Natural Standard® Patient Monograph, Copyright © 2014 (www.naturalstandard.com). All Rights Reserved. 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 healthcare provider before making decisions about therapies and/or health conditions.

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.

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).

Dosing
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (over 18 years old)
The recommended daily intake by the U.S. Food and Nutrition Board of the Institute of Medicine for men more than 18 years old is 90 milligrams of vitamin C daily; for women more than 18 years old, it is 75 milligrams daily; for pregnant women more than 18 years old, it is 85 milligrams daily; and for breastfeeding women more than 18 years old, it is 120 milligrams daily. Recently, some experts have questioned whether the recommended daily intake should be raised. Others have recommended an additional 35 milligrams daily intake in some individuals, such as smokers.

The upper limit of intake (UL) should avoid exceeding 2,000 milligrams daily in men or women more than 18 years old (including pregnant or breastfeeding women).
Vitamin C administered by mouth or injection is effective for curing scurvy. 100-250 milligrams of vitamin C was given by mouth four times daily for one week. Some experts have recommended 1-2 grams daily for two days, followed by 500 milligrams daily for one week. Symptoms should begin to improve within 24-48 hours, and be completely cured within seven days. Treatment should be under strict medical supervision. For asymptomatic vitamin C deficiency, lower daily doses may be used.

For antioxidant effects, 200-1,000 milligrams of vitamin C has been given daily for four weeks to a year; 300-3,000 milligrams of vitamin C has been injected into the vein, from a single dose to a duration of eight weeks.

For breast cancer prevention, 500 milligrams of vitamin C has been taken by mouth daily.
For cancer prevention, 120-2,000 milligrams of vitamin C has been taken by mouth daily for six to eight years.

For preventing the common cold in people in extreme environments, 200 milligrams or more of vitamin C has been taken by mouth daily for up to 14 days.
For preventing the common cold in general, 30-3,000 milligrams of vitamin C has been taken by mouth daily for two weeks to eight winters.
For treating the common cold, 200 milligrams to 3 grams have been taken by mouth daily for three to five days or longer.

For preventing complex regional pain syndrome in people with wrist fractures, 500 milligrams of vitamin C has been taken by mouth daily for 50 days.
For fertility, 750 milligrams of vitamin C has been taken by mouth daily for six months.
For heart conditions, 2 grams of vitamin C has been given by mouth before surgery, followed by 1 gram daily for five days.

For H. pylori infection, 400-1,000 milligrams of vitamin C has been given by mouth daily for up to seven weeks.
For high blood pressure, 60-4,000 milligrams of vitamin C has been given by mouth daily for 6-16 weeks.

For kidney disease, 3 grams of vitamin C was given by mouth before the kidney-toxic procedure, then 2 grams after the procedure in the evening and again the following morning; 100-200 milligrams of vitamin C has been taken by mouth daily.
For liver disease, 120-3,000 of milligrams vitamin C has been taken by mouth daily for one day to six months; effectiveness on liver disease was lacking.

For life extension, 60-2,000 milligrams of vitamin C has been taken by mouth daily for one month to 9.5 years.
For preventing nitrate tolerance, 3-6 grams of vitamin C has been taken by mouth daily.
For pregnancy, 100-1,000 milligrams of vitamin C has been taken by mouth up to four times daily during pregnancy until delivery.
For prostate cancer, 500 milligrams of vitamin C has been taken by mouth daily for an average of eight years.

For anemia, 200-300 milligrams of vitamin C has been injected into the vein three times weekly, for 3-6 months.
For preventing gout, 500-1,500 milligrams of vitamin C from food and/or supplements has been taken daily.
For skin aging, preparations containing 5-10% vitamin C were applied on the skin daily.
Children (under 18 years old)

The recommended daily intake by the U.S. Food and Nutrition Board of the Institute of Medicine for infants 0-12 months old is the amount of vitamin C in human milk; for children 1-3 years old, it is 15 milligrams; for children 4-8 years old, it is 25 milligrams; for children 9-13 years old, it is 45 milligrams; and for adolescents 14-18 years old, it is 75 milligrams for boys and 65 milligrams for girls. The tolerable upper intake levels (UL) for vitamin C are 400 milligrams daily for children 1-3 years old; 650 milligrams daily for children 4-8 years old; 1,200 milligrams daily for children 9-13 years old; and 1,800 milligrams daily for adolescents and pregnant and lactating females 14-18 years old.

For metabolic abnormalities, 100 milligrams of vitamin C has been taken by mouth.
For scurvy or vitamin C deficiency in children, 100-300 milligrams of vitamin C has been taken by mouth daily in divided doses for two weeks. Older or larger children may require doses closer to adult recommendations. If vitamin C is unavailable, orange juice may be used. Symptoms should begin to improve within 24-48 hours, with resolution within seven days. Treatment should be under strict medical supervision.

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 provider before starting a new therapy. Consult a healthcare provider 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

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.

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