Table of Contents
Most probiotic shopping advice tells you to look for a high CFU count and a reputable brand. That is fine as far as it goes, but it skips the harder question: which format are you actually buying? A 50-billion-CFU capsule, a bottle of kefir and a soil-based spore supplement all get filed under “probiotics,” yet they behave completely differently in your gut, your fridge and your wallet.
So let’s compare them properly. Below are the main options on the market, what each one is genuinely good at, and where each one falls short.
Capsules, ferments, spore strains, drinks: the four real contenders
Nearly everything sold as a probiotic falls into one of four groups:
- Freeze-dried capsules and sachets with named, dose-controlled strains (Lactobacillus rhamnosus GG, Bifidobacterium longum 35624, Saccharomyces boulardii CNCM I-745)
- Fermented foods such as kefir, live yoghurt, sauerkraut and kimchi
- Spore-based and soil-based products built around Bacillus species that survive stomach acid
- Drinks and shots, from supermarket kombucha to tiny probiotic yoghurt drinks
Each group has a different story about shelf stability, strain transparency, cost per day and how much evidence sits behind it. Here’s how they stack up.
Single strain or multi-strain blends
Walk down any supplement aisle and the packaging pushes diversity: 12 strains, 20 strains, 30 strains. More sounds better. It usually isn’t the deciding factor.
Where a single strain earns its keep
Almost all of the strongest clinical evidence points at specific, single strains used for specific purposes. Saccharomyces boulardii CNCM I-745 has trial data behind it for antibiotic-associated diarrhoea. L. rhamnosus GG has been studied for years in children’s gut infections. A single-strain product gives you 10 billion CFU of one organism, which means you know exactly what you’re getting.
Where blends make more sense
A broad blend mimics the diversity of a healthy gut more closely, and some people do respond better to them, particularly for general day-to-day bloating. The catch is dilution. A 30-strain capsule with 10 billion CFU total averages around 330 million CFU per strain, which is a rounding error compared with a targeted single-strain dose. If you want to dig into how strain identity and CFU counts interact, this breakdown of strains, CFUs and real benefits is worth twenty minutes of your time.
The CFU arms race
Labels shouting “100 billion!” are mostly marketing. For most everyday uses, 1 to 20 billion CFU is a sensible range, and higher numbers only matter for specific clinical situations. Two things count for more than the headline figure: whether the CFU count is guaranteed at expiry rather than at manufacture, and whether the manufacturer tested survival through stomach acid. A 10 billion capsule that arrives alive beats a 100 billion capsule that dies in the gastric fluid.
Capsules versus fermented food
Fermented foods have an advantage supplements can’t buy: they arrive with live cultures and the fibre, organic acids and metabolites those cultures produced. Kefir typically carries dozens of species. A spoonful of raw sauerkraut brings bacteria plus prebiotic plant fibre in the same mouthful.
The trade-offs are real, though. You rarely know the dose, the strains vary batch to batch, and salt content adds up if you’re eating kraut daily. Live yoghurt is limited to a handful of starter species, and heat-treated products labelled “with cultures” contain dead bacteria. Fermented food also demands fridge space and regularity, which is where a lot of people quietly fall off.
Supplements win on precision and convenience: a fixed dose, a known strain, a shelf-stable blister pack you can carry in a bag. They lose on breadth. Many people land on a hybrid, using a capsule for consistency and ferments for diversity. If you’re building that routine from scratch, this step-by-step walkthrough to choosing probiotics for your gut covers the practical selection order.
Spore-based probiotics: tougher, but less studied
Bacillus coagulans, Bacillus subtilis and similar spore-formers coat themselves in a protein shell that survives stomach acid and even room-temperature storage. No refrigeration, long shelf life, and they reliably reach the small intestine. For travel or for anyone who has killed a fridge-dependent bottle by leaving it in a hot car, that’s a genuine advantage.
The downside is the evidence base. Spore strains are transient rather than long-term colonisers, they don’t appear in traditional fermented foods, and the research on them is thinner than for older Lactobacillus and Bifidobacterium strains. They’re a reasonable option, not an automatic upgrade.
Kombucha, shots and probiotic drinks
This is where labels get creative. Most commercial kombucha is pasteurised or filtered before bottling, so the cultures are gone by the time you drink it. Probiotic shots often deliver a genuinely named strain, but at a sugary, low-volume dose. Sweetened yoghurt drinks can carry 8 to 10 billion CFU of a well-studied strain and still add 12 grams of sugar per bottle.
Read two numbers: sugar per serving and whether the label says “live and active cultures” with a specific strain name. If both check out, a drink is a perfectly good delivery vehicle, especially for people who won’t swallow capsules.
Synbiotics and prebiotic pairing
Synbiotics combine a probiotic with a prebiotic fibre, usually inulin, FOS or PHGG. The logic is sound: feed the bacteria you just swallowed so they stand a better chance of settling in. In practice, the prebiotic dose needed to matter is often large enough to trigger gas and bloating in sensitive people during the first week. Start low. And if you’re also reworking your diet, the same comparison thinking applies to the best meal plan for weight loss, which puts fibre variety ahead of any single supplement.
Matching the format to the situation
There’s no universal winner, only a format that fits the job:
- After a course of antibiotics: a targeted single strain, especially S. boulardii, started at the right point in the schedule. Timing probiotics around antibiotics matters more than brand here.
- Travel or irregular routines: shelf-stable capsules or spore-based products, no fridge required.
- General gut diversity on a budget: homemade kefir or live yoghurt, roughly a dollar a day and broad-spectrum.
- Sensitive stomach or IBS: a low-CFU single strain, introduced slowly, with a prebiotic added only if you tolerate it.
- Kids who won’t swallow pills: sachets or a well-chosen yoghurt drink with a named strain.
The comparison habit carries over to other supplement categories too, where multivitamins, single nutrients and greens powders trade off in much the same way as the best vitamins for women compared across formats. Convenience versus precision versus cost, every time.
Where your money is best spent
Ignore the strain count on the front of the bottle and check three things on the back: full genus, species and strain code (for example, Lactobacillus plantarum LP299V rather than just “L. plantarum”); CFU guaranteed at expiry; and third-party testing, either a batch certificate on the brand’s site or a USP or NSF mark.
Then do the arithmetic. A $45 bottle of 30 capsules is $1.50 a day. A litre of kefir that lasts five days is about 80 cents a day and delivers more species. A $12 supermarket kombucha with no live cultures is $12 wasted.
For most adults, a mid-range 10 to 20 billion CFU capsule with named strains, taken daily for four to six weeks, is a fair first experiment. If nothing changes, stop. If it helps, either keep going or shift the money into kefir and fermented vegetables, which tend to be cheaper and easier to sustain long-term. Rotate formats if you like, but give each one at least a month before you judge it, because your gut takes time to respond and the marketing promises far faster results than biology delivers.
