By Mary Ellen Posthauer RDN, CD, LD, FAND
Metabolic Roles of Vitamin C
The major function of vitamin C (ascorbic acid) in wound healing is assisting in the formation of collagen, the most important protein of connective tissue. Vitamin C, a water-soluble vitamin found in water-filled foods, dissolves in water and is transported in the bloodstream. Excess amounts are excreted in the urine; however, since the body does not store vitamin C, food sources should be consumed on a regular basis. Vitamin C supplementation has been shown to increase tensile strength and collagen synthesis by assisting in the hydroxylation of lysine and proline, major constituents of collagen.
Vitamin C is the principal water-soluble antioxidant in plasma. As an antioxidant, vitamin C's action is twofold: first, by being oxidized itself, vitamin C regenerates already oxidized substances such as iron or copper to their active form; second, in the process, the vitamin removes the damaging oxidizing agent. In the intestines it enhances iron absorption by protecting it from oxidation. Individuals who are taking an iron supplement will increase their iron absorption by eating foods high in vitamin C at the same time. Vitamin C is a cofactor with iron during the hydroxylation of proline and lysine in the production of collagen, making it important for tissue repair and regeneration. Vitamin C and iron deficiencies are both manifested by decreased collagen synthesis, which can result in delayed healing and capillary fragility. Wounds may fail to heal because scar tissue doesn't form. Ascorbic acid deficiency is also associated with impaired immune function, which can decrease the ability to fight infection.
Deficiency Symptoms
Scurvy, the vitamin C deficiency disease, is rare except in severely malnourished individuals. Vitamin C deficiency symptoms include petechial hemorrhage, bleeding gums, ecchymoses, and hyperkeratosis. Scurvy is easily reversed with the consumption a moderate dose of 100mg daily of vitamin C, which is achieved with the consumption of fruits and vegetables. The current Dietary Reference Intake (DRI) for vitamin C is 90mg for men and 75mg for women. Due to the oxidative damage of nicotine, smokers are encouraged to increase their intake of vitamin C by 35mg. Significant sources are citrus fruits, dark green vegetables, cantaloupe, strawberries, peppers, tomatoes, potatoes, papaya, and mangoes.
Despite the apparent benefits of vitamin C, research has not proven that taking high doses will accelerate pressure ulcer healing. A randomized control trial by Dr. Gerben ter Riet demonstrated no improvement in pressure ulcer healing with 1000mg supplemental vitamin C (1). However, individuals with wounds should continue to consume a balanced diet with a good source of vitamin C daily. Oral nutritional supplements prescribed for individuals with wounds contain vitamin C, along with other vitamins and minerals. If an individual has a poor appetite or does not eat a balanced diet, a daily multivitamin that meets the RDI's would be appropriate. The multivitamin should be taken with food at a consistent time each day. Taking large doses of vitamin C may cause adverse effects, such as gastrointestinal distress and diarrhea, which may negatively impact wound healing.
Sources
1. ter Riet G, Kessels A G, & Knipschild P G. (1995). Randomized clinical trial of ascorbic acid in the treatment of pressure ulcers. J Clin Epidemiol, 48(12), 1453-1460.
2. Vilter RW. Nutritional aspects of ascorbic acid: uses and abuses. West J Med 1980;133:485-492.
3. Molnar JA. Overview of Nutrition and Wound Healing. In: Molnar J, editor. Nutrition and Wound Healing . First Edition ed. Boca Raton, FL: CRC Press; 2007. p. 1-14.
4. Ronchetti IP, Quaglino D, Bergamini G. Ascorbic Acid and Connective Tissue. Subcellular Biochemistry, Volume 25: Ascorbic Acid: Biochemistry and Biomedical Cell Biology. Plenum Press, New York, 1996.
About The Author
Mary Ellen Posthauer RDN, CD, LD, FAND is an award winning dietitian, consultant for MEP Healthcare Dietary Services, published author, and member of the Purdue University Hall of Fame, Department of Foods and Nutrition, having held positions on numerous boards and panels including the National Pressure Ulcer Panel and the American Dietetic Association's Unintentional Weight Loss work group.
The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.
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