In this issue, Susan Weiner, MS, RDN, CDE, CDN, talks with nutrition and wound care expert Nancy Collins, PhD, RDN, LD, NWCC, FAND, about the role of nutrition in prevention and treatment of diabetic foot ulcers. Nutrition is a critical component of healing diabetic foot ulcers, particularly as it relates to immune function, malnutrition, glycemic control, and weight loss and weight maintenance. Diabetes educators should include nutrition assessment and intervention as key components of the overall diabetes treatment plan to help patients with diabetic foot ulcers maximize their nutritional status and promote wound healing.
Nutrition is not often the first thing clinicians think of when dealing with diabetic foot ulcers. How important is it, and exactly what role does nutrition play?
Collins: Nutrition does indeed play an important role in the prevention and treatment of diabetic foot ulcers. A poor diet can result in altered immune function, malnutrition and poor glycemic control, all of which are risk factors for poor healing. Malnutrition and nutrient deficiencies can impair collagen synthesis, prolong inflammation, decrease phagocytosis causing dysfunction of B and T cells, and decrease the mechanical strength of the skin. Once a patient has a wound, achieving and maintaining a healthy body weight can help maximize wound healing because obesity can negatively affect glycemic control. Often just losing extra weight can help with glucose control and, in turn, wound healing. Of course, weight loss proves very challenging for most patients. This is where referral to a registered dietitian nutritionist with expertise in diabetes can help.
How does elevated blood glucose interfere with wound healing?
Collins: High blood glucose can lead to defective white blood cell function and make a diabetic foot ulcer susceptible to infection. It also can affect the production of inflammatory molecules, interfere with collagen synthesis and change cellular morphology. In a study of patients at the Johns Hopkins Wound Center, elevated HbA1c was significantly associated with poor wound healing.
Food choices, including the timing and carbohydrate content of meals and snacks, can affect glycemic control. Any form of carbohydrate when eaten in excess (including whole grains and not just simple sugars) can affect blood glucose, so portion control of all carbohydrates is important. Choosing whole-grain breads and cereals, instead of refined grains, will provide added fiber, vitamins and minerals. A registered dietitian nutritionist can help patients learn to choose appropriate carbohydrate portions and balance food with oral medications and insulin to help optimize glycemic control.
Are there vitamins or supplements that can maximize the rate of healing?
Collins: Many micronutrients are involved in wound healing, including vitamins A and C, magnesium, copper and zinc. Unfortunately, few studies address optimal intake levels or whether supplementation is beneficial. What we do know is that every patient should meet the Dietary Reference Intakes for vitamins and minerals for these and other nutrients daily. In addition, sometimes supplementation of specific nutrients is recommended if a deficiency is confirmed or suspected. The big unanswered question is whether we should supplement above the reference level, and if so, by how much? Many clinicians recommend additional vitamin C and zinc. Vitamin C is water soluble and may help in other areas, so I am not too worried about it if a patient wants to take additional vitamin C. Zinc, however, is more concerning because it is not water soluble, and long-term zinc supplementation may in turn cause a copper deficiency, so I am more hesitant to supplement zinc beyond correction of a deficiency.
I have heard that some patients receive amino acid supplementation. Can you explain amino acids and which ones are typically supplemented?
Collins: Amino acids are the building blocks of protein. A polypeptide chain is comprised of three categories of amino acids. Indispensable amino acids, also known as essential amino acids, are not synthesized by humans and must come from the diet. Dispensable amino acids, also known as nonessential amino acids, are produced by the body in sufficient amounts under normal, healthy conditions. Conditionally indispensable amino acids are produced in sufficient amounts by healthy individuals; however, in the presence of certain disease states or underlying physiologic stress, such as a chronic wound, supplementation often is required to achieve an adequate supply. Two conditionally indispensable amino acids that often are supplemented are arginine and glutamine.
In addition, a metabolic byproduct of leucine called beta-hydroxy-beta-methylbutyrate, or HMB, often is supplemented. HMB is a compound found in small amounts in the body and is available in certain foods, such as grapefruit, alfalfa and catfish. Approximately 5% of leucine is converted to HMB, which helps produce new tissue by slowing muscle breakdown and enhancing protein synthesis. Since the conversion rate is not high and the foods it is found in are not typically consumed in great amounts, we may supplement.
How do these amino acids aid in wound healing?
Collins: Nutrition intervention for wound healing has come far. Some of the latest information about amino acids explores the relationship between arginine, glutamine and leucine and a cellular protein called target of rapamycin, or TOR. TOR is involved in the cell signaling for protein synthesis and wound healing. It is a protein kinase that functions as a central element in signaling pathways involved in cell growth and proliferation, as well as in pathways of protein breakdown.
Mammalian target of rapamycin (mTOR) was discovered when rapamycin was tested as a cell growth inhibitor and a potential anticancer agent. Amino acids are involved because arginine, glutamine and leucine all activate mTOR signaling. This is consistent with what is known about the roles of these amino acids in promoting anabolic processes, such as in wound healing. Evidence is accumulating to show that when the mTOR pathway is disrupted somehow, wound healing is altered.
Today’s wound management has become very technologically advanced, which may overshadow fundamental approaches such as nutrition. Without the proper amounts of nutritional substrate from which to build new tissue, wound healing may be impaired, so be certain to monitor your patient’s nutritional status for the best outcomes.
- Christman AL, et al. J Invest Dermatol. 2011;doi:10.1038/jid.2011.176.
- Jones MS, et al. Surg Infect (Larchmt). 2014;doi:10.1089/sur.2013.158.
- Tsourdi E, et al. BioMed Res Int. 2013;doi:10.1155/2013/385641.
- For more information:
- Nancy Collins, PhD, RDN, LD, NWCC, FAND, is a registered dietitian nutritionist with expertise in wound care, malnutrition and medico-legal issues. She can be reached at www.drnancycollins.com.
- Susan Weiner, MS, RDN, CDE, CDN, is the 2015 AADE Diabetes Educator of the Year and author of The Complete Diabetes Organizer and Diabetes: 365 Tips for Living Well. She is the owner of Susan Weiner Nutrition PLLC and is the Endocrine Today Diabetes in Real Life column editor. She can be reached at firstname.lastname@example.org.
Disclosure: Collins reports she is a consultant and member of the speakers bureau for Abbott Nutrition. Weiner reports she is a clinical adviser to Livongo Health.