Dr Libby: Should you be taking a probiotic?

There is emerging evidence that probiotics may reduce the severity of  IBS symptoms.

There is emerging evidence that probiotics may reduce the severity of IBS symptoms.

As more and more evidence emerges about the importance of the gut microbiome to so many aspects of our health, probiotic supplementation is becoming more common.

And it's something I'm frequently asked about.


Probiotics are beneficial bacteria. But for probiotic supplements to have any potential benefits, they must be scientifically proven to survive digestion (meaning they need to survive exposure to stomach acid) and reach the large intestine alive.

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They also need to be in a sufficiently high dose to have an effect, plus the pH level of the local environment (inside the intestines) needs to be appropriate for the bacteria to take up residence.


There is currently science for and against the use of probiotic supplements for many health conditions, and so the jury is still out as to whether they are beneficial or not.

There isn't just one universal probiotic – different strains of bacteria have different actions and health benefits, and the actions of a particular strain cannot be extrapolated to other strains, even within the same species.

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So supplements can contain different probiotic strains as well as different doses of the strains, which influences their effect in the body. Adding to this complexity is the fact that we don't all respond to probiotic supplementation in the same way – our individual response can depend on the species that are already residing in our gut, as well as our own health status.

A 2016 scientific review published in the Genome Medicine journal by researchers in Denmark found that probiotic supplements generally don't impact the gut bacteria profile of healthy adults. Yet we know that our gut microbiome is greatly impacted by our way of eating.

So rather than supplementing probiotics, I prefer to encourage people to focus on eating real whole foods (including some fermented foods) to support and maintain a healthy gut bacteria profile. Research also shows that within about two weeks of ceasing probiotic supplementation, the strains that were present in the supplement are no longer detectable in the waste leaving the body, indicating that they don't have long-lasting effects.

However, science tells us that probiotics can be beneficial in certain health conditions. Let's explore these now.


There is good evidence that certain strains of probiotics can help to prevent antibiotic-associated diarrhoea; specifically Lactobacillus rhamnosis GG (LGG) and Saccharomyces boulardii (S. boulardii).


There is emerging evidence that probiotics may reduce the severity of  IBS symptoms. However, given that IBS can manifest as different symptoms depending on the person, probiotics are unlikely to be a magic fix and a probiotic supplement may or may not benefit you.

What helps one person may not help another, and in fact, could actually worsen their symptoms. If you decide to trial a particular probiotic supplement, it should be taken for at least four weeks to assess how it affects you. Remember, your body is your best barometer.

However, if you have IBS and you are currently in the elimination or challenge phases of a low FODMAP diet, I do not recommend taking a probiotic supplement, as this could cloud your results and make it more difficult to identify which (if any) of the high FODMAP foods you react to.


In patients with mild to moderately active ulcerative colitis, studies suggest that specific probiotics may help to induce and maintain remission. The specific probiotics that may assist include E. Coli Nissle 1917 and a mixture of eight strains, similar to those showing promise in IBS.

Generally, probiotics are safe for adults to take, however those with food allergies should always check that the probiotic is free from their specific allergen, and they shouldn't be taken by immunocompromised or critically ill people unless medically supervised.

Dr Libby is a nutritional biochemist, best-selling author and speaker. The advice contained in this column is not intended to be a substitute for direct, personalised advice from a health professional. See drlibby.com

 - Stuff


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