George W. Robinson. © 1999 California Academy of Sciences.

Most people think of honey as a sweetener, as this has been its most common use for hundreds of years. However, honey has also been used as a remedy for a number of different illnesses. Over the last century there has been considerable research on its anti-bacterial properties. Recently, it has been shown to have beneficial effects on wounds as a topical agent to promote healing.

There are many potential mechanisms by which honey may inhibit pathogenic organisms and promote wound healing. Its osmotic properties, acidity and hydrogen peroxide content all appear to contribute, as do the phytochemicals it contains.

Honey is composed of 84% fructose and glucose, with very low water content. This high osmotic state will completely inhibit the growth of a majority of staphylococcus and streptococcus species, as well as fungi such as tinea. This is why undiluted honey does not need to be refrigerated, and can be preserved for very long periods at room temperature.

Honey has a pH of between 3.2 and 4.5. This is inhibitory to many pathogens whose optimal growth pH is around 7.3. A pH between 3 and 4.5 is inhibitory to such human pathogens as Escherichia coli, Salmonella sp., Pseudomonas aeruginosa and Streptococcus pyogenes.

While osmotic properties and acidity contribute, the major antibacterial activity in honey has been attributed to the hydrogen peroxide produced enzymatically as the bees make the honey. Bees secrete an enzyme called glucose oxidase from their hypopharyngeal glands into the nectar that is the raw material for production of honey. This enzyme plays a key role in the transformation of nectar into honey. Hydrogen peroxide is produced as a side-product in this reaction, and it serves to preserve the honey.

The levels of hydrogen peroxide produced would be effective as a sterilizing agent only during the ripening of honey. Full-strength honey has negligible peroxide levels because this substance is short-lived in the presence of transition metal ions and ascorbic acid in honey, which catalyze its decomposition to oxygen and water. The glucose oxidase enzyme is practically inactive in full-strength honey, and it only gives rise to hydrogen peroxide when honey is diluted.

In undiluted honey, acid produced by the action of the enzyme drops the pH to a point that actually inhibits further enzyme action. However, on dilution, the enzymatic activity increases by a factor of 2,500–50,000, thus giving a “slow-release” antiseptic at a level that is antibacterial but not tissue-damaging (Molan PC. The Antibacterial Activity of Honey. 1. The Nature of the Antibacterial Activity. Bee World. 1992; 73: 5–28. Molan PC. The Antibacterial Activity of Honey. 2. Variation in the Potency of the Antibacterial Activity. Bee World. 1992; 73: 59–76).

Researchers have identified a number of phytochemicals in honey that also have antibacterial activity. These include: pinocembrin, terpenes, benzyl alcohol, 3,5-dimethoxy-4-hydroxybenzoic acid (syringic acid), methyl 3,5-dimethoxy-4-hydroxybenzoate (methyl syringate), 3,4,5-trimethoxybenzoic acid, 2-hydroxy-3-phenylpropionic acid, 2-hydroxybenzoic acid and 1,4-dihydroxybenzene. However, in typical honey samples, the quantities of these compounds are far too low to account for any significant antimicrobial activity.

Assessment of Antimicrobial Effects

Various types of honey from different areas of the world have been tested for their antimicrobial effects. This is generally done in vitro by measuring the minimum inhibitory concentrations (MIC) of honeys against various microorganisms. A majority of this work has been done in New Zealand, where honey is a major export product (Allen KL, Molan PC, Reid GM. A Survey of the Antibacterial Activity of Some New Zealand Honeys. J Pharm Pharmacol. 1991; 43: 817–822).

In these studies, 345 varieties of honey were tested. The variances ranged from virtually no antibiotic effect to very potent effects. These variances are thought to be due to the levels of hydrogen peroxide produced by the honey and the stability of the glucose oxidase content. Glucose oxidase is destroyed by high temperatures and light exposure. Therefore, honey to be used as an antimicrobial should be kept at a cool temperature and in a dark area.

The most potent antimicrobial effects were found with “honeydew” honey, a type of bee-produced honey from the mountainous coniferous forest regions of central Europe, and honey made from the flowers of the Manuka tree (Leptospermum scoparium) in New Zealand. The Manuka tree grows only in New Zealand; the Maori people have used medicinal substances derived from Manuka for thousands of years. A close relative of the Melaleuka (“Tea Tree”) species found in Australia, Manuka also produces an oil with potent anti-microbial effects.

Manuka honey has been found to have high antimicrobial activity against multiple organisms, and about half of the samples of this type of honey showed an exceptionally high level of non-peroxide anti-microbial activity (Allen KL, Molan PC, Reid GM. The Variability of the Antibacterial Activity of Honey. Apiacta. 1991; 26: 114–121). Manuka honey also has the greatest anti-microbial effect at a dilution of 54 times. This exceeds all other honeys evaluated, which were only effective up to a 10-fold dilution (Willix DJ, Molan PC, Harfoot CJ. A Comparison of the Sensitivity of Wound-infecting Species of Bacteria to the Antibacterial Activity of Manuka Honey and Other Honey. J Appl Bacteriol. 1992; 73: 388–394). From a modern clinical perspective, one of the most important findings is that Manuka honey is effective against methacillin-resistant S. aureus (Allen KL, Hutchinson G, Molan PC. The Potential for Using Honey to Treat Wounds Infected with MRSA and VRE. Proceedings of the First World Wound Healing Congress, 10–13 September 2000, Melbourne, Australia).

Clinical Use of Honey in Wound Healing

Undiluted honey can be used as a topical anti-microbial for wounds, burns and skin ulcers. Clinical observations indicate that it can quickly reduce inflammation, swelling, and pain. It also reduces unpleasant odors, and promotes a sloughing of necrotic tissue without the need for debridement. Wound dressings can be removed painlessly and without causing damage to re-growing tissue. Healing occurs rapidly with minimal scarring, in many cases, averting the need for skin grafting. In many of the reported cases, honey was used on infected lesions not responding to standard antibiotic and antiseptic therapy. It was found in almost all cases to be very effective in rapidly clearing up infection and promoting healing (see Further Reading below).

Potential Therapy for Gastric Ulcers and Gastroenteritis

Honey has a long history as a traditional therapy for dyspepsia. With the discovery of Helicobacter pylori as a key causative agent in peptic ulcer disease and gastroesophageal reflux, this begins to make sense. In one of the most interesting clinical studies involving honey to date, researchers tested the sensitivity of H. pylori to honey, using isolates of the pathogen from biopsies of gastric ulcers. All five isolates tested were found to be sensitive in an agar well diffusion assay to a 20% (v/v) solution of a manuka honey with an average level of non-peroxide activity, but none showed sensitivity to a 50% (v/v) solution of a honey in which the antibacterial activity was due primarily to its content of hydrogen peroxide.

Assessment of the minimum inhibitory concentration by inclusion of manuka honey in the agar showed that the presence of 5% (v/v) honey completely inhibited growth of a further seven isolates tested over the incubation period of 72 hours. This speaks to the non-peroxide activity of manuka honey as a major contributor of the antimicrobial effect (Al Somai N, Coley KE, Molan PC, Hancock BM. Susceptibility of Helicobacter pylori to the Antibacterial Activity of Manuka Honey. J Royal Soc Med. 1994; 87: 9–12).

Manuka honey has also been tested for treatment of gastroenteritis in infants with substantial benefit. In this situation, it was used in place of glucose as an oral rehydration fluid. It was effective as a nutrient and anti-microbial agent simultaneously. It also showed antimicrobial effect against common pathogens associated with pediatric gastritis, including E. coli (multiple strains), Salmonella (multiple strains), Shigella (multiple strains), Vibrio (multiple strains) and Yersinia (Haffejee IE, Moosa A. Honey in the Treatment of Infantile Gastroenteritis. Br Med J. 1985; 290: 1866–1867).

Treatment of Tinea Infection

Natural honey has been compared with artificial honey, that is, a synthetic honey-like analog manufactured in a lab, against various types of dermatophyte infections. Although the concentrations of honey needed to eradicate the fungi was higher than what is needed to inhibit bacterial pathogens, honey was effective against multiple common dermatophytes.

Most good supermarkets and health food stores carry a wide variety of honeys. For therapeutic purposes, it is best to select minimally processed brands, as they are far more likely to retain all of the antimicrobial phytochemicals, enzymes and other substances. These compounds may be lost in honey that has been heat-treated or otherwise adulterated. If possible, choose a product that is certified organic, meaning that it has been gathered by bees in areas that have been minimally treated with pesticides. Manuka honey packaged for antimicrobial use, in the US, is available only through the Synergy Company, 2279 South Resource Blvd., Moab, Utah 84532, 1-800-259-5366, www.synergy-co.com.

Further Reading

Majno G. (1975) The Healing Hand. Man and Wound in the Ancient World. Harvard University Press, Cambridge, Massachusetts.

Ransome HM. (1937) The Sacred Bee in Ancient Times and Folklore. George Allen and Unwin, London.

Bulman MW. (1955) Honey as a Surgical Dressing. Middlesex Hosp J. 55: 188–189.

Hutton DJ. (1966) Treatment of Pressure Sores. Nurs Times. 62: 1533–1534.

Cavanagh D, Beazley J, Ostapowicz F. (1970) Radical Operation for Carcinoma of the Vulva. A New Approach to Wound Healing. J Obstet Gynaecol Br Cmwlth. 77: 1037–1040.

Blomfield R. (1973) Honey for Decubitus Ulcers. J Am Med Assoc. 224: 905.

Burlando F. (1978) Sull’azione Terapeutica del Miele nelle Ustioni. Minerva Dermat. 113: 699–706.

Armon PJ. (1980) The Use of Honey in the Treatment of Infected Wounds. Trop Doct. 10: 91.

Bose B. (1982) Honey or Sugar in Treatment of Infected Wounds? Lancet. 963.

Dumronglert E. (1983) A Follow-up Study of Chronic Wound Healing Dressing with Pure Natural Honey. J Natl Res Counc Thail. 15: 39–66.

Kandil A, Elbanby M, Abd-Elwahed K, Abou Sehly G, Ezzat N. (1987) Healing Effect of True Floral and False Nonfloral Honey on Medical Wounds. J Drug Res (Cairo). 17: 71–75.

Effem SEE. (1988) Clinical Observations on the Wound Healing Properties of Honey. Br J Surg. 75: 679–681.

THE REDUX: Honey is a safe and effective alternative for the treatment of wound infections including MRSA. It can also speed the wound healing process. Clinical research indicates that honey is a safe and effective treatment for peptic ulcer, gastritis and infantile gastroenteritis. It is also a safe and effective topical treatment for Tinea infections. Manuka honey, derived from flowers of the Manuka tree growing in New Zealand, has the most potent anti-microbial effect of the 345 types of honey tested.