How Diet Influences The Wound-Healing Process?

Overview

A skin wound is a tissue injury that compromises the anatomical integrity and function of the epidermis. Healing a wound entails skin tissue repair. An injury to the epidermis triggers the start of the wound-healing process, which could take up to years to recover fully. 

The highly organised cellular, molecular and immune systems are a part of this dynamic process. Inflammation, proliferation, and remodelling are the three processes of wound healing that overlap. Any delay in these processes causes wounds to heal abnormally. Wound healing starts with primary healing, followed by secondary healing. 

Primary healing is the smooth, uncomplicated healing of a well-approximated, non-infected wound. Primary healing works best for surgical wounds, as they heal neatly with minimal scarring. Infection, dehiscence, hypoxia, and immunological dysfunction can all alter the usual course of a wound's healing process, starting the secondary healing stage. Granulation tissue forms during secondary healing, and epithelisation covers this fresh tissue. These wounds are more prone to infection and slow healing.¹

In a sequence of overlapping phases, tissue reconstitution results from wound healing. Haemostasis, inflammation, proliferation, and the development of mature scar tissue are all part of this process. The following table shows the normal wound healing process.

A proper diet is necessary for optimal wound healing. Nutritional deficits hinder the wound-healing process. Furthermore, poor wound tensile strength and higher infection rates are related to malnutrition. Patients who are malnourished may develop pressure ulcers, infections, and delayed wound healing, which leads to chronic wounds that never heal.³

Nutrients essential for wound healing

Effective wound healing is a complicated process that mainly depends on good nutrition. A healthy diet full of protein, vitamins, minerals, and fluids is crucial in encouraging wound healing. From collagen synthesis to inflammation regulation, nutrients perform specific functions in different stages of recovery. People can make educated dietary decisions to hasten recovery and advance general well-being by understanding the enormous impact of nutrition on wound healing. Below is a list of acronyms to help you remember the essential elements of wound healing: 

• W - Warrior nutrients: These nutrients are similar to the warrior's armour and weapons. Proper nutrients (protein, vitamins, and minerals) build strength and battlefield preparedness
• O - Omega-3 peace: Omega-3 are your body's "peacekeepers," reducing inflammation to allow your wound to heal peacefully
• U - Up and hydrate: water is your secret weapon for healing because it keeps your cells hydrated and energised to function effectively 
• N - New skin vitamins: Your body will heal the wound by producing new skin with the support of vitamins C and A
• D - Don't smoke and drink: Remember smoking and excessive drinking can slow your recovery process. For a quicker recovery, avoid them

Proteins

In response to the wound healing process, ECM and several cell types (inflammatory cells, epithelial cells, and myofibroblasts) work together to coordinate tissue restoration, which is known as fibrogenesis. Several proteins mediate interactions between cells and the cell matrix. Integrins, for example, facilitate intracellular communication between parenchymal and non-parenchymal ECM cells, such as fibroblasts and inflammatory cells. Collagen, one of the most common proteins in the ECM, provides flexibility and strength and aids in maintaining tissue’s structural and physiological integrity. By attracting fibroblasts and encouraging the growth of new tissue in the wound bed, this protein is crucial in controlling the healing of wounds.⁴

Amino acids

Amino acids and other nutrients are essential to the biological processes involved in tissue repair and wound healing. The most prevalent amino acid in plasma - glutamine - is the primary metabolic fuel for rapidly growing cells. It defends against inflammatory damage by promoting the expression of heat shock proteins, which offer cellular defence during inflammation, injury, and stress. Arginine has a wide range of impacts on the immune system and wound healing. Nitric oxide, which aids in collagen production in wound healing, can only be produced using arginine as a metabolic substrate.

Vitamins

Scurvy, caused by a vitamin C deficiency can cause the manifestation of cutaneous wounds. This is because vitamin C plays in collagen synthesis and post-translational modification, acting as a co-factor in the process of hydroxylating proline and lysine residues in procollagen, which is essential for the durability and stability of collagen fibres. Ascorbic acid (vitamin C) acts as an antioxidant and improves neutrophil function.

Insufficient vitamin A hinders the healing of wounds. Vitamin A enhances collagen cross-linking and breaking strength of the wound. Besides mounting an inflammatory response, vitamin A also increases the number of monocytes and macrophages at the wound site, promoting epithelial cell differentiation during the early stages of inflammatory response.⁵

Macronutrients and energy

Carbohydrates

Calories are required to provide energy for healing and carbohydrates are the primary energy source. Carbohydrates are broken down into glucose by digestive enzymes into glucose. Glucose serves as the only source of energy for skin cells. Inflammatory cells need glucose to get rid of germs and necrotic debris.

Additionally, carbohydrates are a vital component in the activity of the enzymes hexokinase and citrate synthase, which are involved in wound-healing processes. Carbohydrates are also crucial for the structural integrity of a wound. This is because carbohydrates can form different types of glycoproteins needed for the intercellular signalling processes, which enables cells to communicate and form structures needed for wound healing.⁶

Created by: Deepika Rana

Fats

Fats are unique in serving as an energy source and signalling molecules. White adipose tissue is one of the regulators of wound inflammation and healing and is a source of pro-inflammatory fat metabolism. 

Lipid components, such as collagen and ECM synthesis, are responsible for tissue growth and wound healing. Omega-3 fatty acids may promote quicker inflammation resolution in the wound microenvironment, which improves the conditions for regeneration and re-epithelialisation. 

Although omega-3 fatty acid supplementation might reduce inflammation, its comprehensive impact on wound healing is still unknown.^5,6

Created by: Deepika Rana

Hydration and fluid intake

Importance of hydration

According to some theories, water is the single most significant external component influencing healing at its optimal level. In these situations, the drying effect that results from a physical breach of the skin barrier properties boosts the increased fluid output from blood vessels. 

Excess fluid flows out from the injured tissue as exudates, but the outflow from blood vessels can quickly exceed the tissue's ability to absorb liquid. Granulation tissue accumulates on a fresh tissue matrix created by collagen production. The activation of new blood vessels into the highly vascularised granulation tissue supplies the oxygen and nutrients required to support tissue synthesis during the granulation phase of healing. 

The physical skin barrier is re-established at the original wound site due to tissue remodelling and re-epithelialisation. The skin's barrier functions recover to an extent equivalent to the skin's pre-injury state over the following days/weeks as tissue is regenerated.

Benefits of moist wound healing

• Faster healing of wounds 
• Enhance the pace of epithelialisation 
• Promote dermal/wound bed healing responses, such as cell proliferation and the production of the ECM 
• Minimises scarring 
• Retaining growth factors at the site of a wound 
• Lower rates of wound infection 
• Reduces pain sensitivity 
• Facilitates autolytic debridement⁷

Role of micronutrients

Copper

Numerous metabolic activities call for modest amounts of copper, a vital element. Under controlled conditions, copper affects healing by promoting the production of ECM components like fibrinogen, collagen synthesis, and integrins, the primary mediators of cell attachment to the ECM. The human body has a good metabolism for copper. In many physiological and metabolic activities, such as angiogenesis, skin production, expression, and stability of extracellular skin proteins, copper is an essential mineral with antibacterial characteristics.⁸

Zinc

Many intracellular enzymatic processes involved in healing wounds use zinc as a cofactor. The substance possesses substantial antimicrobial effects, acts as an antioxidant, and gives protection against epithelial apoptosis. Although zinc deficiency hinders wound healing and topical zinc promotes it, zinc supplementation does not appear to improve wound healing.

Selenium

Based on specific theories, it could hasten the healing of burn patients' wounds. Selenium's antioxidant properties aid in wound recovery.

Iron

The synthesis of collagen necessitates iron as a cofactor. Some theories in the critical care literature imply iron supplementation moderates the immune response in inflammatory situations, particularly in the extension of inflammation found in iron deficiency. There is no proof yet that taking an iron supplement speeds up wound healing.⁵

Antioxidant compounds

Antioxidants are essential for wound healing because they help to control oxidative stress, inflammation, and tissue repair.

Avoidance of harmful substances

The harmful effects of cigarette smoke's poisonous components, including nicotine, carbon monoxide, and hydrogen cyanide, reveal several ways that slow the healing process. Nicotine is a vasoconstrictor that decreases nutrient blood flow to the skin, causing tissue ischemia and delayed wound healing. While hydrogen cyanide prevents the enzyme systems required for oxidative metabolism and oxygen transport at the cellular level, carbon monoxide reduces oxygen transport and metabolism.¹⁰

Alcohol consumption hinders wound healing and raises the risk of infection, according to clinical data and animal trials. Alcohol use reduces host resistance, and being intoxicated when injured increases the likelihood of acquiring an infection in the wound. 

Although the specific effects depend on the pattern of exposure (i.e., chronic vs. acute alcohol exposure, amount drank, duration of consumption, time from alcohol exposure, and alcohol withdrawal), studies have shown that alcohol has dramatic effects on host-defence mechanisms. 

Acute ethanol exposure may delay wound healing by inhibiting the early inflammatory response, wound closure, angiogenesis, collagen synthesis, and protease equilibrium at the wound site.²

Considerations for special cases

Diabetes primarily causes the inflammatory conditions to become chronic, disrupts the angiogenic process, reduces endothelial progenitor cells, and causes an imbalance in the regulation of the ECM. Neutrophils and macrophages quickly penetrate the lesion site in diabetes, as shown in physiological wound repair, due to chemotactic chemokines that are notably higher in diabetes. Diabetes affects the ability to produce various growth factors necessary for starting and maintaining the healing process. Furthermore, diabetes appears to affect the maturation phase of wound healing.¹¹

The loss of immune function caused by malnutrition hurts the body's reaction to infection. It also predisposes people to skin infections by making their skin thin and fragile, more prone to wounds. Malnutrition also increases immobility by reducing the synthesis of collagen, which is necessary for healing.¹²

Summary

Conscious dietary choices can have a favourable effect on the way wounds heal. Emphasising a nutritious, balanced diet full of protein, vitamins, minerals, antioxidants, and healthy fats can aid in tissue regeneration, reduce inflammation, and speed up recovery. A customised strategy that maximises your body's innate healing capacities should be developed with a healthcare practitioner consultation or certified dietician, especially if you have dietary demands or medical issues.