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Vitamin C
What is it? Overview Usage Side Effects and Warnings

Vitamin C Usage

Written by FoundHealth.


Effect of Vitamin C on Gout

Although most animals can make vitamin C from scratch, humans have lost the ability over the course of evolution. We must get it from food, chiefly fresh fruits and vegetables. One of this vitamin's...

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Effect of Vitamin C on Autism

Vitamin C is a powerful antioxidant that neutralizes damaging natural substances called free radicals. It works in water, both inside and outside of cells. Vitamin C complements another antioxidant...

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Effect of Vitamin C on Cervical Cancer

Vitamin C is the single most popular vitamin supplement in the United States and perhaps the most controversial, as well. In the 1960s, two-time Nobel Prize winner Dr. Linus Pauling claimed that...

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Effect of Vitamin C on Viral Upper Respiratory Infections (Colds and Influenza)

Vitamin C supports immune function, but the exact effect of vitamin C on colds and flu is not clear. Vitamin C serves numerous functions in the body, from producing collagen to working as an...

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Effect of Vitamin C on Lyme Disease

Vitamin C can be added to the diet of someone with Lyme disease to both support the collagen tissues (discussed in Lyme Disease Treatment: Herbs Overview section as being one of the major...

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Effect of Vitamin C on Hypertension

The exact role of vitamin C in lowering blood pressure is not yet clear. Vitamin C is a powerful antioxidant that neutralizes damaging natural substances called free radicals. It works in water,...

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Effect of Vitamin C on Bipolar Disorder

It is thought that vitamin C might play a role in helping to treat bipolar disorder, though this has yet to be extensively studied.

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Therapeutic Uses

According to numerous double-blind, placebo-controlled studies, regular use of vitamin C supplements can slightly reduce symptoms of colds and modestly shorten the length of the illness. 1 However, taking vitamin C at the onset of a cold probably will not work. 2 Regular use of vitamin C does not seem to help preventcolds. 3 One exception is the “post-marathon sniffle”—colds that develop after heavy exercise. 4 Vitamin C may be helpful for preventing this condition, although not all studies agree. 5 Two double-blind studies suggest that the use of vitamin C combined with vitamin E might slightly reduce the risk of developing preeclampsia , a complication of pregnancy. 6 However, a much larger follow-up study failed to find benefits. 7 Two studies conducted by a single research group have found that vitamin C at a dose of 500 mg daily might help prevent reflex sympathetic dystrophy, a poorly understood condition that can follow injuries such as fractures. 8 Over time, the body develops tolerance to drugs in the nitrate family (such as nitroglycerin ). Some evidence suggests that use of vitamin C can help maintain the effectiveness of these medications. 9 10 11 Other small double-blind trials suggest that vitamin C might be helpful for anterior uveitis (when taken in combination with vitamin E ), 12 autism , 13 easy bruising , 14 minor injuries , 15 protecting the liver in nonalcoholic steatohepatitis, 16 speeding recovery from bedsores, 17 treating female infertility (specifically, a condition called "luteal phase defect"), 18 and preventing early rupture of the chorioamniotic membranes ("the water breaking") in pregnancy . 19 Vitamin C might also improve the effectiveness of antibiotic treatment for Helicobacter pylori, the cause of most peptic ulcers . 20 Preliminary evidence suggests that cream containing vitamin C may improve the appearance of aging or sun-damaged skin . 21 Inconsistent evidence suggests that oral or topical vitamin C, taken by itself or in combination with vitamin E , may also help protectthe skin against sun damage. 22 23 24 25 26 27 28 Double-blind studies of vitamin C for the following conditions have yielded mixed results: asthma , 29 male infertility , 30 reducing the muscle soreness that typically develops after exercise, 31 and hypertension . 32 Note: Unexpectedly, one study found that a combination of vitamin C (500 mg daily) and grape seed oligomeric proanthocyanidins (OPCs) (1,000 mg daily) slightly increasedblood pressure. 33 Whether this was a fluke of statistics or a real combined effect remains unclear.

Limited and in some cases contradictory evidence suggests possible benefit in the prevention or treatment the following conditions:

  • Allergies 34 35
  • Atrial fibrillation following coronary artery bypass grafting (CABG) 36
  • Bladder infections during pregnancy 37
  • Gallbladder disease (in women) 38
  • General anesthetics 39
  • Glaucoma 40
  • Gout 41
  • Obesity 42 43
  • Vascular dementia 44

Intravaginal use of vitamin C tablets might be helpful for non-specific vaginitis. 45

Observational studies indicate that people with a higher intake of vitamin C have a lower incidence of cataracts , macular degeneration , heart disease , cancer , and osteoarthritis . 46 However, these findings do not indicate that vitamin C supplementswill help prevent or treat these conditions. Observational studies are notoriously unreliable for showing the efficacy of treatments; only double-blind studies can do that, and only one has been performed that directly examined vitamin C’s potential benefits for preventing these conditions. (For more information on why double-blind studies are so important, see Why Does This Database Rely on Double-blind Studies? ) Two large double-blind trials exploring the effectiveness of vitamin C for heart disease prevention—one in women at high risk181 and the other in men at low risk— 47 failed to find any benefit at all.

Vitamin C has been proposed as a treatmentfor cancer, but this claim is very controversial, and there is as yet no scientifically meaningful evidence that it works. 48 49 50 Massive doses of vitamin C have at times been popular among people with HIV infection based on highly preliminary evidence. 51 An observational study linked high doses of vitamin C with slower progression to AIDS. 52 However, a double-blind study of 49 people with HIV who took combined vitamins C and E or placebo for 3 months did not show any significant effects on the amount of HIV detected or the number of opportunistic infections. 53 Furthermore, one study found that vitamin C at a dose of 1 g daily substantially reduced blood levels of the drug indinavir, a protease inhibitor used for the treatment of HIV infection. 54 This could potentially cause the drug to fail.

In a study of 80 women with Chlamydia trachomatisinfection, adding vitamin C to doxycycline and triple sulfa vaginal cream reduced discharge and pain associated with intercourse. 55 One substantial study failed to find vitamin C useful for improving high cholesterol . 56 According to a double-blind, placebo-controlled study of 141 women with cervical dysplasia (early cervical cancer), vitamin C, taken at a dosage of 500 mg daily, does nothelp to reverse the dysplasia. 57 Vitamin C also does not appear to be helpful for treating Raynaud’s phenomenon caused by scleroderma . 58


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  4. Peters EM, Goetzsche JM, Grobbelaar B, Noakes TD. Vitamin C supplementation reduces the incidence of postrace symptoms of upper-respiratory-tract infection in ultramarathon runners. Am J Clin Nutr. 57(2):170-4.
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  21. Traikovich SS. Use of topical ascorbic acid and its effects on photodamaged skin topography. Arch Otolaryngol Head Neck Surg. 125(10):1091-8.
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  28. Werninghaus K, Meydani M, Bhawan J, Margolis R, Blumberg JB, Gilchrest BA. Evaluation of the photoprotective effect of oral vitamin E supplementation. Arch Dermatol. 130(10):1257-61.
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  44. Masaki KH, Losonczy KG, Izmirlian G, Foley DJ, Ross GW, Petrovitch H, Havlik R, White LR. Association of vitamin E and C supplement use with cognitive function and dementia in elderly men. Neurology. 54(6):1265-72.
  45. Petersen EE, Magnani P. Efficacy and safety of vitamin C vaginal tablets in the treatment of non-specific vaginitis. A randomised, double blind, placebo-controlled study. Eur J Obstet Gynecol Reprod Biol. 117(1):70-5.
  46. Hankinson SE, Stampfer MJ, Seddon JM, Colditz GA, Rosner B, Speizer FE, Willett WC. Nutrient intake and cataract extraction in women: a prospective study. BMJ. 305(6849):335-9.
  47. Sesso HD, Buring JE, Christen WG, et al. Vitamins E and C in the prevention of cardiovascular disease in men: the Physicians' Health Study II randomized controlled trial. JAMA. 2008;300:2123-2133.
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  53. Allard JP, Aghdassi E, Chau J, Tam C, Kovacs CM, Salit IE, Walmsley SL. Effects of vitamin E and C supplementation on oxidative stress and viral load in HIV-infected subjects. AIDS. 12(13):1653-9.
  54. Slain D, Ansden J, Khakoo R, et al. Effects of high-dose vitamin C on the steady state pharmacokinetics of the protease inhibitor Indinavir in healthy volunteers. Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) Meeting; Sept 13-17, 2003; Chicago, IL. Poster A-1610.
  55. Khajehei M, Keshavarz T, Tabatabaee HR. Randomised double-blind trial of the effect of vitamin C on dyspareunia and vaginal discharge in women receiving doxycycline and triple sulfa for chlamydial cervicitis. Aust N Z J Obstet Gynaecol. 49(5):525-30.
  56. Kim MK, Sasaki S, Sasazuki S, Okubo S, Hayashi M, Tsugane S. Long-term vitamin C supplementation has no markedly favourable effect on serum lipids in middle-aged Japanese subjects. Br J Nutr. 91(1):81-90.
  57. Mackerras D, Irwig L, Simpson JM, Weisberg E, Cardona M, Webster F, Walton L, Ghersi D. Randomized double-blind trial of beta-carotene and vitamin C in women with minor cervical abnormalities. Br J Cancer. 79(9-10):1448-53.
  58. Mavrikakis ME, Lekakis JP, Papamichael CM, et al. Ascorbic acid does not improve endothelium-dependent flow-mediated dilatation of the brachial artery in patients with Raynaud's phenomenon secondary to systemic sclerosis. Int J Vitam Nutr Res. 2003;73:3-7.


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