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Vitamin C, the water soluble antioxidant

  Vitamin C the water soluble antioxidant http://healthfully.org/rc/id20.html   1/3/16

Ascorbic acid [vitamin C] has two essential functions, in chemical biological syntheses; and as a scavenger for reactive chemicals--especially oxygen.  Thus in addition to functioning as a vitamin, it is a very effective water-soluble antioxidant, one that is used as a food preservative.  “Vitamin C is a cofactor in at least eight enzymatic reactions, including several collagen synthesis reactions that, when dysfunctional, cause the most severe symptoms of scurvy.  Ascorbate[1] may also act as an antioxidant against oxidative stress.  In animals, these reactions are especially important in wound-healing and in preventing bleeding from capillaries.  However, the fact that the enantiomer D-ascorbate (not found in nature) has identical antioxidant activity to L-ascorbate, yet far less vitamin activity, underscores the fact that most of the function of L-ascorbate as a vitamin relies not on its antioxidant properties, but upon enzymatic reactions that are stereospecific. "Ascorbate" without the letter for the enantiomeric form is always presumed to be the chemical L-ascorbate.  Ascorbic acid is a weak sugar acid structurally related to glucose. In biological systems, ascorbic acid can be found only at low pH, but in neutral solutions above pH 5 is predominantly found in the ionized form, ascorbate.[2]  All of these molecules have vitamin C activity, therefore, and are used synonymously with vitamin C, unless otherwise specified.  The biological role of ascorbate is to act as a reducing agent, donating electrons to various enzymatic and a few non-enzymatic reactions. The one- and two-electron oxidized forms of vitamin C, semidehydroascorbic acid and dehydroascorbic acid, respectively, can be reduced in the body by glutathione and NADPH-dependent enzymatic mechanisms.  Glutathione in cells and extracellular fluids helps maintain ascorbate in a reduced state” Wiki. 

“The vast majority of animals and plants are able to synthesize vitamin C, through a sequence of enzyme-driven steps, which convert monosaccharides to vitamin C. In plants, this is accomplished through the conversion of mannose or galactose to ascorbic acid.[9] In some animals, glucose needed to produce ascorbate in the liver (in mammals and perching birds) is extracted from glycogen [in cells as needed]…  In reptiles and birds the biosynthesis is carried out in the kidneys.  Most simians consume the vitamin in amounts 10 to 20 times higher than that recommended by governments for humans.  This discrepancy constitutes much of the basis of the controversy on current recommended dietary allowances. It is countered by arguments that humans are very good at conserving dietary vitamin C, and are able to maintain blood levels of vitamin C comparable with other simians, on a far smaller dietary intake.  Although the body's maximal store of vitamin C is largely determined by the renal threshold for blood, there are many tissues that maintain vitamin C concentrations far higher than in blood. Biological tissues that accumulate over 100 times the level in blood plasma of vitamin C are the adrenal glands, pituitary, thymus, corpus luteum, and retina.[40] Those with 10 to 50 times the concentration present in blood plasma include the brain, spleen, lung, testicle, lymph nodes, liver, thyroid, small intestinal mucosa, leukocytes, pancreas, kidney, and salivary glands[3]  Wiki. High concentrations give protection from oxidative damage to those tissues; and it “protects phagocytic cells involved in the defense against pathogens”, at.  This protection from oxidation and infection is the logic behind the use of high-dose supplementation.  

In addition to its roles as an antioxidant (note above), ascorbate functions as an electron donor for 8 different enzymes.  It is essential for the production of the ubiquitous connective tissue collagen the production of carnitine, the neurotransmitters including the catecholamines norepinephrine and epinephrine, serotonin, the regulation of histamines, absorption of iron in the non-heme form found in plants.  As an antioxidant it rejuvenates vitamin E.  Both vitamins are found in LDL, which they protect from oxidative damage.    Ascorbate supplement seem prudent, but what has clinical trials and animal research uncover?  I must cherry pick the results because of pharma’s tobacco ethic, which entails the NIH & pharma’s junk science are widely published.  Over and over again I uncover in the details research design that deliberately produces negative results; this is consistent with pharma’s financial goals--see for typical examples, and.  Journals rely upon pharma for income and articles, thus their articles are subject to a sham review.

Antioxidant:  Vitamin C readily scavenges reactive oxygen and nitrogen species and may thereby prevent oxidative damage to important biological macromolecules such as DNA, lipids [LDL, HDL & others], and proteins. We found compelling evidence for antioxidant protection of lipids by vitamin C in biological fluids, animals, and humans….     Although the data on protein oxidation in humans are sparse and inconclusive, the available data in animals consistently show an antioxidant role of vitamin C.  Vitamin C also reduces redox active transition metal ions in the active sites of specific biosynthetic enzymes” short, full, 1999.  In this paper, we show that it is indeed ascorbate that completely protects plasma lipids against detectable peroxidative damage induced by aqueous peroxyl radicals and that ascorbate is the only plasma antioxidant that can do so. Plasma devoid of ascorbate, but no other endogenous antioxidant, is extremely vulnerable to oxidant stress and susceptible to peroxidative damage to lipids … ascorbate is a physiological antioxidant of major importance for protection against diseases & degenerative processes caused by oxidant stress” at.  This protective function explains why certain tissues accumulate 100 times the blood level of vitamin C (page 1 above).  The oxidative damage process along with glycation causes the age related diseases that afflict seniors.  Ascorbic acid is protective against hydrogen peroxide a causal factor for Parkinson’s and Alzheimer’s diseases (a 78% reduction after 3 years).  Note other protective agents include CoQ10, vitamin E and estradiol which protect in a complimentary way.

[1] Ascorbic acid is an organic acid which can react with a base such as sodium or calcium hydroxide to form a salt (sodium or calcium ascorbate).  In the body these salts are bioequivalent to ascorbic acid (vitamin C), the term “ascorbate” denotes vitamin C. 

[2]  “Ascorbate that completely protects plasma lipids against detectable peroxidative damage … to lipids [includes LDL] at, also.

[3] Because of transport to those tissues listed, blood measurements of glutathione level will not significantly rise with oral administration.  A second cause is that “hydrolysis of glutathione by intestinal and hepatic gama glutamyltransferase, dietary glutathione is not a major determinant of circulating glutathione” at.

Cancer:  “Epidemiologic evidence of a protective effect of vitamin C for non-hormone-dependent cancers is strong. Of the 46 such studies in which a dietary vitamin C index was calculated, 33 found statistically significant protection, with high intake conferring approximately a twofold protective effect compared with low intake. Of 29 additional studies that assessed fruit intake, 21 found significant protection.  For cancers of the esophagus, larynx, oral cavity, and pancreas, evidence for a protective effect of vitamin C or some component in fruit is strong and consistent. For cancers of the stomach, rectum, breast, and cervix there is also strong evidence. Several recent lung cancer studies found significant protective effects of vitamin C or of foods that are better sources of vitamin C than of beta-carotene” AJCN, 1991.  Linus Pauling holds that vitamin C functions through immune functions; thus the use cytotoxic drugs that damage the immune system (standard chemotherapies) entail minimal benefit from high-does vitamin C.  In 1974 Cameron and Campbell preformed a matching study using patients in a hospital in Scotland which doesn’t use chemotherapy on terminal patient.  Fifty patients were treated with a daily dose of 10 g of vitamin C.  Later Pauling and Cameron compared their treated patient group with 1000 untreated patients.  The mean survival time is more than 4.2 times as great for the ascorbate subjects (more than 210 days) as for the controls (50 days)” at 1976.  “The results clearly indicate that this simple and safe form of medication is of definite value in the treatment of patients with advanced cancer” at NAS, 1976; and for their discussion of the mechanism of prevention of metastatic cancer at ARGIS.[1] “Our results also suggest that ascorbic acid is a potent anticancer agent for prostate cancer cells” The Prostate 1998.  Resistance to development of cancer:  The factors involved in host resistance are briefly reviewed, and the relationship between these factors and ascorbic acid metabolism is presented in detail. It is shown that many factors involved in host resistance to neoplasia are significantly dependent upon the availability of ascorbate” at 1979.   A mechanism for ascorbate toxicity to cancer cells:  Here, we show that a Warburg effect triggered by activation of the hypoxia-inducible factor (HIF) pathway greatly enhances Vc-induced toxicity in multiple cancer cell lines…. Through affect upon the cancer metabolism… for the preferential effect of Vc on cancer cells” at 2014.  An experiment using IV infusion of vitamin C for treating cancer in rats had positive results, at 2015, and.  It confirmed the Warburg hypothesis. Thus a ketogenic diet would improve efficacy of mega vitamin C—see Warburg effect 2011.   

Benefits of Ascorbate high dose supplement:  A variety of evidence supports that “immuno-stimulant, anti-inflammatory, and anti-carcinogenic effects are well documented in the existing biomedical literature”, at 1984.

Cardiovascular Disease, Stroke All Causes of Mortality:  “A meta-analysis of 44 clinical trials has shown a significant positive effect of vitamin C on endothelial functions [prevents endothelial dysfunction thus cardiovascular disease] when taken at doses greater than 500 mg per day. The researchers noted that the effect of vitamin C supplementation appeared to be dependent on health status, with stronger effects in those at higher cardiovascular disease risk” Wiki. The same conclusion was drawn in a trial on 17 volunteers, publish AHA.  By inhibiting the oxidative modification of LDL, ascorbate prevented the uptake and degradation of oxidatively modified LDL by the scavenger-receptor mechanism of cultured human monocyte derived macrophages” a step leading to atherosclerosis at 1990.  This role explains why LDL carries two antioxidants, CoQ10 and Vitamin C. “Vitamin C was shown to protect neutrophils from reactive oxygen species during phagocytosis, to prevent endogenous oxidative damage to lymphocytes … to lipids, proteins and DNA, which has been implicated as a major contributing factor in the development of chronic diseases such as cardiovascular disease, cancer, and cataract… in the maintenance of endothelial function, mainly by preventing or reversing endothelial dysfunctions leading to the development of CVD” at.  For 730 elderly who completed a dietary record of 7 days in 1973-4, “Mortality from stroke… the highest third of distribution of vitamin C intake had a relative risk of 0,5 compared with those in the lowest third, after adjustment for age, sex, and established cardiovascular risk factors” at.  “Based on serum AA  those with normal to high had a lower CVD by 25% and all causes of mortality of 29%” at; “Risk of mortality in the top ascorbic acid quintile was about half the risk in the lowest quintile, at.[2]  This protection explains why the heart has an elevated level of vitamin C.   

Immune Enhancing Function: a number of studies support its promotion of immune function.  “The high cellular concentration of vitamin C and its rapid decline in plasma and leukocytes during stress and infection suggests a role in the process of immune response” at.  For the common cold, the results have been a modest benefit, not enough to justify its usage for this purpose.  But for other infections which result in oxidative stress, ascorbate is beneficial, at. 

Rheumatoid arthritis (RH) and Osteoarthritis:  The rapid depletion of ascorbic acid at sites of inflammation, as in the inflamed rheumatoid joint, may therefore facilitate proteolytic damage” in an article on the protection of inflamed rheumatoid joints,1987.  Our studies indicate that in some cases the intake required to maintain adequate vitamin C levels in the plasma are much above the average requirement for normal individuals” at 1936.  Aspirin therapy for arthritis requires 8 years are longer before its significantly “decreases the prevalence of symptomatic atherosclerosis.” at. 

Gout (an inflammatory arthritis caused by high level of uric acid in the blood which from crystals in joints and tendons, most often involving the big toe.  Affects about 2% of the Western population.)  Supplementation with 500 mg/day of vitamin C for 2 months reduces serum uric acid, suggesting that vitamin C might be beneficial in the prevention and management of gout and other urate-related diseases” at 2005.

Asthma:  From our review, we found a number of studies that support the use of vitamin C in asthma and allergy. Significant results include positive effects on pulmonary function tests, broncho-provocation challenges  with  methacholine  or histamine or allergens,  improvement in white blood cell function and motility, and a decrease  in    respiratory infectionsat, 1994;protection from through antioxidant effect” at, and 36% lower level ascorbate  at.  

RECOMMENDATION:   Based upon this review of the literature, a general knowledge of cell biology, pathology, & the natural high levels of vitamin C found in various tissues for protection from oxidative damage, its low cost, and the lack of side effects; for all these reasons, I recommend 500 mg per day starting in the 2nd decade and being increased to 1 g in the 5th, and 1.5 grams in the 7th.  FORM of ascorbate:   I prefer vitamin C in the form of sodium ascorbate.[3]  I mix a portion of the powder into tea or juices.  Another choice which I also use is the pleasant-tasting chewable sodium ascorbate 500 mg which is sweetened with sorbitol; available from Costco.  Because it is used as an antioxidant--not vitamin function--the addition of bioflavonoids is not beneficial to the consumer.  The record of research on bioflavonoids is polluted with marketing studies to show benefit.  Those studies by pharma and government are designed to show that vitamin C offers no benefits—a sign that it does.  Business is a corrupt master of science.   Cheaper is better because, price matters to most people.   Over the internet I purchased 5 kg of sodium ascorbate and I take 2 gm daily. 

[1] Pharma in damage control mode has funded studies using patients who had received chemotherapy prior to concluded that vitamin C “is not effective against advanced malignant diseases…,” at 1985, and there are a number of other articles.  But Pauling used those who immune system had not been compromised by chemotherapy, because Vitamin C enhances immune functions. 

[2] This is weak evidence for the benefit of vitamin C, because it doesn’t control for the beneficial effect of modify the diet so that fruits are eaten instead of the standard deserts, and that of the eating fruits are more likely to have an assortment of diet and lifestyle differences that are healthful.  Fruits as an alternative to other sweets has a lower effect upon insulin, and hyperinsulinemia (such as in type 2 diabetes) is associated with significantly higher death rate, for diabetes it is 2 fold.  

[3] I once recommended calcium ascorbate but after watching Dr. Jason Fung lecture on the lack of benefit, and modest harm caused by calcium supplements, I have concluded that supplement is of no benefits.  Many primitive oriental societies on traditional diet have intakes of calcium in the range of 300 mg, yet osteoporosis is essentially unknown—Dr. Jason Fung, 2013.

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Disclaimer:  The information, facts, and opinions provided here is not a substitute for professional advice.  It only indicates what JK believes, does, or would do.  Always consult your primary care physician for medical advice, diagnosis, and treatment.