Prebiotics, Probiotics and Postbiotics: What’s the Difference?

Gut health has become one of the biggest focuses in modern wellness – and for good reason. The gut microbiome (the entire collection of microbes that reside in our gut and their respective functions) play an important role in digestion, immune function, metabolism, and even mood.

Among the most talked about microbiome supporting ingredients are prebiotics, probiotics, and postbiotics. While they sound similar, each works differently within the body and offers unique health benefits.
So, what exactly are they, and how do they support gut health and overall wellbeing?

What Are Prebiotics, Probiotics and Postbiotics and How Do they Work?

Prebiotics

Prebiotics are non-digestible fibres and compounds that feed beneficial gut bacteria already living in the microbiome. Rather than adding bacteria directly, prebiotics help existing microbes grow and thrive.

Common prebiotics include:

• Inulin
• Fructooligosaccharides (FOS)
• Galactooligosaccharides (GOS)
• Resistant starch

Natural food sources of prebiotics include garlic, onion, bananas, oats, and legumes as well as fibre supplements like psyllium husk and partially hydrolysed guar gum (PHGG).

Probiotics

Probiotics are live microorganisms that provide health benefits when consumed in adequate amounts. They help support a balanced gut microbiome by introducing beneficial bacteria into the digestive system.

Common probiotics include:

• Lactobacillus strains
• Bifidobacterium strains

Probiotics are commonly found in fermented foods such as yoghurt, kefir, kimchi, natto and miso as well as certain probiotic supplements

Postbiotics

Postbiotics are beneficial compounds produced by probiotics during fermentation or microbial activity. Unlike probiotics, postbiotics are not live organisms but can be inactivated compounds that come from live bacteria.
They can include:

• Short-chain fatty acids (SCFAs) such as butyrate
• Peptides
• Cell wall fragments
  

Postbiotics are naturally present in a variety of fermented foods such as yoghurt, kombucha, sauerkraut and pickled vegetables. Postbiotics are gaining attention because they may offer some of the benefits of probiotics while being more stable and easier to formulate into products and supplements – although research in this area is only in the early stages.

Possible Benefits of Prebiotics, Probiotics and Postbiotics

Support Digestive Health

Prebiotics may help improve bowel regularity and stool consistency by supporting healthy bacterial growth. A variety of probiotics have been studied for digestive support and may help maintain gut balance during periods of stress, travel, dietary changes, or antibiotic use.

Strengthen the Gut Barrier

A healthy gut lining helps prevent unwanted substances from crossing into the bloodstream. Certain probiotics and postbiotics may help strengthen intestinal barrier function and support gut lining integrity.

Support Immune Function

The gut is the largest immune organ in the body and hosts a major share of immune cells. Research suggests certain prebiotics, probiotics and postbiotics may help regulate immune responses and support healthy inflammation balance.

Promote Short-Chain Fatty Acid Production

When prebiotics are fermented by gut bacteria, they produce postbiotics called SCFAs. These SCFAs, namely butyrate, help nourish gut cells, providing fuel for them and support the gut lining, as well as influencing metabolic and immune pathways.

Support Whole-Body Health

Emerging research links prebiotics, probiotics and postbiotics with possible benefits for:

• Metabolic health
• Blood sugar regulation
• Weight management
• Skin health
• Mood and cognitive wellbeing

While research is ongoing, the gut microbiome is increasingly recognised as a key contributor to overall health.

What Does the Research Say?

The strongest clinical evidence currently exists for specific probiotic strains and targeted digestive health effects, including:

• Antibiotic-associated diarrhoea
• Irritable bowel syndrome (IBS)
• Constipation
• General digestive support

Prebiotics also have strong evidence for supporting beneficial bacteria growth and digestive regularity.
Postbiotics are a newer and rapidly evolving category. Early research is promising, particularly for immune support, gut barrier health, and inflammation balance, although larger human studies are still needed.
Importantly, responses can vary significantly between individuals depending on diet, lifestyle, microbiome composition, and the specific strain or ingredient used.

The Bottom Line

• Probiotics are the beneficial microbes
• Prebiotics feed beneficial microbes
• Postbiotics are the helpful compounds those microbes produce

Together, they help support a healthier gut environment, which may positively influence digestion, immunity, metabolism, and overall wellbeing.
As research into the gut microbiome continues to evolve, prebiotics, probiotics, and postbiotics will likely become increasingly recognised for their potential to not only support gut health, but also broader aspects of health including immunity, metabolism, and overall wellbeing.

Written by Dr Jasmine Millman (APD, PhD)

Help Yourself Dietitians are all PhD qualified, ensuring evidence like this is matched to your eating preferences and habits in an empathic and empowering way that suits your lifestyle.

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