How to choose the right probiotic for you

Choosing the right probiotic can be confusing due to the sheer number of products on the market and the fact that it is often not clear whether or not they will help you.

In order to understand how probiotics work and how to select an effective one you need to know a bit about the following:

• What kind of bacteria they are (strain)
• The dose (i.e. number of bacteria)
• Whether you should take a liquid or capsule
• If the strain or product has been clinically trialled and what for, i.e. will they actually help you?

Understanding probiotics: The basics

Probiotics are defined scientifically as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, i.e. you. Therefore, any product you buy must have evidence that it is in the right dose, format and strain.

This definition is important because many products that are sold do not meet these criteria, haven’t been tested in clinical trials, or they use combinations of strains that have never been studied together. If you don’t know the strain, then you don’t know if it will help you.

Imagine you go shopping and tell someone you are going to buy vegetables for a dish, but you don’t know which vegetables you need for the particular dish. How will you know that it is the right one if you buy aubergines when you need peppers? A silly example, perhaps, but I’m sure you get the point.

Knowing why you are taking them

The first step in choosing a probiotic is to identify your goal.

Are you looking to support immunity during the cold and flu season, help with IBS-type symptoms (diarrhoea and/or constipation) or because you are taking antibiotics, or to reduce thrush relapse?  

Each condition requires a different probiotic strain and sometimes a different format or dose.

For example, Lactobacillus rhamnosus GG (often abbreviated LGG) is a well-studied probiotic with proven efficacy in preventing antibiotic-associated diarrhoea when taken at a dose of 10 billion colony-forming units (CFUs) twice daily during antibiotic treatment. Another strain, Bifidobacterium BB12, has demonstrated effectiveness in reducing colic symptoms in infants and may have benefits in reducing upper respiratory tract infections when paired with LGG.

Dosing: Is more always better?

Many of my clients think more is better (e.g. fibre, vitamins and probiotics), but this isn’t necessarily the case.

Some evidence even suggests that lower doses may be more effective for certain issues, and I regularly recommend a probiotic that has good evidence to help with SIBO, which only has one million bacteria (CFU). Nevertheless, taking a dose lower than the one shown to be effective is unlikely to offer benefit, and higher doses may not add value.

Beware of multi-strain formulations

More strains do not necessarily mean better outcomes. Microbes are competitive by nature, so their joint effects cannot be assured to be better for you.  

If you have been recommended or decide to take more than one probiotic, then splitting dosing them, so that you take one in the morning and one in the afternoon may be a better strategy as they are less likely to compete.

Navigating the supplement aisle

When choosing a probiotic for my clients, I follow the below broad principles:

• Know what my client’s goal is and only consider probiotics for specific, evidence-supported conditions (or at least have a rationale for trying a probiotic, rather than pot luck).
• Choose products with clearly labelled genus, species, and strain.
• Match the format (powder, capsule, etc.) and dose to those used in clinical trials as much as possible.
• Check products with many strains that the entire combination has been studied.
• Use reputable resources that identify the clinical indication and product, or ask the company to provide the strain.

Choosing the right probiotic requires a targeted, evidence-based approach. It is not about taking any “good bacteria” and hoping for a general health benefit. Rather, it is about identifying a specific need, matching it to a strain that has been tested and shown to work in high-quality trials, and using that strain in the appropriate format, dose and length of time. This tailored approach ensures not only safety but also increases the likelihood of achieving a meaningful clinical outcome.