When a person becomes hospitalised or affected by chronic health conditions like pressure sores, their nutritional health becomes the responsibility of the people who are looking after them – often, these carers are hospital staff or aged care workers.
Given the time-consuming nature of wound management, it can be easy to overlook the importance of diet in the healing process. Priority is given to external healing techniques, when, in reality, the most effective healing processes are generated by the body itself, which relies on the right combination of nutrients to function.
Although the external components of wound management are important, good nutrition is also critical for successful patient outcomes and ongoing prevention. It’s important for carers to understand the role dietary supplementation can play in the effective healing of wounds and in long-term prevention.
In this article, we’ll break down the role of nutrition in wound healing, examining things like how the body repairs wounds, the types of nutrients used in healing, and how to successfully integrate good nutritional practices into wound management.
How the Body Repairs Wounds
To understand the role nutrition plays in repairing patient wounds, we first need to examine how wound repair actually occurs.
The human body repairs wounds through a dynamic process that can be divided into four different phases: the coagulation phase, the inflammatory phase, the proliferative phase, and the remodelling phase [1, 9].
The coagulation phase is the first phase of wound repair, beginning as soon as an acute skin injury is inflicted. The body forms a fibrin plug (comprising platelets, fibrinogen, fibronectin, vitronectin, and thrombospondin) to begin haemostasis and protect the wound from infection .
The inflammatory phase is the second phase of wound repair, involving localised inflammation, involving redness, warmth, swelling, pain and loss of function [1, 2].
These bodily responses are designed to help prevent infection and kickstart the rest of healing process.
The proliferation phase follows the inflammatory phase. At this point, cells known as fibroblasts begin to advance from the edges of the wounds, using collagen to knit the tissue together . Once the wound is covered, the fibroblasts are transformed into myofibroblasts, and the injured tissue is replaced with new tissue .
After the proliferative phase, the new tissue (granulation tissue) comprises a jumble of different proteins, cells and fibres, including collagen . Gradually, the body reorganises the structure of this tissue to give it better tensile strength, which plateaus at about 80% of its original strength after one year .
The above descriptions are an extremely simplified breakdown of how wound repair works, but they’re enough for us to start understanding the role of nutrition in healing. Let’s move on.
The discipline that involves helping the body quickly and efficiently transition through the three stages of healing is known as ‘wound management’.
Wound management can involve a number of different techniques and potential complications.
Healing by primary intention is the attempt to close a wound through artificial measures like sutures, staples or tissue glue, typically within 4–8 hours of the wound occurring .
Delayed Primary Intention
Tertiary wound closure, or healing by delayed primary intention, normally occurs when a wound has passed the point of primary intention, requires debridement, is the result of severe crushing, is infected or needs extensive cleaning . Once the wound has undergone a period of observation and is found to be clean with good tissue viability, it can be surgically closed.
Healing by secondary intention is when the edges of the wound cannot be closed, meaning that the wound needs to heal from the base upwards . This is often the case with large wounds, pressure wounds or other types of irregular wounds. Moist dressings, topical agents and negative wound therapy are often used to assist with healing by secondary intention. For severe wounds, flaps and skin transplants may also be used.
There are many complicating factors that can slow or reverse wound healing, including:
- Infection of the wound
- Foreign bodies in the wound
- Underlying health conditions
- Poor nutrition
- Certain medications, like immunosuppressive agents, chemotherapeutic agents, corticosteroids, nonsteroidal anti-inflammatory drugs and anticoagulants 
A wound that fails to efficiently progress through the four phases of healing is known as a chronic wound.
How Nutrition Affects Wound Healing
Now we understand the basics of wound healing and wound management, we can examine how nutrition can impact the recovery process.
Macronutrients in Wound Healing
Energy and protein both play essential roles in wound healing, providing fuel for the body to repair damaged tissue.
Protein is arguably the most critical nutritional component of the wound healing process. It’s used for the synthesis of wound-healing enzymes, the proliferation of cells and collagen, and the creation of connective tissue . Remember the fibroblasts we talked about earlier? Without a sufficient supply of protein, they’re are unable to effectively proliferate and close wounds .
Lymphocytes, leukocytes, phagocytes, monocytes and macrophages, which are all immune system cells, are also composed mostly of protein . This means that a protein deficiency prevents the body from effectively creating an immune response (inflammation), increasing the chances of infection and slowing the healing process .
Protein expenditure also increases when a person is injured or sick, so patients, particularly those who are older, will need to increase their protein intake. Here’s a breakdown of Dietary Reference Intakes (DRIs) for exogenous proteins :
- Healthy adults: 0.8 grams/kilogram of body weight per day
- Older adults (65+ years): 1 gram/kilogram of body weight per day
- Injured or sick adults: 1.25–1.5 grams/kilogram of body weight per day
- Severely injured adults or adults with stage III/IV pressure sores: 1.5–2 grams/kilogram of body weight per day
Protein deficiencies can also cause interstitial oedema (fluid accumulation in tissue), which can mask classic symptoms of malnutrition while also contributing to the formation of pressure sores .
Protein deficiency in a wounded patient can cause :
- Slower healing due to impaired collagen synthesis and deposition
- Decreased skin and fascial wound-breaking strength
- Increased wound infection rates
Amino acids are used by the body for many different purposes, but, in the wound-healing process, they are utilised by immune cells for a variety of functions . Two of the most studied amino acids in wound healing are arginine and glutamine.
Studies of the effects of arginine have demonstrated that arginine supplementation can increase lymphocyte proliferation, leading to greater collagen formation and lower rates of fistula formation, ultimately resulting in faster and better wound healing . One study found that oral arginine supplementation over three weeks resulted in a two-fold increase in healing of patients with stage II, III and IV pressure sores .
Glutamine is also heavily utilised by the body; it is a precursor for nucleotides in fibroblasts, is involved in gluconeogenesis (which we’ll talk abut shortly), is an energy source for lymphocytes, and helps stimulate the inflammatory immune response .
When cells like fibroblasts use protein to synthesise collagen and perform other tasks associated with the healing process, they use energy to make it happen . Carbohydrates, along with fats, are the body’s main source of energy.
Cells use energy in the form of adenosine triphosphate (ATP), which is the ‘energy currency’ of cells – it can be stored and used at a cellular level [6, 8]. ATP is typically derived from glucose, which is largely produced via gluconeogenesis in the liver and kidney cortex.
Because gluconeogenesis is relatively inefficient and produces excess glucose, diabetic patients may experience a delayed inflammatory response, slower tissue deposition and delayed wound closure . This condition is known as hyperglycemia, and diabetic patients need to be monitored carefully to ensure the wound healing process isn’t impeded.
When injured patients don’t receive enough carbohydrates, their bodies will be unable to efficiently produce or use fibroblasts, fuel leukocyte activity or stimulate hormone and growth factor production (like that of insulin, which plays a critical role in the proliferative phase of wound healing) .
Like carbohydrates, fats are another useful source of energy for the body. Essential fatty acids play a role in tissue growth, and, as precursors for phospholipids and prostaglandins, indirectly regulate cellular inflammation and metabolism [6, 7, 9]. Although fatty acid deficiencies aren’t common in patients on regular diets, total parenteral feeding may result in a fat-free diet, which means patients will require supplementation .
One study found that supplementation of ω-3 acids could decrease hyperinflammatory responses during the inflammatory phase, resulting in improved wound healing for pressure sores, diabetic-associated wounds and trauma-induced wounds .
Micronutrients in Wound Healing
There are many different micronutrients (vitamins and minerals) that play a critical role in effective wound healing.
Magnesium is essential for wound repair, as it provides structural stability for ATP, which is, in turn, used by immune cells for energy .
Vitamin C, or ascorbic acid, aids with wound healing by deactivating radicals and oxidants, as well as helping collagen synthesis. Palmieri et al recommend “supplementation of vitamin C in doses of about 500mg, combined with at least 17mg zinc […] in combination with arginine” as “helpful for wound healing” .
Vitamin A is also extremely important in the wound-healing process. At a functional level, it increases collagen deposition by fibroblasts and the inflammatory response, leading to better wound healing [5, 7]. It can also help rectify the impaired wound healing caused by corticosteroid, diabetes, tumour formation, cyclophosphamide, and radiation [5, 7]. Supplemental dosages for patients may range from 10,000 to 50,000 IU per day of oral supplements, or 10,000 IU intramuscularly for 10 days, against DRIs of 700 mg per day for females and 900 mg per day for males .
Thiamine, riboflavin, pyridoxine (vitamin B6), folic acid, and pantothenate are all B vitamins that help provide energy for the wound healing process, including leukocyte formation and collagen matrix synthesis .
Vitamin E can actually compromise the healing process by negatively affecting collagen synthesis, antioxidant responses, and the inflammatory phase . It can also neutralise the healing affects of vitamin A [6, 9].
Vitamin K is necessary for effective coagulation, so, while supplementation for otherwise healthy individuals may not have an effect on wound healing, vitamin K-deficient patients should certainly be monitored and supplemented .
Iron is necessary for both collagen synthesis and oxygen transport to tissue, which means deficiencies can impact wound healing. Because iron deficiencies are common in clinical settings, it’s important that patients are regularly screened for symptoms including: “loss of energy (mild fatigue to exhaustion), pallor, sore tongue, digestive tract disturbances, appetite disorders, and brittle spoon-shaped nails” .
Copper is a required cofactor for certain antioxidants, and also plays a role in strengthening the collagen framework [5, 7].
Of all the minerals involved in the healing process, zinc is the most important. It is used in the inflammatory phase to produce antibodies and activate lymphocytes . In the proliferation phase, it is used for DNA replication in both inflammatory cells and fibroblasts . In the remodelling phase, it assists with membrane stability and collagen maturation . Zinc deficiency can impair virtually all aspects of the healing process, so patients should be carefully monitored, particularly if they are elderly – older individuals have more trouble absorbing zinc .
Integrating Nutrition into Wound Management
Now we understand how the body heals and the roles different macro- and micronutrients play in that process, we can start looking at integrating good nutrition into wound management.
The first and most obvious place to start is identifying a patient’s current deficiencies. Familiarity with signs of deficiencies, as well as the use of bedside screening tests and physical examinations (like testing serum visceral protein markers), can help with this [7, 15]. Head to the bottom of this page for an overview of nutritional deficiency symptoms.
Overall caloric intake will also need to be adjusted to account for increased energy requirements – this can vary hugely depending on the type and extent of the patient’s injuries . Other considerations include patient comorbidities and nutrient intake/absorption issues.
Once a suitable diet has been formulated, effective delivery of the recommended nutrients becomes the key clinical concern. While parenteral feeding is suitable for certain severely malnourished patients, it comes with a range of risks, including infection, reduced gut integrity, worse immune responses, and slower healing during the inflammatory phase . Consequently, enteral nutrition is the best course for most patients.
Supplementation may be needed to help the patient consume the required high-energy high-protein diet, particularly if they are elderly, dysphagic or have comorbidities that limit food intake and/or absorption.
For example, patients with sufficient protein intake requiring additional carbohydrates could use a glucose polymer energy supplement like Carb Plus to quickly deliver glucose for conversion to ATP. Carb Plus is a pure carbohydrate powder, meaning volume can be tailored to the requirements of individual patients without clinicians worrying about the nutritional effects of other additives.
For patients with dual energy/protein deficiencies, high-energy high-protein supplements can be used to bolster intake. Pre-thickened drinks like Protein-Fortified Lemon Lime can help patients who are more susceptible to nutritional problems, like people with dysphagia, receive safe, enteral protein-energy supplementation in between meals. Alternatively, ordinarily textured protein-energy drinks like Recover can be a good way for patients with severe or chronic injuries to easily increase their energy intake – Recover also comes loaded with 880 milligrams of L-arginine, helps directly improve wound healing.
Patients with non-specific supplementation needs may also benefit from general nutrition powders like AdVital. In each serve, AdVital contains 27 vitamins and minerals, and 15 grams of protein – magnesium, vitamin C, vitamin A, B vitamins, vitamin K1, iron, copper and zinc are all included. As a neutrally flavoured powder, AdVital can be mixed easily into patient food and fluid, increasing macro- and micronutrient intake without requiring patients to eat or drink more.
The role of nutrition in wound healing is incredibly complex and highly situational, but is critical for both successful outcomes and ongoing prevention.
The impact of certain macro- and micronutrients on specific aspects of the four healing phases is normally the domain of specialists, but it may fall to nurses, other staff and family to monitor patients for signs of deficiencies, and so understanding the basics of nutrition and wound healing is useful for both hospital, aged care workers and patient family members.
For patients who do have deficiencies, enteral supplementation via high-protein high-energy consumables and supplementary powders can be an effective way to combat a lack of macro- and micronutrients.
Importantly, each patient is unique, and their nutritional needs during wound healing may vary depending on their individual pathophysiology, comorbidities, age, and overall health. Supplementation is useful for aiding wound healing, but should only be administered on the advice of a trained specialist to ensure optimal patient outcomes.
Medical information on FlavourCreations.com.au is merely information and is not the advice of a medical practitioner. This information is general advice and was accurate at the time of publication. For more information about nutrition and your individual needs, see your GP or an Accredited Practising Dietitian.
Signs of Nutritional Deficiencies
These signs can indicate certain nutritional deficiencies, although they can also be symptomatic of other conditions. A deficiency may have only some or even none of the listed symptoms. If you suspect a patient has a deficiency, they should be tested prior to targeted interventions.
- Unintentional weight loss over the past six months
- Decreased appetite or lack of food consumption
- Development of new sores or wounds
- Existing wounds failing to heal or degenerating
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