Vitamin C is a water-soluble vitamin, meaning that your body doesn't store it. We get what we need, instead, from food. We need vitamin C for the growth and repair of tissues in all parts of our body. It helps the body make collagen, an important protein used to make skin, cartilage, tendons, ligaments, and blood vessels. Vitamin C is essential for healing wounds, and for repairing and maintaining bones and teeth.

Vitamin C is an antioxidant, along with vitamin E, beta-carotene, and many other plant-based nutrients. Antioxidants block some of the damage caused by free radicals, which occur naturally when our bodies transform food into energy. The build-up of free radicals over time may be largely responsible for the aging process and can contribute to the development of health conditions such as cancer, heart disease, and arthritis.

Evidence suggests that many people may be mildly deficient in vitamin C, although serious deficiencies are rare in industrialized countries. Smoking cigarettes lowers the amount of vitamin C in the body, so smokers are at a higher risk of deficiency. Signs of vitamin deficiency include dry and splitting hair; gingivitis (inflammation of the gums) and bleeding gums; rough, dry, scaly skin; decreased wound-healing rate, easy bruising; nosebleeds; and a decreased ability to ward off infection. A severe form of vitamin C deficiency is known as scurvy.

Low levels of vitamin C have been associated with a number of conditions, including high blood pressure, gallbladder disease, stroke, some cancers, and atherosclerosis (the build-up plaque in blood vessels that can lead to heart attack and stroke). Getting enough vitamin C from your diet (by eating lots of fruit and vegetables) may help reduce the risk of developing some of these conditions. The evidence that taking vitamin C supplements will help or prevent any of these conditions is lacking, however.

What is Vitamin C ?
Vitamin C is a water-soluble vitamin that is necessary for normal growth and development.
Water-soluble vitamins dissolve in water. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of such vitamins in your diet.

Vitamin C is required for the growth and repair of tissues in all parts of your body. It is necessary to form collagen, an important protein used to make skin, scar tissue, tendons, ligaments, and blood vessels. Vitamin C is essential for the healing of wounds, and for the repair and maintenance of cartilage, bones, and teeth.

Vitamin C is one of many antioxidants. Vitamin E and beta-carotene are two other well-known antioxidants. Antioxidants are nutrients that block some of the damage caused by free radicals, which are by-products that result when our bodies transform food into energy.

The buildup of these by-products over time is largely responsible for the aging process and can contribute to the development of various health conditions such as cancer, heart disease, and a host of inflammatory conditions like arthritis. Antioxidants also help reduce the damage to the body caused by toxic chemicals and pollutants such as cigarette smoke.

The body does not manufacture vitamin C on its own, nor does it store it. It is therefore important to include plenty of vitamin C-containing foods in your daily diet.

Where it is found
All fruits and vegetables contain some amount of vitamin C. Foods that tend to be the highest sources of vitamin C include green peppers, citrus fruits and juices, strawberries, tomatoes, broccoli, turnip greens and other leafy greens, sweet and white potatoes, and cantaloupe.

Other excellent sources include papaya, mango, watermelon, brussels sprouts, cauliflower, cabbage, winter squash, red peppers, raspberries, blueberries, cranberries, and pineapples.

When to take/Types to take
Vitamin C supplement are best taken with meal. However, if an individual has a reason to take mega-doses (to combat a cold, for example), then 1000-2000 mg can be taken every two hours or so; even without food. In this instance, however, the individual would be better off using a mineral ascorbate form of vitamin C, which is less likely to induce gastrointestinal difficulties.

Besides a standard tablet or capsule, vitamin C is also available as a crystalline powder, and as chewable tablets or wafers. The chewable form of Vitamin C is particularly appropriate for children.

Since vitamin C is water soluble, most adults would be well served by using a timed release form of Vitamin C is more likely to provide better absorption over a period of several hours.

bioflavonoids greatly increases vitamin C's bioavailability and rate of absorption

Doses
Vitamin C should be consumed every day because it is not fat-soluble and, therefore, cannot be stored for later use.
Infants and Children
0 - 6 months: 40 milligrams/day (mg/day)
7 - 12 months: 50 mg/day
1 - 3 years: 15 mg/day
4 - 8 years: 25 mg/day
9 - 13 years: 45 mg/day
Adolescents
Girls 14 - 18 years: 65 mg/day
Boys 14 - 18 years: 75 mg/day
Adults
Men age 19 and older: 90 mg/day
Women age 19 year and older: 75 mg/day

Side Effects
Vitamin C toxicity is very rare, because the body cannot store the vitamin. However, amounts greater than 2,000 mg/day are not recommended because such high doses can lead to stomach upset and diarrhea.
Too little vitamin C can lead to signs and symptoms of deficiency, including:

Possible Interactions:
If you are being treated with any of the following medications, you should not use vitamin C supplements without first talking to your health care provider:
Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) -- Both aspirin and NSAIDs can lower the amount of vitamin C in the body because they cause more of the vitamin to be lost in urine. In addition, high doses of vitamin C can cause more of these drugs to stay in the body, raising the levels in your blood. Some very early research suggests that vitamin C might help protect against stomach upset that aspirin and NSAIDs can cause. If you regularly take aspirin or NSAIDs, talk to your doctor before taking more than the recommended daily allowance of vitamin C.

Acetaminophen (Tylenol) -- High doses of vitamin C may lower the amount of acetaminophen passed in urine, which could cause the levels of this drug in your blood to rise.

Aluminum-containing antacids -- Vitamin C can increase the amount of aluminum your body absorbs, which could cause the side effects of these medications to be worse. Aluminum-containing antacids include Maalox and Gaviscon.

Barbiturates -- Barbiturates may decrease the effects of vitamin C. These drugs include phenobarbital (Luminal), pentobarbital (Nembutal), and seconobarbital (Seconal).

Chemotherapy drugs -- As an antioxidant, vitamin C may interfere with the effects of some drugs taken for chemotherapy; however, some researchers speculate that vitamin C might help make chemotherapy more effective. If you are undergoing chemotherapy, do not take vitamin C or any other supplement without talking to your oncologist.

Nitrate medications for heart disease -- The combination of vitamin C with nitroglycerin, isosorbide dinitrate (Isordil), or isosorbide mononitrate (Ismo) reduces the body's tendency to build up a tolerance to these medications so that they no longer work. If you take nitrate medications, talk to your doctor about whether you should take vitamin C.

Oral contraceptives (birth control pills) and hormone replacement therapy (HRT) -- Vitamin C can cause a rise in estrogen levels when taken with these drugs, particularly if you are deficient in vitamin C to begin with and start taking supplements. Oral estrogens can also decrease the effects of vitamin C in the body.
Protease inhibitors -- Vitamin C appears to slightly lower levels of indinavir (Crixivan), a medication used to treat HIV and AIDS.

Tetracycline -- Some evidence suggests that taking vitamin C with the antibiotic tetracycline may increase the levels of this medication; it may also decrease the effects of vitamin C in the body. Other antibiotics in the same family include minocycline (Minocin) and doxycycline (Vibramycin).

Warfarin (Coumadin) -- There have been rare reports of vitamin C interfering with the effectiveness of this blood thinning medication. In recent follow-up studies, no effect was found with doses of vitamin C up to 1,000 mg per day. However, if you take warfarin or another blood thinner, talk to your doctor before taking vitamin C or any other supplement.

Research studies / References