Honey: A Biologic Wound Dressing
Honey: A Biologic Wound Dressing
Honey has been used as a wound dressing for thousands of years, but only in more recent times has a scientific explanation become available for its effectiveness. It is now realized that honey is a biologic wound dressing with multiple bioactivities that work in concert to expedite the healing process. The physical properties of honey also expedite the healing process: its acidity increases the release of oxygen from hemoglobin thereby making the wound environment less favorable for the activity of destructive proteases, and the high osmolarity of honey draws fluid out of the wound bed to create an outflow of lymph as occurs with negative pressure wound therapy. Honey has a broad-spectrum antibacterial activity, but there is much variation in potency between different honeys. There are 2 types of antibacterial activity. In most honeys the activity is due to hydrogen peroxide, but much of this is inactivated by the enzyme catalase that is present in blood, serum, and wound tissues. In manuka honey, the activity is due to methylglyoxal which is not inactivated. The manuka honey used in wound-care products can withstand dilution with substantial amounts of wound exudate and still maintain enough activity to inhibit the growth of bacteria. There is good evidence for honey also having bioactivities that stimulate the immune response (thus promoting the growth of tissues for wound repair), suppress inflammation, and bring about rapid autolytic debridement. There is clinical evidence for these actions, and research is providing scientific explanations for them.
Honey has been in use as a wound dressing for thousands of years. In the past few decades, there has been a large amount of clinical evidence has been accumulated that demonstrates the effectiveness of honey in this application. However, it is only in more recent times that the science behind the efficacy has become available. It is now understood that honey is not just sugar syrup with certain physical properties that make it suitable as a wound dressing material, but that it is a biologic wound dressing with multiple bioactive components that can expedite the healing process.
The physical properties of honey alone will positively impact the wound healing environment and the healing process, specifically because honey is acidic and has a pH of around 3.2–4.5, and it is well known that topical acidification of wounds promotes healing by increasing the release of oxygen from hemoglobin. In addition, this pH is less favorable for protease activity, thus reducing the destruction of the matrix needed for tissue repair. The high osmolarity of honey due to its high sugar content is also beneficial to the healing process, as substantiated in reports showing sugar pastes to be effective as wound dressings. The osmotic effect of the sugar draws water out of the wound bed and, although it could be thought that this may potentially harm and dehydrate the wound tissue, this is not the case. If the circulation of blood underneath the wound is sufficient to replace fluid lost from cells, then the osmotic effect of sugar on the surface simply creates an outflow of lymph. This outflow is beneficial to the healing process, as demonstrated by negative pressure wound therapy.
Sugar also draws water out of bacterial cells and, as long as the sugar does not become too diluted by the wound fluid, the growth of bacteria is inhibited. The lowest concentration of sugar known to prevent the growth of Staphylococcus aureus has a water activity of 0.86. Sucrose has this activity at a concentration of 67%; glucose at 55%; and fructose at 56%; however, it has been found that sucrose packed into an abdominal wound only maintains its activity for 4 hours before becoming sufficiently diluted by body fluids, allowing the water activity to increase to 0.897 and S. aureus to grow. The additional bioactivity within the honey itself allows for continued inhibition of bacterial growth even when the osmolarity has been diluted below the point where it should cease to be inhibitory.
There has been only 1 clinical trial reported where honey was compared with sugar for its effectiveness, in which honey was found to be more effective than sugar in reducing bacterial contamination and promoting wound healing. In addition to this 1 comparative clinical trial supporting the increased antimicrobial activity of honey, in vitro research has also been conducted which has provided good scientific evidence for the presence of bioactivity in honey. This bioactivity would be expected to greatly augment the effects of the physical properties on healing of wounds.
Abstract and Introduction
Abstract
Honey has been used as a wound dressing for thousands of years, but only in more recent times has a scientific explanation become available for its effectiveness. It is now realized that honey is a biologic wound dressing with multiple bioactivities that work in concert to expedite the healing process. The physical properties of honey also expedite the healing process: its acidity increases the release of oxygen from hemoglobin thereby making the wound environment less favorable for the activity of destructive proteases, and the high osmolarity of honey draws fluid out of the wound bed to create an outflow of lymph as occurs with negative pressure wound therapy. Honey has a broad-spectrum antibacterial activity, but there is much variation in potency between different honeys. There are 2 types of antibacterial activity. In most honeys the activity is due to hydrogen peroxide, but much of this is inactivated by the enzyme catalase that is present in blood, serum, and wound tissues. In manuka honey, the activity is due to methylglyoxal which is not inactivated. The manuka honey used in wound-care products can withstand dilution with substantial amounts of wound exudate and still maintain enough activity to inhibit the growth of bacteria. There is good evidence for honey also having bioactivities that stimulate the immune response (thus promoting the growth of tissues for wound repair), suppress inflammation, and bring about rapid autolytic debridement. There is clinical evidence for these actions, and research is providing scientific explanations for them.
Introduction
Honey has been in use as a wound dressing for thousands of years. In the past few decades, there has been a large amount of clinical evidence has been accumulated that demonstrates the effectiveness of honey in this application. However, it is only in more recent times that the science behind the efficacy has become available. It is now understood that honey is not just sugar syrup with certain physical properties that make it suitable as a wound dressing material, but that it is a biologic wound dressing with multiple bioactive components that can expedite the healing process.
The physical properties of honey alone will positively impact the wound healing environment and the healing process, specifically because honey is acidic and has a pH of around 3.2–4.5, and it is well known that topical acidification of wounds promotes healing by increasing the release of oxygen from hemoglobin. In addition, this pH is less favorable for protease activity, thus reducing the destruction of the matrix needed for tissue repair. The high osmolarity of honey due to its high sugar content is also beneficial to the healing process, as substantiated in reports showing sugar pastes to be effective as wound dressings. The osmotic effect of the sugar draws water out of the wound bed and, although it could be thought that this may potentially harm and dehydrate the wound tissue, this is not the case. If the circulation of blood underneath the wound is sufficient to replace fluid lost from cells, then the osmotic effect of sugar on the surface simply creates an outflow of lymph. This outflow is beneficial to the healing process, as demonstrated by negative pressure wound therapy.
Sugar also draws water out of bacterial cells and, as long as the sugar does not become too diluted by the wound fluid, the growth of bacteria is inhibited. The lowest concentration of sugar known to prevent the growth of Staphylococcus aureus has a water activity of 0.86. Sucrose has this activity at a concentration of 67%; glucose at 55%; and fructose at 56%; however, it has been found that sucrose packed into an abdominal wound only maintains its activity for 4 hours before becoming sufficiently diluted by body fluids, allowing the water activity to increase to 0.897 and S. aureus to grow. The additional bioactivity within the honey itself allows for continued inhibition of bacterial growth even when the osmolarity has been diluted below the point where it should cease to be inhibitory.
There has been only 1 clinical trial reported where honey was compared with sugar for its effectiveness, in which honey was found to be more effective than sugar in reducing bacterial contamination and promoting wound healing. In addition to this 1 comparative clinical trial supporting the increased antimicrobial activity of honey, in vitro research has also been conducted which has provided good scientific evidence for the presence of bioactivity in honey. This bioactivity would be expected to greatly augment the effects of the physical properties on healing of wounds.