Vitamin C (Ascorbic Acid)
HYG-5552-05
This fact sheet is one in a series containing information to help you select
foods that provide adequate daily amounts of vitamins, minerals, and dietary
fiber. The Dietary Guidelines Advisory Committee just released the Dietary
Guidelines for Americans 2005 that convey the following nine major messages
concerning these topics:
Adequate nutrients within calorie needs
Weight management
Physical activity
Food groups to encourage: fruits and vegetables, whole grains, and nonfat or
low-fat milk and milk products
Fat
Carbohydrates
Sodium and potassium
Alcoholic beverages
Food safety
Why do we need vitamin C?
Vitamin C is a water-soluble, antioxidant vitamin. It is important in forming
collagen, a protein that gives structure to bones, cartilage, muscle, and blood
vessels. Vitamin C also aids in the absorption of iron, and helps maintain
capillaries, bones, and teeth.
What is a “good source” of vitamin C?
A “good source” of vitamin C contains a substantial amount of vitamin C in
relation to its calorie content and contributes at least 10 percent of the U.S.
Adequate Intake (AI) for vitamin C in a selected serving size. The U.S. AI for
vitamin C is 90 milligrams per day for men and 75 milligrams per day for women.
The U.S. AI given is for adults ages 19–50, and the recommended changes are for
pregnant and/or lactating women. Consult your healthcare provider for these
differences. The AI is also increased for smokers. Smoking increases oxidative
stress—as a result, it is recommended that smokers consume 35 more milligrams of
vitamin C per day.
According to recent surveys of the U.S. Department of Agriculture (USDA), the
average intake of vitamin C by American adults was over the AI for vitamin C.
Women tended to consume less than men of the same age. Most nutrition scientists
believe that there are no known advantages in consuming excessive amounts of
vitamin C. The majority of vitamin C is consumed through fruits and vegetables
in the diet.
How can we get enough vitamin C?
Eating a variety of foods that contain vitamin C is the best way to get an
adequate amount each day. Healthy individuals who eat a balanced diet rarely
need supplements. Select foods that are good sources of vitamin C as you follow
the Dietary Guidelines.
How to prepare foods to retain vitamin C.
Vitamin C can be lost from foods during preparation, cooking, or storage. To
prevent loss of vitamin C:
Serve fruits and vegetables raw whenever possible.
Steam, boil, or simmer foods in a very small amount of water, or microwave
them for the shortest time possible.
Cook potatoes in their skins. Be sure to wash the dirt off the outside of
the potato.
Refrigerate prepared juices and store them for no more than two to three
days.
Store cut, raw fruits and vegetables in an airtight container and
refrigerate—do not soak or store in water. Vitamin C will be dissolved in the
water.
What about fortified foods?
Some juices that are not normally a source of vitamin C have vitamin C added.
Examples of these juices include apple and grape. A 3/4-cup (juice glass)
serving of these fortified juices may provide 40 percent or more of the U.S. AI
for vitamin C. Check the label for the exact amount. Vitamin C (ascorbic acid)
is added to frozen peaches to prevent discoloration. Most ready-to-eat cereals
are fortified with vitamin C. Fortified ready-to-eat cereals usually contain at
least 25 percent of the U.S. AI for vitamin C. Because cereals vary, check the
label on the package for the percentage of the U.S. AI for that cereal.
What is a serving?
The amount of vitamin C in a serving depends on the weight of the serving.
For example, 1/2 cup of a cooked vegetable contains more vitamin C than 1/2 cup
of the same vegetable served raw, because a serving of the cooked vegetable
weighs more. Therefore, the cooked vegetable may appear on the list, while the
raw form does not. The raw vegetable has vitamin C, just not enough in a 1/2-cup
serving to be considered a good source.
References
Browne, M. B. 1993. Label Facts for Healthful Eating. Mazer
Corporation, Dayton, OH.
Duyff, Roberta. 2002. American Dietetic Association: Complete Food and
Nutrition Guide 2nd ed. John Wiley and Sons, Inc., Hoboken, NJ.
Escott-Stump, Mahan. 2000. Krause’s Food, Nutrition, and Diet Therapy,
10th ed. W. B. Sanders Company, Philadelphia, PA.
Federation of American Societies for Experimental Biology, Life Sciences
Research Office. Prepared for the Interagency Board for Nutrition Monitoring and
Related Research. 1995. Third Report on Nutrition Monitoring in the United
States: Volumes 1 and 2. U.S. Government Printing Office, Washington, DC.
Subcommittee on the 10th Edition of the RDAs, Food and Nutrition Board,
Commission on Life Sciences, National Research Council. 1994. Recommended
Dietary Allowances, 10th ed. Academy Press, Washington, DC.
U.S. Department of Agriculture, U.S. Department of Health and Human
Services. Your Health: Dietary Guidelines for Americans, 4th ed. Home
and Garden Bulletin No. 232. U.S. Government Printing Office, Washington, DC.
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