Common Name: Vitamin C
Synonyms: Ascorbic acid, ascorbate

Overview:

The main function of vitamin C, a water soluble vitamin, is the growth and repair of tissues all over the body. Although most animals can make vitamin C from its raw materials, humans can not. The vitamin C our bodies need must come from the food we eat. As vitamin C is not stored in the body, to keep health, it must be eaten every day. Vitamin C helps the body manufacture collagen, a key protein in all connective tissue, cartilage and tendons of the body. It is also important in the body’s ability to heal.

Humans can not survive without vitamin C. A severe deficiency of vitamin C can affect every system in the body. A severe vitamin C efficiency or scurvy was a common ailment from ancient times until the early 19th century. This was because fresh fruits and vegetables were not readily available throughout the year. Sailors, who were often at sea for months or years at a time, were especially susceptible to scurvy. In the late 1700’s, it was discovered that citrus fruit could prevent the development of this debilitating disease. The symptoms that accompany scurvy are: wounds that refuse to heal, inflamed and bleeding gums, weakened tooth enamel, fatigue and malaise, swollen and painful joints, scaly, dry skin, anemia, muscle weakness, frequent infections, diarrhea, pulmonary and kidney problems and eventually coma and death.

Vitamin C is involved in the manufacturing and repair of all the body’s connective tissue components, elastin, fibronectin, the matrix of the bones as well as cellular procollegen secretion. Vitamin C is aids in the absorption, transport and storage of iron and is involved in the synthesis of corticosteroids, aldosterones. It is also involved in the conversion of cholesterol into bile salts. These are not the only roles of vitamin C. Vitamin C may be the most important water-soluble antioxidant in the body. Vitamin C is thought to play a role in preventing certain chronic degenerative disorders such as coronary artery disease and cancer. It also plays a role in: preventing atherosclerosis, helping to lower blood pressure, strengthening the immune system, protecting the eye from UV light damage as well as possible antiviral and anti-inflammatory roles.

Benefits

The benefits of vitamin C supplements have been a hotly debated topic for decades. There has been extensive investigation into what the role of vitamin C is in disease prevention and health maintained. What has been found out is:

• Vitamin C’s antioxidant effects have been well established. Vitamin C has been in several studies of small groups of people suggested that 2000mg of vitamin C (3 glasses of orange juice) helped to decrease total cholesterol and LDL (the bad cholesterol) cholesterol levels as well as the levels of triglycerides. At the same time vitamin C was lowering cholesterol and triglycerides, it was raising HDL (the good cholesterol).

• Many studies of vitamin C have shown that vitamin C supplementation has positive effects in maintaining cardiovascular health.

The studies in Finland were especially dramatic. The Finnish men suffer from a very high mortality rate from coronary artery disease. Finnish men also have low levels of vitamin C. These studies found that the more vitamin C deficient the test subject was the greater the risk of suffering a fatal heart attack.

Platelet clumping (often called platelet aggregation) plays a significant role in atherosclerosis. In two studies where patients received 2,000mg to 3000mg of vitamin C daily the clumping of platelets was reduced. Studies that used doses of 250mg did not show the same effect.

• Epidemiological studies (the study of the causes, distribution, and control of disease in populations) have repeatedly shown that low intake of vitamin C is closely linked with hypertension. A recent double-blind, placebo-controlled study showed that the group who received 500mg of vitamin C for 30 days showed a 13mm of Hg drop in systolic blood pressure when compared to those who received no vitamin C. Population based studies have linked high blood pressure with the damage caused by free radicals

Many other studies have shown that the oral administration or intra-arterial infusion of from 1,000 to 2000mg of vitamin C exerted a positive effect on the vasodilatation (the ability of the arteries to expand allowing increased circulation to vital areas of the body such as the heart) in patients who suffered from coronary artery disease. These positive effects were especially noted in those who smoked or suffered from type 1 and type 2 diabetes.

In a report from the First National Health and Nutrition Exam, a strong link was seen between vitamin C intake and death. A review of this study’s findings showed that as the vitamin C intake increased the mortality rate decreased. Among men with the highest vitamin C intake the lower the SMR (standardized mortality ratio) was. In men with the highest vitamin C intake this was 0.65 for all causes of death, 0.78 for cancers and .58 for cardiovascular disease. In women this inverse relationship was also seen but it was not as dramatic, 0.90 for all causes, 0.86 for cancers and 0.75 for cardiovascular disease.

• Vitamin C’s ability to inhibit the breakdown of cellular DNA appears to account for its ability to protect against various forms of cancer. Numerous epidemiological and case controlled studies show a consistent relationship between high vitamin C intake and the lower incidence of cancer, particularly colo-rectal, stomach, lung, breast, esophageal, oral, and larynx-pharynx cancers.

In a review of 75 of these studies, 54 found that high vitamin C intake correlated with a reduced risk of developing cancer. In vitro (in the test tube) and animal studies, it has been shown that vitamin C reduces the toxicity of standard cancer therapies while at the same time increasing their effectiveness. Other researchers have shown that not only does vitamin C protect normal cells from the toxic effects of cancer therapies but it helps in the destruction of the cancer cells as well.

Many population studies have shown a strong connection between vitamin C intake and the development of cancer. A 29% reduction in the development of all types of cancer was seen in men taking 113mg of vitamin C daily. This was compared with those who were taking less. Another study found that in men who were taking over 300mg of vitamin C there was an associated 21% reduction in the risk of developing cancer when compared to those taking less than 49mg.

• Studies have indicated that vitamin C enhances the ability of the immune system to fight of infections and maintain individual health. In vitro and animal studies have shown that vitamin C can change the numbers of lymphocytes and phagocytes (white blood cells that fight of infections) as well as control the number of natural killer cells and antibodies. Placebo-controlled studies have consistently shown that supplements of vitamin C in doses greater than 1000mg or more daily help to combat not only the symptoms of the common cold but

shortened the duration as well. The best results were seen in studies were the vitamin C supplementation was 200mg or greater. Studies have also shown that vitamin C is beneficial in other respiratory disease such as pneumonia and bronchitis. In three controlled studies the incident of these respiratory infections were greatly reduced when vitamin C was used as a supplement.

• In case-controlled studies, high vitamin C intake was strongly linked to a reduction of cataract development. A 70% reduction in the risk of developing cataracts was seen when vitamin C was taken at a dose of 300mg or more per day. Another study showed a 75% reduction when 490mg or more was taken on a daily basis. It is believed that Vitamin C slows the clumping of proteins in the lens that causes the gradual clouding of the lens seen in cataract development. This has been demonstrated in animal and human lens. One study of women who took vitamin C for 10 years showed a major reduction in the development of cataracts as compared to those who did not supplement with vitamin C.

• The level of vitamin C has been found to be inversely proportion to the incidence of gallbladder disease in women.

• There is growing evidence that vitamin C that vitamin C can inhibit the growth of the bacteria Helicobacter pylori in both in vitro and animal studies. Helicobacter pylori are the bacteria that are responsible for the development of stomach ulcers. Stomach ulcers can turn into cancer of the stomach. In vitro studies showed that high concentrations of vitamin C inhibited the growth of Helicobacter pylori by 90%. This inhibition in the growth of these bacteria was confirmed in animal studies using high oral doses of vitamin C.

• Vitamin C supplementation has also been shown to reduce the risk of RSD. RSD is a set of symptoms that occasionally develops in the legs or arms after fractures and other injuries. It involves persistent pain, changes in skin temperature, redness, swelling, and difficulty in movement. Its cause is unknown, and it has proven difficult, if not impossible, to treat. RSD causes significant suffering and disability. In this double blind, placebo-controlled study patients who suffered wrist fractures were given 500mg of vitamin C daily for 50 days. These patients were followed for a year. The incidence of RSD was greatly reduced in those who received the vitamin C supplements.

• Vitamin C has been found to protect endothelial cells and reduce the capillary permeability seen in burn patients. This capillary permeability results in a tremendous loss of fluids seen in burn patients. This same cell protective mechanism of vitamin C is also seen in its ability to speed wound healing and to protect against gum disease.

Dietary Sources

Although citrus fruit is the most popular way of getting vitamin C, some vegetables actually have higher vitamin C content. Red chili peppers, sweet peppers, kale, parsley, collard and turnip greens contain large amounts of vitamin C. So are broccoli, Brussels sprouts, watercress, cauliflower, cabbage and strawberries. As vitamin C is partially destroyed by heat, fresh fruits and vegetables contain more vitamin C than cooked ones do.

	Citrus Fruits		Chili Peppers
	Sweet Peppers		Cabbage
	Collard, Turnip Greens and Kale		Parsley
	Pineapple		Tomatoes
	Potatoes		Winter Squash
	Strawberries		Blueberries
Cranberries

Recommended Dosage:

Daily intake of dietary vitamin C (according to the U.S. RDA), are listed below.

Pediatric

• Neonates 1 to 6 months: 30 mg
• Infants 6 to 12 months: 35 mg
• Children 1 to 3 years: 40 mg
• Children 4 to 6 years: 45 mg
• Children 7 to 10 years: 45 mg
• Children 11 to 14 years: 50 mg
• Adolescent girls 15 to18 years: 65 mg
• Adolescent boys 15 to18 years: 75 mg

Adult

• Men over 18 years: 90 mg
• Women over 18 years: 75 mg
• Breastfeeding women: first 6 months: 95 mg
• Breastfeeding women: second 6 months: 90 mg

The U.S. government has issued recommendations regarding "tolerable upper intake levels" (ULs) for vitamin C. The UL can be thought of as the highest daily intake over a prolonged time known to pose no risks to most members of a healthy population. The ULs for vitamin C are as follows:

• Children 1–3 years, 400 mg
  4–8 years, 650 mg
  9–13 years, 1,200 mg
• Males and females 14–18 years, 1,800 mg
  19 years and older, 2,000 mg
• Pregnant women 2000 mg (1,800 mg if18 years old or younger)
• Nursing women 2000 mg (1,800 mg if18 years old or younger)

Although scurvy is rare in the United States, subtle vitamin C deficiency is very common. One study estimates that 40% of Americans do not get enough vitamin c in their diets.

Although many health groups encourage the use of huge doses of vitamin C as much as 20,000 to 30,000 mg daily, no studies to date have shown that these mega doses over any greater health. What researchers have found out that the more vitamin C ingested over 200mg daily, the vitamin C excreted by the kidneys matches the amount over the 200mg taken in. What this means is that no matter how much vitamin C is taken in, the level of vitamin C in the blood does not increase over this 200mg level. These studies, however did not measure the amount of vitamin C in the tissues nor the difference in taking these doses several times a day rather than just once.

SMOKING CIGARETTES SIGNIFICANTLY REDUCES THE LEVELS OF VITAMIN C IN THE CODY. SMOKERS SHOULD INCREASE THEIR VITAMIN C INTAKE BY 35mg IN ALL AGE GROUPS.

Vitamin C increases the absorption of dietary iron

Contra-indications

• Vitamin C is often made commercially from corn. Those who suffer from allergies to corn or corn products should check their source of vitamin C. Some people are allergic to rose hips, another source of vitamin C. Again, those with an allergy to rose hips should check their source of vitamin C.

• In healthy adults oral doses up to 3000mg daily are well tolerated. When atking oral doses over 3,000mg a day the only adverse side effects are gastrointestinal such as nausea, abdominal cramps and diarrhea.

• In people with a history of kidney stones or who are in kidney failure should restrict their intake of vitamin C to 100mg a day.

• People who suffer from a genetic condition known as glucose-6-phosphate dehydrogenase deficiency, hemochromatosis (a condition that causes a toxic build up of iron in the tissue) or a history of intestinal surgery should also avoid high doses of vitamin C.

• Women who are pregnant or breastfeeding should consult a health care provider before supplementing with large doses of vitamin C.

Drug interactions

If you are taking any of the following medications or having any blood tests done, please consult a qualified healthcare practioner before starting a Vitamin C regime.

• Aluminum containing antacids: when large doses of vitamin c are taken at the same time as aluminum containing antacids, an increase in the excretion of aluminum in the urine. This suggests that vitamin C increases the absorption of aluminum.
• Aspirin: the absorption of vitamin C is inhibited by high doses of aspirin.
• Chemotherapeutic agents: Vitamin C may strengthen the anticancer activity of drugs used in the treatment of cancer such as cisplatin, doxorubicin and paclitaxel. This is based on in vitro and animal studies.
• Vitamin C/flavonoid combinations: Preparations that also contain grapefruit flavonoids may interact with some medications. Drugs that may be affected include the calcium channel blocker felodipine as well as carbamazepine, cyclosporines. Lovastatin, simvastation, saquinavir and nisoldipine. A qualified healthcare practioner should be consulted before using any grapefruit product.
• Copper: It has been documented that high doses of vitamin C may affect the copper levels in men.
• Flavonoids: Vitamin C and flavonoids seem to strengthen the ability of both substances to do their jobs.
• Iron: Vitamin C increases the absorption of iron. In those with high iron stores this could lead to a potentially toxic iron overload. Those with hemochromatosis, sideroblastic anemia, sickle cell anemia, thalassemia and G6PD deficiency.
• Large doses of vitamin C may interfere with the following laboratory tests:

• Bilirubin assay were it can cause falsely elevated bilirubin levels.
• Creatinine levels. Large doses of vitamin C can cause falsely elevated urine and serum creatinine levels.
• Glucose levels. Large doses of vitamin C can cause falsely elevated glucose levels when using clinitest and falsely lowered glucose levels when using clinistix and Tes-tape.
• Stool occult blood test. Doses of vitamin C larger than 1000mg a day can lead to a false negative test for occult blood in the stool

• Acetaminophen: Vitamin C decreases the amount of acetaminophen (tylynol). Acetaminophen can become toxic at high levels. A healthcare practioner should be consulted before starting a vitamin C regime when acetaminophen is taken on a regular basis.

• Vitamin C may intensify the effects of furosemide a loop diuretic

• Beta channel blockers: vitamin C decreases the absorption of propranolol used in the treatment of high blood pressure. If taking both vitamin C and a beta-blocker it is best to take them at different times.

• Cyclosporine has been shown to decrease the blood levels of vitamin C.

• Nitroglycerine and other nitrate medications: Taking vitamin C when on nitrate medications for heart disease decreases the build up of these drugs in the body and helping to prevent the occurrence of nitrate tolerance.

• Tetracycline: Studies have shown that taking vitamin C with tetracycline increases the level of this antibiotic in the blood.

• There have been no reports of vitamin C overdoses in the literature

Web References

1. http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/
2. http://www.umm.edu/altmed/ConsSupplements/VitaminCAscorbicAcidcs.html
3. http://healthlibrary.epnet.com/GetContent.aspx?token=e0498803-7f62-4563-8d47-5fe33da65dd4&chunkiid=21522
4. http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/vit_0264.shtml

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