Can Bacteria Grow in Raw Honey? Understanding the Science

October 7, 2025 •

3 min read

Archaeologists have famously discovered pots of honey in ancient Egyptian tombs that are still perfectly edible thousands of years later. This incredible longevity is a direct result of honey's unique chemical composition, which creates a highly inhospitable environment for microbes. But can bacteria grow in raw honey under any circumstances?

Quick Summary

Pure, raw honey possesses natural antibacterial properties that prevent microbial growth due to its low water activity, high sugar content, and acidic pH. Though bacterial spores can exist, they are unable to germinate and multiply, making properly stored honey safe for consumption by most people.

Key Points

High Sugar Content Creates Osmotic Pressure: Raw honey's high sugar concentration dehydrates and kills most bacteria by drawing water out of their cells through osmosis.
Low Water Activity Inhibits Growth: The low moisture content in honey, typically under 18%, provides an inhospitable environment for microbial proliferation.
Natural Acidity is a Microbial Deterrent: Honey's acidic pH (3.2-4.5) inhibits the growth of many common bacteria that thrive in neutral conditions.
Enzymes Produce Antibacterial Agents: The glucose oxidase enzyme added by bees creates a slow-release of hydrogen peroxide, providing a natural antiseptic effect.
Not Safe for Infants Under One Year: Honey can contain Clostridium botulinum spores, which can cause infant botulism in babies under 12 months, whose digestive systems cannot neutralize them.
Proper Storage is Key to Longevity: Honey is hygroscopic, meaning it absorbs moisture. If stored improperly and its water content increases, it can become susceptible to fermentation by yeast.

Honey's Natural Antimicrobial Defenses

Raw honey possesses a combination of potent, naturally occurring characteristics that collectively create an environment where harmful bacteria cannot thrive. These properties are responsible for honey's remarkable shelf life and are the reason it is historically known for its medicinal uses.

The Role of Low Water Content and Osmotic Pressure

One of the most critical factors is honey's low water content, typically less than 18%. Nectar, which is the raw material bees collect, contains up to 70% water. Bees diligently work to evaporate this excess moisture, primarily by fanning the nectar with their wings, until it reaches a low enough percentage.

This low water content leads to a high osmotic pressure, where the concentration of sugars is far greater than the water within a bacterial cell. Through a process called osmosis, water is drawn out of the bacteria and into the surrounding honey, dehydrating and killing the microorganisms.

The Impact of Acidity

Another significant antibacterial mechanism is honey's naturally acidic pH, which typically ranges from 3.2 to 4.5. Most bacteria, including common pathogens like E. coli and Salmonella, require a neutral or slightly alkaline environment to grow and flourish. The acidic conditions in honey inhibit the growth of these microbes, adding another layer of defense against spoilage and infection.

The Power of Hydrogen Peroxide and Other Compounds

During honey production, bees add an enzyme called glucose oxidase to the nectar. This enzyme remains mostly inactive in undiluted honey but becomes active when honey is exposed to air or moisture, producing gluconic acid and a small, steady release of hydrogen peroxide. Hydrogen peroxide acts as a potent antiseptic that further inhibits microbial growth without damaging host tissues, which is why honey has been used for centuries to treat wounds. Some honeys, most notably Manuka, also contain unique non-peroxide antibacterial compounds like methylglyoxal (MGO) that contribute to their antimicrobial strength.

Comparison of Raw Honey and Artificial Honey

To highlight honey's unique properties, consider the differences between pure, raw honey and an artificial, sugar-based syrup designed to mimic it. These distinctions showcase why honey is far more than just a sugar solution.


Feature	Raw Honey	Artificial Honey (Sugar Syrup)
Water Activity	Very low (0.56–0.62)	Variable, often higher, requiring preservatives
Antimicrobial Enzymes	Contains glucose oxidase from bees, producing hydrogen peroxide.	None present.
Acidic pH	Naturally acidic (3.2–4.5), inhibiting most bacterial growth.	pH is typically neutral or higher unless acid is added.
Bioactive Compounds	Contains flavonoids and phenolic acids with antioxidant properties.	Lacks natural antioxidants and other beneficial compounds.
Source of Antibacterials	Combination of osmotic effect, acidity, enzymes, and phytochemicals.	Relies solely on osmotic pressure from high sugar concentration.

The Risks and Limitations: Infant Botulism and Contamination

Despite its strong antibacterial properties, there are crucial exceptions to consider. The most significant risk is infant botulism, which is why health authorities worldwide recommend that honey never be given to infants under one year of age. Honey, both raw and processed, can contain dormant spores of the bacterium Clostridium botulinum. While harmless to adults and older children, whose mature digestive systems can neutralize the spores, an infant's underdeveloped gut microflora cannot. In rare cases, the spores can germinate in the infant's intestines, releasing a toxin that can lead to infant botulism.

Another limitation is contamination that can occur during storage or if honey is improperly diluted. When honey is left unsealed, it can absorb moisture from the air due to its hygroscopic nature, which can raise the water content enough for spoilage yeasts to cause fermentation. Similarly, mixing honey with water or using a dirty spoon introduces moisture and microbes, which can compromise its preservative qualities. Proper storage in a sealed container is essential to maintain honey's natural defenses.

Conclusion

In summary, bacteria cannot grow and multiply in pure, raw honey due to its unique combination of natural antibacterial mechanisms: low water content and high osmotic pressure, natural acidity, and the presence of hydrogen peroxide and other bioactive compounds. While honey is exceptionally resilient, this does not mean it is entirely sterile. It can contain bacterial spores, most notably those of Clostridium botulinum, which pose a serious risk to infants under 12 months. For adults and older children, however, these spores are harmless. For those over one year of age, pure, properly stored honey is a safe and shelf-stable product, thanks to a combination of physical, chemical, and enzymatic defenses that create an environment hostile to most microbial life.

Frequently Asked Questions

No, raw honey is not completely sterile and can contain bacterial spores, yeast, and mold that come from sources like flowers, dust, and bees. However, honey's powerful antibacterial properties prevent these microorganisms from growing and multiplying.

The primary reason is honey's high sugar concentration and low water content. This creates a high osmotic pressure, which draws water out of bacterial cells and causes them to dehydrate and die.

Honey is dangerous for infants under one year old because it can contain spores of Clostridium botulinum. An infant's digestive system is not mature enough to block the germination of these spores, which can release toxins that cause infant botulism.

Yes, honey's antibacterial properties can be compromised if it absorbs too much moisture, if it's mixed with other liquids, or if it is exposed to high heat. Dilution reduces the osmotic and acidic effects that inhibit bacterial growth.

Pasteurization (heating) can reduce or eliminate some of the heat-sensitive enzymes, like glucose oxidase, which produces hydrogen peroxide. While pasteurized honey retains the antibacterial effect of its high sugar content and low pH, it may have less overall antimicrobial power than raw honey.

Yes, studies have shown that some types of medical-grade honey, such as Manuka, are effective against antibiotic-resistant bacteria like MRSA. This is due to honey's multiple antimicrobial mechanisms, making it difficult for bacteria to develop resistance.

Peroxide activity is due to the hydrogen peroxide produced by the glucose oxidase enzyme. Non-peroxide activity, found prominently in Manuka honey, is attributed to other compounds like methylglyoxal (MGO) that are stable even when hydrogen peroxide is neutralized.