Wound healing is the process of repair that follows injury to the skin and other soft tissues.
Wounds may result from trauma or from a surgical incision. In addition, pressure ulcers (also known as decubitus ulcers or bed sores), a type of skin ulcer, might also be considered wounds. The capacity of a wound to heal depends in part on its depth, as well as on the overall health and nutritional status of the individual.
Following injury, an inflammatory response occurs and the cells below the dermis (the deepest skin layer) begin to increase collagen (connective tissue) production. Later, the epithelial tissue (the outer skin layer) is regenerated. Dietary modifications and nutritional and herbal supplements may improve the quality of wound healing by influencing these reparative processes or by limiting the damaging effects of inflammation.
What are the symptoms of wound healing?
Symptoms include swelling, stiffness, tenderness, discoloration, skin tightness, scabbing, itching, and scar formation.
Dietary changes that may be helpful for wound healing
Building and repairing tissue requires adequate amounts of calories and protein to fuel the repair mechanisms, as the skin and underlying tissues are made of protein. While major wounds from extensive injuries or major surgery significantly raise protein and calorie requirements, optimal healing of minor wounds should not require changes from a typical, healthful diet.1 In a study of malnourished people with skin ulcers, those who were given a diet containing 24% protein showed a significant reduction in the size of the ulcer, whereas those given a diet containing 14% protein had no significant improvement.2 This study suggests an increase in dietary protein can improve wound healing in malnourished people. It is not known whether the same benefit would be observed in well-nourished people.
Nutritional supplements that may be helpful for wound healing
Supplementation with bromelain, an enzyme derived from pineapple stem, prior to and following a surgical procedure has been shown to reduce swelling, bruising, healing time, and pain.3 Bromelain supplementation has also been shown to accelerate the healing of soft-tissue injuries in male boxers.4 The amount of bromelain used in these studies was 40 mg four times per day, in the form of enteric-coated tablets. Enteric-coating prevents the stomach acid from partially destroying the bromelain. Most currently available bromelain products are not enteric-coated, and it is not known if such products would be as effective as enteric-coated bromelain.
Thiamine (vitamin B1),5 pantothenic acid (vitamin B5),6 and other B vitamins7 have all been shown to play a role in wound healing in animal studies. For this reason, although human research is lacking, some alternative healthcare practitioners recommend a high-potency B vitamin supplement to promote wound healing.
Vitamin C is needed to make collagen (connective tissue) that strengthens skin, muscles, and blood vessels and to ensure proper wound healing. Severe injury appears to increase vitamin C requirements,8 and vitamin C deficiency causes delayed healing.9 Preliminary human studies suggest that vitamin C supplementation in non-deficient people can speed healing of various types of wounds and trauma, including surgery, minor injuries, herniated intervertebral discs, and skin ulcers.10 11 A combination of 1–3 grams per day of vitamin C and 200–900 mg per day of pantothenic acid has produced minor improvements in the strength of healing skin tissue.12 13
Zinc is a component of many enzymes, including some that are needed to repair wounds. Even a mild deficiency of zinc can interfere with optimal recovery from everyday tissue damage, as well as from more serious trauma.14 15 One controlled trial found the healing time of a surgical wound was reduced by 43% with oral supplementation of 50 mg of zinc three times per day, in the form of zinc sulfate.16
Whether oral zinc helps tissue healing when no actual zinc deficiency exists is unclear,17 but doctors often recommend 30 mg of zinc per day for four to six weeks to aid in the healing of wounds. Topical zinc-containing treatments, on the other hand, have improved healing of skin wounds even when there is no deficiency.18 19 Long-term oral zinc supplementation must be accompanied by copper supplementation to prevent a zinc-induced copper deficiency. Typically, if 30 mg of zinc are taken each day, it should be accompanied by 2 mg of copper. If 60 mg of zinc are used, it should be accompanied by 3 mg of copper each day.
Preliminary20 and controlled21 studies of people with severe burns and other types of injuries22 showed that supplementation with 10–30 grams of ornithine alpha-ketoglutarate (OKG) per day significantly improved wound healing and decreased the length of hospital stays. Improved healing from major trauma and surgery has also been demonstrated with oral supplements including several grams per day of glutamine.23
Vitamin A plays a central role in wound healing,24 but the effect of supplemental vitamin A in people who have suffered a minor injury and are not vitamin A-deficient remains unclear. Vitamin A supplements have been shown to improve healing in animal studies,25 and may be especially useful in a topical ointment for skin injuries in people taking corticosteroid medications.26 Although there are no studies in humans, some doctors recommend 25,000 IU of vitamin A per day, beginning two weeks prior to surgery and continuing for four weeks after surgery.
Animal studies have shown that supplementing with vitamin E can decrease the formation of unwanted adhesions following a surgical wound. In addition, wound healing was more rapid in animals fed a vitamin E-rich diet than in those fed a standard diet.27 In another study, however, wound healing was inhibited by supplementation with a massive amount of vitamin E (equivalent to about 35,000 IU).28 This adverse effect of vitamin E was prevented by supplementation with vitamin A. Although the relevance of these studies to humans is not clear, many doctors recommend supplementing with both vitamins A and E in order to enhance wound healing and prevent adhesion formation. Typical amounts recommended are 25,000 IU of vitamin A per day and 400 IU of vitamin E per day, beginning two weeks prior to surgery and continuing for four weeks after surgery.
Topical application of vitamin E is sometimes recommended for preventing or treating post-injury scars, although only three controlled studies have been reported. Two of these trials found no effect on scar prevention after surgery,29 30 and one trial found vitamin E improved the effect of silicon bandages on large scars called keloids.31
Copper is a required cofactor for the enzyme lysyl oxidase, which plays a role in the cross-linking (and strengthening) of connective tissue.32 Doctors often recommend a copper supplement as part of a comprehensive nutritional program to promote wound healing. A typical amount recommended is 2–4 mg per day, beginning two weeks prior to surgery and continuing for four weeks after surgery.
Other trace minerals, such as manganese, copper, and silicon, are known to be important in the biochemistry of tissue healing.33 34 35 36 However, there have been no controlled trials exploring the effect of oral supplementation of these minerals on the rate of healing.
Glucosamine sulfate and chondroitin sulfate may both play a role in wound healing by providing the raw material needed by the body to manufacture connective tissue found in skin, tendons, ligaments, and joints.37 Test tube and animal studies have found that these substances, and others like them, can promote improved tissue healing.38 39 40 41 42 One controlled trial in humans found that wounds healed with greater strength when they were treated topically with a chondroitin sulfate-containing powder.43 However, no research has investigated the value of oral supplements of glucosamine or chondroitin for wound healing in humans.
Arginine supplementation increases protein synthesis and improves wound healing in animals.44 Two controlled trials have shown increased tissue synthesis in surgical wounds in people given 17–25 grams of oral arginine per day.45 46
Carnosine is a small molecule composed of the amino acids histidine and alanine. The exact biological role of carnosine is not completely understood, but animal research demonstrates that it promotes wound healing.47 More research is warranted in this area.
Are there any side effects or interactions with wound healing?
Refer to the individual supplement for information about any side effects or interactions.
Herbs that may be helpful for wound healing
While many herbs may be useful in wound healing, it is important that wounds be properly cleaned and dressed before any herbal preparations are applied. This will prevent infection.
In animal studies of skin inflammation, both topical and oral aloe vera have proven beneficial in decreasing inflammation and promoting cellular repair.48 49 Topical aloe vera has facilitated wound healing in controlled human research, as well.50 In one controlled trial, however, topical aloe vera gel was inferior to conventional management of surgical wounds.51
One preliminary trial found that a gotu kola extract helped heal infected wounds (unless they had reached bone).52 A review of French studies suggests that topical gotu kola can help wounds.53 One study found gotu kola extract helpful for preventing and treating enlarged scars (keloids).54 Standardized extracts of gotu kola containing up to 100% total triterpenoids are generally taken, providing 60 mg once or twice per day. Animal studies have shown that constituents in gotu kola, called asiaticosides, increase antioxidant levels during wound healing and facilitate repair of connective tissues.55 56
Horse chestnut contains a compound called aescin that acts as an anti-inflammatory and reduces edema (swelling with fluid) following trauma, particularly sports injuries, surgery, and head injury.57 A topical aescin preparation is popular in Europe for the treatment of acute sprains during sporting events.
A topical preparation of chamomile combined with corticosteroids and antihistamines has been used to speed wound healing in elderly people with stasis ulcers caused by inadequate circulation,58 as well as in people who had tattoos removed.59 Topical use of chamomile ointment was also found to successfully treat mild stasis ulcers in elderly bedridden patients.60
Topical application of honey has been used since antiquity to accelerate skin wound healing.61 Honey has been shown to inhibit the growth of several organisms responsible for wound infections.62 63 64 In one preliminary study, nine infants with large, open infected wounds that failed to heal with conventional treatment were treated successfully with topical application of honey.65 Fresh unprocessed honey was applied to wounds in amounts of 5–10 ml twice daily for a period of 21 days. All infants showed marked clinical improvement after 5 days, and the wounds were closed and free of infection by 21 days. The use of honey to treat wounds should be supervised by a doctor.
Used topically, some practitioners consider arnica to be among the best vulnerary (wound-healing) herbs available.66 Topical use of arnica is approved by the German government for improving wound healing.67 Arnica is poisonous if taken internally.
Calendula flowers were historically considered beneficial for wound healing, reducing inflammation and fighting infection as a natural antiseptic.68 Like echinacea, calendula is approved in Germany for use in treating poorly healing wounds.69 Generally 1 tablespoon (15 grams) of calendula flowers is steeped in hot water for 15 minutes, then cloths are dipped into the liquid to make compresses. Such compresses should be applied for at least 15 minutes, initially several times per day, then tapering off as the wound improves.
Traditional herbalists sometimes recommend the topical use of herbs such as St. John’s wort, calendula, chamomile, and plantain, either alone or in combination, to speed wound healing. Clinical trial in humans have not yet validated this traditional practice.
Echinacea is used among European practitioners of herbal medicine to promote wound healing70 and is approved by the German government for this use.71 Creams or ointments are applied several times a day to minor wounds.
Comfrey has anti-inflammatory properties that may decrease bruising when the herb is applied topically.72 Comfrey is also widely used in traditional medicine as a topical application to help heal wounds.73 Witch hazel can also be used topically to decrease inflammation and to stop bleeding.74 Native Americans used poultices of witch hazel leaves and bark to treat wounds, insect bites, and ulcers.75 Horsetail can be used both internally and topically to decrease inflammation and promote wound healing.76
Chaparral has been used topically to decrease inflammation, and pain, and promote healing of minor wounds.77 For topical use, cloths can be soaked in oil preparations or tea of chaparral and applied several times per day (with heat if helpful) over the affected area. Powdered chaparral can be applied directly to minor wounds, after they have been adequately cleansed.
Alginic acid is one of the main constituents in bladderwrack (Fucus vesiculosus), a type of brown algae (seaweed). Calcium alginate has shown promise as an agent to speed wound healing in animal studies78 but has not been demonstrated to be effective in humans.
Australian Aboriginals used the leaves of tea tree to treat cuts and skin infections, crushing and applying them to the affected area. Modern herbalists recommend tea tree oil (at a strength of 70–100%) applied moderately in small areas at least twice per day to the affected areas of skin.79 For a variety of reasons, some researchers have suggested that tea tree oil should not be used to treat burns.80
Are there any side effects or interactions with wound healing?
Refer to the individual herb for information about any side effects or interactions