Vitamin C Usage

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...

Read more about Gout and Vitamin C.

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...

Read more about Autism and Vitamin C.

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...

Read more about Cervical Cancer and Vitamin C.

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...

Read more about Viral Upper Respiratory Infections (Colds and Influenza) and Vitamin C.

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...

Read more about Lyme Disease and Vitamin C.

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,...

Read more about Hypertension and Vitamin C.

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

Read more about Bipolar Disorder and Vitamin C.

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