Is MGO in Manuka Honey Toxic? Separating Fact from Fiction

According to research, the methylglyoxal (MGO) found in Manuka honey is largely deactivated during digestion, indicating that dietary intake is unlikely to be toxic to healthy individuals. However, the question, 'Is MGO in Manuka honey toxic?' warrants a deeper look into both its powerful antibacterial properties and potential risks.

Quick Summary

Methylglyoxal (MGO) gives Manuka honey its antibacterial power. Research shows that while high concentrations can be toxic in lab settings, dietary MGO is safely metabolized in humans. Concerns about Advanced Glycation End-products (AGEs) are largely mitigated by the body's natural processes and low absorption.

Key Points

• Dietary MGO is Not Toxic: For healthy individuals, the MGO from Manuka honey is largely deactivated during digestion, with low systemic absorption.

• MGO’s Selective Action: The compound's toxicity is selective, primarily targeting bacteria and pathogens without harming human cells at typical concentrations.

• Context Matters for AGEs: Concerns about MGO-derived Advanced Glycation End-products (AGEs) are based on isolated lab studies and high endogenous levels in metabolic disorders, not normal dietary intake.

• Cautions for Specific Groups: Individuals with diabetes, bee allergies, infants under one year, and chemotherapy patients should exercise caution or avoid Manuka honey.

• Choose Certified Honey: Look for verified MGO or UMF ratings on labels to ensure you are purchasing authentic, high-quality Manuka honey.

• Higher MGO, Higher Potency: The MGO rating directly correlates with the honey's antibacterial strength, which is important for therapeutic applications.

What is Methylglyoxal (MGO)?

Methylglyoxal, or MGO, is a naturally occurring compound that is the primary source of Manuka honey's distinctive non-peroxide antibacterial activity. Unlike other honeys that rely on hydrogen peroxide for their antimicrobial effect, Manuka's potency is directly linked to its MGO concentration. This compound forms over time from dihydroxyacetone (DHA), a precursor found in the nectar of the Manuka flower. The higher the MGO rating displayed on the label, the greater the concentration of this compound and the more potent the honey's antibacterial properties. For years, this potency has been celebrated, but more recently, questions have been raised about its safety.

MGO's Role in Manuka Honey

MGO's antibacterial mechanism involves a selective process where it binds to bacterial proteins and genetic material, interfering with their function and growth. It has shown remarkable effectiveness against a range of harmful bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). This is why medical-grade Manuka honey, often with very high MGO ratings, is used in clinical settings for wound care. Beyond its antimicrobial properties, MGO also contributes to the honey's anti-inflammatory and antioxidant effects.

The Case for MGO's Safety in Manuka Honey

When the body ingests Manuka honey, the MGO doesn't circulate freely in high concentrations. Multiple studies suggest that dietary MGO has low bioavailability and is largely degraded in the intestine. A key 2025 study highlighted that after simulated digestion, only 5–20% of the initial MGO remained, with no significant increase in systemic MGO levels detected in healthy volunteers. The human body also has a natural detoxification pathway, involving enzymes that effectively neutralize methylglyoxal.

Selective vs. Systemic Toxicity

A crucial distinction must be made between how MGO acts on bacterial cells and its effect on human cells. At the concentrations found in Manuka honey, MGO exhibits a kind of 'selective toxicity,' effectively targeting harmful bacteria without harming human cells. This is different from the high-concentration, isolated MGO used in some laboratory experiments, which can indeed be cytotoxic. This difference explains why Manuka honey can be safely used on wounds to fight infection while being harmless to the surrounding healthy tissue.

The Counter-Argument: Concerns over MGO Toxicity

Some research, often in vitro or focused on internal metabolic disorders, has raised concerns about methylglyoxal. For instance, studies have linked the accumulation of Advanced Glycation End-products (AGEs), for which MGO is a precursor, to chronic diseases like diabetes, neurodegenerative disorders, and cardiovascular disease. High endogenous (internally produced) levels of MGO are observed in people with diabetes and renal failure, not from dietary intake. These studies can be misinterpreted to suggest that MGO from Manuka honey is equally dangerous, but they often fail to account for the body's natural detoxification and the honey's low bioavailability.

Potential Risks and How They Are Mitigated

• AGE Formation: While MGO can contribute to AGE formation, a healthy body effectively manages this process. Ingested MGO from honey is a minor contributor compared to endogenous production or highly processed foods. A clinical trial on healthy individuals showed no increase in AGE biomarkers after consuming high-UMF Manuka honey.
• High Concentrations: The high concentrations of isolated MGO used in laboratory studies are not representative of a typical dietary intake. For internal consumption, the risk of systemic toxicity is low due to poor absorption and rapid metabolic clearance.
• Pre-existing Conditions: For individuals with compromised health, particularly uncontrolled diabetes, who already have elevated systemic MGO, adding large quantities of high-MGO honey might not be advisable. However, the sugar content is often a more pressing concern for this group.

MGO Manuka Honey vs. Other Honey Varieties

Feature	MGO Manuka Honey	Standard Honey (e.g., Clover)
Antibacterial Component	Primarily Methylglyoxal (MGO)	Primarily Hydrogen Peroxide
Potency	Higher, stable, and heat-resistant antibacterial activity	Lower and heat-sensitive antibacterial activity
MGO Concentration	High (e.g., 100+ mg/kg to 1000+ mg/kg)	Very low (typically < 20 mg/kg)
Primary Use	Medicinal (wound care, internal wellness)	Culinary, general health benefits
Source	Bees pollinating the Manuka bush	Bees pollinating various flowers
Bioactivity	Distinctive, stable, non-peroxide activity	Dependent on hydrogen peroxide production

Who Should Be Cautious About Manuka Honey?

While Manuka honey is safe for most, specific groups should consult a healthcare provider before consumption:

• Diabetics: Due to its high sugar content, Manuka honey can affect blood sugar levels, and individuals should monitor their intake carefully.
• Allergy Sufferers: People with known allergies to bees or pollen may experience an allergic reaction.
• Infants: Honey should never be given to infants under 12 months due to the risk of infant botulism.
• Chemotherapy Patients: Manuka honey can interact with some chemotherapy drugs, and professional medical advice is essential.

Conclusion: Is MGO in Manuka Honey Toxic? The Final Verdict

For the average, healthy adult, the naturally occurring MGO in Manuka honey is not toxic when consumed as part of a normal diet. The body possesses efficient detoxification mechanisms, and the dietary MGO is not fully absorbed into the bloodstream. Concerns about MGO-related damage are largely extrapolated from laboratory studies using isolated MGO at concentrations far beyond what is found in honey or are related to high endogenous MGO in people with severe metabolic conditions. Manuka honey remains a celebrated natural remedy, valued for its potent antibacterial and healing properties, which stem from MGO. By respecting the recommended dosages and being mindful of personal health conditions, consumers can safely enjoy its benefits.

For more information on the critical evaluation of MGO's effects, consult research on the topic, such as this study: Critical evaluation of toxic versus beneficial effects of methylglyoxal.

How to Choose a Safe Manuka Honey

• Check the MGO rating: For general wellness, a moderate MGO level (e.g., 100+) is sufficient. Higher levels are for targeted therapeutic uses.
• Look for certification: Choose products with third-party certifications like the Unique Manuka Factor (UMF) or validated MGO grading to ensure authenticity and quality.
• Consider the source: Quality Manuka honey is sourced and tested in Australia or New Zealand, where the Manuka bush grows.
• Consult a professional: If you have a pre-existing condition, talk to a healthcare provider to determine if Manuka honey is right for you.

Safe and Responsible Consumption Practices

• Use Manuka honey in moderation due to its high sugar content, especially if you have blood sugar concerns.
• Do not heat Manuka honey above 45°C to preserve its raw, bioactive properties.
• Store it in a cool, dry place away from direct sunlight to maintain potency.
• For topical application, especially on wounds, consider medical-grade honey and consult a doctor.

Frequently Asked Questions

Is the high MGO level in Manuka honey safe to consume?

Yes, for most healthy individuals, the MGO levels in Manuka honey are safe to consume. The body naturally metabolizes and detoxifies dietary MGO, and research indicates that it has low bioavailability and is not systemically toxic in a normal dietary context.

Does MGO cause Advanced Glycation End-products (AGEs)?

While MGO is a precursor to AGEs, the small amount of dietary MGO from honey is not a significant contributor to AGE accumulation compared to endogenous production or highly processed foods. A healthy body efficiently processes and detoxifies MGO.

Is MGO harmful to healthy human cells?

The MGO in Manuka honey exhibits selective toxicity, meaning it is harmful to bacteria but not to healthy human cells at the concentrations found in the honey. This is why medical-grade Manuka honey is used safely on wounds.

Can people with diabetes eat Manuka honey?

People with diabetes should consult their doctor before consuming Manuka honey. Like all honey, it has a high sugar content and can affect blood sugar levels, which must be carefully managed.

Why shouldn't infants have honey?

Infants under 12 months should never be given honey due to the risk of infant botulism, a rare but serious foodborne illness caused by bacterial spores that can be present in honey.

How does the body detoxify MGO?

The human body has a natural pathway called the glyoxalase system, involving enzymes that efficiently detoxify and neutralize methylglyoxal, rendering it harmless.

How does MGO in Manuka honey differ from MGO in other contexts?

MGO is naturally produced within the human body and found in other foods, but usually at much lower levels than in Manuka honey. Concerns about toxicity often arise from the effects of high endogenous MGO in people with metabolic diseases or from high concentrations of isolated MGO used in lab experiments, not from dietary intake.