Vitamin C (ascorbic acid) is one of the widely known of all of the vitamins. It is a cell protector, immunity booster, and powerful antioxidant. The body's ligaments, tendons, and collagen (a protein found in connective tissues) rely on the presence of vitamin C to stay strong and healthy. It indirectly protects the fat-soluble vitamins A and E as well as some of the B vitamins, such as riboflavin, thiamine, folic acid, and pantothenic acid, from oxidation. It helps build resistance to infection; aids in the prevention & treatment of the common cold and helps the absorption of iron. It is therefore an important part of a healthy diet.

How can we get enough vitamin C?
Eating a variety of foods that contain vitamin C is the best way to get an adequate amount. It is found in fruits such as guava, kiwi, mangos, oranges, strawberries, papaya, tangerines and grapefruit, and vegetables including tomatoes, peppers and broccoli, cauliflower and sweet potato, among others. Animal products contain almost no vitamin C. Some juices such as grape and apple have vitamin C added. A 3/4-cup serving of these fortified juices may provide 40 percent or more of the RDA for vitamin C. Most ready-to-eat cereals are also fortified with vitamin C. Check the labels on the packages for the percentage of the RDA.

How to prepare foods to retain vitamin C
Vitamin C is highest in fresh, raw, foods as it is easily destroyed during food preparation, such as chopping, exposure to air, cooking, and being submerged in water.

Serve fruits and vegetables raw whenever possible.
Steam, boil, or simmer foods in a minimal amount of water, or microwave them for the shortest time possible.
Cook potatoes in their skins.
Freshly squeezed juices are best consumed immediately or within 12 hours.
Store cut raw fruits and vegetables in an airtight container and refrigerate, do not soak or store in water.

Recommended intake
The RDA for vitamin C for nonsmoking men and women is 60 mg a day (for smokers it's 100 mg). Recently experts have suggested increasing the RDA to between 100 and 200 mg a day for all adults, and many recommend getting much more of this vitamin to maximize its health benefits. However, only 250mg of vitamin C can be absorbed at any one time, so if you wish to take a higher dose, spread it out throughout the day.

Too little
A deficiency of vitamin C can cause bleeding and inflamed gums, loose teeth, poor wound healing, purplish spots, easy bruising and many other problems, but just 10 mg of vitamin C a day prevents this. Less than 50 mg a day, however, can result in an increased risk of heart attack, cataracts, and a reduced life span.

Too Much
Because vitamin C is water-soluble and excess is flushed out, it is hard to get too much. But while many people are able to tolerate high doses of vitamin C no ill effects, others may suffer from mouth ulcers, diarrhea, gas, and bloating at doses above 2,000 mg; these problems subside when the dose is reduced.

Benefits
Vitamin C may help to:

Lessen the severity and duration of colds and flu. Taking vitamin C at the first sign may keep the illness from fully developing, and you will probably recover faster.
Speeds wound healing and minimize the effects of bruising. Helps the body to repair and maintain itself by reinforcing cell walls and strengthening blood vessels, and accelerates healing by inhibiting inflammation.
Keep gums strong and healthy. Taken daily, it protects gum tissue against cell damage and speeds healing.
Increase resistance to heart disease and angina. Studies have linked the presence of low levels of vitamin C to a greater risk of heart attacks and angina in people with existing heart disease. Research also indicates that, when taken with vitamin E, vitamin C helps protect LDL cholesterol from oxidation, thus preventing plaque buildup in coronary arteries.
Prevent certain cancers. As a powerful antioxidant, it may help to fight cancer by protecting healthy cells from free-radical damage and inhibiting the proliferation of cancerous cells.
Protect against cataracts. It may keep the lens of the eye from being damaged by cigarette smoke and ultraviolet (UV) light, both types of exposure linked to cataract formation.
Relieve allergies, eczema, sinusitis, and asthma. It is a natural antihistamine blocking the effect of inflammatory substances produced in response to allergens such as pollen. Vitamin C is frequently recommended with other antioxidants for sinusitis and studies have shown that it helps with asthmatic symptoms, as asthma sufferers are often deficient in this and other vitamins.
Prevent migraines. Taken with pantothenic acid, it boosts the production of hormones that help deal with the effects of stress-induced migraines.
Improve memory. As an antioxidant, it plays a key role in maintaining healthy nerve cells, and is often taken in combination with vitamin E to help prevent memory loss.
Fight chronic fatigue syndrome. Vitamin C taken with mixed carotenoids helps strengthen a weakened immune system, believed to be a factor in this disorder.
Control gallstone formation. Gallstones can develop when bile contains high concentrations of cholesterol. Vitamin C may help to lower the risk of this occurring by reducing bile cholesterol levels.
Combat the effects of aging and extend life. Used in combination with other antioxidants, such as vitamin E and flavonoids, it may combat the effects of aging caused by free-radical damage. It may also help you live longer.

Precautions

Large doses of may interfere with the body's absorption of copper and selenium; be sure to get enough of these minerals through food or supplements.
Large doses may cause a false positive result for glucose in the urine.
If you have hemochromatosis, a genetic tendency to store excess iron, don't take more than 500 mg a day.
Vitamin C can distort the accuracy of medical tests for colon cancer and hemoglobin levels. Let your doctor know if you're taking vitamin C supplements.