Vitamin C
 

Vitamin C Introduction

Vitamin C (ascorbic acid) has remained one of the most beneficial and most consumed vitamins in this past century. Since the origin of the disease Scurvy was discovered in the latter 1920’s, Vitamin C’s importance has not been neglected by society or the scientific community. Vitamin C has a long and varied history of supplementation not only relating to Scurvy, but also as an immune system enhancer, and is heralded by many as an anti-cancer agent.

Today we know that this water-soluble vitamin cannot be manufactured in our bodies. Other primates, guinea pigs, exotic species, and most importantly, human beings lack the proper enzyme to synthesize Vitamin C in our bodies. This important aspect means that it is a dietary essential; we must depend on proper supplementation and sound diet to derive this valuable nutrient source.

There are two biologically active forms of Vitamin C:

  • l-ascorbic acid
  • l-dehydroascorbic acid

Vitamin C Food Sources

Fruits and Vegetables provide for nearly all of our daily intake of Vitamin C. With the exception of milk, animal sources are nearly devoid of this vitamin. [1]

Food (Fruits)Serving Size
Ready-to-eat cereals, fortified 1 ounce
Apple (raw) 1 med
Banana (raw) 1 med
Blueberries (raw) ½ cup
Grapefruit (raw) ½ medium
Orange 1 med
Orange Juice (fresh, canned, or reconstituted frozen, unsweetened ¾ cup
Peaches (raw) 1 med
Pineapple (canned, juice-pack, chunks) ½ cup
Plum (raw) 1 med
Strawberries, raw, frozen, or canned ½ cup

Food (Vegetables)Serving Size
Artichoke 1 medium
Asparagus ½ cup
Beans ½ cup
Broccoli, Raw ½ cup
Cabbage ½ cup
Cauliflower (rare or cooked) ½ cup
Onion 1 large
Peas ½ cup
Pepper (green, red, raw) ½ cup
Potato (with skin) 1 med
Spinach ½ cup
Tomato, Red, Raw, Ripe 1 cup

Food (Meat, Poultry, Fish, and Alternatives)Serving Size
Beef or Pork 3 oz.
Chicken ½ cup diced

Vitamin C is a very unstable vitamin, easily losing its chemical structure and use in our bodies. It can be destroyed by heat, [Iron|iron]], copper, and exposure to oxygen. As with all water-soluble vitamins, supplementation is beneficial because soaking and cooking foods that contain Vitamin C severely impairs its biological activity.

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The average intake of Vitamin C in the typical American diet. The other foods category includes legumes, nuts, soy (0.1%), and other miscellaneous foods (0.8%). [1]

Vitamin C Uses

Research for Vitamin C has been an extended effort among leading scientists to discover new applications for this nutrient. Currently we know that vitamin C is integral in the formation of collagen, a protein that gives structure to bones; cartilage, muscle, and blood vessels. It also helps to maintain capillaries, bones, teeth, and aids in the absorption of iron. [2]

Vitamin C’s most intriguing function may lye within its antioxidant properties. (see Vit.E for antioxidant info) Combined with Vitamin E, these two vitamins enhance each others’ chemical potency and protective anti-oxidative properties from free radical damage. Another preventative measure provided by Vitamin C is its ability to lower stressor hormones (norepinephrine and epinephrine) and inflammatory reactions in the body. This is likely due to the anti-histamine activity found in its many chemical constituents.

The immune system is an important factor for our body’s protection from illnesses ranging from the common cold, to the most severe of chronic diseases, like cancer. Clinical studies indicate that the severity and duration of these afflictions may be lessened when Vitamin C is taken in moderately higher dosages. [3, 4] As well, when persons are taking aspirin, birth control pills, or dilantin, Vitamin C intake must be increased. Wound healing and scar tissue formation is another important element of Vitamin C supplementation. Physicians often prescribe patients extra Vitamin C (100 - 300 milligrams (mg) per day) after various surgeries, including burned patients. [5]

The dietary supplementation of vitamin C may also support HDL (good) cholesterol levels, while preventing the conversion to LDL cholesterol (bad) levels; also inhibiting the development of atherosclerotic plaque that encases ones arteries due to elevated LDL levels in the blood. [7, 8]

Osteoporosis is another chronic disease that Vitamin C may positively influence. There has been much research done regarding Vitamin C and its impact upon bone density. As bone mineral density decreases with age, this important water-soluble vitamin may help to nourish and support overall bone mineral density. [8] This is very important in elderly populations. According to the National Osteoporosis Foundation, over half of Americans older than fifty have significantly lowered bone mineral density; of these, some 80% are women. [9] Long term supplementation with Vitamin C may prove extremely beneficial in these persons.

Vitamin C Dosages

RDA dosages defined: [10]

AdultsSmokersChildren PregnancyLactation
60mg/day 100/mg day Age 0-11 45 mg/day 70mg/day 95mg/day
Age 11-18 50mg/day

Vitamin C Toxicities

Many toxicities have been studied and routinely occur when large doses of Vitamin C are implemented. Toxicities that may result with “mega doses” of Vitamin C (over 2.5 grams/day) include:

  • Drop in plasma ascorbate levels
  • Kidney Stones
  • Gastrointestinal irritation
  • Uricosuria (uric acid in urine) - 15% of population [seen in people predisposed to gout] [11]
  • Impaired bactericidal activity of leucocytes
  • Possible fetal teratogen

Vitamin C Deficiencies

Deficiency is very rare. Signs include bleeding gums, loose teeth, easy bruising, dry rough skin, loss of appetite, slow healing and extreme cases; the development of scurvy. [12] These symptoms usually result from nutritional negligence, alcoholism, or also in the occurrence of extreme poverty. All deficiency symptoms respond rapidly to either the natural or synthetic ingestion of ascorbic acid (Vitamin C). It is extremely important to note that if symptoms are not detected and the deficiency not corrected, death is eminent.

References

1. Gerrior SA, Zizza C. 1994. Nutrient Content of the U.S. Food Supply, 1090-1990. Home Economics Research Report No. 52. U.S. Department of Agriculture, Washington, D.C.

2. 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.

3. Pauling L. How to Live Longer and Feel Better. New York: W.H. Freeman and Company; 1986:118-21.

4.Van Straten M, Josling P. Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled survey. Adv Ther. May2002;19(3):151-9. J. 1954;71:562-68.

5. Ringsdorf WM Jr, et al. Vitamin C and Human Wound Healing. Oral Surg Oral Med Oral Pathol. Mar1982;53(3):231-36.

6. Jialal I, et al. Physiologic Levels of Ascorbate Inhibit the Oxidative Modification of Low Density Lipoprotein. Atherosclerosis. Jun1990;82(3):185-91.

7.Cheung MC, Zhao XQ, Chait A, Albers JJ, Brown BG. Antioxidant supplements block the response of HDL to simvastatin-niacin therapy in patients with coronary artery disease and low HDL. Arterioscler Thromb Vasc Biol. Aug2001;21(8):1320-6.

8. Morton DJ, Barrett-Connor EL, Schneider DL. Vitamin C supplement use and bone mineral density in postmenopausal women. J Bone Miner Res. Jan2001;16(1):135-40.

9. National Osteoporosis Foundation. Disease Statistics. Available at: http://www.nof.org/osteoporosis/stats.htm. Accessed Jul2002.

10. Clinical Nutrition Service, Warren Grant Magnuson Clinical Center, National Institutes of Health (NIH), NIH. Vitamin E December. 9. 2002. http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/101840.shtml

11. Mitch WE, et al. Effect of large oral doses of ascorbic acid on uric acid excretion by normal subjects. Clin Pharmacol Ther. Mar1981;29(3):318-21.

12. Herbert, Victor. “Vitamins and Minerals Plus Antioxidant Supplements” Total Nutrition Ed. Victor Herbert, M.D., Genell J. Subak-Sharpe, M.S. New York: Saint Martin’s Griffin, 1995. 94-118