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Demystifying probiotics: what you need to know

Probiotics are increasingly gaining traction as being potentially beneficial to health, not just for digestive health but also having wider effects on our bodies.


Purported benefits of probiotics range hugely from improving our immune systems to enhancing mental wellbeing, with research indicating they can potentially alleviate symptoms of anxiety and depression.


I get lots of questions about probiotics and it can be confusing to pick through the plethora of information on them, so I thought it might be helpful to explain a little more about them.




What is a probiotic?


The term probiotic was originally used to describe the opposite action of an antibiotic.

Probiotics contain live friendly bacteria and/or yeasts that are naturally present in our bodies and are considered capable of exerting health benefits when administered in adequate amounts.


Classification of probiotics


There are many, many strains of probiotics with different characteristics, features, actions, and they are classified by their genus, species, and strain.

An analogy that helps to explain this classification is using the concept of dog breeds.

Strain: the breed of dog

Genus: all dogs are canines (canis) and the species is familiaris (aka domesticated dog)

There is clearly great diversity within the dog species with hugely varying physical and character traits, from the Great Dane to the Jack Russell.

Probiotics are much the same in terms of their characteristics and actions.

An example of a probiotic: Lactobacillus rhamnosus GG:

Lactobacillus (genus)

rhamnosus (species)

GG (strain)


Probiotic strength


In addition to the classification system, probiotics have varying strengths, and these are measured as CFU (colony forming units). Most probiotics range from 1-10 billion CFUs, however, higher strengths are available, although that does not necessarily mean better.


More important considerations are that the probiotic is formulated in such a way to survive the harsh acidic environment of the stomach to reach the intestines, where they can exert an effect, and whether the combination of bacterial strains have been featured in clinical studies and deemed beneficial.



What about probiotic foods?


Probiotic foods, such as live yoghurts & fermented foods, have beneficial properties but do not contain sufficient levels of live bacteria to exert the same therapeutic benefits as probiotics. Furthermore, any friendly bacteria present are unlikely to survive exposure to stomach acid.


Probiotics versus prebiotics


Prebiotics (either food, such as bananas, onions, etc, or supplements) do not contain any live bacteria. Instead, they contain beneficial fibres that promote and feed friendly bacteria in the gut.


They can be hugely beneficial in their own right as a food and are often incorporated into good quality probiotics to encourage friendly bacteria growth and diversity.


3 things probiotics can’t do:


Probiotics counter a poor diet – probiotics cannot be relied upon to counter a poor diet. In order the thrive, friendly bacteria need to be fertilised by plenty of fibre, especially prebiotic fibre, along the way – eating a beige western diet is not going to achieve this!


Probiotics stay in the gut: A more recent theory is that oral probiotics may not result in colonisation in the gut, rather that they pass through and exert benefits as they do so. A useful way of explaining their action is to think of probiotics as gardeners and our guts as the garden – the probiotics help to encourage growth and diversity of friendly bacteria, rather than being the plants themselves.


Probiotics benefit everyone: Everyone has a different gut microbiome and what works for one individual may not benefit another. It is not quite as simple as naming and shaming individual bacteria as ‘good’ or ‘bad’. Interactions between a person’s unique gut microbiome and their present overall gut health are key to how well probiotic supplementation works – or is even necessary. Generally, when a person presents with digestive symptoms, I prefer to conduct a stool test to determine targeted gut protocol.


Probiotic safety:

Although probiotics contain species naturally found in the body and deemed generally safe, there is some risk of undesired colonisation being created and there are some schools of thought that argue that probiotics could undesirably evolve once in the gut.

Immunocompromised people should not take probiotics because this may lead to infection.

I hope that helps – my next blog will explore how probiotics may specifically benefit mental wellbeing.

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