Smaller Larger

Vitamin C (Ascorbic Acid) by Mary Calvagna, MS

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
Playing a major role in collagen formation
Aiding in amino acid metabolism and hormone synthesis
Assisting in the synthesis of a neurotransmitter, norepinephrine
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) [miligrams per day]
Age Group (in years)	Females	Males
1-3	15	15
4-8	25	25
9-13	45	45
14-18	65	75
14-18 Pregnancy	80	n/a
14-18 Lactation	115	n/a
19-50	75	90
19-50 Pregnancy	85	n/a
19-50 Lactation	120	n/a
50+	75	90

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
Hair loss
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
Abdominal cramps
Formation of kidney stones in susceptible people

Major Food Sources

Food	Serving size	Vitamin C content (mg)
Strawberries	1 cup	85
Broccoli, cooked	½ cup	51
Kiwi	1 medium	64
Orange	1 medium	70
Pepper, red, raw	½ cup	95
Broccoli, cooked	½ cup	51
Cantaloupe	½ cup	29
Tomato juice	¾ cup	33
Brussels sprouts, cooked	½ cup	48
Orange juice	¾ cup	62-93
Cabbage, cooked	½ cup	28
Tomato, raw	1 medium	17
Grapefruit	½ medium	38
Green peas, frozen, cooked	½ cup	8
Grapefruit juice	¾ cup	62-70
Spinach, cooked	½ cup	9
Green pepper, sweet, raw	½ cup	60
Potato, baked with skin	1 medium	17
Avocado	1 medium	24
Pineapple	1 cup	24
Cauliflower, raw	½ cup	26
Snow peas, frozen, cooked	½ cup	20

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—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.
Infants—Feeding babies evaporated or boiled milk can cause vitamin C deficiency. This is because heat can destroy the vitamin C found in cow's milk.
People with limited variety in their diet—Indigent individuals who prepare their own food; food faddists; and people with mental illness may not be able to prepare meals that contain a variety of foods to obtain sufficient vitamin C.
People with malabsorption and certain chronic diseases—Those with certain medical conditions like severe intestinal malabsorption, renal disease, or cancer may not be able to absorb enough vitamin C.

Antioxidant Capabilities

Free radicals are normal by-products of metabolism, but they can cause chain reactions that result in cell damage. This cell damage 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 prevention of certain conditions like age-related macular degeneration, cataracts, cancer, and cardiovascular diseases. Currently there is not sufficient evidence to recommend vitamin C for any of these conditions.

Respiratory Infections

Many people believe that taking mega-doses of vitamin C will cure a cold. There is no scientific evidence to support this idea in the general population. However, there may be some preventative benefit in people exposed to extreme physical stress, cold environments, or those not getting enough vitamin C normally. Studies have found that taking vitamin C daily may help slightly reduce the symptoms and the duration of a cold. But taking vitamin C after the onset of the cold does not appear to effect the course of the illness. In addition, a review of studies on vitamin C found that it may be able to prevent and treat pneumonia, particularly in people who do not get enough vitamin C in their diet.

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

References:

Ascorbic acid. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/. Updated November 7, 2011. Accessed September 19, 2012.
Vitamin C. Office of Dietary Supplements National Institutes of Health.website. Available at: http://ods.od.nih.gov/factsheets/vitaminc.asp. Accessed July 6, 2010.
Vitamin C. Oregon State University Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/index.html. Updated December 2009. Accessed September 19, 2012.
Vitamin C (ascorbic acid). University of Maryland Medical Center website. Available at: http://www.umm.edu/altmed/articles/vitamin-c-000339.htm. Updated July 7, 2011. Accessed September 19, 2012.
10/30/2009 DynaMed Systematic Literature Surveillance http://www.dynamicmedical.com/what.php : Hemila H, Louhiala P. Vitamin C for preventing and treating pneumonia. Cochrane Database Syst Rev. 2009;(3):CD005532.

Last reviewed September 2012 by Brian Randall, MD

All EBSCO Publishing proprietary, consumer health and medical information found on this site is accredited by URAC. URAC's Health Web Site Accreditation Program requires compliance with 53 rigorous standards of quality and accountability, verified by independent audits. To send comments or feedback to our Editorial Team regarding the content please email us at HLEditorialTeam@ebscohost.com.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.