Is it possible to create a definitive ranking of the best probiotics? In practice, it is almost impossible — because different products contain different active bacterial strains, and there is no single "universal" bacterium that helps with everything. However, there are clear guidelines that can help you make an informed choice. Depending on your specific needs, health concerns, or goals, different probiotics will be the best fit. Understanding what to look for — and what to pay attention to — makes all the difference.
What to Look for When Choosing a Probiotic
While no single probiotic works for every situation, there are several universal criteria that can guide you towards a quality product. Paying attention to these factors before purchasing can help ensure that you get a supplement that is both effective and appropriate for your needs.
Bacterial Strain Identification
The most important criterion when selecting a probiotic is the specific strain of bacteria it contains. A high-quality supplement will clearly state the genus, species, and strain — expressed as an alphanumeric code — on its label. For example: Lactobacillus rhamnosus HN001, where Lactobacillus is the genus, rhamnosus is the species, and HN001 is the specific strain.
This level of detail matters because it is the strain that determines the supplement's effectiveness for a given purpose. Different strains of the same species can have very different effects in the body. Furthermore, the strains used should ideally be clinically studied — meaning there is evidence that they survive the passage through the digestive system and retain their beneficial properties upon reaching the gut.
Expiry Date and Shelf Stability
With probiotics, the expiry date is more than a formality. Probiotics contain live organisms, and as the product ages, the number of viable bacteria gradually decreases. The closer a product is to its expiry date, the greater the risk that it no longer delivers the stated number of colony-forming units (CFU). An expired probiotic may have little to no beneficial effect at all. Most probiotics do not guarantee strain stability throughout the shelf life, so purchasing fresh stock — and checking dates carefully — is essential.
Dosage — CFU Count
The dosage of a probiotic is expressed in CFU (colony-forming units) — the number of live bacteria per capsule or serving. This information should be clearly stated on every product. According to available guidelines, an effective daily dose typically ranges between 5–10 billion CFU (5–10 × 10⁹) or approximately 250–500 mg per day, depending on the strain and intended use. Higher doses are not necessarily better — the right amount depends on the specific strain and the condition being addressed.
Packaging and Storage
Packaging and storage conditions may seem like minor details, but they play an important role in preserving the viability of live bacteria. Probiotic organisms can be sensitive to light, heat, and moisture. Look for products packaged in dark glass or opaque materials that protect against UV exposure. Also check whether the product requires refrigeration — some strains are shelf-stable, while others need to be stored in the fridge to maintain their potency.
[tip:When buying probiotics, always check three things on the label: the specific bacterial strain (not just genus and species), the guaranteed CFU count at time of expiry (not just at manufacture), and storage requirements.]
Which Probiotic Strains to Choose — A Guide by Need
Most people reach for probiotics during antibiotic therapy, but the right bacterial strains can support the body in many other situations as well. Understanding which strains are best suited to your specific concern is key to choosing an effective product. Below is a practical overview of the most well-studied strain-to-need pairings.
During Antibiotic Use
Lactobacillus rhamnosus GG and Saccharomyces boulardii are among the most widely recommended strains for preventing antibiotic-associated diarrhoea. These strains help protect the gut flora while the antibiotic is active, reducing the risk of digestive disruption.
For Travellers
Those travelling to regions where food and water quality may be a concern can benefit from Saccharomyces boulardii, Lactobacillus acidophilus, or Bifidobacterium bifidum — strains that may help protect against traveller's diarrhoea and digestive discomfort.
For Lactose Intolerance
Lactobacillus bulgaricus, Lactobacillus acidophilus, and Streptococcus thermophilus produce lactase — the enzyme responsible for breaking down lactose in the intestines. These strains may help improve the digestion and absorption of dairy products in lactose-sensitive individuals.
For Irritable Bowel (IBS)
Bifidobacterium infantis 35624, Lactobacillus plantarum DSM9843, and Bifidobacterium bifidum MIMBb75 are strains associated with supporting healthy gut motility, reducing bloating, and easing other digestive complaints. A truly effective probiotic for sensitive bowels should contain one or more of these strains.
For Skin Conditions (Eczema)
Lactobacillus rhamnosus and Lactobacillus fermentum have been studied for their potential to ease itching and flaking associated with eczema. These strains have shown particular promise in children, where they tend to be most effective.
For Immune Support
Bifidobacterium animalis lactis Bi-07 and Lactobacillus acidophilus NCFM are strains linked to immune system support, potentially helping to reduce the duration and severity of common colds and seasonal infections.
For Intimate Health
Lactobacillus acidophilus, Lactobacillus rhamnosus GR-1, and Lactobacillus reuteri RC-14 are strains with clinically supported effectiveness in managing and preventing intimate infections. Given the prevalence of such infections, these strains are often recommended as part of a comprehensive approach to women's wellness.
[note:Probiotic research is an evolving field. New properties and applications for known strains are continually being discovered. Always look for products that reference clinically studied strains for the specific concern you wish to address.] [products:jarrow-formulas-saccharomyces-boulardii-plus-mos-90-veg-capsules, aliness-probiobalance-rhamnosus-gg-balance-5-billion-probiotic-30-veg-capsules, now-foods-probiotic-10-25-billion-100-veg-capsules, aliness-probiobalance-ibs-balance-5-billion-probiotic-30-veg-capsules, swanson-femflora-probiotic-for-women-60-capsules, now-foods-saccharomyces-boulardii-60-veg-capsules, aliness-probiobalance-woman-probiotics-prebiotics-30-veg-capsules]
When and How Long to Take Probiotics
The most common reason people start taking probiotics is antibiotic therapy — and this is indeed one of the most important situations for probiotic support. However, a very common mistake is stopping supplementation the moment the antibiotic course ends. Some people continue until the probiotic pack runs out, but even that is often not sufficient.
Effective restoration of the gut microbiome after antibiotics typically requires approximately two months of continued probiotic supplementation. Only with this sustained approach can the gut flora be meaningfully rebuilt. Stopping too early may leave the microbiome in an imbalanced state, which can contribute to ongoing digestive issues.
But antibiotics are not the only reason to consider probiotics. Prolonged stress and an exhausting lifestyle can also disrupt the gut microbiome, leading to poor wellbeing, digestive complaints such as bloating and gas, and increased susceptibility to illness. A healthy, balanced gut flora is closely linked to overall comfort and vitality.
Probiotics are also an excellent option for infants struggling with constipation, colic, and bloating — though paediatric use should always be guided by a healthcare professional. Recent research has even pointed to a connection between the balance of gut bacteria and body weight, suggesting that an imbalanced microbiome may contribute to weight gain and difficulty losing weight.
For a comprehensive selection of probiotic supplements — from single-strain formulas to multi-strain complexes — explore our probiotic collection, featuring products from trusted brands like NOW Foods, Jarrow Formulas, Aliness, and Swanson. Those looking for broader digestive support may also benefit from our digestive system supplements.
[products:swanson-epic-pro-25-strain-probiotic-30-veg-capsules, healthy-origins-natural-probiotic-30-billion-cfu-60-veg-capsules, life-extension-florassist®-balance-30-capsules, jarrow-formulas-jarro-dophilus-eps-probiotic-120-capsules, aliness-probiobalance-forte-probiotics-prebiotics-30-veg-capsules, now-foods-probiotic-10-50-billion-50-veg-capsules] [warning:Probiotics are generally safe for most people, but individuals with severely compromised immune systems or serious underlying health conditions should consult a healthcare professional before starting supplementation. For infants and young children, always seek medical advice before introducing any probiotic product.]
Key Takeaway: There is no single "best" probiotic — the right choice depends entirely on your individual needs. Focus on products that clearly identify specific bacterial strains, provide an adequate CFU count, and have been clinically studied for your particular concern. Whether you are supporting your gut during antibiotic therapy, seeking immune system reinforcement, or addressing digestive discomfort, choosing the right strain is far more important than choosing the most expensive product. And remember — effective probiotic therapy takes time, so plan for at least two months of consistent supplementation for meaningful results.
