Vitamin C is a vitamin. Some animals can make their own vitamin C, but people must get this vitamin from food and other sources. Good sources of vitamin C are fresh fruits and vegetables, especially citrus fruits. Vitamin C can also be made in a laboratory.
Most experts recommend getting vitamin C from a diet high in fruits and vegetables rather than taking supplements. Fresh-squeezed orange juice or fresh-frozen concentrate is a better pick than ready-to-drink orange juice. The fresh juice contains more active vitamin C. Drink fresh-frozen orange juice within one week after reconstituting it for the most benefit. It you prefer ready-to-drink orange juice, buy it 3 to 4 weeks before the expiration date, and drink it within one week of opening.
Historically, vitamin C was used for preventing and treating scurvy. Scurvy is now relatively rare, but it was once common among sailors, pirates, and others who spent long periods of time onboard ships. When the voyages lasted longer than the supply of fruits and vegetables, the sailors began to suffer from vitamin C deficiency, which led to scurvy.
These days, vitamin C is used most often for preventing and treating the common cold. Some people use it for other infections including gum disease, acne and other skin infections, bronchitis, human immunodeficiency virus (HIV) disease, stomach ulcers caused by bacteria called Helicobacter pylori, tuberculosis, dysentery (an infection of the lower intestine), and skin infections that produce boils (furunculosis). It is also used for infections of the bladder and prostate.
Some people use vitamin C for depression, thinking problems, dementia, Alzheimer’s disease, physical and mental stress, fatigue, and attention deficit-hyperactivity disorder (ADHD).
Other uses include increasing the absorption of iron from foods and correcting a protein imbalance in certain newborns (tyrosinemia).
There is some thought that vitamin C might help the heart and blood vessels. It is used for hardening of the arteries, preventing clots in veins and arteries, heart attack, stroke, high blood pressure, and high cholesterol.
Vitamin C is also used for glaucoma, preventing cataracts, preventing gallbladderdisease, dental cavities (caries), constipation, Lyme disease, boosting the immune system, heat stroke, hay fever, asthma, bronchitis, cystic fibrosis, infertility, diabetes, chronic fatigue syndrome (CFS), autism, collagen disorders, arthritis and bursitis, back pain and disc swelling, cancer, and osteoporosis.
Additional uses include improving physical endurance and slowing aging, as well as counteracting the side effects of cortisone and related drugs, and aiding drug withdrawal in addiction.
Sometimes, people put vitamin C on their skin to protect it against the sun, pollutants, and other environmental hazards. Vitamin C is also applied to the skin to help with damage from radiation therapy.
How does it work?
Vitamin C is required for the proper development and function of many parts of the body. It also plays an important role in maintaining proper immune function.
- Vitamin C deficiency. Taking vitamin C by mouth or injecting as a shot prevents and treats vitamin C deficiency, including scurvy. Also, taking vitamin C can reverse problems associated with scurvy.
Likely Effective for
- Iron absorption. Administering vitamin C along with iron can increase how much iron the body absorbs in adults and children.
- A genetic disorder in newborns called tyrosinemia. Taking vitamin C by mouth or as a shot improves a genetic disorder in newborns in which blood levels of the amino acid tyrosine are too high.
Possibly Effective for
- Age-related vision loss (age-related macular degeneration; AMD). Taking vitamin C in combination with zinc, vitamin E, and beta-carotene daily seems to help prevent vision loss or slow the worsening of AMD in patients with advanced AMD. There is not enough evidence to know if this combination helps people with less advanced macular disease or if it prevents AMD. Using vitamin C with other antioxidants, but without zinc, does not seem to have any effect on AMD.
- Decreasing protein in the urine (albuminuria). Taking vitamin C plus vitamin E can reduce protein in the urine in people with diabetes.
- Hardening of the arteries (atherosclerosis). Taking vitamin C by mouth seems to decrease the risk of artery hardening. Vitamin C also appears to slow the rate at which artery hardening worsens. More research is needed to understand the effects of vitamin C intake from the diet or supplements on this condition once it has developed.
- Cancer. Consuming vitamin C in the diet might decrease the risk of developing mouth cancers and other cancers. Some research suggests that increasing vitamin C intake through fruits and vegetables reduces the risk of cancer. However, taking vitamin C supplements does not appear to reduce cancer risk.
- Common cold. There is some controversy about the effectiveness of vitamin C for treating the common cold. However, the majority of evidence shows that taking high doses of vitamin C might shorten the course of the cold by 1 to 1.5 days in some patients. Taking vitamin C is not effective for preventing the common cold.
- Chronic pain condition (complex regional pain syndrome). Taking vitamin C after a wrist fracture seems to decrease the risk of developing a chronic pain condition called complex regional pain syndrome.
- Kidney problems related to contrast media used during a diagnostic test called angiography. Taking vitamin C before and after an angiography seems to reduce the risk of developing kidney problems.
- Redness (erythema) after cosmetic skin procedures. There is some evidence that using a particular vitamin C skin cream can decrease the amount and duration of skin redness following laser resurfacing for scar and wrinkle removal.
- Lung infections caused by heavy exercise. Using vitamin C before heavy physical exercise, such as a marathon, might prevent upper respiratory infections that sometimes follow heavy exercise.
- Gallbladder disease. There is some evidence that taking vitamin C might help to prevent gallbladder disease in women. However, vitamin C does not seem to have this effect in men.
- Ulcers in the stomach caused by bacteria called H. pylori. Taking vitamin C seems to decrease some of the side effects caused by treatment for H. pylori infections. After H. pylori bacteria are killed, vitamin C appears to decrease the development of precancerous lesions in the stomach. However, other research suggests that vitamin C does not improve healing from H. pylori infection.
- Abnormal breakdown of red blood cells (hemolytic anemia). Treatment with vitamin C can improve hemolytic anemia.
- High blood pressure. Taking vitamin C along with conventional blood pressure-lowering medications appears to decrease systolic blood pressure (the top number in a blood pressure reading) by a small amount, but does not seem to decrease diastolic pressure (the bottom number). Taking vitamin C supplements alone does not seem to affect blood pressure.
- Lead poisoning. Consuming vitamin C in the diet seems to lower blood levels of lead.
- Helping medicines used for chest pain work longer. Taking vitamin C by mouth seems to help medicines used for chest pain, such as nitroglycerine, work longer.
- Osteoarthritis. Taking vitamin C from dietary sources or from calcium ascorbate supplements seems to prevent cartilage loss and worsening of symptoms in people with osteoarthritis.
- Physical performance. Eating more vitamin C as part of the diet might improve physical performance and muscle strength in older people. Also, taking vitamin C supplements might improve oxygen intake during exercise in teenage boys.
- Sunburn. Taking vitamin C by mouth along with vitamin E seems to prevent sunburn. However, taking vitamin C alone does not prevent sunburn.
- Wrinkled skin. Skin creams containing vitamin C or vitamin C in combination with acetyl tyrosine, zinc sulfate, sodium hyaluronate, and bioflavonoids (Cellex-C High Potency Serum) seem to improve wrinkles in facial skin that is aged by sun exposure.
Possibly Ineffective for
- Bronchitis. Taking vitamin C by mouth does not seem to have any effect on bronchitis.
- Alzheimer’s disease and dementia. Vitamin C, consumed as part of the diet, as a supplement, or together with vitamin E, does not seem to reduce the risk of developing Alzheimer’s disease or dementia. However, some research suggests that high, long-term use of vitamin C and E supplements is associated with a reduced risk of Alzheimer’s disease.
- Eye disease associated with a medicine called interferon. Taking vitamin C daily by mouth does not seem to reduce the risk of eye disease associated with interferon therapy in people with liver disease.
- Lung cancer. Research suggests that taking vitamin C, alone or together with vitamin C, does not reduce the risk of lung cancer or death due to lung cancer.
- Death from any cause. Some research suggests that high vitamin C blood levels are associated with a lower risk of death from any cause. However, other research shows that taking vitamin C daily together with vitamin E, beta-carotene, selenium, and zinc does not lower the risk of death. Overall, most research suggests that vitamin C supplements do not reduce the risk of death.
- Pancreatic cancer. Research shows that taking vitamin C together with beta-carotene plus vitamin E does not reduce the risk of pancreatic cancer.
- High blood pressure during pregnancy (pre-eclampsia). Some research suggests that taking vitamin C by mouth along with vitamin E seems to prevent high blood pressure during high-risk pregnancies. However, most research shows that taking vitamin C with vitamin E does not reduce the risk of high blood pressure during pregnancy.
- Complications during pregnancy. Research suggests that taking vitamin C, alone or with vitamin E, does not reduce the risk of complications during pregnancy.
- Prostate cancer. Research shows that taking a combination of vitamin C, vitamin E, beta-carotene, selenium, and zinc does not reduce the risk of prostate cancer. Overall, most evidence suggests that taking vitamin C supplements does not reduce the risk of developing prostate cancer.
- Skin problems related to radiation cancer treatments. Applying a vitamin C solution to the skin does not prevent skin problems caused by radiation treatments.
- Stroke. Most research suggests that taking vitamin C by mouth does not lower the risk for stroke.
Insufficient Evidence for
- Hay fever (Allergic rhinitis). There is conflicting evidence about the effects of vitamin C for improving symptoms of hay fever. Taking vitamin C does not seem to prevent hay fever.
- Damage to heart caused by the cancer drug anthracycline. Research suggests that taking vitamin C, along with vitamin E and other ingredients, does not reduce the risk of heart damage caused by the cancer drug anthracycline.
- Stomach damage caused by aspirin. Some research suggests that taking vitamin C might prevent stomach damage caused by aspirin.
- Asthma. There is some evidence that people with asthma might have low vitamin C levels. However, research suggests that taking vitamin C does not reduce the risk of developing asthma or improve asthma symptoms.
- Attention deficit-hyperactivity disorder (ADHD). Some evidence suggests that taking high doses of vitamin C does not reduce ADHD symptoms. Other research suggests that taking lower doses of vitamin C might improve some symptoms such as restlessness and self-control in children with ADHD.
- Autism. Early evidence suggests that taking vitamin C reduces the severity of autism symptoms in children.
- Bladder cancer. Taking vitamin C does not seem to affect survival from bladder cancer.
- Breast cancer. Research on the effects of vitamin C for treating breast cancer conflicts. Some research suggests that high vitamin C intake in the diet reduces breast cancer risk, while other research suggests it has no effect. There is no evidence that taking vitamin C supplements reduces the risk of developing breast cancer.
- Burns. Early evidence suggests that using a vitamin C infusion within the first 24 hours of severe burns reduces wound swelling.
- Heart disease. Research on the use of vitamin C for heart disease is unclear. More research on the use of vitamin C supplements for preventing heart disease is needed. However, increasing vitamin C intake in the diet might provide some benefit.
- Cataracts. There is conflicting information about the use of vitamin C to prevent cataracts. Vitamin C plus vitamin E and beta-carotene does not seem to have any significant effect on age-related loss of vision due to cataracts in well-nourished people who take the supplement long-term (for an average of 6.3 years). On the other hand, other research suggests that taking multivitamins that contain vitamin C for 10 years seems to prevent cataracts. Use of supplements for shorter periods does not appear to work.
- Cervical cancer. Some limited research suggests that taking vitamin C reduces the risk of cervical cancer.
- Damage to the colon due to radiation exposure (chronic radiation proctitis).Early research suggests that taking vitamin C plus vitamin E might improve some symptoms of chronic radiation proctitis.
- Colorectal cancer. Taking vitamin C together with vitamin E and beta-carotene does not seem to reduce the risk of colorectal cancer. Vitamin C intake from the diet also does not appear to be linked to colorectal cancer risk.
- Poor blood circulation in the legs (chronic venous insufficiency). Research suggests that taking a specific product (Cyclo 3 Fort) containing butchers broom extract, hesperidin methyl chalcone, and vitamin C reduces pain, cramps, and other symptoms in people with poor blood circulation in the legs.
- Dental plaque. Chewing gum containing vitamin C appears to reduce dental plaque.
- Diabetes. Some research suggests that taking vitamin C decreases blood sugar and cholesterol levels in people with diabetes. However, other research suggests that vitamin C does not improve blood sugar in people with diabetes. Vitamin C does not appear to decrease the risk of developing diabetes.
- Endometrial cancer. Research suggests that vitamin C intake from the diet slightly lowers the risk of endometrial cancer.
- Esophageal cancer. Taking vitamin C along with beta-carotene plus vitamin E does not reduce the risk of developing esophageal cancer. However, higher vitamin C intake in the diet appears to be linked to a lower risk of esophageal cancer.
- Stomach cancer. Not all research agrees on whether or not taking vitamin C supplements or getting extra vitamin C in the diet can prevent stomach cancer. Taking vitamin C supplements in combination with beta-carotene or beta-carotene plus vitamin E does not seem to reduce the risk of stomach cancer. However, some evidence suggests that taking vitamin C alone might keep precancerous sores in the stomach from progressing to cancer in people at high risk for stomach cancer.
- Gout. Research shows that increased vitamin C intake from the diet is linked to a lower risk of gout in men.
- HIV/AIDS. Taking vitamin C daily together with vitamin A, beta-carotene, vitamin E, selenium, and coenzyme Q-10 seems to have some benefits for people with HIV/AIDS. However, neither high nor low doses of vitamin C affect how much of the virus is active in the body.
- HIV transmission. Taking vitamin C along with vitamin B and vitamin E during pregnancy and breast-feeding seems to reduce the risk of transmitting HIV to the infant.
- High cholesterol. Taking vitamin C daily does not seem to lower cholesterol in people with normal cholesterol levels. However, research suggests that taking vitamin C reduces low-density lipoprotein (LDL or “bad”) cholesterol in people with high cholesterol.
- Infertility. There is early evidence that women with certain fertility problems might benefit from taking vitamin C daily.
- Leukemia. There is some evidence that vitamin C might enhance the effects of the drug arsenic trioxide (Trisenox) in people with leukemia.
- Mental stress. Limited evidence suggests that vitamin C might reduce blood pressure and symptoms during times of mental distress.
- Liver disease (nonalcoholic steatohepatitis). Early research suggests that taking vitamin C together with vitamin E might improve some aspects of liver function in people with a certain liver disease called nonalcoholic steatohepatitis. However, it does not seem to decrease liver swelling in people with this condition.
- Osteoporosis. Some evidence suggests that vitamin C might improve bone strength. However, higher vitamin C blood levels in postmenopausal women have been linked to lower bone mineral densities. More information is needed on the effects of vitamin C on bone mineral density.
- Ovarian cancer. Consuming vitamin C in the diet does not seem to affect the risk of developing ovarian cancer.
- Parkinson’s disease. Research suggests that increased vitamin C intake in the diet does not reduce the risk of Parkinson’s disease.
- Pneumonia. Some research suggests that vitamin C might reduce the risk of pneumonia, as well as the duration of pneumonia once it develops.
- Bed sores (pressure ulcers). Some evidence suggests that taking vitamin C does not improve wound healing in people with pressure ulcers. However, other research suggests that taking vitamin C reduces the size of pressure ulcers.
- Sickle cell disease. Taking vitamin C with aged garlic extract and vitamin E might benefit people with sickle cell disease.
- Bacterial infection in the nervous system (tetanus). Some evidence suggests that taking vitamin C daily along with conventional treatment reduces the risk of death in children with tetanus.
- Urinary tract infections (UTI). Research suggests that taking vitamin C does not prevent UTIs in older people.
- Kidney disease.
- Cystic fibrosis.
- Lyme disease.
- Chronic fatigue syndrome (CFS).
- Dental cavities.
- Other conditions.
More evidence is needed to rate vitamin C for these uses.