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.

Function 

Vitamin C is needed for the growth and repair of tissues in all parts of your body. It is used to:

• Form an important protein used to make skin, tendons, ligaments, and blood vessels
• Heal wounds and form scar tissue
• Repair and maintain cartilage, bones, and teeth

Vitamin C is one of many antioxidants. Antioxidants are nutrients that block some of the damage caused by free radicals.

• Free radicals are made when your body breaks down food or when you are exposed to tobacco smoke or radiation.
• The buildup of free radicals over time is largely responsible for the aging process.
• Free radicals may play a role in cancer, heart disease, and conditions like arthritis.

The body is not able to make vitamin C on its own, and it does not store vitamin C. It is therefore important to include plenty of vitamin C-containing foods in your daily diet.
For many years, vitamin C has been a popular remedy for the common cold.

• Research shows that for most people, vitamin C supplements or vitamin C-rich foods do not reduce the risk of getting the common cold.
• However, people who take vitamin C supplements regularly might have slightly shorter colds or somewhat milder symptoms.
• Taking a vitamin C supplement after a cold starts does not appear to be helpful.

Food Sources

All fruits and vegetables contain some amount of vitamin C.
Fruits with the highest sources of vitamin C include:

• Cantaloupe
• Citrus fruits and juices, such as orange and grapefruit
• Kiwi fruit
• Mango
• Papaya
• Pineapple
• Strawberries, raspberries, blueberries, cranberries
• Watermelon

Vegetables with the highest sources of vitamin C include:

• Broccoli, Brussels sprouts, cauliflower
• Green and red peppers
• Spinach, cabbage, turnip greens, and other leafy greens
• Sweet and white potatoes
• Tomatoes and tomato juice
• Winter squash

Some cereals and other foods and beverages are fortified with vitamin C. Fortified means a vitamin or mineral has been added to the food. Check the product labels to see how much vitamin C is in the product.
Cooking vitamin C-rich foods or storing them for a long period of time can reduce the vitamin C content. Microwaving and steaming vitamin C-rich foods may reduce cooking losses. The best food sources of vitamin C are uncooked or raw fruits and vegetables.

Side Effects

Serious side effects from too much vitamin C are 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:

•  Anemia
• Bleeding gums
• Decreased ability to fight infection
• Decreased wound-healing rate
• Dry and splitting hair
• Easy bruising
• Gingivitis
• Nosebleeds
• Possible weight gain because of slowed metabolism
• Rough, dry, scaly skin
• Swollen and painful joints
• Weakened tooth enamel

A severe form of vitamin C deficiency is known as scurvy, which mainly affects older, malnourished adults.

Recommendations

The Recommended Dietary Allowance (RDA) for vitamins reflects how much of each vitamin most people should get each day. The RDA for vitamins may be used as goals for each person.

How much of each vitamin you need depends on your age and gender. Other factors, such as pregnancy and illnesses, are also important.

The best way to get the daily requirement of essential vitamins, including vitamin C, is to eat a balanced diet that contains a variety of foods.

Dietary Reference Intakes for vitamin C:

Infants

• 0 - 6 months: 40* milligrams/day (mg/day)
• 7 - 12 months: 50* mg/day

*Adequate Intake (AI)

Children

• 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
• Pregnant teens: 80 mg/day
• Breastfeeding teens: 115 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
• Pregnant women: 85 mg/day
• Breastfeeding women: 120 mg/day

Smokers or those who are around secondhand smoke at any age should increase their daily amount of vitamin C an additional 35 mg per day.

Women who are pregnant or breastfeeding and those who smoke need higher amounts of vitamin C. Ask your doctor what amount is best for you.

References

Escott-Stump S, ed. Nutrition and Diagnosis-Related Care . 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2008.  

Sarubin Fragaakis A, Thomson C. The Health Professional's Guide to Popular Dietary Supplements . 3rd ed. Chicago, Il: American Dietetic Association; 2007. 

Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000. 

Douglas RM, Hemila H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev ; 2007(3):CD000980.