Vitamin C and pressure ulcers

Advances in Skin & Wound Care,  Jul/Aug 2002  by Collins, Nancy

• E-mail
• Print
• Link

Q: We are revising our nutrition protocol for patients with pressure ulcers. Should we routinely provide supplemental vitamin C for patients with pressure ulcers and, if so, how much? A:Vitamin C is often associated with wound healing because it is essential for collagen formation. Adequate amounts of vitamin C are needed to form a cosubstrate in the hydroxylation of proline to hydroxyproline and lysine to hydroxylysine. Hydroxyproline and hydroxylysine are essential for stabilizing the triple helix structure of collagen with strong hydrogen bonding and crosslinks. Without this stabilization, the structure disintegrates rapidly.1 Vitamin C also gives tensile strength to newly built collagen; without this, new tissue could not stretch without tearing. Tensile strength is an important aspect in pressure ulcer healing because healed pressure ulcers are susceptible to future skin breakdown.

Vitamin C is perhaps best known for its antiscorbutic and antioxidant properties. In cells and body fluids, vitamin C helps prevent damage to tissues, which may be important in preventing certain diseases. In the intestines, vitamin C protects iron from oxidation, enhancing iron absorption.2 Vitamin C also gives strength to capillary walls in vascular tissue.

Requirements

Most clinicians refer to the National Academy of Sciences-- National Research Council (NAS-NRC) Recommended Dietary Allowances (RDAs) for specific recommendations of vitamin C intake. The NAS-NRC updated its recommendations for vitamin C in 2000 as part of the Dietary Reference Intakes (DRI) program. The DRI provides RDAs and Upper Limits (ULs) that are age- and gender-specific. The UL is the maximum level of daily intake that is not likely to pose a risk of adverse effects.

Table 1 outlines RDAs and ULs for vitamin C; however, the RDA is for healthy people and does not address illness or infirmity. The RDA of vitamin C is 75 mg per day for healthy adult females and 90 mg per day for healthy adult males.3 Females require a lower amount of vitamin C because of their smaller lean body mass. Individuals who smoke require an additional 35 mg per day because smoking increases oxidative stress and metabolic turnover of vitamin C.3

The Agency for Health Care Policy and Research (AHCPR, now the Agency for Healthcare Research and Quality) clinical practice guideline for the treatment of pressure ulcers states that vitamin and mineral deficiencies have been demonstrated in the majority of patients in nursing home studies. The guideline recommends a daily high-potency vitamin and mineral supplement for all patients suspected of having a vitamin deficiency. Although this recommendation has a strength of evidence rating of C4-meaning there is clinical opinion but no collection of rigorous, controlled studies to back it up-it seems practical to provide additional vitamin C to patients who are suspected of having a deficiency. In fact, most of the wound healing literature includes recommendations to provide adequate amounts of vitamin C for healing based on its function in the hydroxylation of hydroxyproline rather than on the results of specific placebo-controlled studies.

Sources of Vitamin C

Vitamin C is a water-soluble vitamin. Water-soluble vitamins are not stored in the body and must be replenished daily. Vitamin C is the most unstable of all water-soluble vitamins, with cooking. handling, and processing affecting its content in food. The vitamin is easily destroyed by oxygen, alkalis, and high temperature, and it also reacts with the metallic ions of iron and copper.

All health care menus should include at least 1 daily source of vitamin C. Food is always the best source of nutrients and many foods contain vitamin C. In addition, manufacturers sometimes add vitamin C to foods as a preservative because of its well-known antioxidant properties.

Despite the best nutritional plans, however, your patient may not be getting as much vitamin C as you think. Not every patient will consume 100% of a menu item containing vitamin C or even choose it on a selective menu. Vitamin C also may not be present in its projected amounts because of the way the food was handled or due to seasonal variations in fresh produce. In addition, the amount of vitamin C excreted is elevated during times of psychological or physiologic stress, such as experiencing a pressure ulcers This is because vitamin C plays a role in the hydroxylation of certain steroids synthesized in adrenal tissues. When a patient is under stress, the stress hormone activity is high, depleting the adrenal tissue of vitamin C.2

Deficiency of Vitamin C

The deficiency state of vitamin C is known as scurvy, which is characterized by lack of integrity of the blood vessels, including fragile, easily ruptured capillaries with diffuse tissue bleeding.2 Clinicians often notice gingivitis and bleeding gums in patients with a vitamin C deficiency, as well as bruised skin with many pinpoint hemorrhages. The skin may become rough, brown, and blotchy with bruises. Wound healing may become impaired due to the lack of normal collagen synthesis. Symptoms of scurvy will typically manifest after 45 to 80 days of vitamin C deprivation5 and can be reversed with 100 mg of vitamin C per day.6