Probiotics and prebiotics: What's the difference? | Activia Canada

Probiotics and Prebiotics: What’s the Difference?

Probiotics and prebiotics are two of the most talked-about concepts in gut health, yet they are frequently confused, or used interchangeably. This article breaks down what sets them apart, how each one interacts with the gut microbiota, and why they are often discussed together.

Probiotics vs Prebiotics: Understanding the Basics

What Are Probiotics?

Probiotics are defined by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO)¹ as live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. In simple terms, probiotics are live bacteria that can be consumed through foods or supplements, which can support health. Different strains of probiotics offer different benefits.

Not all fermented foods contain probiotics². Foods like kimchi and sauerkraut are produced through fermentation³ — a natural process in which microorganisms break down complex compounds — but the microorganisms they contain do not always meet the scientific criteria to be called probiotics. Probiotic yogurt, kefir, and fermented milk are examples of foods where specific, well-studied probiotic strains are intentionally added and maintained through to consumption.

What Are Prebiotics?

Prebiotics are not microorganisms themselves, they are the nutrients that selectively feed them. Prebiotics are a type of dietary component – mostly fibres – that pass through the upper digestive tract undigested and serve as fuel for beneficial bacteria in the colon⁴. While the concept has evolved over the years, the most current scientific definition describes a prebiotic as "a substrate that is selectively utilized by host microorganisms, conferring a health benefit." ⁵

Prebiotics are found naturally in many everyday foods, and what we eat plays a direct role in nourishing certain microorganisms that make up our gut microbiota. Prebiotics can help keep your gut supplied with the nutrients beneficial bacteria rely on. The most well-known prebiotics are dietary fibres. However, not all fibres are prebiotics!

To put it simply: probiotics or the microorganisms, and prebiotics are the nutrients those microorganisms rely on.

Key Differences Between Probiotics and Prebiotics

Nature and Mechanism

At their core, prebiotics or probiotics do very different things. Probiotics are live microorganisms that, when consumed in adequate amounts, introduce bacteria that help support the gut ecosystem and offer health benefits. Prebiotics, on the other hand, are non-digestible dietary components that serve as fuel for specific microorganisms already living there.

Our gut is home to a community of approximately 100 trillion microorganisms; collectively known as the gut microbiota; that play a necessary role in how our body functions. Both probiotics and prebiotics interact with this community, but through distinct mechanisms:

How They Interact With the Gut Microbiota

The gut bacteria and other microorganisms that make up the gut microbiota interact to support digestion and help keep potentially harmful bacteria in check. A helpful way to think about the difference between prebiotics and probiotics: probiotics are the seeds; the beneficial live microorganisms introduced through the foods we eat; while prebiotics are the soil that nourishes them. Including prebiotic and probiotic foods in your diet is one way to help support your gut health, as both play distinct but complementary roles.

A probiotic may also work more effectively when paired with prebiotic components that selectively nourish specific beneficial gut bacteria groups, most notably Bifidobacterium and Lactobacillus⁶. This selective stimulation of beneficial bacteria is sometimes referred to as the bifidogenic effect. The relationship between prebiotic and probiotic intake reflects how interconnected these two concepts truly are.

How Probiotics and How Prebiotics Works in the Gut

Probiotics

For probiotics to do anything useful, they first have to survive the journey through your digestive system; and that is no small feat. From the moment they are consumed, probiotic microorganisms must withstand stomach acidity, digestive enzymes, and bile salts before reaching the intestine intact. Once there, they interact with the existing gut microbiota, participating in the complex microbial exchanges that take place in the digestive tract.

This is why the source of probiotics matters. Some fermented foods can deliver these beneficial live microorganisms as part of a nutrient-rich food matrix that may help support their survival.

Prebiotics

Prebiotics work differently. Rather than introducing new microorganisms, prebiotic fibres travel through the upper digestive tract undigested and arrive in the colon intact, where they become a food source that can selectively help the good bacteria in the gut thrive.⁷ When prebiotic fibres reach the colon, the gut bacteria ferment them, producing short-chain fatty acids (SCFAs); including butyrate, acetate, and propionate; compounds that interact with intestinal cells and play a role in the broader gut microbial ecosystem.⁸

Dietary variety plays an important part here. A diverse diet rich in fibre-containing foods helps support a diverse, rich and balanced gut microbiota, and while certain probiotics introduce specific beneficial microorganisms, many fibre-rich foods naturally contain prebiotic components that nourish specific bacteria already present in the gut.

Foods That Contain Probiotics and Prebiotics

What we eat plays a direct role in nourishing both our bodies and the gut microbes that live within us. Many foods naturally contain either probiotics or prebiotics; including fermented foods like sauerkraut, kimchi, as well as fibre-containing foods such as whole grains foods, vegetables, and legumes; and including a variety of both in your diet is a straightforward way to support a diverse gut microbiota.

It is worth keeping in mind that some fermentation-based food undergo processes like pasteurization, cooking or filtering which may eliminate the beneficial live microorganisms cultures. When looking for probiotic-containing foods, check that the product label identifies the probiotic strain & the amount of the probiotic in colony forming units (CFU) per serving size along with its substantiated and accepted health claim.

Understanding Prebiotics vs Probiotics

While they are often mentioned in the same breath, probiotics and prebiotics are fundamentally different. Probiotics are beneficial microbes, found in or added to certain food (like probiotic yogurt), pill, or powder form, that provide specific health benefits when consumed in adequate amounts. Prebiotics feed specific microbes in the gut, and can improve the composition of our gut microbiota by encouraging good bacteria to flourish. Some are found in fibre rich foods.Together, they interact with the gut microbiota, the complex ecosystem of trillions of microorganisms that plays a role in digestion and other body processes.

By consuming sources of both, you are taking care of your gut health. You can pair them in everyday meals like probiotic yogurt with banana, kefir in a smoothie or look for foods labelled with added probiotics and prebiotics.

If you are looking for a simple way to incorporate probiotic foods into your daily routine, explore Activia's range of products. The new Activia Expert’s range contains both prebiotics and prebiotics.

Every time you eat is an opportunity to feed your gut microbiota – so include probiotic and prebiotic rich foods each day!