Targeted Nutritional Strategies
Essential Nutrients for Wound Healing
Based on extensive biological and metabolic changes that occur after trauma, nutritional supplementation is often required. The following nutritional factors have been shown to support the body's enhanced metabolic demands:
Calories. Wound healing consumes energy. Ordinarily, carbohydrates and fats are the main sources of energy. During the stress response, proteins are also broken down to provide energy. To prevent loss of lean body mass, sufficient energy supply has to be maintained. After trauma, caloric requirements may be increased up to 25 to 30 calories per kilogram of body weight daily (Leininger 2002).
Carbohydrates. Carbohydrates are a rich source of cellular energy during wound healing. After a wound, carbohydrates:
- Help meet the body's heightened energy requirements
- Aid in fibroblast movement, which is vital in wound healing
- Enhance white blood cell activity to strengthen immune response
Protein. Proteins are a vital component of collagen synthesis. Therefore, insufficient protein can affect the rate and quality of wound healing. Trauma increases the demand for protein. This requirement is further increased in the event of sepsis or stress. Wound healing requires 1.5 to 3 grams per kilogram (of body weight) per day of protein; this requirement may vary depending on the type of wound (Leininger 2002).
Fats. Fats are a concentrated source of calories. Supplementation with certain fatty acids is essential. They play the chief role in cell membrane structure and function, as well as help wound healing. It is recommended that 20% of calories be obtained from fat, especially monounsaturated fat. Fats are also implicated in the synthesis of new cells; therefore, low fat levels would delay wound healing.
Vitamin A. Vitamin A is indispensable for normal growth and differentiation of skin, making it significant in wound healing. Vitamin A increases the strength of scar tissue. It is required for an adequate inflammatory response and has been used to counteract the catabolic effect glucocorticosteroids exert on wound healing (Ehrlich 1973). The improvement in wound healing from vitamin A supplementation is also attributed to an increase in collagen cross-linking, which results in higher tensile strength (Seifter 1975).
Vitamin C. Wound healing requires more vitamin C than diet alone can provide (MacKay 2003). As vitamin C is water soluble, it has to be taken daily. Vitamin C is important for proper function of the enzyme protocollagen hydroxylase, which generates collagen. Vitamin C forms bonds between strands of collagen fibers and helps provide extra strength and stability. It is also essential for synthesis of the intracellular matrix of tissues such as bone, skin, blood vessel walls, and connective tissue. Finally, vitamin C is a potent antioxidant; studies have shown elevated levels of reactive oxygen species (a kind of free radical) in wounds (Gupta 2002; Sen 2002).
Zinc. Zinc is a trace mineral present in the body in only a small quantity. However, it is found in many tissues, including bone, skin, muscle, and organs, and is required in as many as 300 enzymatic reactions. Zinc is used in DNA synthesis, cell division, and protein synthesis; also, it mediates the maturation of T-lymphocytes (Prasad 1995).The body's need for zinc increases during cell proliferation and protein secretion.
Water. Meeting hypermetabolic needs may leave the body dehydrated. Not only is it essential to maintain hydration, but the need for hydration increases if a wound is draining or a person is on an air-fluidized therapy bed. Trauma patients' daily requirement of water may range from 1500 to 2000 milliliters (mL) (Leininger 2002).
The Therapeutic Role of Nutrition
Hypermetabolic effects of stress may require special or high-dose nutrients for enhanced wound healing and uneventful recovery.
Arginine. Arginine fuels the cellular immune response and fights against bacterial challenges. It is an essential precursor to protein synthesis at the wound site and increases local wound immune function. Researchers have found that in the case of trauma and surgery, arginine requirements increase to 17 to 25 grams of oral arginine daily, in contrast to the normal daily requirement of 5 grams (Barbul 1991; Kirk 1993). Enhanced wound healing has been observed with large doses of arginine (Patel 2005).
Glutamine. Glutamine is a key substrate for fast-growing and multiplying cells, including white blood cells. Glutamine stimulates the proliferation of fibroblasts, thereby helping in wound closure. It is the major amino acid lost during any tissue injury, implying a significant role in the preservation of lean body mass. According to researchers, glutamine possesses anabolic properties, which are effective in wound healing only when present in amounts 2 to 7 times greater than required in healthy persons (Roth 1990).
Bromelain. Bromelain is a proteolytic enzyme derived from pineapple stem. This anti-inflammatory enzyme possesses the ability to break down or dissolve proteins. This property can be utilized to reduce muscle and tissue swelling, especially following injuries or surgery (MacKay 2003). Use of oral bromelain over the postoperative period results in faster resolution of swelling and decreased dependence on analgesics in fracture patients (Kamenicek 2001). Similar results have been recorded after dental surgery (Tassman 1964) and musculoskeletal trauma (Masson 1995).
Glucosamine. Glucosamine provides the raw material needed to repair connective tissue found in skin, tendons, ligaments, and joints (McCarty 1996; Zupanets 2002). Animal studies show that levels of glucosamine increase in injured tissue during healing (Lehto 1985). Although human studies on the effect of glucosamine during wound healing have not yet been published, recent reviews of perioperative nutrition recommend glucosamine 1500 mg daily until healing is complete (MacKay 2003).
Aloe vera. The healing properties of aloe vera have been known for centuries. Used as a topical application, aloe stimulates collagen synthesis and has been shown to promote wound healing (Chithra 1998a). Animal studies have demonstrated beneficial effects of aloe vera in healing frostbite, electrical injuries, and diabetes (Miller 1995; Chithra 1998b; Davis 1987, 1988). Aloe vera improves the permeability of cell walls, boosts nutrient influx into cells, and removes toxins from cells (Vogler 1999).
Curcumin. Curcumin, an extract of the spice turmeric, is used to reduce inflammation as well as treat wounds and skin ulcers. Research shows that it has antioxidant properties and other health benefits (Nirmala 1999). It also improves formation of new skin and the migration of immune cells necessary for wound healing (Sidhu 1999). Specifically, it has been shown to enhance muscle regeneration in muscle injury (Thaloor 1999).
Omega-3 fatty acids. Omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are anti-inflammatory and have wide-ranging effects. They stimulate the immune system by enhancing T-cell and natural killer cell activity. Because the body's need for fats increases under conditions of stress, omega-3 fatty acids play an important role in the healing process.
Boosting Growth Factors
Growth factors are small proteins that enable cells to communicate. There are 7 major growth factor families: epidermal growth factor, transforming growth factor-beta, insulin-like growth factor 1, interleukins, platelet-derived growth factor, fibroblast growth factor, and colony-stimulating factors.
Growth factors have a number of functions in wound healing (Steenfos 1994):
- Forming granulation tissue
- Increasing connective tissue by creating new blood supply
- Promoting remodeling and growth of new skin
- Attracting proteins and immune cells to fight infection
Studies have shown that various growth factors are diminished after trauma. For instance, serum levels of insulin-like growth factors are decreased during critical illness (Timmins 1996). Nutrients that stimulate secretion of growth factors may assist recovery from trauma. Various supplements have been studied for the ability to boost growth factors, including the amino acid arginine, omega-3 fatty acids, and nucleotides (Daly 1992).
Arginine, a semi-essential amino acid, helps in wound healing and recovery from stress. In addition, arginine enhances immune response of trauma patients. In a study of healthy people and surgical and intensive care unit patients, arginine was shown to increase lymphocyte and monocyte proliferation and enhance helper T cell formation (Kirk 1990). Arginine also increases intestinal calcium absorption and collagen synthesis.
Ornithine alpha-ketoglutarate (OKG), a salt formed of two molecules of ornithine and one molecule of alpha-ketoglutaric acid, is a promising anticatabolic agent that promotes wound healing and protein synthesis. Researchers have hypothesized that OKG works by upregulating glutamine and arginine production (Cynober 1991).
Glutamine supplementation in critically ill patients has been shown to improve gut-associated lymphoid tissue function and enhance immune defense against infection (Jones 1999).