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Vitamin C

 

Natural Standard Monograph, Copyright © 2014 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified health care professional before making decisions about therapies and/or health conditions.

Related Terms

  • Acide ascorbique (French), acide cévitamique (French), acide iso-ascorbique (French), acide L-ascorbique (French), ácido ascórbico (Spanish), antiscorbutic vitamin, ascorbate, ascorbate de calcium, ascorbate de sodium, ascorbic acid (AA), ascorbyl palmitate, calcium ascorbate, cevitamic acid, iso-ascorbic acid, L-ascorbic acid, magnesium ascorbate, palmitate d'ascorbyl (French), selenium ascorbate, sodium ascorbate, vitamina C (Spanish), vitamine antiscorbutique (French), vitamine C (French).

Background

  • Vitamin C (ascorbic acid) is a water-soluble vitamin, which is needed by the body to form collagen in bones, cartilage, muscle, and blood vessels. Dietary sources of vitamin C include fruits and vegetables, particularly citrus fruits such as oranges.
  • Severe deficiency of vitamin C causes scurvy. Although rare, scurvy results in severe symptoms and can cause death. People with scurvy are treated with vitamin C and should be under medical supervision.
  • Many uses for vitamin C have been proposed, but evidence of benefit in scientific studies is lacking. In particular, research on asthma, cancer, and diabetes remains inconclusive, and a lack of benefit has been found for the prevention of cataracts or heart disease.
  • The use of vitamin C in the prevention or treatment of colds remains controversial. Extensive research has been conducted. Overall, vitamin C lacked an effect on the development of colds and on cold symptoms. However, the duration of the cold shortened slightly. Notably, people living in extreme circumstances, including soldiers in the subarctic, skiers, and marathon runners, had a 50% decrease in the risk of developing a cold. This area merits additional research and may be of particular interest to athletes or people in the military.

Evidence

 

Uses based on scientific evidence 

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare professional.

Grade* 

Vitamin C deficiency (scurvy) 

Scurvy is caused by a lack of vitamin C in the diet. Although scurvy is uncommon, it may occur in malnourished individuals, those that need more vitamin C (such as pregnant or breastfeeding women), or infants. If vitamin C is unavailable, orange juice can be used for scurvy in infants. Symptoms should begin to improve in 1-2 days, and end completely within seven days. Treatment should be under strict medical supervision.

A 

Common cold prevention (extreme environments) 

Vitamin C reduced the risk of developing colds, by roughly 50% in people under physical stress or in extreme conditions, such as soldiers in the subarctic, skiers, and marathon runners. This area merits more research and may be of particular interest to elite athletes or military personnel.

B 

Iron absorption enhancement 

Based on scientific research, vitamin C appears to improve absorption of iron or iron supplements taken by mouth. Further research is needed to reach a firm conclusion.

B 

Urinary tract infection 

Vitamin C may decrease the risk of developing urinary tract infections during pregnancy and in the elderly. Further research is needed to confirm this finding.

B 

Age-related macular degeneration (AMD) 

There is a lack of evidence showing beneficial effects of vitamin C alone in the treatment of AMD, an eye disorder which causes loss of vision. Further research is needed in this area.

C 

Alzheimer's disease 

There is limited research on the effects of vitamin C alone on the progression of Alzheimer's disease. Further research is needed before a conclusion can be made.

C 

Anemia 

Research has shown that vitamin C may improve the absorption of dietary iron. Limited research has shown that vitamin C may improve outcomes of anemia, a disorder where there is a short supply red blood cells. Additional research is needed before a conclusion can be made.

C 

Antioxidant 

Limited research showed that vitamin C lacked a clear anti-oxidant effect. Further information is required to form conclusions.

C 

Arthritis (osteoarthritis, rheumatoid arthritis) 

Vitamin C may slow disease progression in individuals with osteoarthritis. However, high-quality research is needed to conclude if vitamin C is beneficial for both osteoarthritis and rheumatoid arthritis.

C 

Asthma 

It has been suggested that low levels of vitamin C may increase the risk of developing asthma. Research on the use of vitamin C in asthma remains inconclusive. More research is needed before a clear conclusion can be drawn.

C 

Autism 

Ascorbic acid may decrease the severity of symptoms in children with autism, a mental disorder. More trials are needed before a conclusion can be made.

C 

Bleeding stomach ulcers caused by aspirin 

Early evidence suggests that vitamin C may help with stomach damage caused by aspirin. More research is needed before a clear conclusion can be drawn.

C 

Breast cancer prevention 

Limited research examined the role of vitamin C in breast cancer. There was a lack of conclusive results. Additional studies are needed.

C 

Burns 

Early research suggested that vitamin C may have positive effects in people with severe burns. Additional studies are needed before a conclusion can be made.

C 

Cancer prevention 

Dietary intake of fruits and vegetables high in vitamin C has been associated with a reduced risk of cancer. The role of vitamin C is unclear. Limited research showed that vitamin C supplements lacked a protective effect on certain cancers. Further research is needed to draw conclusions.

C 

Cancer treatment 

Vitamin C has a long history of being used as a part of cancer therapy. Clear evidence of benefit of using vitamin C is lacking. More well-designed studies are needed before a firm conclusion can be made.

C 

Chemotherapy adjunct 

Early research showed that vitamin C lacked additional benefit for people with cancer when together with chemotherapy, or drug-therapy for cancer. Additional studies are needed in this area.

C 

Chronic venous insufficiency 

Due to limitations in research, the role of vitamin C alone is unclear in chronic venous insufficiency, a disease that occurs when insufficient blood is pumped back to the heart. Additional studies are needed.

C 

Colon cancer 

In limited research, vitamin C lacked an effect on colon cancer occurrence or death from cancer. Additional studies are needed before a conclusion can be made.

C 

Common cold treatment 

The use of vitamin C for cold symptom treatment has showed mixed results in human research. Further research is needed in this area.

C 

Complex regional pain syndrome 

Clinical research suggests that vitamin C may be beneficial for complex regional pain syndrome, which involves long-term pain usually in an arm or leg. Further research is needed to draw conclusions.

C 

Cystic fibrosis 

The role of vitamin C is unclear in people with cystic fibrosis, a disease with mucus build-up in the body. Additional research is needed in this area.

C 

Dementia 

The role of vitamin C alone in dementia is unclear due to the limited research that is available. Further research is needed.

C 

Diabetic eye disease  

In limited research, the role of vitamin C for diabetic eye disease and diabetic nerve pain was unclear. Well-designed trials are needed.

C 

Endometrial cancer prevention 

In human research, the effects of vitamin C supplementation are mixed regarding the prevention of endometrial cancer, a cancer of the uterus lining. Further research is needed before a conclusion can be made.

C 

Erythropoietic protoporphyria (EPP) 

Erythropoietic protoporphyria (EPP) is a rare inherited blood disorder characterized by extreme skin-sensitivity to sunlight. More research is needed to determine if vitamin C is beneficial for this condition.

C 

Exercise recovery 

Vitamin C may help prevent damage to fat and muscle caused by exercise and may improve physical ability. More research is needed before a conclusion can be made.

C 

Fertility 

Limited research showed that vitamin C improved pregnancy rate in women with cysts on their ovaries. Further research is needed to determine the effects of vitamin C supplementation on fertility.

C 

Gallbladder disease 

Vitamin C supplementation may decrease the risk of gallbladder disease in women. Well-designed trials are needed to draw conclusions.

C 

Heart conditions 

Early evidence suggests that vitamin C supplementation may reduce the risk of abnormal heart rhythms after surgery. Additional studies are needed.

C 

H. pylori infection  

Adding vitamin C to standard therapy (omeprazole, amoxicillin, and clarithromycin) for stomach ulcers due to H. pylori may allow the dose of clarithromycin to be lower. Other research showed that vitamin C lacked an effect on H. pylori infection. Further research is needed to confirm this result.

C 

High blood pressure 

In human research, vitamin C supplementation has been shown to decrease blood pressure. Further research is needed in this area.

C 

High cholesterol 

According to studies in humans, vitamin C supplementation may be beneficial in people with high cholesterol. More research is needed in this area.

C 

HIV (transmission) 

Supplementation of mothers with HIV disease with vitamin B, vitamin C, and vitamin E may reduce child mortality and HIV transmission through breast milk. Well-designed studies are needed.

C 

Ischemic heart disease 

Due to its antioxidant properties, vitamin C has been used in people with ischemic heart disease, a condition where there is insufficient blood supply to the heart. Early data suggests that vitamin C may have a benefit on blood flow in the heart. Further research is needed to confirm this finding.

C 

Kidney disease 

Limited research suggests that vitamin C may reduce the risk of kidney disease from the dye used in coronary angiography, a procedure to examine blood vessels. Additional trials are needed before a conclusion can be made.

C 

Lead toxicity 

Consuming vitamin C from dietary sources may lower blood concentrations of lead. Additional studies are needed.

C 

Life extension 

Research has shown that vitamin C lacked effects on extending life, or preventing mortality. Further research is needed.

C 

Liver disease 

Administration of vitamin C in individuals with cirrhosis may have some benefit. However, in people with chronic hepatitis C, vitamin C lacked effectiveness. Additional studies are needed before a conclusion can be made.

C 

Lung disease 

An oxidant-antioxidant balance may play a role in maintaining proper lung function. Limited studies have examined the role of vitamin C alone for lung diseases. Additional research is needed before a conclusion can be made.

C 

Metabolic abnormalities 

Limited research suggests that daily high-dose vitamin C may aid with alkaptonuria, a metabolic disorder where the urine turns black upon touching air. Also, vitamin C may improve tyrosinemia in infants, a genetic disorder of tyrosine metabolism that results in problem with the liver, kidney, and brain. Well-designed trials are needed in this area before a conclusion can be made.

C 

Nitrate tolerance 

Vitamin C may prevent nitrate tolerance in people using nitroglycerin under the tongue. Well-designed research is needed in this area before a conclusion can be made.

C 

Nutritional support (infants) 

Limited research showed a lack of benefits and harmful effects of vitamin C given for the first 28 days of life in premature infants. Additional studies are needed before a conclusion can be made.

C 

Parkinson's disease 

Research showed that intake of vitamin E, vitamin C, and carotenoids may lack benefit for Parkinson's disease. The effects of vitamin C alone are unclear. More studies are needed.

C 

Physical work capacity 

Limited research suggests that higher intake of vitamin C may be related to improved physical performance and muscle strength in the elderly. Well-designed trials are needed before a conclusion can be made.

C 

Plaque (on teeth) 

In early research, less plaque on the teeth and less bleeding of the gums were observed after the use of vitamin C chewing gum. Further research is needed to confirm these results.

C 

Pneumonia (prevention) 

The role of vitamin C is unclear in the prevention of pneumonia. Further research is needed to draw conclusions.

C 

Pregnancy 

It is unclear if vitamin C is beneficial when taken during pregnancy. It has been suggested that preterm birth may increase with vitamin C supplementation. However, early research also shows that vitamin C may lessen the chance of early water breaking. Further research is needed. A healthcare practitioner should be consulted before taking any herbs or supplements during pregnancy.

C 

Pressure ulcers 

Early research shows conflicting results when taking vitamin C for pressure ulcers. Further research is needed.

C 

Prostate cancer 

Vitamin C has been used in prostate cancer treatment. Early evidence shows that vitamin C lacks an effect on decreasing prostate cancer risk. Further research is needed for conclusions to be drawn.

C 

Proteinuria (albuminuria) 

Vitamin C with vitamin E may reduce albumin in the urine in people with type 2 diabetes. Further research is needed in this area.

C 

Skin aging (wrinkles) 

Creams with 3-10% vitamin C may improve the appearance of wrinkled skin. Further research is needed before a conclusion can be made.

C 

Skin conditions  

A water-based formulation of vitamin C used on the skin may decrease skin irritation after laser treatments for scar and wrinkle removal. Well-designed studies are needed for a conclusion to be drawn.

C 

Skin damage caused by the sun  

Limited research showed that vitamin C applied to the skin may decrease damage caused by the sun. Further research is needed to confirm this finding.

C 

Skin pigmentation disorders  

Limited evidence suggests that vitamin C may play a role in perifollicular pigmentation, or increased color near the hair follicle. Additional studies are needed before a conclusion can be made.

C 

Stroke prevention 

Evidence is mixed for the use of vitamin C for decreasing the risk of stroke. More research is needed in this area.

C 

Tetanus 

Tetanus is a severe infection that may be prevented by vaccination. Vitamin C may prevent death from tetanus infection. However, more high-quality studies are needed.

C 

Type 2 diabetes 

The effects of vitamin C in people with diabetes are mixed. Additional studies are needed.

C 

Vaginitis (inflammation of the vagina) 

Early research shows that vitamin C used in the vagina may help with vaginitis, or infection and inflammation of the vagina. Further research is needed to confirm this finding.

C 

Cataracts (eye disease) 

Research for using vitamin C for cataracts, a disease where the vision becomes cloudy, produced mixed results. Further research is needed to draw conclusions.

D 

Common cold prevention (general) 

Extensive research has shown that vitamin C taken by mouth lacked an effect on cold prevention.

D 

Heart disease prevention 

Foods containing vitamin C have been linked to a lower risk of heart disease. However, research has shown that taking vitamin C supplements lacks an effect on heart disease prevention. Further research is needed.

D 

 

*Key to grades: 

A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use (it may not work);
F: Strong scientific evidence against this use (it likely does not work).

For full grading rationale, click here.

Uses based on tradition or theory 

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified health care professional

ADHD, allergic rhinitis, anti-inflammatory, back pain, bedsores, bladder inflammation, blood clots, blood disorders, blood vessel disorders, bloody urine, boils, bone loss, bronchitis, bursitis (joint inflammation), cervical dysplasia (abnormal pap smear), chronic fatigue syndrome (extreme tiredness that continues), clogged arteries, connective tissue disorders, constipation, dental conditions, depression, detoxification (removing toxins), drug withdrawal, endurance, excessive menstrual bleeding, fatigue, flu, fractures, glaucoma (increased eye pressure), gout, gum disease, idiopathic thrombocytopenic purpura (blood clotting disorder), immune disorders, infectious diarrhea, inflammatory skin conditions, jellyfish stings, Lyme disease, melasma (dark skin patches), mental performance, muscle soreness, prostate inflammation, sickle cell disease (abnormal blood cells), stomach ulcer, stress, toxicity, tuberculosis, urine acidification, viral infections, wound healing.


Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.

Allergies

  • Avoid if sensitive or allergic to any ingredients present in Vitamin C products.

Side Effects and Warnings

  • Vitamin C is generally regarded as safe in amounts normally obtained from foods. Vitamin C supplements are also generally regarded as safe in most individuals in recommended amounts.
  • Vitamin C may cause abdominal cramps or pain, chest pain, dental erosion, dizziness, diarrhea, faintness, fatigue, flushing, gut blockage, headache, heartburn, increased risk of lung cancer, increased risk of Parkinson's disease, inflamed esophagus, injection site discomfort, nausea, red blood cell complications, skin tingling or irritation, slowing of endurance training, thickening of blood vessels close to the heart, urinary complications, and vomiting.
  • High doses of vitamin C have been associated with multiple adverse effects. These include blood clotting, death (heart-related), kidney stones, pro-oxidant effects, problems with the digestive system, and red blood cell destruction. In cases of toxicity due to massive ingestions of vitamin C, forced fluids, and diuresis may be beneficial.
  • Use cautiously in chronic, large doses. Healthy adults who take chronic large doses of vitamin C may experience low blood levels of vitamin C when they stop taking the high doses and resume normal intake.
  • Vitamin C in high doses appears to interfere with the blood-thinning effects of anticoagulants such as warfarin. Caution is advised in people with bleeding disorders or those taking drugs that affect bleeding. Dosing adjustments may be necessary.
  • Vitamin C may affect blood sugar levels. Caution is advised in people with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
  • Vitamin C may increase blood pressure. Caution is advised in people with high blood pressure.
  • Use cautiously in people with cancer (e.g. lung), cataracts, glucose-6-phosphate dehydrogenase deficiency, anemia and related conditions, disorders of the gut, kidney stones, or sickle cell disease.
  • Use cautiously in people after angioplasty and in pregnant women at risk of high blood pressure during pregnancy.
  • Use cautiously in greater than recommended doses in breastfeeding women.
  • Use cautiously in people taking antibiotics, anticancer agents, HIV medications, barbiturates, estrogens, fluphenazine, or iron supplements.
  • Use injected vitamin C cautiously, especially in high doses, as it may lead to kidney function problems.
  • Use vitamin C tablets cautiously, as dental erosion may occur from chewing vitamin C tablets often.
  • Avoid in people with known allergy or sensitivity to any ingredients in Vitamin C products.
  • Avoid high doses of vitamin C in people with conditions aggravated by increased acid, such as advanced liver disease, gout, a disease where kidneys fail to remove extra acid from the body, or a disease with early breakdown of red blood cells.
  • Avoid high doses of vitamin C in people with kidney failure or in those taking agents that may damage the kidneys.

Pregnancy and Breastfeeding

  • Vitamin C intake from food is generally considered safe during pregnancy and breastfeeding.
  • Use cautiously in greater than recommended doses in pregnant and breastfeeding women.
  • Use vitamin C cautiously in those at risk of high blood pressure during pregnancy.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy.

Interactions with Drugs

  • Vitamin C in high doses may interfere with the blood-thinning effects of aspirin, anticoagulants such as warfarin(Coumadin®) or heparin, and anti-platelet drugs such as clopidogrel (Plavix®).
  • Vitamin C may affect blood sugar levels. Caution is advised when using medications that may also affect blood sugar. People taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
  • Vitamin C may affect blood pressure. Caution is advised in people taking agents that affect blood pressure.
  • Vitamin C may also interact with acetaminophen, acidifying agents, agents for Parkinson's disease, agents that affect the immune system, agents that increase urine flow, agents used for asthma, agents used for the heart, lungs, stomach or intestines, agents used for the teeth, eyes or the skin, agents used to regulate heart rate, aldose reductase inhibitors, antacids, antibiotics, anticancer drugs, aspirin, barbiturates, birth control taken by mouth, cholesterol-lowering agents, estrogens, fluphenazine, HIV medications, indinavir, kidney agents, levodopa, nicardipine, nicotine-containing products (such as cigarettes, cigars, chewing tobacco, or nicotine patches), progesterones, proton pump inhibitors (PPIs), and salicylates.

Interactions with Herbs and Dietary Supplements

  • Vitamin C in high doses may interfere with the blood-thinning effects of anticoagulant and anti-platelet herbs and supplements.
  • Vitamin C may affect blood sugar levels. Caution is advised when using herbs or supplements that may also affect blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
  • Vitamin C may affect blood pressure. Caution is advised in people taking herbs or supplements that affect blood pressure.
  • Vitamin C may also interact with acerola, acidifying herbs and supplements, aldose reductase inhibitors, antacids, antibacterials, anticancer herbs and supplements, antioxidants, antiretrovirals, Cherokee rosehip, cholesterol-lowering herbs and supplements, chromium, copper, grape seed extract, grapefruit, herbs and supplements for Parkinson's disease, herbs and supplements that affect the immune system, herbs and supplements that increase urine flow, herbs and supplements used for asthma, herbs and supplements used for birth control, herbs and supplements used for the heart, lungs, stomach or intestines, herbs and supplements used for the teeth, eyes or the skin, herbs and supplements used to regulate heart rate, hormonal herbs and supplements, iron, kidney herbs and supplements, lutein, niacin, phytoestrogens, phytoprogesterones, salicylates, tobacco, urine acidifying herbs and supplements, and vitamins B12 and E.

Authors

Selected References

Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

  1. Bjelakovic G, Nikolova D, Gluud LL, et al. Antioxidant supplements for prevention of mortality in healthy participants and people with various diseases. Cochrane.Database.Syst.Rev. 2012;3:CD007176.
  2. Coombes JS and Fassett RG. Antioxidant therapy in hemodialysis people: a systematic review. Kidney Int 2012;81(3):233-246.
  3. Cortes-Jofre M, Rueda JR, Corsini-Munoz G, et al. Drugs for preventing lung cancer in healthy people. Cochrane.Database.Syst.Rev. 2012;10:CD002141.
  4. Dror DK and Allen LH. Interventions with vitamins B6, B12 and C in pregnancy. Paediatr.Perinat.Epidemiol. 2012;26 Suppl 1:55-74.
  5. Evans JR and Lawrenson JG. Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration. Cochrane.Database.Syst.Rev. 2012;11:CD000254.
  6. Harrison FE. A critical review of vitamin C for the prevention of age-related cognitive decline and Alzheimer's disease. J Alzheimers.Dis. 2012;29(4):711-726.
  7. Hemila H and Chalker E. Vitamin C for preventing and treating the common cold. Cochrane.Database.Syst.Rev. 2013;1:CD000980.
  8. Hovdenak N and Haram K. Influence of mineral and vitamin supplements on pregnancy outcome. Eur.J Obstet.Gynecol.Reprod.Biol. 2012;164(2):127-132. >
  9. Juraschek SP, Guallar E, Appel LJ, et al. Effects of vitamin C supplementation on blood pressure: a meta-analysis of randomized controlled trials. Am J Clin.Nutr 2012;95(5):1079-1088.
  10. Konrad G and Katz A. Are medication restrictions before FOBT necessary?: practical advice based on a systematic review of the literature. Can.Fam.Physician 2012;58(9):939-948.
  11. Levis S and Theodore G. Summary of AHRQ's comparative effectiveness review of treatment to prevent fractures in men and women with low bone density or osteoporosis: update of the 2007 report. J Manag.Care Pharm 2012;18(4 Suppl B):S1-15.
  12. Li H, Zou Y, and Ding G. Dietary factors associated with dental erosion: a meta-analysis. PLoS.One. 2012;7(8):e42626.
  13. Morris MC, Beckett LA, Scherr PA, et al. Vitamin E and vitamin C supplement use and risk of incident Alzheimer disease. Alzheimer Dis.Assoc.Disord. 1998;12(3):121-126.
  14. Perez L, Heim L, Sherzai A, et al. Nutrition and vascular dementia. J Nutr Health Aging 2012;16(4):319-324.
  15. Vodopivec-Jamsek V, de Jongh T, Gurol-Urganci I, et al. Mobile phone messaging for preventive health care. Cochrane.Database.Syst.Rev. 2012;12:CD007457.
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