What are prebiotics, probiotics, and postbiotics and how do they work?

What are the best foods for naturally improving your gut health?

The microbes living in your gut - known as the microbiome - are crucially important to your health.

Results from our PREDICT study show that there is a distinct signature of ‘good’ and ‘bad’ microbial species in your gut that are strongly associated with 'good' and 'bad' markers of health. We have also identified specific foods and dietary patterns that encourage these ‘good’ and ‘bad’ bugs to thrive. ‍

The gut microbiome is hugely variable from person to person. Through our research, we have found that even identical twins have very different gut microbiomes, with unrelated individuals sharing 30% and twins sharing 34% of the same gut microbes.

If we zoom in even closer it becomes clear that each of us has a unique set of genetic variants (strains) of each microbial species present in each of our guts. This makes us unique microbially! 

But just because your microbiome is unique to you doesn't mean it's permanent. While you can’t change your genes, you can modify your microbiome.

You may have heard the terms prebiotics, probiotics, and postbiotics, referring to foods and supplements that claim to boost the ‘good’ bacteria in your gut. 

The biology of pre-, pro- and postbiotics

• A healthy and diverse microbiome is critical to good health
• Probiotics contain live microbes that will (hopefully) populate our gut and give us health benefits
• Prebiotics are food for our beneficial gut inhabitants
• Postbiotics are helpful chemicals produced by the microbes in our gut
• We can manipulate and improve our microbiome using pre-, pro-, and postbiotic food and supplements
• We all have unique microbiomes, so to best nurture your microbiome you need to know what’s in there.
  

Prebiotics – Food for your microbes

What are they? 

Prebiotics are nutrients in food that we can't digest ourselves, such as fiber. Instead, they provide food for the bacteria in your gut and encourage their growth. 

Why are they healthy?

The microbiome functions like any ecosystem – survival of the fittest - so the bugs that survive in your gut are the ones that have plenty to eat. 

And if you provide the right food, the microbes that like to eat it will come, just like putting out birdseed will encourage feathered friends to visit. So eating prebiotics can help increase the number and diversity of organisms in our microbiome.

Where do they come from? 

Unsurprisingly, lots of the molecules we need to feed our gut bacteria come from our food. 

To count as a 'prebiotic,' the molecule must selectively stimulate the growth or activity of microbes that are beneficial to our health. Most prebiotic molecules are plant fibers, so eating lots of plants is always a good start!

Here are some of the most common prebiotic molecules and where you can find them:

• Fructooligosaccharides (FOS) – asparagus, onions, leeks, garlic, bananas, Jerusalem artichokes, chicory root
• Galactooligosaccharides (GOS) – legumes like chickpeas and lentils
• Inulin – asparagus, onions, leeks, garlic, bananas, Jerusalem artichokes, chicory root
• Beta-glucan – some mushrooms, barley, oats, rye, and other whole grains 
  

Probiotics – Living gut bugs

What are they? 

The World Health Organization defines "probiotics" as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host." In other words, they are living microbes in food that make it to your gut and (hopefully) set up camp there, providing some kind of benefit.

Why are they good for us? 

Eating probiotics may help increase the number and diversity of the bacteria in our gut, this can help reduce the growth of pathogenic microbes living in our gut, aid digestion, boost the helpful chemicals that our gut bacteria produce (more on that below), and prime our immune system. 

Where can I get some? 

Fermented foods, including yogurt, kefir, kimchi, and sauerkraut contain live bacteria and act as probiotics. 

Postbiotics – Microbe waste, gut treasures

What are they? 

As microbes in your gut eat prebiotics in your food, they produce waste molecules called metabolites. These waste molecules, along with dead cells and parts of cells produced by your microbiome, are known as 'postbiotics.' 

Why are they healthy?

In this case, our gut bugs’ trash is our body’s treasure.

Scientists have identified hundreds of postbiotic chemicals that are produced in the microbiome and play many different roles in protecting your health. They include:

• Vitamins B and K that maintain cell health and help with blood clotting, respectively.
• Short-chain fatty acids which help maintain your gut lining, act as signals to your body and brain, influence your metabolism, and have anti-inflammatory effects
• Antimicrobial molecules that kill harmful microbes
• Bacterial fragments and cells that can prime your immune system to help fight off infections.
  

Where do they come from?

A healthy, diverse microbiome that is well fed will naturally produce metabolites, so if you keep your microbiome robust and healthy, it will keep churning out those yummy postbiotics. Some foods also contain postbiotic chemicals like short-chain fatty acids, and you can buy supplements containing postbiotics, which may offer some benefits to some people. 

How can I best support my microbiome?

If you want to learn more about the microbes in your gut, take a look at the ZOE test kit, which includes the most advanced gut microbiome test in the world. We use deep shotgun sequencing to understand exactly which bacteria call your gut home to provide you with personalized recommendations for foods that support optimal gut health.

Want to understand how ZOE can help you discover the best foods for your gut bugs? Click here for our free evaluation.