Probiotics: What You Need to Know
Probiotics have been around for centuries, but they’re now exploding in popularity. While there isn’t strong evidence that probiotics provide significant benefits for healthy people, there are studies showing that certain strains can help with specific health conditions.
What Exactly Is a Probiotic?
Many of us already know that probiotics are beneficial bacteria that live in our gut and can be taken through food or supplements. But in scientific terms, probiotics are defined by a specific set of characteristics.
To be considered a true probiotic, a product must:
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Contain live microbes
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Be administered in adequate amounts
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Be proven to confer a health benefit to the host
Just because a food or supplement contains “live cultures” doesn’t mean it contains probiotics. For example, many fermented foods contain live bacteria — but it’s often unclear which microbes are present, whether they survive digestion, or if they provide any measurable benefit.
Probiotic Classification: Genus, Species, and Strain
Probiotics are differentiated at three levels:
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Genus: e.g. Bifidobacterium
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Species: e.g. animalis
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Strain: e.g. BB-12
Most commercial probiotics belong to the Lactobacillus and Bifidobacterium genus. However, their effects are strain-specific, meaning the exact strain determines its benefit.
A great example of this is E. coli — one strain causes severe illness, while another can actually help reduce gut inflammation and constipation. So when choosing a probiotic, focus on the strain, not just the genus or species.
Health Benefits of Probiotics
The research on probiotics has come a long way — but there’s still plenty to learn. Even so, there’s strong evidence for certain strains being beneficial for particular conditions.
Think of probiotics like medication: different types treat different issues, and not all are interchangeable.
Evidence-Based Uses for Probiotics
Probiotics may play a role in:
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Reducing antibiotic-associated diarrhoea – strongest evidence for S. boulardii (10 million CFU twice daily during and one week post antibiotics).
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Preventing travellers’ diarrhoea – S. boulardii may help here too.
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Preventing and reducing duration of URTI (upper respiratory tract infections) – L. casei and other Lactobacillus or Bifidobacteria strains show promise.
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Managing IBS symptoms – including diarrhoea and constipation (e.g. multi-strain mix VSL#3, B. infantis).
Emerging evidence also suggests potential benefits for other gut, immune, and mental health conditions. Most probiotic doses range from 100 million to 50 billion CFU (colony forming units) or higher.
What About Fermented Food?
Fermentation uses bacteria or yeast to create foods such as kombucha, kefir, sauerkraut, and yoghurt. These foods generally contain a variety of live cultures that may support a healthy gut microbiome.
While research is ongoing, fermented foods offer plenty of nutritional benefits beyond probiotics alone — such as vitamins, enzymes, and fibre. Including them in your diet is a great idea for overall gut health.
However, if you’re trying to treat a specific condition, a targeted probiotic supplement with clinically tested strains may be more effective.
Want to Learn More About Gut Health and Performance?
If you’re curious about how probiotics can support athletic performance, immunity, and recovery, check out our Probiotics for Athletes guide for practical, evidence-based advice on choosing the right strain for your goals.