Vitamin C (Ascorbic Acid)
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Vitamin C (Ascorbic Acid)

Vitamin c image Vitamin C, also called ascorbic acid, is a water-soluble vitamin. Water-soluble vitamins are stored in the body in very limited amounts, and are excreted through the urine. Therefore, it is a good idea to have them in your daily diet. Vitamin C is sensitive to light, heat, and air and can be destroyed during food preparation, cooking, or storage.

Functions

Vitamin C's functions include:

  • Acting as an antioxidant in the body, protecting:
    • Intracellular fluid
    • Blood
    • Interstitial fluid
    • Plasma lipids
    • LDL cholesterol
  • Playing a major role in collagen formation
  • Aiding in amino acid metabolism and hormone synthesis
  • Assisting in the conversion of the amino acid tryptophan to the neurotransmitter serotonin
  • Helping break down cholesterol and synthesize bile
  • Playing a role in the absorption, metabolism, and utilization of other nutrients, such as folate, calcium, and iron
  • Promoting healing of wounds and burns

Recommended Intake:

Age Group (in years) Recommended Dietary Allowance
(mg/day)
FemalesMales
1-31515
4-82525
9-134545
14-186575
14-18 Pregnancy80n/a
14-18 Lactation115n/a
19-507590
19-50 Pregnancy85n/a
19-50 Lactation120n/a
50+7590

Smoking increases oxidative stress and metabolic turnover of vitamin C. Therefore, the RDA for smokers is increased by 35 mg/day. For example, if you are a 22-year-old female smoker, your RDA for vitamin C is 110 mg/day.

Vitamin C Deficiency

Intakes of less than 10 mg per day of vitamin C can result in scurvy. Symptoms of vitamin C deficiency include:

  • Bleeding gums
  • Easy bruising
  • Impaired wound and fracture healing
  • Joint pain and swelling
  • Loose and decaying teeth
  • Anemia
  • Bone fragility

Vitamin C Toxicity

The tolerable upper intake level (UL) for vitamin C from dietary sources and supplements combined is:

  • Ages 1-3: 400 mg/day
  • Ages 4-8: 650 mg/day
  • Ages 9-13: 1,200 mg/day
  • Ages 14-18: 1,800 mg/day
  • Ages 19+: 2,000 mg/day

Because excess vitamin C is excreted in the urine, toxicity is rare. It can happen, though, with several large doses throughout the day. Symptoms of vitamin C toxicity include:

  • Nausea
  • Diarrhea
  • Formation of kidney stones in susceptible people

Major Food Sources

FoodServing size Vitamin C content
(mg)
Strawberries1 cup95
Papaya1 cup85
Kiwi1 medium70
Orange1 medium70
Pepper, red or green, raw½ cup65
Broccoli, cooked½ cup60
Cantaloupe¼ medium60
Kale, cooked1 cup55
Brussels sprouts, cooked½ cup50
Orange juice½ cup50
Pepper, red or green, cooked½ cup50
Mango1 cup45
Grapefruit½ medium40
Snow peas, fresh, cooked½ cup40
Grapefruit juice½ cup35
Artichoke, boiled1 medium30
Sweet potato, baked with skin1 medium28
Potato, baked with skin1 medium25
Avocado1 medium24
Pineapple1 cup24
Cauliflower, raw½ cup23
Snow peas, frozen, cooked½ cup20

Health Implications

Populations at Risk for Vitamin C Deficiency

The following populations may be at risk for vitamin C deficiency and may require a supplement:

  • People who smoke cigarettes—Due to an increased metabolic turnover of vitamin C, smokers have lower blood vitamin C levels. It is recommended that smokers take 35 mg more per day than the applicable RDA.
  • People who drink excessive amounts of alcohol—Studies have shown that alcoholics have lower blood vitamin C concentrations. This may, in part, be due to a nutritionally inadequate diet.
  • The elderly—Studies have shown that older adults have lower levels of serum vitamin C. This may be due to a diet lacking in essential nutrients.

Antioxidant Capabilities

Free radicals are normal by-products of metabolism, but they can cause chain reactions that result in significant cell destruction. This cell destruction can, in turn, increase the risk of chronic diseases, including certain forms of cancer and cardiovascular disease.

Antioxidants have the ability to stop this chain reaction. Vitamin C functions in the body as an antioxidant. Because of this antioxidant capability, vitamin C is being studied for a possible role in chronic disease prevention.

The Common Cold

Many people believe that taking mega-doses of vitamin C will prevent or cure a cold. There is no scientific evidence to support this idea. However, studies have found that taking vitamin C daily (1,000 mg/day) may help slightly reduce the severity of symptoms and the duration of a cold.

Tips For Increasing Your Vitamin C Intake:

To help increase your intake of vitamin C:

  • Serve fruits and vegetables raw whenever possible.
  • Leave the skin on potatoes and sweet potatoes.
  • Add sliced strawberries, mango, or kiwi to your breakfast cereal.
  • Use mashed avocado in place of mayonnaise as a sandwich spread.
  • Throw snow peas in your stir-fry.
  • Replace your morning coffee with a glass of orange or grapefruit juice.
  • If you take a vitamin supplement, make sure it contains vitamin C.

RESOURCES:

American Dietetic Association
http://www.eatright.org/Public/

Harvard School of Public Health
http://www.hsph.harvard.edu/nutritionsource/

CANADIAN RESOURCES:

Canadian Digestive Health Foundation
http://www.cdhf.ca/aboutcdhf.htm

Dietitians of Canada
http://www.dietitians.ca/

References:

Advanced Nutrition and Human Metabolism. West Publishing Company; 1995.

Food and Nutrition Information Center. US Department of Agriculture website. Available at: http://www.usda.gov/wps/portal/usdahome.

"How much vitamin C do you need?" JAMA Patient Page. April 12, 1999;281.

The Nutrition Desk Reference. Keats Publishing; 1995.



Last reviewed June 2008 by Dianne Scheinberg MS, RD, LDN

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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