Prebiotics: the secret hero?

So, by now we know that one route to improving your chances of a healthy hormonal balance and the healthy development of your baby’s brain and immune system is ensuring your gut is in a good state click here for a reminder as to why it is so fundamental.

What’s a ‘good state?’ At this point, given the relatively early stage science is at with understanding the gut microbiome, we mean ensuring that the bacteria within are diverse and there are no major imbalances.

How do we achieve this?

Well, first is reducing stress and avoiding medications where you possibly can. Not always easy. However, one easy and very powerful way is via what you eat click here for more on this. This has been shown to be able to change the makeup of your microbiome in as little as 24 hours.

Probiotics, Prebiotics, Synbiotics? Now its getting confusing. What are all these different things?

Probiotics (note the ‘O’) are the ones that most people have probably heard of. These add in bacteria (theoretically) in to the gut. They have become big business and you can now buy them almost anywhere from supplements to promises of their wondrous powers added to foods, yogurts and even baby formula. To be honest science is still out on these, especially the shop bought ones click here for more on this . However, Prebiotics (note the ‘E’) are looking a bit more interesting and here’s why….

So what is a Prebiotic?

Well, in very simple terms, they feed the existing bacteria in your gut. Prebiotics are usually starches which the body itself cannot digest/absorb but the bacteria within your gut can. Essentially feeding them directly. Thats what we want.

Glenn Gibson and Marcel Roberfroid first defined a prebiotic as ‘A non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improves host health’

We now know that it is more than ‘one’ or a ‘limited number’, the definition has since been updated and that the possibilities are actually much more extensive. It is likely in fact that prebiotics feed and stimulate a whole host of bacteria in the gut.

The other good thing they do is to help with the production of another wonderous thing: The Short Chain Fatty Acid. What’s that? Click here for why these are so crucial . SCFAs are actually pretty fascinating (promise!) so well worth checking them out. In short though, they have been linked to helping with all kinds of good stuff - anti inflammatory/promoting good gut barrier function etc.

Bottom Line: prebiotics have been shown to increase the growth of bifidobacteria and lactobacilli. These are generally seen as the good guys. These are shown to contribute to what we want: improvement in gut barrier function, immunity, reduction of potentially pathogenic bacteria (e.g., clostridia), and enhanced SCFA production.

Question is: Do they actually work?

Once again, studies here aren’t exactly water tight or entirely conclusive, however ‘Inulin, oligofructose, and FOS have been extensively studied as prebiotics, and have been shown to significantly increase fecal bifidobacteria at fairly low levels of consumption (5–8 g per day)’ (1)

We also know that there has been some evidence of improved immune function as a result: ‘Oligofructose consumption was found to reduce febrile illness associated with diarrhea or respiratory events, and reduce antibiotic use in infants’ (2)

So far, so good.

At this stage we don't yet really know enough about the details and specifics (which prebiotic impacts which bacteria for example), but we know they have a potentially powerful impact. ‘Different prebiotics will stimulate the growth of different indigenous gut bacteria. Prebiotics have enormous potential for modifying the gut microbiota, but these modifications occur at the level of individual strains and species and are not easily predicted’ (3)

So once again, it is relatively early days in our understanding. On the whole though, feeding the bacteria we do have seems like a good idea, particularly as diversity within our gut microbiome is key - especially when we are growing a healthy baby. Click here for more on this.

So, Where can I find prebiotics?

According to a paper by Markowiak and Slizewska looking at the effects of probiotics and prebiotics on health site potential sources:

  • tomatoes

  • artichokes

  • bananas

  • asparagus

  • berries

  • garlic

  • onions

  • chicory

  • green vegetables

  • legumes

  • lentils

  • oats

  • linseed

  • barley

  • wheat

Once again, research is relatively nascent in this area, but fibre and prebiotics are generally at this stage at least recognised as a safe, sensible way to boost and support your gut health and eating these foods is safe while you’re pregnant. Get involved.

  1. SLAVIN J: Fibre and prebiotics: Mechanisms and Health Benefits: Nutrients. 2013 Apr: 5(4): 1417-1435

  2. SLAVIN J: Fibre and prebiotics: Mechanisms and Health Benefits: Nutrients. 2013 Apr: 5(4): 1417-1435

  3. MARKOWIAK P, SLIZEWSKA K: Effects of Probiotics, Prebiotics and Synbiotics on Human Health. Nutrients: 2017 Sep: 9(9): 1021

  4. MARKOWIAK P, SLIZEWSKA K: Effects of Probiotics, Prebiotics and Synbiotics on Human Health. Nutrients: 2017 Sep: 9(9): 1021


This article is for informational purposes only. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The information on this website has been developed following years of personal research and from referenced and sourced medical research. Before making any changes we strongly recommend you consult a healthcare professional before you begin.