Vitamin C is water soluble, unstable and is very sensitive to oxygen. Its potency can be lost through exposure to light, heat and air. A primary function of vitamin C is maintaining collagen, wound healing wounds and burns and in forming red blood cells. It helps to fight infections and is an antihistamine. Vitamin C also aids in the metabolism of the amino acids phenylalanine and tyrosine. It converts the inactive form of folic acid to the active form, folinic acid. It protects other vitamins from oxidation.
Vitamin C is absorbed through the mucous membranes of the mouth, stomach and upper part of the small intestine. Absorption decreases with increasing dosages so it is best to take several small doses throughout the day rather than a large dose all at once.
Stress, smoking, steroids, high fever, prolonged use of antibiotics, exposure to DDT or chemical fumes, aspirin and other pain killers and birth control pills increase the need for vitamin C. Copper is a vitamin C antagonist.
High doses of C are usually not toxic. In some people large doses may produce a slight burning sensation while urinating, loose bowels, intestinal gas or skin rashes. Large doses of C may be a problem for people who tend to form kidney stones. Some people have a rare genetic disease that causes them to form kidney stones when large doses are taken.
The named disease of vitamin C deficiency is scurvy. Early symptoms are lassitude, weakness, irritability, weight loss and vague myalgias and arthralgias. Multiple splinter hemorrhages may form a crescent near the distal ends of the nail and are more extensive and friable, and bleed readily in extreme deficiency. Secondary infection, gangrene and loosening of the teeth eventually occur. Cum changes occur only with natural teeth or hidden roots. Old scars break down, new wounds fail to heal and spontaneous hemorrhages may occur in any part of the body.
Other symptoms and signs of scurvy include bulbar conjunctival hemorrhage, femoral neuropath from hemorrhage into femoral sheaths, oliguria, edema of the lower extremities, impaired vascular reactivity and arthritis resembling rheumatoid arthritis. Bleeding gums are not the most characteristic feature of scurvy. The hyperkeratotic hair follicle with surrounding hyperemia or hemorrhage is almost pathognmonic.
Vitamin C stimulates the production of interferon and acts as an inactivator against viruses, including herpes, vaccinia, hepatitis, polio, encephalitis, measles and pneumonia. It has been used to counteract bleeding in the GI tract caused by aspirin or alcohol. It prevents the formation of carcinogenic nitrosamines from nitrites and nitrates. It helps with recovery from heart attacks.
AMERICAN JOURNAL OF CLINICAL NUTRITION, 1991;53: 2701-282s “Vitamin C and Cancer Prevention: The Epidemiological Evidence:, The protective effect of vitamin C for nonhormone dependent cancers is strong. 33 out of 46 studies evaluating dietary vitamin C have shown significant protection. 21 of 29 studies found fruit intake to be protective as well.
According to the symposium held by the National Cancer Institutes of Health in 1990: Vitamin C has multiple complex biological effects, probably more widespread than any other nutrient. Some of the effects relate to vitamin C’s chemical properties and not from its role as a vitamin. Vitamin C’s interaction with enzymes is important. Studies were reported on its effect as a free radical scavenger. Vitamin C was the most effective of all free radical scavengers tested. Vitamin C deficiency was shown to reduce leukocyte morphology and reduce its chemotactic response. Vitamin C has been shown to suppress chemically induced transformation of cancer cells. It has also been shown that ascorbate prevents oncogenic transformation of cells infected with certain viruses such as the mouse sarcoma virus. The development of mammary tumors in animal models has been delayed in ascorbate treated animals. The radioprotective effects of ascorbic acid were also shown in animal models. Ascorbate stimulates alkaline phosphatase activity which is necessary for mineralization.
Archives Family Medicine September 1994, 3:809-820 “The Merging Role of Vitamins as Antioxidants” Oxidation may be involved in atherosclerosis by altering LDL to where it may effect the endothelium and start the athersclerotic process. LDL can carry molecules of vitamin E, beta-carotene and CoQ10 which may conteract or delay lipid peroxidation. High level vitamin E supplementation decreases LDL susceptibility to oxidation in vitro. Vitamin C helps regenerate oxidized vitamin E back to its reduced or antioxidant state. Vitamin C is regenerated via glutathione, using selenium as a cofactor. Vitamin C supplementation can help maintain red blood cell glutathione. In a cohort study of 11,000 people there was a significant reduction in cardiovascular disease and total death in individuals who had higher intakes of vitamin C. In an 8 year follow-up of the 80,000 women in the Nurses Health Study the top 5th of the cohort with the resp to vitamin E intake averaging 200 IU/day had a relative risk of major coronary artery disease of .66. There is an association between supplementary ascorbic acid and vitamin E intake over the previous 5 years and the decreased risk for senile cataracts of 2 1/2 times; with regards to cataract formation, glutathione and vitamin C are present in the lens of the eye as the antioxidant enzymes glutathione peroxidase, catalase and superoxide dismutase. Individuals consuming more than 300mg/d of C or 400 IU of E have about 1/3 the risk of developing cataracts. Vitamin C has also been associated with the decreased risk of many gastrointestinal cancers.
American Journal of Clinical Nutrition 1994; 59; 110-4″Relationship Between Dietary Vitamin C Intake and Pulmonary function in the First National Health and Nutrition Examination Survey” This study evaluated vitamin C intake and pulmonary function utilizing expiratory volume in 1 second (FEV1) in 2,526 adults between 1971 and 1974. After adjusting for variables, dietary vitamin C intake was positively and significantly associated with the level of FEV1. The authors conclude that vitamin C has a protective effect on pulmonary function. This beneficial effect was not restricted to just smokers. Vitamin C intake appears to have more benefit in asthmatic and bronchitis patients. The beneficial effect may be due to vitamin C’s antioxidant capabilities. It appears to improve immune function, decrease the responsiveness of airways and protect against exercise induced bronchospasm in asthmatic subjects who are taking vitamin C.