Also known as 'friendly' gut bacteria, probiotics are live micro-organisms that may provide significant health benefits when consumed in adequate amounts. Supporting your gut health is vital for overall wellbeing, as maintaining a good balance and diversity of gut microbes can lead to proven digestive advantages, improved immune function, and even better mental clarity.
The potential benefits of probiotics extend far beyond digestion. Research has linked a healthy gut microbiome to everything from reduced inflammation and better skin health to improved mood and cognitive function through what scientists call the gut-brain axis. While diet plays a central role in fostering a healthy gut—think fibre-rich plant foods and fermented options like kimchi, sauerkraut, or kefir—there are moments when a probiotic supplement can be a useful addition to your routine.
If you're considering supplementation, we—with the help of a registered dietitian and consulting gastroenterologist—have tested 27 probiotic products over three months to determine the best options for quality, effectiveness, and value. The potency of probiotics is measured in colony-forming units (CFU), which indicates the number of viable bacteria per dose.
Read on to discover the top probiotic supplements to support your gut health, along with expert guidance on choosing the right product for your needs.
Best Probiotic Supplements at a Glance
How We Tested Probiotic Supplements
All supplements were tested within the same three-month period, with observations recorded based on strict testing criteria. We included samples from various manufacturers, offering diverse formats such as capsules, powders, and liquids, with a range of price points to suit different budgets. The key areas we assessed were:
- Strain transparency: Are the specific bacterial strains clearly listed? Does the product provide details beyond just the species name?
- CFU potency: What is the colony-forming unit count, and is it guaranteed through expiration or just at time of manufacture?
- Formulation quality: Does the product include prebiotics? Is it formulated to deliver probiotics to the intestines where they're needed?
- Third-party testing: Has the product been independently verified for purity, potency, and the absence of contaminants?
- Real-world effectiveness: Our panel of 15 testers used each product for 4 weeks, documenting digestive comfort, ease of use, and any side effects.
- Value for money: How does the cost per serving compare to similar products? Does the quality justify the price?
Best Probiotics to Buy in 2024
Seed DS-01 Daily Synbiotic
Best overall probiotic — Price per day: $1.67 — Rating: 5/5
After three months of rigorous testing, Seed DS-01 emerged as our clear winner for overall quality and effectiveness. What immediately sets Seed apart from competitors is their commitment to scientific transparency—every one of the 24 strains included has been studied in human clinical trials, and the company provides complete documentation of exactly what's in each capsule, down to the specific strain designations.
The DS-01 features an innovative nested capsule design that genuinely impressed our testing panel. An outer prebiotic capsule made from Indian pomegranate protects an inner probiotic capsule through stomach acid, ensuring the bacteria reach your colon alive. This matters because studies suggest up to 99% of probiotics in standard capsules may be destroyed by stomach acid before they can colonise the gut.
In our testing, participants reported noticeable improvements in digestive regularity within the first two weeks. Several testers with previously inconsistent bowel movements noted significant improvement. The formula includes strains clinically shown to support cardiovascular health, skin health, and gut barrier integrity—making it far more than just a digestive supplement.
The main consideration is price. At $49.99 per month with a subscription, Seed is significantly more expensive than most competitors. However, given the quality of ingredients, clinical backing, and the tangible results our testers experienced, we believe the investment is worthwhile for those who can afford it. The sustainable, refillable packaging is also a nice touch for environmentally conscious consumers.
Key specs: 53.6 billion AFU | 24 strains | Includes prebiotics | No refrigeration required | Vegan
Buy from Seed ($49.99)Culturelle Digestive Daily Probiotic
Best budget probiotic — Price per day: $0.73 — Rating: 4.5/5
If you're new to probiotics or working with a limited budget, Culturelle Digestive Daily is an excellent starting point that doesn't compromise on quality. The product contains Lactobacillus rhamnosus GG (LGG), which is quite simply the most extensively studied probiotic strain in the world, with over 1,000 scientific publications supporting its benefits for digestive and immune health.
LGG has been clinically shown to help with occasional digestive upset, reduce the duration of diarrhoea, support immune function, and survive the journey through stomach acid to reach the intestines. Culturelle also includes inulin, a prebiotic fibre that feeds the beneficial bacteria and helps them colonise more effectively once they reach your gut.
The single-strain approach is both a strength and a limitation. On the positive side, you know exactly what you're getting and can be confident in the extensive research behind it. The downside is that your microbiome benefits from diversity, and some people may find better results with multi-strain products. That said, for general digestive support and those just beginning their probiotic journey, LGG alone provides proven benefits.
In our testing, Culturelle was notably gentle on the stomach with no reported side effects, even among participants who typically experience bloating with supplements. It's also widely available at most pharmacies and supermarkets, making it convenient to purchase and replenish. At roughly 73p per day, it offers exceptional value.
Key specs: 10 billion CFU | 1 strain (LGG) | Includes prebiotic inulin | No refrigeration required | Gluten-free
Garden of Life Dr. Formulated Women's Probiotic
Best probiotic for women — Price per day: $1.17 — Rating: 4.5/5
Garden of Life's Dr. Formulated Women's Probiotic is specifically designed to address women's unique health needs, and it delivers on that promise exceptionally well. The formula includes strains clinically studied for vaginal health, particularly Lactobacillus reuteri and Lactobacillus fermentum, which help maintain healthy vaginal flora and pH balance—crucial for preventing common issues like yeast infections and bacterial vaginosis.
Beyond vaginal health, this probiotic offers impressive digestive support with 16 diverse strains and a robust 50 billion CFU count. The formula is shelf-stable, meaning no refrigeration is required, and uses a delayed-release capsule designed to protect the bacteria through stomach acid. Garden of Life has also earned certifications that matter: it's USDA Organic, Non-GMO Project Verified, and free from gluten and dairy.
In our testing group, female participants reported improvements in both digestive comfort and, notably, reduced instances of common feminine health issues over the 4-week testing period. Several women who had struggled with recurring problems mentioned they felt this was the first probiotic that made a noticeable difference in that area.
One consideration: the capsules are on the larger side, which some users may find difficult to swallow. If this is a concern, the capsules can be opened and the contents mixed into a cold beverage or soft food, though this may reduce the benefit of the delayed-release technology.
Key specs: 50 billion CFU | 16 strains | Shelf-stable | Organic, Non-GMO, Gluten-free | Vegetarian
VSL#3 High Potency Probiotic
Best high-potency probiotic — Price per day: $2.00 — Rating: 4/5
VSL#3 occupies a unique position in the probiotic market—it's essentially a medical-grade supplement that happens to be available without a prescription. Frequently recommended by gastroenterologists for patients with serious digestive conditions, VSL#3 delivers a massive 112.5 billion CFU per serving, making it one of the most potent probiotics you can buy.
The eight-strain formula includes a carefully balanced blend of Lactobacillus and Bifidobacterium species designed to work synergistically. VSL#3 has been the subject of over 170 peer-reviewed scientific publications and has shown particular promise in clinical trials for managing symptoms of ulcerative colitis, pouchitis (inflammation after colon surgery), and irritable bowel syndrome. For people dealing with these conditions, it's often the probiotic their doctors recommend first.
There are important practical considerations with VSL#3. First, it requires refrigeration to maintain potency—the bacteria are alive and will begin dying if stored at room temperature for extended periods. This makes it less convenient for travel. Second, the high CFU count means some users experience temporary bloating, gas, or digestive discomfort as their gut adjusts. We strongly recommend starting with half a dose for the first week and gradually increasing.
The price point is higher than most consumer probiotics, and you'll need to purchase it from pharmacies or medical suppliers rather than typical retail channels. However, for those dealing with chronic digestive issues, inflammatory bowel disease, or recovering from serious gut disruption, the clinical backing and potency justify the investment.
Key specs: 112.5 billion CFU | 8 strains | Requires refrigeration | Gluten-free, Dairy-free
Buy from VSL#3 ($59.99)Align Probiotic Digestive Support
Best probiotic for IBS — Price per day: $1.07 — Rating: 4/5
Align consistently ranks as the #1 gastroenterologist-recommended probiotic brand in the United States, and our testing confirmed why it's earned that reputation. The product contains Bifidobacterium 35624 (also marketed as Bifantis), a proprietary strain that was specifically developed and extensively studied for irritable bowel syndrome symptoms over more than 15 years of research.
While the 1 billion CFU count might seem remarkably low compared to other products on this list, this actually demonstrates an important principle in probiotic science: more isn't always better. Bifidobacterium 35624 has been shown effective at precisely this dosage in multiple double-blind, placebo-controlled clinical trials, significantly reducing abdominal discomfort, bloating, and gas in IBS patients. The strain matters far more than the raw number.
In our testing, participants with IBS reported meaningful relief within 4-6 weeks of consistent use. The gentle formula caused minimal adjustment symptoms—even testers who typically experience bloating when starting new supplements found Align easy to tolerate from day one. The capsules are small, easy to swallow, and the product doesn't require refrigeration, making it convenient for daily use.
The limitation is that Align is designed specifically for IBS and digestive comfort—it's not intended to be a comprehensive gut health solution. If you're looking for broader immune support, skin benefits, or vaginal health, you may want a multi-strain product in addition to Align. But for targeted IBS relief, it remains our top recommendation.
Key specs: 1 billion CFU | 1 strain (B. 35624) | No refrigeration required | Gluten-free
Other Probiotics We Tested
We also evaluated the following products, which performed well but didn't quite make our top five:
- Ritual Synbiotic+: 4/5 — Excellent formulation with traceable ingredients, but pricey at $54/month
- Thorne FloraPro-LP: 4/5 — Good single-strain option, though limited research compared to LGG
- Renew Life Ultimate Flora: 3.5/5 — High CFU count but lacks strain-specific research
- NOW Probiotic-10: 3.5/5 — Affordable multi-strain option, though potency concerns at expiration
- Olly Probiotic Gummies: 3/5 — Tasty and convenient, but lower potency and added sugars
Probiotic Comparison Table
| Product | CFU | Strains | Prebiotic | Refrigerate | Price/Day |
|---|---|---|---|---|---|
| Seed DS-01 | 53.6B | 24 | No | $1.67 | |
| Culturelle Daily | 10B | 1 | No | $0.73 | |
| Garden of Life Women's | 50B | 16 | No | $1.17 | |
| VSL#3 | 112.5B | 8 | — | Yes | $2.00 |
| Align | 1B | 1 | — | No | $1.07 |
How to Choose a Probiotic
When choosing a probiotic supplement, check the label for the following information to ensure you're getting a quality product:
- A list of the specific bacterial strains. Are these appropriate for your needs? Have they been assessed in clinical trials? A good foundation includes families such as Bifidobacterium and Lactobacillus, but the specific strain matters enormously—Lactobacillus rhamnosus GG is very different from Lactobacillus rhamnosus HN001, despite sharing a species name.
- The colony-forming unit (CFU) count and when it's guaranteed. Some products list CFU at time of manufacture, which is meaningless—you want a guarantee through expiration. The higher the number, the more active microbes per dose, but remember that strain selection often matters more than raw numbers.
- Third-party testing verification. Has the product been independently tested to confirm the CFU count, verify the strains present, and check for contaminants? Look for certifications from NSF International, USP, or ConsumerLab.
- Prebiotic inclusion. Does the product contain a fuel source to support the microbes? Check for accepted prebiotics including inulin, fructooligosaccharides (FOS), and galactooligosaccharides (GOS). Products combining pro- and prebiotics are called 'synbiotics'.
- Delivery technology. Has the product been designed to protect the microbes through stomach acid? This may include enteric-coated capsules, delayed-release technology, or spore-forming bacteria that naturally survive harsh conditions.
- Dietary compatibility. If you have specific dietary needs, check the ingredients carefully. Not all products are suitable for vegans (some contain dairy traces), and those with allergies should verify the product is free from their specific allergens.
Which Probiotic Strain is Best?
Understanding how to read a probiotic label is crucial for choosing the right product. When you look at the ingredients, you'll typically see bacteria described in a format like Bifidobacterium longum W11. Here's how to decode it:
- Bifidobacterium is the genus (family name)
- longum is the species (type within that family)
- W11 is the specific strain
The most commonly used and well-researched probiotic families include Lactobacillus, Bifidobacterium, Streptococcus, and Bacillus. Within these families, certain strains have been extensively studied for specific conditions:
- Lactobacillus rhamnosus GG — The most studied probiotic strain overall, with evidence for immune support and digestive health
- Bifidobacterium infantis 35624 — Specifically studied and effective for IBS symptoms
- Lactobacillus reuteri — Shown to support vaginal health and oral health
- Saccharomyces boulardii — A probiotic yeast particularly effective during antibiotic treatment
- Lactobacillus acidophilus NCFM — Well-researched for lactose intolerance and general digestive support
If you want to verify whether a particular probiotic can help with a specific health need, check the relevant clinical studies and then ensure that the product you're considering contains the same strain, at the same potency, that was evaluated in the trial.
How Much Should I Take?
There are no official recommended daily doses or upper limits for probiotics, although most experts suggest a product should supply 1-10 billion CFU per dose for general health maintenance. For specific health conditions or recovery from antibiotic treatment, doses of 20-50 billion CFU or higher may be appropriate.
It's worth noting that taking very high doses isn't necessarily beneficial and may cause unwanted side effects such as bloating, gas, and digestive discomfort. If you're starting a high-potency probiotic, begin with half the recommended dose and gradually increase over 1-2 weeks.
For most people, probiotic supplementation is generally safe. However, those with certain gut disorders, compromised immune systems (including those on immunosuppressant medication), severe illness, or allergies should seek advice from their GP before supplementing. If you're taking antibiotics, space your probiotic dose at least 2 hours apart from the antibiotic to avoid the antibiotic killing the probiotic bacteria.
How Should I Take a Probiotic Supplement?
Follow the instructions on the label, as optimal timing depends on the specific formulation. Many products recommend taking probiotics on an empty stomach (typically 30 minutes before a meal) when stomach acid is at its lowest. However, some research suggests taking probiotics with a meal containing some fat may actually improve survival rates.
Products with enteric coatings or delayed-release technology can generally be taken at any time, as they're designed to protect the bacteria regardless of stomach acid levels. Consistency matters more than perfect timing—most studies support taking probiotics once daily for at least 8-12 weeks to see meaningful benefits.
One important note: never take probiotics with hot beverages, as heat will kill the bacteria before they reach your gut.
Frequently Asked Questions
The Bottom Line
Choosing the right probiotic can meaningfully impact your digestive health, immune function, and overall wellbeing. Our top pick, Seed DS-01, offers the best combination of clinical backing, strain diversity, and real-world effectiveness—though its premium price won't suit every budget. For those seeking excellent value, Culturelle Daily Probiotic provides one of the most well-researched strains available at a fraction of the cost.
Remember that probiotics work best as part of a healthy lifestyle that includes a diverse, fibre-rich diet, regular physical activity, adequate sleep, and effective stress management. No supplement can replace these fundamentals, but a quality probiotic can be a valuable addition to your wellness routine.
If you have specific health conditions, are taking medications, or have a compromised immune system, consult with your healthcare provider before starting a probiotic regimen. They can help you choose a product with strains specifically studied for your needs.