The Role of Nutrition in Wound Healing
Wound healing is a complicated sequence of biological and molecular events that occur over distinct phases. Acute wounds exhibit no pathophysiological defects, allowing them to heal quickly. Chronic non-healing wounds, on the other hand, have underlying pathophysiological abnormalities that prevent them from achieving a predictable sequence of repair, resulting in impaired or delayed healing. Chronic wounds place an enormous strain on healthcare resources in the U.S., with up to $25 billion spent annually.
Wound care, efforts aimed at speeding the rate of healing in acute and chronic wounds, include societal, social, physiologic, immunologic, and physical processes. However, an essential, yet often ignored piece of the puzzle is the role of nutritional management. Malnutrition is a risk factor with significant effects on the chronicity of wounds in patients of various demographics. This article will discuss the impact of macronutrients and micronutrients in the wound healing phases as well as some recognized tools utilized by healthcare professionals for diagnosing patients with chronic wounds that are at risk due to malnutrition.
How Malnutrition Affects Wound Healing
According to the WHO, malnutrition is an imbalance, deficiency, or overconsumption in a person’s intake of energy and nutrients. Some risk factors that contribute to malnutrition include a lack of appetite, temporary loss of the sense of taste and smell, a high-calorie diet, or inability to feed oneself. Physiological symptoms of malnutrition include extreme weight loss (anorexia), obesity, and localized or general fluid accumulation in some patients.
Very high or low body mass index (BMI) measurements can also be a symptom of malnutrition. According to research, senior populations (65 years or older) are at a disproportionate risk of nutritional deficiencies than other demographics. Factors that could contribute to malnutrition in the elderly include health conditions, lower energy levels, psychological stress, and economic challenges that affect the type, quantity, and quality of food consumed daily.
The Role of Macronutrients and Micronutrients
Chronic wounds place an increased energy and nutrient demand on the body to support healing processes. Supplementing macronutrients, such as proteins, carbohydrates, fats, and fluids, and micronutrients, including amino acids and vitamins, can have beneficial effects on various phases of wound healing.
Proteins enable fibroblast proliferation in chronic wounds. They aid collagen synthesis and the formation of platelet plugs, leukocytes, monocytes, and lymphocytes. Chronic non-healing wounds, such as pressure ulcers, venous ulcers, and diabetic lesions increase the demand for proteins and energy by up to 250% and 50% respectively. Also, large quantities of proteins are lost via wound exudates. Protein-calorie malnutrition (PCM), also known as Protein-energy malnutrition (PEM), is a common risk factor affecting wound chronicity and results from protein and energy-deficient diets.
Carbohydrates essential for insulin production, which supports anabolic processes in the proliferative phase of wound healing. They release energy to facilitate inflammation, angiogenesis, collagen synthesis, and increased cellular activity. Adequate intake of carbohydrates is known to promote fibroblast production and increase leukocyte activity. However, excessive sugar levels in the blood (hyperglycemia) can increase the risk of infection and lower granulocyte function.
Like carbohydrates, fats release additional energy to support the healing process in chronic wounds, such as inflammation, angiogenesis, collagen synthesis, and cellular proliferation. Their lipid components aid the growth of new tissue and wound remodeling. Fats also play a role in absorbing fat-soluble micronutrients, such as Vitamins A, D, and E, and Omega-3 and Omega-6 fatty acids. They can be obtained from a variety of sources including dairy products.
Amino acids, such as arginine and glutamine, can play key roles in wound healing, although they are conditionally essential. Arginine, which is synthesized from citrulline in the liver and kidney, is a known precursor to nitric oxide, which aids the inflammatory response. Moreover, arginine also aids collagen synthesis for the wound repair process. The recommended daily dosage of arginine supplements in patients with chronic wounds with adequate protein intake is about 4.5 g/day. However, it is non-beneficial in patients with protein deficiency. Glutamine, which can be derived endogenously, can also help to minimize the risk of infectious complications and inflammatory injury in patients with chronic wounds and may serve as an energy source.
The roles of vitamins in wound healing have been studied extensively over the years and are found to aid several enzymatic processes that improve wound outcomes. Vitamin A deficiency in patients with chronic wounds results in decreased antibody production and altered B-cell and T-cell functions during wound inflammation and impairs collagen synthesis during remodeling. Vitamin A supplementation has been found to regulate the proliferation of fibroblasts, melanocytes, epithelial cells, and endothelial cells by binding itself to retinoic acid receptors. B Vitamins (thiamine, folic acid, riboflavin, cobalamins, pyridoxine, and pantothenate) serve as essential cofactors for facilitating anabolic processes in wound healing and enzymatic reactions for leukocyte formation. A deficiency of B vitamins in patients with chronic wounds may result in an increased risk of infectious complications and impaired antibody production. Also, Vitamin C supplementation is useful for preventing the production of free radicals and increases the rate of wound healing by aiding angiogenesis, collagen synthesis, and cellular migration and transformation.