October 13, 2016

Sweet Science of Honey

by Bonnie Denmark

Honey has been called a miracle food. In addition to its obvious taste bud appeal, honey keeps indefinitely. And what makes for a virtually eternal shelf life also potentially makes for good medicine.

Honey has been used medicinally for thousands of years. Sumerian clay tablets (1900-1250 BCE) attest to the common use of the superfood in prescriptions. Papyrus documents show that ancient Egyptians (1550 BCE) used honey in ointments for eye and skin ailments. In ancient Greece, Hippocrates (~460 – ~370 BCE) touted honey as a remedy for coughs and wounds. A Chinese medicine book from 220 BCE prescribes honey for indigestion and other conditions. Ancient Ayurvedic texts from India recommend honey as a treatment for a host of infirmities, among them diabetes, parasites, intestinal complaints, lung ailments, and wounds. The Qu’ran, (7th century CE) says of bees: “From inside them comes a drink of varying colors, containing healing for mankind” (an-Nahl: 68-69). One of the earliest known Western medical textbooks, Bald’s Leechbook, written in the 9th century, lists honey as an ingredient in a recipe for eye salve.

With advances in pharmaceuticals over the nearly hundred years since Alexander Fleming’s discovery of penicillin, honey fell out of use in general medicine. Modern medicine prefers its remedies to be synthesized in a lab where components can be closely controlled. But the advent of antibiotic-resistant bacteria – or superbugs – has left the medical community wringing its hands and has sparked honey’s comeback in therapeutic applications.

Recent studies have demonstrated honey’s effectiveness as an antimicrobial agent. Honey is complex, with over 200 chemical compounds. Among the many weapons in honey’s arsenal is hydrogen peroxide, a known germ fighter. Also, with a pH between 3.2 and 4.5, honey is too acidic for bacteria to survive (see our module Acids and Bases to learn about the pH scale). In addition, honey generally has a moisture content of 18.8% or less, an environment in which very few microorganisms can survive. Further, honey’s high sugar concentration gives it an osmotic effect, so it draws water out of bacteria and kills them.

A bee visiting a Manuka flower in New Zealand. (©Avenue, Wikimedia Commons)

Different honeys have different properties because of the flowers they are made from. Honey made from the nectar of flowers from the Manuka tree in New Zealand and Australia has been found particularly effective in fighting bacteria and is now used in medical grade preparations to treat chronic wounds. Manuka honey lacks hydrogen peroxide but has other chemical components that give it an extra dose of microbe-fighting power. In particular, it has methylglyoxal (MGO), a compound that is found in only very small quantities in other honeys.

The Centers for Disease Control and Prevention identified six superbugs that have been wreaking havoc in hospitals. One thing that makes superbugs so hard to treat is that bacterial cells band together to form a biofilm, a slimy coating that is not readily penetrated by antibiotics.

MRSA biofilm. Biolfilms render bacteria difficult to treat with conventional antibiotics. (Photo Credit: Janice Haney Carr, Centers for Disease Control and Prevention, Public Health Image Library #7484)

Non-healing wounds are responsible up to 4% of health care costs, with bacterial infections involving biofilms affecting around 13 million Americans each year. Whereas staph infections used to be treatable with a variety of antibiotics such as amoxicillin, penicillin, oxacillin and others, MRSA and other superbugs don’t respond to these conventional treatments. However, recent investigations have confirmed the antibacterial muscle of honey, even against superbugs. Several studies have shown that honey prevents and destroys biofilms. In a 2012 study, a Cardiff Metropolitan University team found that even small concentrations of Manuka honey prevented biofilms from forming, and that it killed up to 85% of bacteria within existing biofilms within two hours in a lab. Dr. Susan Meschwitz, Assistant Professor of Chemistry at Salve Regina University in Newport, Rhode Island, offers an explanation: Honey may inhibit quorum sensing, which is how bacteria cells communicate, allowing them to attack with a coordinated group effort and form a biofilm.

Since traditional antibiotics target only specific bacteria, they are limited in the scope of their usefulness and end up contributing to resistance among those strains. In contrast, honey foils more than 80 types of bacteria, and so far honey has not been shown to contribute to resistance. “The unique property of honey lies in its ability to fight infection on multiple levels, making it more difficult for bacteria to develop resistance,” says Meschwitz.

 

LEARN MORE

Learn more at the Honey and Pollination Center of the Robert Mondavi Institute at the University of California-Davis

 

KEY SOURCES

American Chemical Society (ACS). Honey offers new approach to fighting antibiotic resistance. ScienceDaily, 16 March 2014.

Chepulis, L. (2008).  Healing Honey. Brown Walker Press.

Eteraf-Oskoue, T., & Najafi, M. (2013). Traditional and Modern Uses of Natural Honey in Human Diseases: A Review. Iran J Basic Med Sci. 2013 Jun; 16(6): 731–742.

Written by

Bonnie Denmark holds an MA in linguistics and teacher certification in English, ESL, and Spanish. She has devoted her professional life to educational and accessibility issues as a computational linguist, multimedia curriculum developer, educator, and writer. She has also worked nationally and internationally as a language instructor, educational technology consultant, and teacher trainer. Bonnie joined the Visionlearning team as a literacy specialist in 2011, assisting the project by developing comprehension aids for science modules and creating other STEM learning materials.