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 gallbladder disease, 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.