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Vitamin C Stops Histamine There's no doubt that vitamin C can help tame allergic reactions, at least under laboratory conditions. Several studies have shown that high levels of vitamin C help reduce histamine release from mast cells and also make histamine break down faster once it is released. Not only that, but studies have also shown that vitamin C deficiency can send blood levels of histamine through the roof. Only two studies have been done in humans, however. One small study, by researchers at Methodist Hospital in Brooklyn, New York, found that people who took 1,000 milligrams of vitamin C every day for three days had significant reductions in blood levels of histamine. In another study, Italian researchers found that people with hay fever were better able to maintain the volume of air they could exhale if they were taking 2,000 milligrams of vitamin C a day. (In many allergic reactions, air passages narrow and restrict the flow of air into the body.) Other studies have shown that vitamin C may also help dampen some of the inflammation associated with chronic allergies. "My experience is that vitamin C can have modest beneficial effects for inhalant allergies and asthma if it's taken on a regular basis," says Richard Podell, M.D., clinical professor of family medicine at the University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School in Piscataway, New Jersey, and author of "When Your Doctor Doesn't Know Best: Errors That Even the Best Doctors Make and How to Protect Yourself." Vitamin C has not been proved to help much if it's taken once symptoms begin, Dr. Podell says. "But if you take it before you're exposed to whatever is causing your allergies and allow it to get into your bloodstream, it is helpful, although it doesn't work as dramatically as do standard anti-asthma drugs," he adds. He recommends taking the slow-release form of vitamin C--ester-C or calcium ascorbate--in 500- to 1,000-milligram doses twice a day. (If you take regular vitamin C, you'll see the best results if you take several hundred milligrams three or four times a day, he notes.) ----- http://www.globalherbalsupplies.com/vitamin_information/vitamin-c.htm Vitamin C (ASCORBIC ACID, CALCIUM ASCORBATE) Information Vitamin C is a water soluble vitamin. Also known as Ascorbic acid (3-oxo-L-gulofuranolactone), Anti-scorbutic Acid, Hexuronic Acid, Cevitannic Acid, L-xyloascorbic Acid, Ascorbyl Palmitate, Ascorbyl Nicotinate. Isolated from fruits, paprika and adrenal glands in 1922 by Dr. Albert Szent-Gyorgi. It can be prepared by synthesis from glucose, or extracted from plant sources such as rose hips, blackcurrants or citrus fruits. It is easily oxidized in air. Man is one of the few mammals unable to manufacture Ascorbic Acid in his liver. Vitamin C Chemical Structure, C6H8O6 Function accumulates iron in bone marrow, spleen and liver antioxidant which helps defend cells from the effects of smoke, pollution and other highly reactive substances called free radicals controls blood cholesterol levels converts amino acids into substances needed for normal brain and nerve functions converts Folic Acid into active form Folinic Acid essential for the formation of intercellular material, bone and teeth essential for the absorption of iron fights bacterial and viral infections helps in healing helps produce anti-stress hormones maintains elasticity of the skin maintains healthy blood capillaries maintains healthy reproductive organs may help protect against certain cancers, cataracts and heart disease necessary in production of red blood cells prevents allergic reactions (antihistamine activity) prevents hemorrhaging promotes healthy cell development and resistance to infections promotes wound healing protects Vitamin E vital for collagen formation which is the connective tissue protein in all cells ----- http://www.dietitian.com/allergie.html http://health.discovery.com/diseasesandcond/encyclopedia/1952.html ----- http://www.orst.edu/dept/lpi/infocenter/vitamins/vitaminC/c.html DISEASE PREVENTION The amount of vitamin C required to prevent chronic disease appears to be more than that required simply for prevention of scurvy. Much of the information regarding vitamin C and the prevention of chronic disease is based on prospective studies, where vitamin C intake is assessed in large numbers of people who are followed over time to determine whether they develop specific chronic diseases. Cardiovascular diseases (heart disease and stroke): Seven out of 12 prospective studies, which examined large numbers of people (700 to 87,000) over a number of years (3 to 20), found a significant relationship between higher levels of vitamin C intake and a lower risk of heart disease and stroke (1). The remaining studies, which did not find a relationship between vitamin C intake and cardiovascular diseases, compared individuals who were already consuming close to 100 mg daily with those consuming higher amounts. A careful experimental study at the NIH demonstrated that some human tissues (leukocytes) tend to become saturated with vitamin C at a dose of 100 mg/day (7). Thus, it is possible that once tissue saturation has been achieved, additional protective effects of vitamin C against cardiovascular diseases are small and therefore difficult to detect in prospective studies. Consistent with this possibility, at least 6 prospective studies have found low blood levels of vitamin C at baseline to be associated with a subsequent increase in the risk of heart disease or stroke (1,8). In a prospective study that followed more than 2,000 residents of a rural Japanese community for 20 years, the risk of stroke in those whose blood levels of vitamin C were in the highest quartile (1/4) was only 59% of those whose blood levels were in the lowest quartile (9). Additionally, the risk of stroke in those who consumed vegetables 6 to 7 days of the week was only 58 % of the risk in those who consumed vegetables 0 to 2 days of the week. The participants' blood levels of vitamin C were highly correlated with their fruit and vegetable intake. Therefore, as in many studies of vitamin C intake and cardiovascular disease risk, it is difficult to separate the effects of vitamin C on stroke risk from the effects of other components of fruits and vegetables, emphasizing the benefits of a diet rich in fruits and vegetables. Cancer: A large number of studies have shown that increased consumption of fresh fruits and vegetables is associated with a reduced risk for most types of cancer (10). Such studies are the basis for dietary guidelines endorsed by the U.S. Department of Agriculture and the National Cancer Institute, which recommend at least 5 servings of fruits and vegetables per day. A number of case-control studies have investigated the role of vitamin C in cancer prevention. Most have shown that higher intakes of vitamin C are associated with decreased incidence of cancers of the mouth, throat and vocal chords, esophagus, stomach, colon-rectum, and lung. Because the possibility of bias is greater in case control studies, prospective studies are generally given more weight in the evaluation of the effect of nutrient intake on disease. In general, prospective studies in which the lowest intake group consumed more than 86 mg of vitamin C daily have not found differences in cancer risk, while studies finding significant cancer risk reductions found them in people consuming at least 80 to 110 mg of vitamin C daily (1). A prospective study of 870 men over a period of 25 years found that those who consumed more than 83 mg of vitamin C daily had a striking 64% reduction in lung cancer compared with those who consumed less than 63 mg per day (11). Although most large prospective studies found no association between breast cancer and vitamin C intake, two recent studies found dietary vitamin C intake to be inversely associated with breast cancer risk in certain subgroups. In the Nurses' Health Study, premenopausal women with a family history of breast cancer who consumed an average of 205 mg/day of vitamin C from foods had a 63% lower risk of breast cancer than those who consumed an average of 70 mg/day (12). In the Swedish Mammography Cohort, women who were overweight and consumed an average of 110 mg/day of vitamin C had a 39% lower risk of breast cancer compared to overweight women who consumed an average of 31 mg/day (13). A number of observational studies have found increased dietary vitamin C intake to be associated with decreased risk of stomach cancer, and laboratory experiments indicate that vitamin C inhibits the formation of carcinogenic compounds in the stomach. Infection with the bacteria, helicobacter pylori (H. pylori) is known to increase the risk of stomach cancer and also appears to lower the vitamin C content of stomach secretions. Although two intervention studies did not find a decrease in the occurrence of stomach cancer with vitamin C supplementation (6), more recent research suggests that vitamin C supplementation may be a useful addition to standard H. pylori eradication therapy in reducing the risk of gastric cancer (14). Cataracts: Cataracts are a leading cause of blindness in the U.S. Cataracts occur more frequently and become more severe as people age. Decreased vitamin C levels in the lens of the eye have been associated with increased severity of cataracts in humans. Some, but not all, studies have observed increased dietary vitamin C intake (15) and increased blood levels of vitamin C (16) to be associated with decreased risk of cataracts. Those studies that have found a relationship suggest that vitamin C intake may have to be higher than 300 mg/day for a number of years before a protective effect can be detected (1). Recently, a 7-year controlled intervention trial of a daily antioxidant supplement containing 500 mg of vitamin C, 400 IU of vitamin E, and 15 mg of b-carotene in 4,629 men and women found no difference between the antioxidant combination and a placebo on the development and progression of age-related cataracts (17). Therefore, the relationship between vitamin C intake and the development of cataracts requires further clarification before specific recommendations can be made. Lead toxicity: Although the use of lead paint and leaded gasoline has been discontinued in the U.S., lead toxicity continues to be a significant health problem, especially in children living in urban areas. Abnormal growth and development has been observed in infants of women exposed to lead during pregnancy, while children who are chronically exposed to lead are more likely to develop learning disabilities, behavioral problems, and to have low IQs. In adults, lead toxicity may result in kidney damage and high blood pressure. In a study of 747 older men, blood lead levels were significantly higher in those who reported total dietary vitamin C intakes averaging less than 109 mg/day compared to men who reported higher vitamin C intakes (18). A much larger study of 19,578 people, including 4,214 children from 6 to 16 years of age, found higher serum vitamin C levels to be associated with significantly lower blood lead level (19). An intervention trial that examined the effects of vitamin C supplementation on blood lead levels in 75 adult male smokers found that 1,000 mg/day of vitamin C resulted in significantly lower blood lead levels over a 4-week treatment period compared to placeb (20). A lower dose of 200 mg/day did not significantly affect blood lead levels, despite the finding that serum vitamin C levels were not different than those of the group that took 1,000 mg/day. The mechanism for the relationship between vitamin C intake and blood lead levels is not known, although it has been postulated that vitamin C may inhibit intestinal absorption or enhance urinary excretion of lead. DISEASE TREATMENT Cardiovascular diseases: Vasodilation: The ability of blood vessels to relax or dilate is compromised in individuals with atherosclerosis. The damage to the heart muscle caused by a heart attack and damage to the brain caused by a stroke is related, in part, to the inability of blood vessels to dilate enough to allow blood flow to the affected areas. The pain of angina pectoris is also related to insufficient dilation of the coronary arteries. Treatment with vitamin C has consistently resulted in improved dilation of blood vessels in individuals with atherosclerosis as well as those with angina pectoris, congestive heart failure, high cholesterol, and high blood pressure. Improved blood vessel dilation has been demonstrated at a dose of 500 mg of vitamin C daily (21). Hypertension (high blood pressure): Individuals with high blood pressure are at increased risk of developing cardiovascular diseases. Several studies have demonstrated a blood pressure lowering effect of vitamin C supplementation. One recent study of individuals with high blood pressure found that a daily supplement of 500 mg of vitamin C resulted in an average drop in systolic blood pressure of 9% after 4 weeks (22). It should be noted that those participants who were taking anti-hypertensive medication continued taking it throughout the 4-week study. Because the findings regarding vitamin C and high blood pressure have not yet been replicated in larger studies it is important for individuals with significantly high blood pressure to continue current therapy (medication, lifestyle changes, etc.) in consultation with their health care provider. Cancer: Studies in the 1970's and 1980's conducted by Linus Pauling and colleagues suggested that very large doses of vitamin C (10 grams/day intravenously for 10 days followed by at least 10 grams/day orally indefinitely) were helpful in increasing the survival time and improving the quality of life of terminal cancer patients (23). However, two randomized placebo-controlled studies conducted at the Mayo clinic found no differences in outcome between terminal cancer patients receiving 10 grams of vitamin C/day orally or placebo (24) There were significant methodological differences between the Mayo Clinic and Pauling's studies, and recently, two researchers from the NIH suggested that the route of administration (intravenous versus oral) may have been the key to the discrepant results (25). Intravenous (IV) administration can result in much higher blood levels of vitamin C than oral administration, and levels that are toxic to certain types of cancer cells in culture can be achieved with intravenous but not oral administration of vitamin C. Thus, it appears reasonable to reevaluate the use of high-dose vitamin C as cancer therapy. Currently, there is no clinical evidence suggesting that vitamin C would adversely affect the survival of cancer patients. However, vitamin C should not be used in place of therapy that has been demonstrated effective in the treatment of a particular type of cancer, for example, chemotherapy or radiation therapy. If an individual with cancer chooses to take vitamin supplements, it is important that the clinician coordinating his or her treatment is aware of the type and dose of each supplement. While research is underway to determine whether combinations of antioxidant vitamins might be beneficial as an adjunct to conventional cancer therapy, definitive conclusions are not yet possible (26). In a presentation at a meeting of the American Cancer Society, a scientist suggested that supplemental vitamin C might enhance the growth of cancer cells or protect them from cell-killing free radicals produced by radiation and some forms of chemotherapy. An article published in the Spring/Summer 2000 issue of the Linus Pauling Institute newsletter, Is vitamin C harmful for cancer patients?, provides additional insight on this topic. Diabetes mellitus: Numerous observational studies have found that people with diabetes have lower plasma levels of vitamin C (approximately 30% lower) than do people without diabetes. However, a number of methodological flaws have been attributed to such studies, and it is not clear whether diabetes is the cause of lower plasma levels of vitamin C. Recently a large population-based study found no difference in blood levels of vitamin C between over 200 individuals with newly diagnosed diabetes and 1,800 individuals without diabetes once dietary intake of vitamin C and cigarette smoking were taken into consideration (27). Though few studies have demonstrated improved blood glucose levels upon supplementation of diabetic individuals with vitamin C, doses of between 100 and 600 mg of vitamin C daily have been found to normalize cellular sorbitol levels, which may have implications for decreasing some of the long-term complications of diabetes (28). Cardiovascular diseases are the leading cause of death in individuals with diabetes (See Disease Prevention: Cardiovascular Diseases). Vitamin C has also been found to improve blood vessel dilation, which is often impaired in diabetic individuals (See Disease Treatment: Cardiovascular Diseases). The link between cardiovascular diseases and diabetes may be related to increased oxidative stress, giving credibility to the idea that the antioxidant properties of vitamin C may benefit individuals with diabetes. While the role of vitamin C in the management of diabetes is by no means clear, maintaining an adequate intake of vitamin C may help prevent some of the complications of diabetes. Common cold: The work of Linus Pauling stimulated public interest in the use of large doses (greater than 1 gram/day) of vitamin C to prevent infection with the viruses responsible for the common cold. Reviews of the research conducted on this issue over the past 20 years conclude that, in general, large doses of vitamin C do not have a significant effect on the incidence of the common cold (29). However, a few studies have indicated that certain susceptible groups (e.g., individuals with low dietary intake and marathoners) may be less susceptible to the common cold when taking supplemental vitamin C. Additionally, large doses of vitamin C have been found to decrease the duration and severity of colds, an effect that may be related to the antihistamine effects found to occur with large doses (2 grams) of vitamin C (30). .... Does vitamin C promote oxidative damage under physiological conditions? Vitamin C is known to function as a highly effective antioxidant in living organisms. However, in test tube experiments, vitamin C can interact with some free metal ions to produce potentially damaging free radicals. Although free metal ions are not generally found under physiological conditions, the idea that high doses of vitamin C might be able to promote oxidative damage in vivo has received a great deal of attention. Widespread publicity has been given to a few studies suggesting a pro-oxidant effect of vitamin C (35,36), but these studies turned out to be either flawed or of no physiological relevance. A recent comprehensive review of the literature found no credible scientific evidence that supplemental vitamin C promotes oxidative damage under physiological conditions or in humans (37). Studies that report a pro-oxidant effect for vitamin C should be evaluated carefully to determine whether the study system was physiologically relevant, and to rule out the possibility of methodological and design flaws. _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
