Conditionally Essential Amino Acids and Nutritional Supplements in Wound Care
by Mary Ellen Posthauer RDN, CD, LD, FAND
The protein in the food we eat supplies the body with the amino acids necessary to make its own protein. There are certain amino acids that the body cannot produce, and some that are unable to be made fast enough to meet the body’s needs. The nine amino acids that must be supplied from the protein in foods are called “essential” or “indispensable” amino acids.
Last month I discussed the importance of offering clients with wounds food sources with high biological value. Valuable biological foods contain all of the essential amino acids necessary to repair tissue, fight infection, and reduce protein energy malnutrition.
When the body experiences periods of extreme trauma or stress from thermal injury, sepsis, surgery, or wounds, nonessential amino acids become conditionally essential, or conditionally indispensable. The physiological demands of recovery may result in the need for these nonessential amino acids to be greater than the body’s ability to produce them. As a result of these demands, the body’s supply of nonessential amino acids must be provided by the diet. Arginine, glutamine, and cystine are examples of conditionally essential amino acids that have been combined with other nutrients in supplements formulated for wound healing.
L-Arginine is 32% nitrogen, and has several functions including accelerating insulin secretion, stimulating protein regeneration, and promoting the transport of amino acids into the cells. Nitric oxide is essential for wound healing because it increases the oxygen and blood flow to the wound, increases collagen formation, and reduces inflammation. While arginine is the only producer of nitric oxide, 40% of ingested arginine is broken down by the intestines and liver, which reduces the amount available for nitric oxide production. One wound care product is formulated with citrulline, a precursor to arginine. Citrulline circumvents the liver and intestine breakdown, converts to arginine, and increases nitric oxide production.
Several studies have shown a reduction in PUSH scores when individuals consumed oral supplements containing arginine. However, the composition of the supplements usually included protein, ascorbic acid, and zinc, making it difficult to conclude whether reduced pressure ulcer healing time was the result of the arginine alone or in combination with the other nutrients.
Glutamine functions as a fuel source for fibroblasts and epithelial cells needed for healing. While the safe maximum dosage for glutamine has been established as 0.57 grams per kilogram of body weight, studies on the effectiveness of consuming supplements containing glutamine to heal wounds are inconclusive.
Cystine is required to synthesize glutathione, the cell's major antioxidant that plays a key role during tissue repair and collagen synthesis. It promotes positive nitrogen balance by minimizing muscle breakdown and rebuilding lean body mass (LBM).
HMB is an amino acid metabolite found in foods that slows protein breakdown and promotes the production of lean body mass. Since lean body mass decreases as we age, its preservation is important for healing, especially for the frail elderly. An oral nutritional supplement formulated with glutamine, HMB, and arginine to increase collagen formation is marketed for wound healing.
There are a variety of nutritional supplements containing a blend of protein, amino acids, and other key nutrients for wound healing. Research to confirm the impact of these conditionally essential amino acids on wound healing continues to be important.
Barbul A, Lazarou SA, Efron DT, Wasserkrug HL, Efron G. Arginine enhances wound healing and lymphocyte immune response in humans. Surgery 1990;108:331-7.
Desneves K J, Todorovic B E, Cassar A, & Crowe T C. Treatment with supplementary arginine, vitamin C and zinc in patients with pressure ulcers: a randomized controlled trial. ClinNutr. 2005 Dec; 24(6):979-87.
van Anholt RD, Sobotka L, Meijer EP, Heyman H, Groen HW, Topinková E, van Leen M, Schols JMGA.Specific nutritional support accelerates pressure ulcer healing and reduces wound care intensity in non-malnourished patients. Nutrition. 2010 Sep;26(9):867-72.
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.