Q: How much protein does a patient with a wound require? What are some ways to increase the amount of protein in the diet?
A: Protein is an essential nutrient for health. Understanding the role of protein in the body is an important first step in determining how much and what kind a patient with a wound will need.
Functions of Protein
The primary function of dietary protein is to provide amino acids.1 Protein is different than carbohydrates and fats because it contains approximately 16% nitrogen, which gives rise to amino acids. Amino acids are classified as essential or nonessential.2 The essential amino acids must be supplied through diet because the body either cannot manufacture them or cannot do so in sufficient quantities to meet physiologic needs. The nonessential amino acids can be made by the body if given sufficient building blocks to do the job.
Protein has many specific functions in the body, including helping to maintain fluid and acid-base balance, acting as a transporter of certain materials, playing a role in the immune system, and providing energy if there is insufficient glucose and fatty acids to keep the cells furnished adequately.3 Perhaps the most important function of protein in a patient with a wound is growth and repair. The body constantly deposits protein into new cells to replace protein that has been lost. New living tissue cannot be built without protein, so it follows that no wound can heal without adequate protein from which to build new tissue.
The National Research Council's recommended dietary allowance (RDA) for protein is 0.8 grams of protein per kilogram of body weight each day.3 For example, based on the RDA, a 120-pound adult would require 43.6 grams of protein per day (120 lbs ÷ 2.2 = 54.5 kg × 0.8). Generally, 1 ounce of protein is equivalent to 7 grams, so 43.6 grams is approximately 6 ounces per day. The typical American consumes almost double that amount each day. Table 1 shows the protein content of various food groups.4
The RDA is based on the needs of healthy adults. Most patients, especially those with wounds, would not fall into the category of "healthy adult." This raises the question of how much protein above the RDA should be estimated for a patient with multiple diagnoses, including a wound. Thomas5 states that the provision of 1.2 to 1.5 g/kg of protein per day should be the goal for a patient with a wound. According to Demling et al,6 a patient with protein-energy malnutrition, wounds, and a history of involuntary weight loss may have protein needs of 1.5 to 2.0 g/kg. DeBiasse7 states that 1.5 g/kg of protein is appropriate for most critically ill patients, except those who have a large burn injury or those who are highly stressed; for these patients, 2.0 g/kg of protein is reasonable.
Many other sources could be cited, but the recommendation generally ranges from 1.2 to 2.0 g/kg of protein. The best policy is to evaluate the whole patient and use clinical judgment. Minimally, this evaluation should include a physical examination for signs and symptoms of catabolism, a dietary history to determine usual dietary protein intake, a weight history to determine if involuntary weight loss has occurred, and protein laboratory studies to determine current protein stores. Wound history, drainage, and depth of tissue destruction should also be taken into account.
For wound healing to take place, both energy and protein needs must be met. If energy (calories) is insufficient, the protein will be utilized to provide glucose rather than to enhance tissue repair.
Increasing Protein Intake
To reach the level of 1.5 g/kg of protein or higher per day, supplementation will usually be necessary. There are many ways to supplement protein. The most common way is by providing a canned beverage. Table 2 lists the calorie and protein content of various supplements from several major companies. Many more products are available with differing levels of calories and protein. When reviewing products for cost-effectiveness, remember that an 8-ounce glass of whole milk provides 150 calories and 8 grams of protein.
Most patients tire quickly of the same supplement day after day. If a supplement is not consumed, it does no good and is a waste of money. Variety is key and items such as high-protein cookies, high-protein gelatins, nutrition bars, and enriched foods (eg, soups and mashed potatoes) should be served. Many products can add nutrient density to meals, including protein powders. Protein powders are generally well accepted by patients and can be added to prepared foods. Most powders provide 4 to 5 grams of high quality protein per tablespoon. Adding 1 tablespoon to each meal provides an extra 12 to 15 grams of protein per day.
All protein is not of the same quality. Emphasis should be placed on providing high-biologic value protein that is easily digested and absorbed, such as protein commonly found in eggs, meat, poultry, and fish. If budget constraints restrict the number of convenience products available, recipe modification and certain food preparation techniques can be used to provide higher amounts of calories and protein in common foods. Snacks may be as simple as a hard-boiled egg (80 calories and 7 grams of protein) or cheese sticks. For patients who consume at least 75% of most meals, another technique is to serve an extra ounce of entree at each meal because the entree usually contains high-quality protein. Encourage milk drinkers to consume an extra glass of milk (or chocolate milk for variety). If a patient drinks only coffee, a product such as NuBasics Coffee from Nestle Clinical Nutrition may be served to provide 125 calories and 6.25 grams of protein per 6 ounce cup; an ordinary cup of coffee has no appreciable calories or protein. Again, the best policy is to treat each patient as an individual and find out what foods would be accepted and preferred. A variety of flavors and textures are crucial to the success of any supplementation program.
1. Williams SR. Nutrition and Diet Therapy. 8th ed. St Louis, MO: Mosby-Year Book, Inc; 1997. p 95.
2. Mahan LK, Escott-Stump S. Krause's Food, Nutrition & Diet Therapy. 10th ed. Philadelphia, PA: WB Saunders Company; 2000. p 54.
3. Cataldo CB, DeBruyne LK, Whitney ER. Nutrition and Diet Therapy. 4th ed. Minneapolis/St. Paul: West Publishing Co; 1995. p 77-91.
4. Florida Dietetic Association. Handbook of Medical Nutrition Therapy: The Florida Diet Manual. 2000 ed. Tallahassee, FL: Florida Dietetic Association; 2000. p L1.6.
5. Thomas DR. Specific nutritional factors in wound healing. Adv in Wound Care. 1997;10(4):40-3.
6. Demling RH, Stasik L, Zagoren AJ. Protein-energy malnutrition and wounds: nutritional intervention. Treatment of Chronic Wounds Number 10. Hauppauge, NY: Curative Health Services, 2000.
7. DeBiasse MA, Wilmore DW. What is optimal nutrition support? New Horizons. 1994;2:122-30.