Manuka Honey and Probiotics: The Science Behind Nature's Prebiotic Powerhouse

How Manuka Honey Feeds Beneficial Gut Bacteria

Manuka honey's prebiotic power comes in part from its complex carbohydrate content (specifically oligosaccharides) that resist digestion and become food for beneficial bacteria.

What are oligosaccharides?

While most of the carbohydrates in Manuka honey consist of simple sugars, it contains a small proportion of complex sugars that your digestive system can't break down, such as pentose and nigerose⁵.

The journey through your digestive system

When you consume Manuka honey, here's what happens:

In your stomach and small intestine, the simple sugars get absorbed quickly for energy. But the oligosaccharides keep moving. Your digestive enzymes can't break them down because you lack the specific enzymes needed to process their chemical structures.

By the time they reach your large intestine (colon), these oligosaccharides are still intact. This is where your beneficial bacteria live, and where they're waiting for their next meal.

Selective fermentation

Once in the colon, specific beneficial bacteria (such as Lactobacillus and Bifidobacterium species) recognise these oligosaccharides as food. They ferment them through a process that:

• Allows the bacteria to multiply and thrive

• Produces beneficial compounds called short-chain fatty acids (SCFAs)

• Creates an environment that discourages harmful bacteria

The beneficial compounds produced

When beneficial bacteria ferment Manuka honey's oligosaccharides, they produce SCFAs, including:

• Propionic acid: has anti-inflammatory properties

• Butyric acid: provides energy for colon cells

• Acetic acid: helps regulate appetite and metabolism

• Lactic acid: supports gut lining health (not technically a SCFA but a precursor)

Studies comparing Manuka honey mixed with yoghurt to plain yoghurt found significantly higher levels of these beneficial acids in the Manuka version². The yoghurt had a "more favourable fermentation metabolite profile, especially the lactic and propionic acids"².

This is why Manuka honey doesn't just feed probiotics, but also helps create the beneficial compounds that support your entire digestive system.

The Unique Selective Action: Supporting Good Bacteria, Fighting Bad

You might be wondering: "If Manuka honey is famous for killing bacteria, won't it harm the good bacteria too?"

This is where Manuka honey becomes even more useful.

The dual-action discovery

In 2008, researchers tested UMF™ 20+ Manuka honey against three beneficial probiotic strains and three harmful pathogenic bacteria at the same time¹. What they discovered was remarkable.

The beneficial bacteria that increased in growth:

• Lactobacillus reuteri

• Lactobacillus rhamnosus

• Bifidobacterium lactis

The harmful bacteria that were inhibited:

• Escherichia coli O157:H7

• Salmonella typhimurium

• Staphylococcus aureus

Even more interesting was that the effect was dose-dependent, meaning that the more Manuka honey used (within a specific range), the stronger both effects became¹.

Why this matters

Unlike antibiotics, which indiscriminately kill both beneficial and harmful bacteria, Manuka honey appears to act selectively. It's like having a security system that knows the difference between welcome guests and unwanted intruders.

This selective action comes from Manuka honey's multiple antimicrobial mechanisms working together:

• High natural acidity (low pH)

• Osmotic effect from high sugar content

• Presence of hydrogen peroxide

• Phenolic compounds

• Methylglyoxal (MGO) - unique to Manuka honey

The combination of these factors creates an environment where beneficial bacteria can adapt and thrive, while pathogenic bacteria struggle to survive.

How Manuka Honey Makes Probiotics More Resilient

Beyond simply feeding beneficial bacteria, evidence suggests that Manuka honey may make them stronger, meaning they are better able to survive the harsh journey through your digestive system.

The stress-training effect

Researchers discovered that exposure to low, non-lethal levels of MGO (methylglyoxal, Manuka honey's signature antibacterial compound) triggers a protective response in certain probiotic strains⁹.

Think of it like altitude training for athletes. The mild challenge of less oxygen makes their bodies adapt, becoming stronger when they return to normal conditions. Similarly, sub-lethal MGO exposure appears to ‘train’ probiotic bacteria to handle stress better.

Evidence of enhanced survival

When researchers tested probiotic survival under conditions similar to your digestive system, such as stomach acid (pH 2) and bile salts (refrigeration was also used for extended periods of time), they found that probiotics grown with Manuka honey showed "enhanced survivability" compared to probiotics grown without it⁹.

Specifically, they showed:

• Better tolerance to stomach acid (pH 2 for 90 minutes)

• Improved resistance to bile salts

• Maintained higher viable counts during storage

Studies using fermented milk found that probiotic counts with Manuka honey were more than double those without honey after 28 days of refrigerated storage.

Why this happens

Whilst scientists are not 100% sure why this happens, the current working theory is that Lactobacillus reuteri (one of the most-studied probiotic strains) naturally produces a compound called reuterin, which is structurally similar to MGO⁹. This means these bacteria may have already evolved mechanisms to handle MGO-like substances.

When exposed to Manuka honey's sub-lethal MGO levels (i.e., not strong enough to kill the good bacteria), they activate these protective mechanisms, making them more robust overall.

The sweet spot

The key is getting the dose right. Studies used MGO concentrations well below levels that would inhibit bacterial growth (typically less than 0.3 mM). At these levels, the MGO strengthens probiotics without harming them.

This is why authentic UMF™-certified Manuka honey works so well: it has verified MGO levels in the optimal range.

Learn more: What Does MGO Mean on Manuka Honey?

Real-World Results: What the Yoghurt Studies Show

Laboratory discoveries are one thing. But does this work in actual food? Researchers tested Manuka honey in fermented milk and yoghurt to find out.

The study setup

Scientists added Manuka honey (at 5% concentration) to fermented milk and yoghurt containing the probiotic Lactobacillus reuteri². They tracked how many probiotics survived over an extended period of time in the refrigerator (28 days for milk, 21 days for yoghurt).

The results

After 28 days, fermented milk with Manuka honey maintained probiotic counts of over 8 log cfu/mL⁹. To put this in perspective, that's more than double the unsweetened control.

For yoghurt, Manuka honey helped maintain counts above 7 log cfu/mL - the minimum threshold considered necessary for health benefits². Plain yoghurt without honey fell below this threshold.

But the numbers alone don't tell the complete story.

What this means for you

Think about what happens when you buy probiotic yoghurt from the supermarket. By the time you eat it (often days or weeks after production), many probiotics have died. Adding Manuka honey helps keep them alive and active for a much longer period.

The studies also measured the beneficial compounds (SCFAs) produced during fermentation. Manuka honey yoghurt produced significantly higher levels of lactic and propionic acids, the beneficial compounds that actually support your gut health².