For thousands of years, honey has been valued not just as a natural sweetener but as a powerful medicinal substance. Ancient Egyptians documented its use in treating wounds on papyrus scrolls dating back to 1500 BCE. Indigenous healing traditions worldwide have incorporated honey into remedies for everything from sore throats to skin infections.
What was once considered folklore has now gained scientific validation. Modern research has uncovered the complex mechanisms that give raw honey its remarkable ability to fight microbes. Unlike many natural remedies with limited scientific backing, honey's antimicrobial properties are well-documented in peer-reviewed literature, with studies conducted at prestigious research institutions worldwide.
At Nettie's Bees, we've long appreciated the difference that truly raw, unprocessed honey makes—not just in flavor, but in preserving the natural properties that make honey such a remarkable substance. In this article, we'll explore the fascinating science behind honey's antimicrobial properties and why the way honey is processed matters significantly for these benefits.
The Remarkable Composition of Raw Honey
Beyond Simple Sweetness: Honey's Complex Makeup
Raw honey is far more than just a simple sugar solution. While it consists primarily of glucose and fructose (about 76%), the remaining constituents create a complex matrix that contributes to its unique properties:
- Water (typically 17-20%)
- Enzymes (including glucose oxidase, invertase, catalase)
- Amino acids and proteins
- Organic acids (gluconic acid being predominant)
- Vitamins and minerals
- Phenolic compounds and flavonoids
- Bee-derived components (including defensin-1)
According to the comprehensive analysis published in the Journal of Agricultural and Food Chemistry, researchers have identified over 200 substances in honey, with composition varying based on floral source, geographic origin, season, and production methods.
The National Honey Board notes that these variations explain why different honey varieties exhibit different levels of antimicrobial activity, with some showing significantly stronger effects than others.
The Living Enzymes in Raw Honey
Among honey's most important components are its enzymes—proteins that catalyze specific biochemical reactions. These enzymes originate from both bee secretions and nectar sources. The key enzymes relevant to honey's antimicrobial properties include:
Glucose oxidase: Perhaps the most significant antimicrobial enzyme in honey, glucose oxidase converts glucose into gluconic acid and hydrogen peroxide when honey is diluted. This enzyme is added by bees during nectar processing.
Catalase: This enzyme breaks down hydrogen peroxide and helps regulate its levels in honey. Primarily derived from pollen, its concentration varies significantly between honey varieties.
Invertase: While primarily involved in breaking down sucrose into glucose and fructose, this enzyme contributes to honey's overall acidity.
Research published in the journal Food Chemistry has demonstrated that these enzymatic activities are highly temperature-sensitive. When honey is heated above 40°C (104°F) during processing, enzyme activity begins to decline significantly. By 70°C (158°F)—a temperature commonly used in commercial honey processing—nearly all glucose oxidase activity is destroyed, substantially reducing antimicrobial potential.
Primary Antimicrobial Mechanisms in Honey
The Hydrogen Peroxide Effect
One of honey's most potent antimicrobial mechanisms involves hydrogen peroxide production. When raw honey is diluted with water (as happens when applied to a wound or mixed with other ingredients), the enzyme glucose oxidase becomes activated.
This enzyme converts glucose in the honey to gluconic acid, producing hydrogen peroxide as a byproduct. Unlike concentrated hydrogen peroxide used as a disinfectant, honey's hydrogen peroxide is produced at low, sustained levels that are antimicrobial without damaging tissue.
Research published in the Archives of Microbiology demonstrated that this "slow-release" delivery system provides effective antimicrobial activity while remaining gentle on human cells—explaining why honey can kill bacteria without harming human tissue.
A study from the University of Waikato in New Zealand quantified this effect, showing that diluted honey maintained significant antibacterial activity for at least 24 hours, providing an extended release of hydrogen peroxide that effectively inhibited bacterial growth.
Osmotic Pressure: The Dehydration Defense
Honey's high sugar concentration (typically around 80%) creates an environment with extremely low water activity. This hypertonic condition exerts strong osmotic pressure on microbial cells, essentially drawing water out of bacteria through osmosis and dehydrating them.
Most bacteria require a water activity (aw) of at least 0.91 to grow, while honey typically has a water activity of 0.56-0.62—far below what microbes can tolerate. This physical property explains why properly harvested and stored honey resists spoilage indefinitely.
Research published in the International Journal of Food Microbiology demonstrated that this osmotic effect contributes significantly to honey's ability to inhibit bacterial growth, independent of other antimicrobial factors.
Acidity: The pH Factor
Raw honey is naturally acidic, with pH levels typically ranging from 3.2 to 4.5. This acidity creates an environment hostile to most bacteria, which generally prefer neutral or slightly alkaline conditions.
The primary acid in honey is gluconic acid, produced during the glucose oxidase reaction. Other organic acids present in smaller quantities include formic, acetic, citric, lactic, malic, and succinic acids.
Studies published in the journal Food Microbiology have shown that honey's acidity alone can inhibit many common pathogens, with the combined effect of acidity and other antimicrobial factors creating a powerful defense against microbial growth.
Specialized Antimicrobial Compounds in Honey
Bee Defensin-1: The Antimicrobial Peptide
In 2010, researchers at the University of Amsterdam made a significant discovery: they identified bee defensin-1, an antimicrobial peptide, in honey. This compound is part of the honeybee's immune system and gets incorporated into honey during production.
Defensins are small cysteine-rich peptides that disrupt bacterial cell membranes, causing leakage of cellular contents and eventual cell death. Research published in the FASEB Journal demonstrated that bee defensin-1 is particularly effective against Gram-positive bacteria, including antibiotic-resistant strains like MRSA (Methicillin-resistant Staphylococcus aureus).
This discovery helped explain why some honeys maintain antimicrobial activity even when hydrogen peroxide is neutralized by catalase, revealing another layer of honey's complex defense system.
Methylglyoxal (MGO): The Manuka Marker
While most honey varieties rely primarily on hydrogen peroxide for their antimicrobial activity, certain types—most notably Manuka honey from New Zealand—contain high levels of methylglyoxal (MGO), a powerful antimicrobial compound.
MGO forms naturally in Manuka honey from the conversion of dihydroxyacetone, a compound found in high concentrations in the nectar of the Leptospermum scoparium (Manuka) plant. Unlike the hydrogen peroxide mechanism, MGO provides stable, non-peroxide antimicrobial activity that isn't affected by catalase.
Research published in Molecular Nutrition & Food Research demonstrated that MGO directly inhibits bacterial growth by interfering with cell division and disrupting the bacterial cell envelope. The concentration of MGO correlates strongly with antimicrobial potency, forming the basis for the Unique Manuka Factor (UMF) rating system used to grade Manuka honey.
Phenolic Compounds and Flavonoids
Honey contains numerous plant-derived phenolic compounds and flavonoids that contribute to its antimicrobial properties. These compounds, which come from plant nectar, include:
- Gallic acid
- Caffeic acid
- p-Coumaric acid
- Ferulic acid
- Quercetin
- Kaempferol
- Chrysin
A comprehensive review published in the Journal of Agricultural and Food Chemistry noted that darker honey varieties typically contain higher concentrations of these compounds, which may explain why darker honeys often demonstrate stronger antimicrobial activity.
These compounds work through multiple mechanisms, including:
- Disrupting bacterial cell membranes
- Inhibiting bacterial toxin production
- Interfering with bacterial quorum sensing (communication)
- Providing antioxidant protection
The Antimicrobial Spectrum: What Honey Can Fight
Honey vs. Common Pathogens
Laboratory studies have tested honey against numerous pathogens, with particularly strong evidence for effectiveness against:
- Staphylococcus aureus (including MRSA strains)
- Pseudomonas aeruginosa
- Escherichia coli
- Streptococcus pyogenes
- Salmonella enterica
- Helicobacter pylori
A meta-analysis published in the Cochrane Database of Systematic Reviews examined multiple clinical trials and found strong evidence supporting honey's effectiveness against these and other common pathogens, particularly in wound care applications.
The most comprehensive laboratory study to date, published in the European Journal of Clinical Microbiology & Infectious Diseases, tested multiple honey varieties against 200 clinical isolates, finding broad-spectrum activity with varying effectiveness based on honey type and bacterial species.
Honey Against Antibiotic-Resistant Bacteria
Perhaps most promising is honey's effectiveness against antibiotic-resistant bacteria—one of modern medicine's most pressing challenges. The World Health Organization has declared antimicrobial resistance "one of the top 10 global public health threats facing humanity."
Research published in Frontiers in Microbiology demonstrated that medical-grade honey effectively inhibited growth of multidrug-resistant bacteria, including:
- Methicillin-resistant Staphylococcus aureus (MRSA)
- Vancomycin-resistant Enterococcus (VRE)
- Carbapenem-resistant Enterobacteriaceae (CRE)
Honey's multi-target approach, attacking bacteria through several different mechanisms simultaneously, makes it extremely difficult for bacteria to develop resistance. Unlike conventional antibiotics that typically have a single target, honey's complex antimicrobial system presents multiple hurdles for bacterial adaptation.
Beyond Bacteria: Antifungal and Antiviral Properties
While most research has focused on antibacterial properties, emerging evidence suggests honey also possesses antifungal and potentially antiviral capabilities.
Studies published in Mycoses have demonstrated honey's effectiveness against Candida species, including drug-resistant strains. The mechanisms appear similar to those affecting bacteria: osmotic effects, hydrogen peroxide production, and phenolic compounds all contribute.
Research on antiviral properties remains preliminary but promising. In vitro studies published in the Archives of Medical Research have shown activity against influenza viruses, herpes simplex virus, and varicella-zoster virus, though more research is needed to confirm clinical relevance.
From Lab to Application: Practical Implications
Medical-Grade Honey
The strong scientific evidence for honey's antimicrobial properties has led to the development of standardized medical-grade honey products now used in clinical settings worldwide. These products undergo rigorous quality control to ensure consistent antimicrobial activity, safety, and purity.
Medical-grade honey is typically sterilized by gamma irradiation, which kills potential pathogens while preserving antimicrobial compounds—unlike heat sterilization, which would destroy key enzymes.
Products include:
- Wound dressings impregnated with honey
- Sterile honey gels for wound application
- Honey-based ointments and creams
- Honey-based lozenges for throat infections
A landmark review published in the British Journal of Surgery analyzed multiple clinical trials and concluded that honey dressings heal partial thickness burns more quickly than conventional dressings and are effective against post-operative wound infections.
Biofilm Disruption
One of honey's most valuable medical applications is its ability to disrupt bacterial biofilms—structured communities of bacteria enclosed in a protective matrix that renders them up to 1,000 times more resistant to antibiotics.
Biofilms are implicated in approximately 80% of persistent infections, including chronic wounds, implant-associated infections, and lung infections in cystic fibrosis patients.
Research published in PLOS ONE demonstrated that honey effectively disrupts established biofilms of Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes—three notorious biofilm formers. The mechanisms involve both direct killing of bacteria and disruption of the extracellular matrix binding the biofilm together.
Honey as a Natural Food Preservative
Honey's antimicrobial properties also make it valuable as a natural food preservative. Historical evidence shows honey was used to preserve foods long before refrigeration, and modern research confirms its effectiveness.
Studies published in the International Journal of Food Microbiology have demonstrated honey's ability to extend shelf life of various foods, inhibiting spoilage organisms and foodborne pathogens.
The combination of multiple preservation factors—osmotic effect, acidity, hydrogen peroxide, and phenolic compounds—makes honey particularly effective at preventing microbial growth in foods.
Raw vs. Processed: Why Processing Matters
The Impact of Heat
Commercial honey processing typically involves heating honey to 70°C (158°F) or higher to facilitate filtering and bottling. Unfortunately, this temperature severely impairs honey's antimicrobial properties.
Research published in the Journal of Food Protection demonstrated that heating honey to 70°C for just 30 minutes destroyed virtually all glucose oxidase activity, eliminating its ability to produce hydrogen peroxide—a key antimicrobial mechanism.
Studies comparing raw and heat-treated honey consistently show significantly reduced antimicrobial activity in processed varieties. A comprehensive analysis in Food Chemistry showed up to 90% reduction in antimicrobial potency after standard commercial heat treatment.
Filtration Effects
Ultra-filtration, another common commercial processing technique, removes pollen, propolis particles, and high-molecular-weight compounds from honey. Unfortunately, this process also eliminates or reduces important antimicrobial components.
Bee defensin-1, certain phenolic compounds, and propolis-derived antimicrobials are often reduced or removed by extensive filtration. Research in the Journal of Food Protection demonstrated that ultra-filtered honey exhibited significantly lower antimicrobial activity compared to minimally filtered samples from the same source.
At Nettie's Bees, we practice minimal processing—just enough straining to remove large particles like wax while preserving all the beneficial components that give honey its natural antimicrobial properties.
Practical Considerations for Maximum Benefit
Selecting the Right Honey for Antimicrobial Use
If you're interested in honey's antimicrobial properties, these factors should guide your selection:
Darker varieties generally show stronger activity: Research published in the Journal of Agricultural and Food Chemistry confirmed darker honeys typically contain higher levels of phenolic compounds and often demonstrate stronger antimicrobial effects.
Raw, unheated honey preserves enzymatic activity: Look for honey specifically labeled as raw and unheated to ensure glucose oxidase and other enzymes remain active.
Special varieties with non-peroxide activity: Some honey varieties, like Manuka, offer additional antimicrobial compounds beyond the standard hydrogen peroxide system. These typically command premium prices but provide verified antimicrobial activity.
Local isn't necessarily better for antimicrobial properties: While local honey offers many benefits, antimicrobial activity depends more on floral source than geographic proximity. Some regions naturally produce honey with stronger antimicrobial properties due to their native plants.
Proper Storage to Preserve Antimicrobial Properties
To maintain honey's antimicrobial potential:
Store at room temperature or cooler: While refrigeration isn't necessary, extreme heat damages enzymes. Ideal storage temperature is between 10-21°C (50-70°F).
Protect from light: UV exposure can degrade phenolic compounds. Store honey in amber glass or opaque containers.
Keep tightly sealed: Honey's hygroscopic nature means it readily absorbs moisture from the air, which can dilute its natural compounds and potentially allow fermentation.
Use within two years for optimal enzyme activity: While honey never "spoils," research in Food Chemistry shows enzyme activity gradually declines over time, even with proper storage.
Conclusion
The antimicrobial properties of raw honey represent one of nature's most sophisticated defense systems—a complex interplay of physical properties, enzymatic reactions, and bioactive compounds working in concert to inhibit microbial growth. From hydrogen peroxide production to osmotic pressure, from bee defensin-1 to plant-derived phenolics, honey attacks harmful microorganisms through multiple pathways simultaneously.
This multifaceted approach not only makes honey effective against a broad spectrum of pathogens but also helps explain why microbes rarely develop resistance to honey—unlike conventional single-target antibiotics.
The science clearly demonstrates that raw, minimally processed honey preserves these valuable properties, while commercial processing methods significantly reduce antimicrobial activity. This understanding highlights the importance of choosing raw honey when these properties are desired.
As researchers continue to unravel honey's complex antimicrobial mechanisms, we gain deeper appreciation for this ancient remedy and find new applications in modern medicine. From wound care to combating antibiotic-resistant infections, honey continues to prove its value as more than just a sweetener.
Supporting sustainable beekeeping practices ensures we preserve not only this remarkable natural resource but also the essential pollination services that honeybees provide to our food system and ecosystems.
