagen formation and
by inhibiting hyaluronidase (an enzyme found in malignant tumors that allows
cancer to be more invasive). |
| RDA |
60 mg per day, 100 mg per day for smokers, pregnant or lactating women,
or persons suffering from infection, stress or fever. |
| Therapeutic
dose |
Dr Linus Pauling routinely recommended 16,000 mg for a 150 pound adult,
based on the observation that a primate would eat that much and other mammals
would manufacture that much. Higher doses have been used therapeutically.
Dr Cameron advocates "bowel tolerance" dosing, i.e., taking increasing amounts
of vitamin C until soft stools and flatulence are induced, then reducing
the dose just below the production of those symptoms. Many people take 500
to 1,000 mg per day. Toxicity Excessive intake of vitamin C induces diarrhea
which generally inhibits continued overdosing. The mineral ascorbate forms
are less acidic and generally better tolerated. Vitamin C does bind with
divalent cations including; iron, calcium and heavy metals such as lead,
arsenic and mercury, cadmium and nickel. While vitamin C is therefore useful
in reducing heavy metal poisoning, prolonged high doses may lead to possible
deficiencies of calcium and iron. In some individuals, vitamin C produces
excess amounts of oxalic acid which theoretically, could cause kidney stone
formation. Persons with a history of gout, kidney stones or kidney disease
should not take doses of vitamin C above the RDA without consulting a physician. |
| Deficiency symptoms |
Scurvy, a hemorrhagic disease characterized by diffuse bleeding and bruising,
joint and limb pain, swollen painful bleeding gums with teeth falling out,
hemorrhages inside bones causing them to thicken and fracture easily, poor
wound healing and muscle weakness. Anemia |
| Toxicity |
No
known toxicity. |
| Best
forms
|
Esterified C (calcium ascorbate and dehydroascorbate with 3 metoblites:
calcium threonate, xylonate and lyxonate), Ascorbyl palmitate, Ascorbic
acid is less expensive but contains sodium. The addition of 4 to 1 bioflavenoids
to C enhances absorbtion and retention of C |
| Food
sources |
Fresh fruits and vegetables, especially citrus fruits, strawberries, cantaloupe,
currents, blueberries, papaya, tomatoes, peppers, leafy greens, broccoli
and Brussels sprouts. |
| Lab
tests |
Vitamin
C can be assayed by testing leucocyte ascorbic acid. Vitamin C interferes
with measurement of serum glucose and occult blood in the stool. |
| Drug
interactions |
Vitamin
C is depleted by Aspirin, Bumetamide, Choline Magnesium Trisalicylate, Corticosteroids,
Ethacrynic Acid, Furosemide, Oral contraceptives, Torsemide. |
| Nutrient interactions |
Assists in the absorption of iron and the synthesis of carnatine (an amino
acid). |
| Metabolism |
In all animals other
than primates (including humans) vitamin C is made from glucose. Presumably,
our primate ancestors didn't need to make their own vitamin C as they
were getting enough from their diet. Vitamin C is concentrated in the
adrenals, brain, liver, pancreas, thymus and spleen. It is unstable,
easily oxidized and destroyed by cooking, oxygen and alkalis. Vitamin
C is absorbed in the small intestine. Absorption is impaired in persons
deficient in hydrochloric acid or suffering from bleeding of the GI tract.
The body stores as much as 4 grams of vitamin C. Excess amounts are
excreted in the urine.
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