Encyclopedia of Diets - A Guide to Health and Nutrition

of the mouth, esophagus, stomach, colon, and lung. It is

not clear that the benefit of this diet is due to vitamin C.

Study results using dietary supplements of vitamin C are

mixed. The American Cancer Society recommends

increasing healthy foods in the diet to reduce cancer risk

rather than taking a dietary supplement.

CARDIOVASCULAR HEALTH.Because vitamin C is

involved in the production of collagen in blood vessels,

researchers have examined the relationship between

vitamin C intake and cardiovascular health. Some

studies found no benefit to vitamin C supplementa-

tion, while others reported that a relatively low dose of

vitamin C reduced the risk of death from strokes.

Vitamin C does not reduce blood levels of cholesterol.

The American Heart Association recommends that to

improve cardiovascular health individuals should

increase their intake of vitamin C (and other vitamins

and mineral) by increasing the amount of fresh vege-

tables in their diet. Research continues in this area.

CATARACTS.Cataracts are the leading cause of

vision impairment worldwide. They develop, usually

in older individuals, because of changes in the proteins

in the lens of the eye. Initial studies suggested that

vitamin C could prevent these changes because of its

antioxidant properties. A recent a 7-year follow-up

study found vitamin C supplements to be of no benefit

in preventing cataracts.

OTHER HEALTH CLAIMS.Claims have been made

that vitamin C can treat or prevent lead poisoning,

high blood pressure (hypertension), asthma, Alz-

heimer’s disease, attention deficithyperactivitydisor-

der (ADHD), infertility, macular degeneration,

premature birth, stomachulcers, autism, and many

other diseases and disorders. None of these health

claims have been proved to the satisfaction of practi-

tioners of conventional medicine.

Precautions

People who smoke cigarettes need more vitamin C

than those who do not. People with cancer also seem

to need more vitamin C.

Large doses of vitamin C as a dietary supplement

may cause indigestion or diarrhea that stops when the

dose is reduced.

Interactions

Vitamin C has few interactions with drugs or

other vitamins. Large doses of vitamin C increase the

amount ofironabsorbed from food in the small intes-

tine. In healthy people, this does not cause any prob-

lems and may be beneficial.

Large daily doses of vitamin C may interfere with

the absorption ofvitamin B 12.

Complications

Vitamin C can be taken in enormous doses without

any serious side effects. At very high doses, it causes

diarrhea. Some researchers who believe that large doses

of vitamin C prevent disease think that the appropriate

daily dose is an amount just slightly less than the

amount that causes diarrhea. This amount varies con-

siderably form person to person.

Parental concerns

Generally, parents should have few concerns

about children getting either too much or too little

Vitamin C. Vitamin C is safe for women to take during

pregnancy and while breastfeeding. It passes into

breast milk. Children under age one should not be

given a dietary supplement containing vitamin C;

their needs should be met through the foods the eat.

Resources

BOOKS

Berkson, Burt and Arthur J. Berkson.Basic Health Publi-

cations User’s Guide to the B-complex Vitamins.Laguna

Beach, CA: Basic Health Publications, 2006.

Gaby, Alan R., ed.A-Z Guide to Drug-Herb-Vitamin Inter-

actions Revised and Expanded 2nd Edition: Improve

Your Health and Avoid Side Effects When Using Com-

mon Medications and Natural Supplements Together.-

New York: Three Rivers Press, 2006.

Lieberman, Shari and Nancy Bruning.The Real Vitamin and

Mineral Book: The Definitive Guide to Designing Your

Personal Supplement Program,4th ed. New York:

Avery, 2007.

Peel, Thomas, ed.Vitamin C: New Research.New York:

Nova Science Publishers, 2006.

Pressman, Alan H. and Sheila Buff.The Complete Idiot’s

Guide to Vitamins and Minerals,3rd ed. Indianapolis,

IN: Alpha Books, 2007.

Rucker, Robert B., ed.Handbook of Vitamins.Boca Raton,

FL: Taylor & Francis, 2007.

PERIODICALS

Kushi, Lawrence H., Tim Byers, Colleen Doyle, et al.

‘‘American Cancer Society Guidelines on Nutrition and

Physical Activity for Cancer Prevention.’’CA: Cancer

Journal for Clinicians, 56 (2006):254-281.<http://

caonline.amcancersoc.org/cgi/content/full/56/5/254>

ORGANIZATIONS

American Cancer Society. 1599 Clifton Road NE, Atlanta

GA 30329-4251. Telephone: 800 ACS-2345. Website:

<http://www.cancer.org>

Vitamin C