How to choose the right probiotic

By Corrine Toyn - Registered Dieitian 

The past several decades has seen a dramatic increase in probiotic products available for purchase, which is due to mounting evidence suggesting that the gut microbiome plays a critical role in both health and disease - but what are probiotics and how do you know which one to take?1

What are probiotics?

Probiotics are live microorganisms that can help restore the natural balance the bacteria in our gut, providing a variety of health benefits.2 Studies have shown probiotics may aid digestion, enhance immunity, and reduce inflammation. They also influence enzyme activity and vitamin status.3,4 According to the World Health Organization (WHO), probiotics are defined as “live microorganisms that when administered in adequate amounts confer a health benefit on the host”.5

Where are probiotics found?

Probiotics can be found naturally in certain foods like yogurt or kefir, but they are also available as dietary supplements.

Are probiotics safe?

Probiotics are generally considered safe for people of all ages, however if your immune system does not function properly due to a medical condition, you may be at risk so please seek advice from your doctor or dietitian.

What are probiotics vs polybiotics?

Additionally, probiotics range from single microorganisms to multi-strain polybiotics, containing various microbial species, strains and dosages. Whilst a probiotic may contain one strain, a polybiotic refers to multiple bacterial species.

Which probiotic should I take?

Unfortunately, there is an alarming amount of un-tested, un-validated and un-proven so called “probiotics” which can’t verify their critical health benefits. So, we’ve captured our top tips to help guide you on how to choose the right probiotic for you.

  1. Make sure it’s safe

When selecting a probiotic supplement, it is of utmost importance to verify the safety and effectiveness of the product. For probiotics to be effective, they must remain alive throughout their shelf life to deliver the promised health benefits. They are also vulnerable to external factors throughout their shelf life such as temperature so check the packaging for storage instructions.

Once they’re consumed, probiotics have a got a tough job! First, they must survive the stomach’s harsh acidic conditions. Then, probiotics should arrive at their destination alive in sufficient amounts to effectively colonise the gut.

Tip: Look for products labelled with the number of colony forming units (CFU) guaranteed to end of their shelf life, not at the time of manufacture.6

  1. Consider the right strain for you

We’ve already mentioned that there a quite a few products on the market. However, did you know that each product has a unique range of strains too? Seems complicated doesn’t it? But, all you need to know is that no probiotic is the same and that it’s important to look at the bacterial strains each probiotic product contains. This also includes evaluating whether there is any scientific evidence available to support a specific strain for the intended symptoms or conditions.

  1. Check the dose

Our gut microbiome is an incredibly complex and unique microbial community comprised of up to 1000 different species of bacteria, virus and fungi.1 To accurately modulate these bacterial populations for improved gut health, probiotics must be ingested in enough of an amount sufficient to have a desired health benefit.5

With that being said, probiotic doses can vary depending on the condition being treated but generally higher doses tend to produce more advantageous results.7

Therefore, when selecting probiotic products, it's important to consider how concentrated the probiotic cultures they contain are as it will affect their efficacy and ability to promote gut health.

Tip: CFU means Colony Forming Unit – the higher this is, the more colonising bacterial units there are (which is a good thing for your gut health!)

  1. Favour diversity

The latest research indicates that having a diverse gut microbiome is essential for overall gut health.8 A comprehensive review published in 2022 demonstrated that differences in gut microbial composition between healthy and chronically ill individuals are usually due to lower microbiome diversity.8

Therefore, to promote optimal gut health, it's advised to take a multi-strain polybiotic with a diversity of well-researched microbial strains, alongside a balanced and varied diet rich in fibre.

  1. Choose your preferred format

When selecting a probiotic, it’s important to think about your lifestyle and dietary preferences. Probiotics are available in a variety of formats, shapes and sizes and may be contained in capsules, sachets or bottles. Some probiotics are liquid, whereas others are freeze-dried into powders or pills, and some are advised to take on empty stomach or mixed with food and drink. Whatever you choose, it should fit into your daily routine and be palatable to you.

In summary…

If you’re considering taking a probiotic, it’s a good idea to make sure you take care on researching the product safety and dose beforehand. It’s important to check that the bacteria strains are supported by scientific research, are applicable to your individual gastrointestinal concerns and that there is a variety of strains to optimise diversity. Lastly, consider what format of probiotic is best for you and your lifestyle.

Always consider consulting your healthcare professional if you have any concerns regarding a health condition or choice of probiotic.


  1. Rowland I. et al. Eur J Nutr 2018; 57(1): 1–24.   
  2. 2022. Available online:,irritable%20bowel%20syndrome%20(IBS).
  3. Wang J, Ji H. Influence of Probiotics on Dietary Protein Digestion and Utilization in the Gastrointestinal Tract. Curr Protein Pept Sci. 2019;20(2):125-131. doi: 10.2174/1389203719666180517100339. PMID: 29769003.
  4. Barkhidarian B, Roldos L, Iskandar MM, Saedisomeolia A, Kubow S. Probiotic Supplementation and Micronutrient Status in Healthy Subjects: A Systematic Review of Clinical Trials. Nutrients. 2021 Aug 28;13(9):3001. doi: 10.3390/nu13093001. PMID: 34578878; PMCID: PMC8472411.
Joint FAO/WHO Expert Consultation on Evaluation of Health and Nutritional Properties of Probiotics in Food Including Powder Milk with Live Lactic Acid Bacteria.

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