Your body does not store vitamin C so you must consume enough each day to maintain good health. Vitamin C is needed 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. Because of this, your body uses a lot of vitamin C to repair wounds. Vitamin C is also needed to form and repair cartilage, bones, and teeth. Large amounts of vitamin C are used by your body during any kind of healing process, whether it's from a cold, infection, disease, injury, or surgery. In these cases you may need extra vitamin C. Vitamin C helps reduce the damage to the body caused by toxic chemicals and pollutants like drugs and cigarette smoke. Smokers especially need extra vitamin C. Research has shown that vitamin C can help prevent cancer and is necessary for a healthy immune system. It also helps maintain good vision as you get older. Vitamin C deficiency may also contribute to weight gain by decreasing metabolic rates and energy expenditures.

Vitamin C can have many positive effects on your body, including the following:

• Boosts immune system functions
• Protects against cancer
• Necessary for wound healing
• Helps prevent cataracts
• Increases HDL (good) cholesterol and reduces LDL (bad) cholesterol and triglycerides 
• Decreases risk of heart disease
• Reduces blood pressure
• Useful in treating allergies
• Maintains healthy blood vessels
• Counteracts asthma spasms
• Helps overcome male infertility
• Helps protect diabetics against long-term complications
• Protects against sunburn and its effects.
• Can assist treatment of bleeding gums, easy bruising, and arthritis
• Assists treatment of arthritis and other inflammatory conditions

If you eat many cured, processed, or preserved meats like bacon, sausage, ham, hot dogs, or sliced luncheon meat, you should know that vitamin C helps prevent these foods from forming cancer-causing "nitrosamines" in the stomach. It's a good idea to eat foods rich in vitamin C, or take vitamin C supplements, at the same time you eat processed meats.

Vitamin C is present in many fruits and vegetables. Foods that are excellent sources of vitamin C include orange juice, green peppers, watermelon, papaya, grapefruit, cantaloupe, strawberries, mango, broccoli, tomato juice, brussels sprouts, cauliflower, and cabbage. Vitamin C is also found in raw and cooked leafy greens (turnip greens, spinach), canned and fresh tomatoes, potatoes, winter squash, raspberries, and pineapple. Vitamin C is sensitive to light, air, and heat. Eating vegetables raw, or minimally cooked, increases their vitamin C content.

You can purchase either natural or synthetic vitamin C, also called ascorbic acid, in a wide variety of supplement forms. Tablets, capsules, and chewable tablets are probably the most popular, but vitamin C also comes in powdered crystalline, effervescent tablet and liquid form. You can purchase dosages ranging from 25 mg to 1,000 mg per tablet. "Buffered" vitamin C is available if you find that regular ascorbic acid bothers your stomach. An esterified form of vitamin C is also available and may be better absorbed by the body. However, laboratory testing concluded that this claim is not true, and has shown that regular vitamin C is absorbed just as well.

Vitamin C is not stored in the body, so it must be replaced as it gets used. The best way to take supplements is with meals two or three times per day, depending on the dosage. Some studies suggest that adults should take between 250 mg and 500 mg twice a day for maximum benefit. Be sure to check with your healthcare provider before taking more than 1,000 mg of vitamin C on a daily basis and before giving vitamin C to a child.

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

Pediatric

• Neonates 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

Adult

• 15 years and older: 60 mg
• Pregnant females: 70 mg
• Breastfeeding females – first 6 months: 95 mg
• Breastfeeding females – second 6 months: 90 mg

Vitamin C is generally non-toxic. In high doses (more than 2,000 mg daily) it can cause diarrhea, gas, or stomach upset. Check with your healthcare provider before taking vitamin C supplements if you have any kidney problems. Infants born to mothers taking 6,000 mg or more of vitamin C may develop rebound scurvy due to sudden drop in daily intake.

Vitamin C taken with aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) may protect the stomach and intestines against injury from these medications. However, high doses of vitamin C (equal to or greater than 500 mg per day) may raise the blood levels of aspirin and other acidic medications. Vitamin C may decrease excretion of acetaminophen in the urine, which may increase blood levels of this medication.

Vitamin C may also affect the levels of furosemide, a diuretic, and propranolol, a beta-blocker; therefore, vitamin C supplements should not be taken at the same time as these medications.

Vitamin C can increase levels of estradiol, an ingredient in some birth control medications and hormone replacement therapies. However, vitamin C may offer antioxidant benefits to women taking birth control medications. You should consult your healthcare provider before using vitamin C supplements if you are taking estradiol.

Cyclosporine, a medication used for the treatment of cancer, may reduce blood levels of vitamin C.

The combination of vitamin C with nitroglycerin and nitrate medications (isosorbide dinitrate and isosorbide mononitrate), used to treat heart disease, reduces the occurrence of nitrate tolerance, an effect by which the body becomes accustomed to the medicine and then requires a brief break from it for it to work properly. For example, people taking nitrate-containing medications generally take the medicine for 12 hours and then have a 12-hour time period without the medicine. Apparently, vitamin C makes nitrate tolerance less likely to happen which may, upon further investigation, translate into greater effectiveness of the nitrate medication.

Taking vitamin C with tetracycline, an antibiotic, may increase the levels of this medication. More research is needed to confirm these effects.

Patients taking warfarin, a blood-thinning medication, should not exceed the RDA for vitamin C. There is a remote possibility that vitamin C could interfere with the effectiveness of this medication.

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