Vitamin C (Ascorbic acid)

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. 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 conditions, 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 or inflammation of the bladder and prostate, nerve pain, pregnancy-related complications.

Some people use vitamin C for depression, thinking problems, dementia, Alzheimer's disease, physical and mental stress, fatigue including chronic fatigue syndrome (CFS), autism, attention deficit-hyperactivity disorder (ADHD), schizophrenia, Lou Gehrig's disease, and Parkinson's disease. It is also used to treat or prevent toxicity caused by certain drugs or metals and to treat peptic ulcers, swine flu, sudden hearing loss, gout, and tetanus.

Other uses include increasing the absorption of iron from foods. Vitamin C is also used in combination with a drug called deferoxamine to increase removal of iron from the blood. Some people use iron to correct a protein imbalance in certain newborns (tyrosinemia). It is also used to prevent the transfer of HIV from mothers to babies during breastfeeding. Vitamin C is also used to help reduce the side effects of bowel preparation.

There is some thought that vitamin C might help the heart and blood vessels. It is used for heart disease, hardening of the arteries, preventing clots in veins and arteries, heart attack, stroke, high blood pressure, high cholesterol, irregular heartbeat after surgery, nitrite tolerance, or inadequate blood flow that causes blood to pool in the legs. It is also thought that vitamin C may increase the healing of burns, ulcers, fractures, and other wounds. Vitamin C is also used to prevent long-term pain after surgery or injury.

Vitamin C is also used for glaucoma, preventing cataracts, preventing gallbladder disease, dental cavities and plaque, constipation, Lyme disease, age-related vision loss, boosting the immune system, heat stroke, hay fever and other allergy-related conditions, asthma and exercise-induced asthma, bronchitis, cystic fibrosis, sickle cell disease, infertility, diabetes, collagen disorders, arthritis and other types of joint inflammation, back pain and disc swelling, cancer, and osteoporosis and other bone conditions.

Additional uses include improving physical endurance and slowing aging, as well as counteracting the side effects of cortisone and related drugs, aiding drug withdrawal in addiction, and reducing side effects of radiation therapy.

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.

Vitamin C is inhaled through the nose to treat hayfever.

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.
Iron absorption.
A genetic disorder in newborns called tyrosinemia.
Age-related vision loss (age-related macular degeneration; AMD).
Decreasing protein in the urine (albuminuria).
Irregular heartbeat (atrial fibrillation).
For emptying the colon before a colonoscopy.
Common cold.
Redness (erythema) after cosmetic skin procedures.
Upper airway infections caused by heavy exercise.
Gout.
Worsening of stomach inflammation caused by medicine used to treat H. pylori infection.
Abnormal breakdown of red blood cells (hemolytic anemia).
High blood pressure.
Lead poisoning.
Helping medicines used for chest pain work longer.
Osteoarthritis.
Physical performance.
Sunburn.
Wrinkled skin.
Asthma caused by exercise.
High phosphate levels.
Infertility.
Pneumonia

By Mouth:

General: The daily recommended dietary allowances (RDAs) are: 90 mg for men and 75 mg for women; Pregnancy and Lactation: age 18 or younger, 115 mg; ages 19 to 50 years 120 mg. People who use tobacco should take an additional 35 mg per day. Do not take more than the following amounts of vitamin C: 1800 mg per day for adolescents and pregnant and breast-feeding women 14 to 18 years, and 2000 mg per day for adults and pregnant and lactating women.

For vitamin C deficiency: 100-250 mg once or twice daily for several days for scurvy.

For empting the colon before a colonoscopy: 2 liters of solution containing polyethylene glycol and vitamin C is used the evening prior to colonoscopy or as a split-dose taken on the evening prior to and the morning of colonoscopy. The most commonly studied product for this indication is MoviPrep (Norgine BV).

For improving iron absorption: 200 mg of vitamin C per 30 mg of iron.

For an age-related eye disease that causes blindness (age-related macular degeneration; AMD: 500 mg of vitamin C, 400 IU of vitamin E, and 15 mg of beta-carotene, with or without 80 mg of zinc, per day for up to 10 years.

For treating the common cold: 1-3 grams daily.

For slowing progression of hardening of the arteries: 250 mg of slow-release vitamin C in combination with 91 mg (136 IU) of vitamin E twice daily for up to 6 years. Also 500 mg of vitamin C plus 400 IU of vitamin E twice daily for one year has been used.

For reducing protein in the urine of patients with type 2 diabetes: 1250 mg of vitamin C with 680 IU of vitamin E per day for 4 weeks has been used.

For preventing irregular heart beat after heart surgery: 1-2 grams of vitamin C per day for 1-3 days before heart surgery followed by 1-2 grams in two divided doses daily for 4-5 days after heart surgery has been used.

For respiratory infections due to exercise: 600 mg to 1 gram of vitamin C per day for 3-8 weeks before heavy exercise has been used.

Worsening of stomach inflammation caused by medicine used to treat H. pylori infection.: 1200 mg of vitamin C daily along with omeprazole has been used.

For hemolytic anemia: 200-300 mg of vitamin C three times per week for 3-6 months has been used.

For high blood pressure: 500 mg of vitamin C per day along with blood pressure-lowering medication has been used.

For preventing nitrate tolerance: 3-6 grams of vitamin C daily has been used.

For osteoarthritis: 1 gram of vitamin C in the form of calcium ascorbate daily for 2 weeks has been used.

For preventing sunburn: 2 grams of vitamin C along with 1000 IU vitamin E taken before sun exposure has been used.

Applied to the Skin:

For skin redness/rash: A formulation containing 10% vitamin C, 2% zinc sulfate, and 0.5% tyrosine applied daily for 8 weeks has been used.

For wrinkled skin: Most topical preparations used for aged or wrinkled skin are applied daily. Studies have used creams containing 3% to 10% vitamin C. In one study a specific vitamin C formulation (Cellex-C High Potency Serum) used 3 drops applied daily to areas of facial skin. Don't apply vitamin C preparations to the eye or eyelids. Also avoid contact with hair or clothes. It can cause discoloration.

Children

By Mouth:

General: The daily recommended dietary allowances (RDAs) are: Infants 0 to 12 months, human milk content (older recommendations specified 30-35 mg); Children 1 to 3 years, 15 mg; Children 4 to 8 years, 25 mg; Children 9 to 13 years, 45 mg; Adolescents 14 to 18 years, 75 mg for boys and 65 mg for girls; Pregnancy and Lactation: age 18 or younger, 115 mg. Do not take more than the following amounts of vitamin C: 400 mg per day for children ages 1 to 3 years, 650 mg per day for children 4 to 8 years, 1200 mg per day for children 9 to 13 years, and 1800 mg per day for adolescents and pregnant and breast-feeding women 14 to 18 years.

For tyrosinemia in premature infants on high protein diets: 100 mg of vitamin C.

For improving iron absorption: 25-70 mg of vitamin C taken with iron-containing foods has been used.

For improving physical performance: 70 mg of vitamin C per day for 2 months has been used in adolescent boys.

Vitamin C is SAFE for most people when taken by mouth in recommended doses, when applied to the skin, when injected into the muscle, and when injected intravenously (by IV) and appropriately. In some people, vitamin C might cause nausea, vomiting, heartburn, stomach cramps, headache, and other side effects. The chance of getting these side effects increases the more vitamin C you take.

Amounts higher than 2000 mg daily are POSSIBLY UNSAFE and may cause a lot of side effects, including kidney stones and severe diarrhea. In people who have had a kidney stone, amounts greater than 1000 mg daily greatly increase the risk of kidney stone recurrence.

Pregnancy and breast-feeding: Vitamin C is SAFE for pregnant or breast-feeding women when taken by mouth in amounts no greater than 2000 mg daily for women over 19 years-old, and 1800 mg daily for women 14 to 18 years-old, or when given intravenously (by IV) or intramuscularly and appropriately. Taking too much vitamin C during pregnancy can cause problems for the newborn baby. Vitamin C is POSSIBLY UNSAFE when taken by mouth in excessive amounts.

Infants and children: Vitamin C is SAFE when taken by mouth appropriately. Vitamin C is POSSIBLY UNSAFE when taken by mouth in amounts higher than 400 mg daily for children 1 to 3 years, 650 mg daily for children 4 to 8 years, 1200 mg daily for children 9 to 13 years, and 1800 mg daily for adolescents 14 to 18 years.

Alcoholism: Alcohol intake can cause the body to excrete vitamin C in the urine. People who regularly use alcohol, especially those who have other illnesses, often have vitamin C deficiency. These people might need to be treated for a longer time than normal to restore vitamin C levels to normal.

Alzheimer's disease: Taking vitamin C along with vitamin E and alpha-lipoic acid might worsen mental function in people with Alzheimer's disease.

Angioplasty, a heart procedure: Avoid taking supplements containing vitamin C or other antioxidant vitamins (beta-carotene, vitamin E) immediately before and following angioplasty without the supervision of a health care professional. These vitamins seem to interfere with proper healing.

Cancer: Cancerous cells collect high concentrations of vitamin C. Until more is known, only use high doses of vitamin C under the direction of your oncologist.

Diabetes: Vitamin C might raise blood sugar. In older women with diabetes, vitamin C in amounts greater than 300 mg per day increases the risk of death from heart disease. Do not take vitamin C in doses greater than those found in basic multivitamins.

A metabolic deficiency called "glucose-6-phosphate dehydrogenase" (G6PD) deficiency: Large amounts of vitamin C can cause red blood cells to break in people with this condition. Avoid excessive amounts of vitamin C.

Blood-iron disorders, including conditions called "thalassemia" and "hemochromatosis": Vitamin C can increase iron absorption, which might make these conditions worse. Avoid large amounts of vitamin C.

Kidney stones, or a history of kidney stones: Large amounts of vitamin C can increase the chance of getting kidney stones. Do not take vitamin C in amounts greater than those found in basic multivitamins.

Heart attack: Vitamin C levels are reduced during a heart attack. However, low vitamin C has not been linked to an increased risk for heart attack.

Kidney transplant rejection: Long-term use of vitamin C in high doses before a kidney transplant may increase the risk of transplant rejection or delay how long it takes until the transplanted kidney works.

Schizophrenia: Taking vitamin C along with vitamin E might worsen psychosis in some people with schizophrenia when taken with antipsychotic drugs.

Sickle cell disease: Vitamin C might make this condition worse. Avoid using large amounts of vitamin C.

Smoking and chewing tobacco: Smoking and chewing tobacco lowers vitamin C levels. Vitamin C intake in the diet should be increased in people who smoke or chew tobacco.