Honey is a substance produced by bees to store as a sugar food source collected as nectar from flowers (and occasionally from the sap of plants). Since the earliest recorded times, humans have taken this honey for use, not only as a food product, but also as a medicine, especially for wound care (Zumla and Lulat, 1989). The bees concentrate the dilute sugar solutions they collect from the plants by evaporating off most of the water. (Honey is typically 17% water, 80% sugars.) They also add enzymes, so that as the honey ripens in the comb its composition changes and it becomes impossible for microbes to grow in it and spoil the stored food. One of these enzymes converts sucrose, the major sugar in nectar and sap, into a more soluble mixture of glucose and fructose.This makes the saturated or supersaturated solution of sugars that is stored as honey. (The difference in texture between liquid honey and solid or ‘creamed’ honey is due to fine crystals of solidified glucose being suspended in the saturated syrup.) The sugar molecules in solution bind up water molecules, thereby denying microbes the water that is essential for their survival. Another enzyme added is glucose oxidase. This converts some of the glucose to gluconic acid, making honey too acidic for microbes to grow (honey has a pH of about 3.5) and, as a by-product of this reaction, forms hydrogen peroxide. This is a sporicidal antiseptic that sterilises the honey that is sealed in the comb. (When subsequently extracted from the comb, honey can be contaminated with microbial spores as the enzyme that produces hydrogen peroxide is inactive at that time because there is insufficient free water. These can survive the acidity and high sugar content.) These factors, which ensure the preservation of honey in the comb, are also useful in suppressing microbial growth when honey is applied to a wound.
Additionally, there are ‘herbal’ factors present which may be of benefit in wound care. Being the concentrated juice from plants, honey contains the various nutrients and herbal chemicals that come from the plants, such as: amino acids, other organic acids, enzymes, vitamins, acetylcholine, flavonoids, carotenoids, polyphenols, minerals and a wide variety of organic chemicals in trace quantities. These are what give different honeys their characteristic colours, flavours and aromas. The colour of honey is also due to products of the Maillard reaction1 and caramelisation of its sugars, hence it gets darker in colour as it ages. Some of the plant-derived chemicals have antioxidant properties and some are known to have antibacterial properties.
It is for topical treatment of infections that honey has been most widely used as a medicine throughout history, and now that its use as a wound dressing has been ‘rediscovered’ by the medical profession, it is on infected wounds that it is mostly being used. The clinical definition of infection is that the area of the wound is showing the classical signs of inflammation (redness, swelling and pain). The clinical focus in treating wounds is to remove the cause of the inflammation by killing the infecting bacteria and removing any pus or dead tissue that provide a medium for their growth. Inflammation in a wound causes many problems, such as making the wound uncomfortable and difficult to manage, but the major problem is that it prevents the tissue repair processes from healing the wound. The various bioactivities of honey work through all of these facets to give rapid healing — honey rapidly debrides wounds (ie. cleans the wound by releasing pus or dead tissue), kills bacteria, directly suppresses inflammation, and stimulates the growth of the various types of cells involved in the production of new tissue to repair the wound.
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