Gut Check: Prebiotics and Probiotics Explained

Gut Check: Prebiotics and Probiotics Explained

Looking for ways to improve your gut health? Learn about the benefits of prebiotics and probiotics in our easy-to-understand guide, complete with food recommendations and more!

The discomfort of an upset stomach or bloating is something nobody wants to experience. Fortunately, incorporating prebiotics and probiotics into your diet can help alleviate these issues. Although people often use the terms interchangeably, prebiotics and probiotics have unique roles in promoting a healthy gut. So, why do prebiotics and probiotics matter for human health? Let's explore.

What are Prebiotics?

Prebiotics are non-digestible fibres that are found in certain foods. Meaning, when you eat foods that are rich in prebiotics, they reach through your gastrointestinal tract intact since your body can’t digest them.

The good thing is these fibres serve as food for the beneficial bacteria living in your gut. When the good bacteria feed on prebiotics, they grow and multiply, helping to maintain a healthy balance of gut bacteria, also known as microbiome diversity, as reported by the University of Michigan School of Public Health.

However, not all types of fibre are prebiotics, so it's vital to choose foods that are specifically high in prebiotic fibre. By doing so, you can help support the growth of good bacteria in your digestive tract and promote gut health.

The Dietary Guidelines for Americans recommends eating a healthy diet that's rich in prebiotic foods to help keep your gut bacteria healthy and thriving. And when your gut bacteria are happy, you're more likely to experience better digestion, stronger immunity, and improved overall health.

Some examples of foods that contain prebiotics include:

  • Chicory root
  • Jerusalem artichokes
  • Garlic
  • Onions
  • Leeks
  • Asparagus
  • Bananas
  • Apples
  • Oats

What are Probiotics?

While prebiotics are food for the good bacteria in our gut, probiotics are the good bacteria themselves. Think of them as the little workers in your gut, making sure everything is working as it should. 

Why are these bacteria so important? Well, your gut is home to trillions of bacteria, both good and bad. Digestion issues such as bloating, constipation, and diarrhoea may be caused by an imbalance between good and bad gut bacteria, research shows.

Probiotic foods work by helping to balance the good and bad bacteria in your gut, which can improve your digestion, immune function, brain health, and even your skin health, says Registered Dietitian Megan Hilbert.

Lactobacillus and Bifidobacterium are two of the most common probiotic strains, according to the National Center for Complementary and Integrative Health. They are beneficial microorganisms that are naturally found in your body and in certain foods like:

  • Yogurt
  • Kefir
  • Kimchi
  • Sauerkraut
  • Kombucha
  • Miso
  • Tempeh

The Relationship Between Food and the Gut Microbiome

Think of your gut microbiome as a bustling city, filled with many different types of inhabitants such as microbes and bacteria that play different roles. Just like how a city needs certain resources to thrive, the gut microbiome needs certain nutrients to stay healthy.

A study revealed that food passes through our intestinal tract, where the nutrients can either be used by our bodies or the bacteria in our guts. Some of these nutrients are prebiotics, and they act like food for the beneficial bacteria in our gut. This helps these bacteria to thrive, just like how a garden needs fertiliser to help plants grow.

In addition to prebiotics, we can also consume probiotics, which are live bacteria that are often found in yoghurt or fermented foods like sauerkraut. Based on the report of Harvard Medical School, probiotics are like friendly reinforcements, helping to balance out the population of bacteria in our gut microbiome.

Overall, eating a balanced diet with lots of fibre-rich foods, like fruits, vegetables, and whole grains, can help to promote a healthy gut microbiome, says Registered Dietitian Nutritionist Kristin Kirkpatrick. Just like how we need an array of foods to stay healthy, our gut microbiome needs a variety of nutrients to stay healthy too.

How Prebiotics and Probiotics Function in the Body

Prebiotics and probiotics work together to maintain a balanced microbiome. Prebiotics provide the food that healthy bacteria need to thrive, while probiotics help to replenish and maintain the population of friendly bacteria in our gut, according to the report of the University of North Dakota.

When we consume prebiotics, they pass through the digestive system mostly unchanged until they reach the colon. There, they're fermented by the microorganisms like bacteria, which produce short-chain fatty acids (SCFAs) as a byproduct. SCFAs are vital for the colon. They give energy to colon cells and control the colon's pH, creating an acidic environment that repels harmful bacteria. This is critical to preventing gastrointestinal diseases, as per the University of Michigan School of Public Health.

Probiotics, on the other hand, can survive the harsh environment of the stomach and make it to the small intestine, where they can begin to colonise and establish themselves, says Registered Dietitian Theresa Gentile. Probiotics can help to maintain the microbiome balance by competing with harmful bacteria for resources and space, producing antimicrobial compounds, thus stimulating the immune system.

So, to sum it up: probiotics are the good bacteria in your gut, while prebiotics are the food that those bacteria need to stay healthy. Without adequate amounts of prebiotics, the good bacteria in your gut can't do their job properly.


Maintaining a healthy gut microbiome is essential, and prebiotics and probiotics play critical roles. Prebiotics provide the fuel that good bacteria need, while probiotics work to sustain and replenish the population of beneficial bacteria in our gut. By incorporating prebiotic and probiotic-rich foods into our diet, we can improve digestive health, enhance our immune system, and even positively impact our mental health.