6 Best Probiotics, Compared Head-to-Head
A best probiotics search usually turns up the same thing: a roundup, a handful of brands, three sentences copied from each product page and a "top pick" that happens to pay the best commission. We're doing it differently, and more openly: we put our own product, Glow25 Balance, directly against five of the best-known probiotics on the UK high street, with real label specs, real UK prices and a clear disclosure of where we have skin in the game.
We compared Glow25 Balance with Optibac For Every Day, Bio-Kult Advanced, Symprove Original, Alflorex Original and Bioglan Biotic Balance Ultimate Flora, judged on the same criteria independent guides use for a genuinely useful probiotic: strains, CFU count, how the bacteria are protected, prebiotic content and price per day.
Quick answer: the best probiotics compared at a glance
Short on time? Here's the short version of our probiotics comparison, sorted by what matters most to you.
Glow25 Balance
A 3-in-1 tribiotic formula with active and inactivated lactic acid bacteria, inulin and golden kiwi extract, plus vitamin B2 and calcium. Further down we break down what each ingredient does, and where Balance does and doesn't beat the other five.
- 10 billion CFU & 5 documented bacterial strains per daily dose
- 2 capsules a day, tasteless, vegan capsule shell
- 60-day money-back guarantee
- Designed to fit alongside a collagen routine
What's in this comparison
- Shop Glow25 Balance
- What actually makes a probiotic "the best"
- The comparison: 6 products, side by side
- Glow25 Balance in detail
- Optibac For Every Day
- Bio-Kult Advanced
- Symprove Original
- Alflorex Original
- Bioglan Biotic Balance Ultimate Flora
- Which one is right for you?
- What the science actually says
- What customers say about Balance
- Frequently asked questions
What actually makes a probiotic "the best"
Independent buying guides for the best probiotics tend to converge on the same handful of criteria, and we've used the same ones here:
- Strains with real evidence – not just a headline number, but whether the specific strains (e.g. Lactobacillus rhamnosus or Bifidobacterium longum) have actually been studied.
- CFU count per daily dose – more on what this means below.
- Protection on the way to the gut – without protection from stomach acid, a large share of bacteria may never arrive alive.
- Prebiotic content – a fibre such as inulin or FOS that feeds the bacteria so they can establish themselves.
- Added nutrients – some formulas pair the bacteria with vitamins or minerals that carry authorised health claims.
- Price per day – the daily dose divided by the standard one-off retail price, so subscription discounts and sales don't skew the comparison.
Best Probiotics UK: 6 Products Compared Side by Side
The table below lays out all six products against the same criteria. Prices per day are based on each product's standard one-off retail price from a major UK retailer, not on time-limited promotions.
| Product | Format & approach | CFU/day & strains | Prebiotic | Protection / delivery | Price/day* |
|---|---|---|---|---|---|
| Glow25 Balance | 2 capsules, 3-in-1 tribiotic (live + inactivated + prebiotic) | 10 bn CFU, 5 documented strains (live & inactivated) | Inulin + golden kiwi extract | Vegan HPMC capsule | ≈ £1.17 |
| Optibac For Every Day | 1 capsule, everyday multi-strain | 5 bn CFU, 6 strains | FOS | Brand states strains are proven to reach the gut alive | ≈ £0.50 |
| Bio-Kult Advanced | 1–2 capsules, once or twice daily, multi-strain | 2 bn CFU per capsule (4 bn at 2 a day), 14 strains | None stated | Strains protected for stomach acid; stored at room temperature | ≈ £0.72 (at 2 capsules a day) |
| Symprove Original | 70 ml water-based liquid, taken daily | 10 bn CFU, 4 strains | None stated | Water-based liquid (no capsule) | ≈ £2.86 |
| Alflorex Original | 1 capsule, single-strain | 1 bn CFU, 1 strain (B. longum 35624) | None stated | HPMC capsule; brand states the strain reaches the gut intact | ≈ £0.85 |
| Bioglan Biotic Balance Ultimate Flora | 1 capsule, high-CFU multi-strain | 20 bn CFU, multi-strain (4 species on the label) | None stated | Blister-packed capsule | ≈ £0.76 |
*Calculated from each product's standard one-off retail price at Boots, Holland & Barrett or Superdrug and its stated daily dose (Bio-Kult at 2 capsules a day; Symprove at the 4 × 500 ml RRP of £79.99 for 28 days, which is often discounted). Subscription and promotional prices may differ. Highlighted: the cheapest option, or our own position.
Two things stand out. First, on price per day, Balance isn't the winner: Optibac and Bioglan cost less than half as much per day, and Bioglan packs in twice our CFU count. Second, the products take quite different approaches: single-strain (Alflorex), multi-strain (Bio-Kult, Optibac, Bioglan), liquid (Symprove) or, in Balance's case, a blend of live and inactivated bacteria with two prebiotics and two micronutrients in one product. What Balance offers instead is that formulation approach, and we'll explain it below.
Glow25 Balance in Detail Our pick
Glow25 Balance is built around a 3-in-1 tribiotic formula: active and inactivated lactic acid bacteria cultures, combined with inulin from chicory root and golden kiwi extract as two separate prebiotic sources. Rather than chasing the highest possible strain count, it uses five documented strains in both active and inactivated form, with 10 billion CFU per daily dose, on the idea that each works through a different mechanism and the two complement each other.
Why calcium and vitamin B2, and not just "more vitamins"? Many probiotics bulk out their formula with a long list of generic vitamins. Balance goes the opposite way: just two nutrients, both relevant to what the product is for. Vitamin B2 (riboflavin) contributes to the maintenance of normal skin and helps protect cells from oxidative stress, relevant because Balance sits within a beauty-focused routine rather than being a generic gut product. Calcium contributes to the normal function of digestive enzymes, a benefit tied directly to digestion.
Golden kiwi extract: the ingredient the other five don't list. The kiwi fruit powder in Balance is made from the whole fruit (skin, flesh and seeds), so it's more than a fibre source. It naturally contains vitamin C and the plant enzyme actinidin, which is being studied in relation to protein digestion. A controlled study using kiwi extract capsules found an increase in Faecalibacterium prausnitzii, one of the most important "good" bacterial strains in the gut, in people with sluggish digestion.[Blatchford et al., 2017] As far as the product listings show, none of the other five products in this comparison uses golden kiwi extract.
What is an HPMC capsule? Balance's capsule shell is made from hydroxypropyl methylcellulose (HPMC), a plant-based coating agent derived from cellulose. Unlike traditional gelatine capsules (made from animal collagen), HPMC is vegan, tasteless and well tolerated. For context, Alflorex also lists HPMC in its capsule, so this is a common standard in the category, not a Balance-only advantage.
The ecosystem advantage: Balance is the only product in this comparison built specifically to complement a collagen routine. A balanced gut supports better nutrient absorption, which may include how well collagen from a powder or capsule can be used by the body.[Wastyk et al., 2021] If you already take collagen, that's a coordinated combination rather than two unrelated products.
Backed by science: every core ingredient in Balance (the lactic acid bacteria cultures, the inulin and the kiwi extract) is grounded in published research rather than marketing claims alone. You'll find the source list and study summaries further down, in "What the science actually says."
Strengths: the broadest formulation approach in this comparison (pre + pro + postbiotics + 2 targeted micronutrients in one product), a dual prebiotic source (inulin + golden kiwi), the only product designed as part of a wider skincare/collagen routine, made in Germany, 60-day money-back guarantee.
Trade-off: at ≈£1.17/day it isn't the cheapest option here, and at 10 billion CFU it sits below Bioglan (20bn), reflecting a focus on strain selection over raw quantity.
Optibac For Every Day
One of the best-known probiotic brands in UK pharmacies. For Every Day (sold in some places as "For Daily Wellbeing") combines six strains from the Lactobacillus, Bifidobacterium and Lactococcus groups, including Lactobacillus acidophilus, with prebiotic FOS fibre. The brand states the strains are scientifically proven to reach the gut alive, and the capsules are vegan.
Strengths: the lowest price per day in this comparison at around 50p, a prebiotic included, widely available on the high street.
Trade-off: 5 billion CFU is the second-lowest dose here, and there are no added micronutrients or skin-specific ingredients. Optibac also sells a stronger "Every Day Extra" with 20 billion CFU at a higher price.
Bio-Kult Advanced
Bio-Kult Advanced is a long-established UK multi-strain formula with 14 live bacterial strains, each capsule guaranteed at a minimum of 2 billion CFU throughout shelf life. The bacteria are protected during freeze-drying so the capsules can be stored at room temperature, and the strains are described as able to survive stomach acid. At two capsules a day, that's 4 billion CFU for about 72p.
Strengths: the widest strain variety in this comparison, a flexible dose (up to four capsules a day, for example when travelling or taking antibiotics), no refrigeration needed.
Trade-off: the per-capsule CFU count is modest, and no prebiotic fibre or added nutrients are listed. The capsule is also vegetarian rather than vegan.
Symprove Original
Symprove is the odd one out: a water-based liquid rather than a capsule, taken as a 70 ml dose each day. It delivers 10 billion live bacteria from four strains (Lactobacillus rhamnosus, Enterococcus faecium, Lactobacillus acidophilus and Lactiplantibacillus plantarum), is vegan and dairy-free, and the Original flavour also contains vitamin C. Once opened, it needs refrigerating and should be used within 14 days.
Strengths: a different format for people who don't like capsules, and a well-known British brand with years of university research behind it.
Trade-off: at roughly £2.86/day at RRP it is the most expensive option here, and it has to be kept cool once opened. No prebiotic fibre is listed.
Alflorex Original
Alflorex takes the opposite approach to multi-strain formulas: a single, heavily studied strain, Bifidobacterium longum 35624, at 1 billion CFU per capsule. The brand states the strain is scientifically proven to reach the gut intact. The capsule is HPMC-based and needs no refrigeration.
Strengths: a clinically studied single strain, one capsule a day, simple and easy to understand.
Trade-off: the lowest CFU count and the smallest strain variety here, and no prebiotic or added micronutrients are listed. Note that research on a single strain doesn't transfer to other products, and vice versa.
Bioglan Biotic Balance Ultimate Flora
Ultimate Flora is a high-strength, once-daily capsule with 20 billion live cultures. The label lists Lactobacillus acidophilus, Lactobacillus rhamnosus, Bifidobacterium longum and the yeast Saccharomyces boulardii. The capsules come in a blister pack.
Strengths: the highest CFU count in this comparison at a low price per day (about 76p), and a probiotic yeast alongside the bacteria.
Trade-off: no prebiotic fibre or added nutrients are listed, and a higher CFU number doesn't by itself mean a better outcome.
Which of the Best Probiotics Is Right for You?
There's no single winner for everyone. The right pick depends on what you're actually optimising for:
Want gut + skin in one
Pre-, pro- and postbiotics plus skin-relevant micronutrients in a single capsule? Glow25 Balance.
Want the lowest price per day
Budget is the main driver? Optibac For Every Day, at roughly 50p a day.
Want maximum strain variety
Prefer a wide spread of strains in one capsule? Bio-Kult Advanced, with 14.
Not a fan of capsules
Prefer to take your probiotic as a drink? Symprove Original, a water-based liquid.
What the Science Actually Says About Probiotics, Prebiotics & Postbiotics
The International Scientific Association for Probiotics and Prebiotics (ISAPP) defines probiotics as live microorganisms that, when administered in adequate amounts, may confer a health benefit on the host.
Worth keeping in mind: these studies describe statistical effects across specific study populations, not individual guarantees. Probiotics aren't a substitute for a balanced diet or medical treatment, and which strain works best is genuinely individual, which is why comparing products against the criteria above is more useful than relying on a single number like CFU count.
What Customers Say About Glow25 Balance
Real feedback on Glow25 Balance. Two of these quotes are translated from the original language, as marked:
"My gut is in balance, my skin is much more radiant."
"I am very satisfied with Glow25 Balance."
"My digestion feels lighter and my stomach is far less bloated."
4.5 / 5 stars from 189 customer reviews on Amazon.de and Otto.de
Frequently Asked Questions About the Best Probiotics
What makes something one of the best probiotics?
A genuinely good probiotic scores well across several criteria at once: well-researched strains, a sensible CFU dose, protection on the way to the gut and, ideally, a prebiotic fibre. Depending on what matters most to you (price, strain variety or an added benefit), a different product from this list may suit you best.
What does CFU actually mean, and how much do I need?
CFU stands for colony-forming units, the measure of how many live, viable bacteria are in a daily dose. Many guides suggest 10–20 billion CFU per day as a sensible range, but a much higher number isn't automatically more effective. What matters more is whether the strains are backed by research and survive the journey to your gut.
What sets Glow25 Balance apart from a plain probiotic?
Balance combines active and inactivated lactic acid bacteria with two prebiotic sources (inulin and golden kiwi extract), plus vitamin B2 and calcium, in one capsule. Most other products in this comparison rely on bacterial strains alone, with at most a single prebiotic.
Which is the cheapest probiotic in this comparison?
Optibac For Every Day comes out cheapest at roughly 50p a day, followed by Bio-Kult Advanced at about 72p a day (at two capsules) and Bioglan Ultimate Flora at about 76p. Prices change often, so check the current price before you buy.
What is golden kiwi extract, and why does Balance include it?
Golden kiwi extract is made from the whole fruit and naturally contains fibre, vitamin C and the enzyme actinidin, which is studied in relation to protein digestion. A study using kiwi extract found increases in an important "good" gut bacterial strain. As far as the product listings show, none of the other five products compared here uses it.
Does a probiotic need to be protected from stomach acid?
Protection can help more bacteria reach the gut alive, and brands approach it in different ways: protected freeze-drying, capsule design or a liquid format. It isn't the only factor, though. Strain selection, dose and included prebiotics all play a role too.
Can I take Glow25 Balance alongside a collagen supplement?
Yes. Balance is designed to complement a collagen routine, ideally taken around 30 minutes apart from collagen powder or capsules. Just don't exceed the recommended daily amount of either product.
Read Next
More background on gut health, probiotics and the microbiome:
Microbiome basics
Usage guide
Science & everyday life
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