Written and medically reviewed by Dr Zeeshan Afzal (MBBS) — Medical Doctor & Medical Content Lead, Welzo
Evidence-based · Honest about what's proven and what isn't · UK-focused
Last updated: July 2026 · Reading time: ~9 minutes
The format difference is the obvious one. The more useful difference is that Symprove sells one product to everybody, while OptiBac sells a different product for each reason you might be buying. Our digestive health guides explain why that distinction matters more than liquid versus capsule, and the probiotics range and wider gut health supplements cover the alternatives.
Table of contents
If you know why you're buying — antibiotics, travel, pregnancy, vaginal health — OptiBac. Its whole model is matching named strains to a specific situation, and it costs a fraction as much per day.
If you want one daily routine and prefer a drink, Symprove. Four catalogue-referenced strains, a water-based carrier, and a research programme behind the delivery system.
Neither is a treatment for anything, and if you have undiagnosed symptoms, that matters more than the choice between them.
Symprove — £80.01 · 146 reviews · Available from Welzo. Four organisms — Lacticaseibacillus rhamnosus, Enterococcus faecium, Lactobacillus acidophilus and Lactiplantibacillus plantarum — all carrying NCIMB catalogue numbers, in a water-based carrier rather than a capsule.
Its genuine strengths: proper strain designations, a funded research programme including work at UCL, and a mechanistically coherent delivery argument — liquid doesn't trigger a full digestive cycle, so transit is quicker and conditions less hostile.
The trade-off is that it asks the same thing of everyone. One 70ml shot each morning on an empty stomach, a ten-minute wait before eating, for an initial 12-week course — whether you're taking it for bloating, for travel, or because you just finished antibiotics. See our Symprove review.
For Those On Antibiotics |
For Women |
Saccharomyces Boulardii |
OptiBac's range runs to fifteen products, and what unites them is that every one names its exact strains with catalogue designations — GR-1®, RC-14®, F-19®, Rosell-11, Rosell-52, HN001, La-14, HN019, and so on.
That's unusual and it's the single most useful thing a probiotic label can do, because probiotic evidence is strain-specific. It also means you can look up what you're taking.
The travel product is a good illustration of the philosophy: it uses Saccharomyces boulardii, a yeast, which is unaffected by antibacterials — the correct organism for that job rather than a generic blend. See Saccharomyces boulardii and OptiBac vs Bio-Kult.
| Product | Price | Approx. per day |
|---|---|---|
| Symprove, 4 × 500ml | £80.01 | ~£2.81 |
| OptiBac Every Day + FOS, 90 caps | £42.02 | ~47p |
| OptiBac For Women, 30 caps | £20.01 | ~67p |
| OptiBac For Those On Antibiotics, 10 caps | £10.10 | Short course only |
Over Symprove's recommended 12-week course, £2.81 a day comes to roughly £236. The equivalent period on OptiBac's everyday product is closer to £40.
That's a six-fold difference, and the evidence doesn't show a six-fold difference in benefit. What the extra buys is the liquid delivery system, the brand's research programme, and a format some people find easier to sustain.
The water-based argument is mechanistically sound. What doesn't exist is a good head-to-head trial comparing a liquid probiotic against an equivalent capsule for the same clinical outcome.
Without that, "more arrives alive" is a surrogate measure — a proxy for the thing you actually care about, not a demonstration of it. Capsules have their own answers to the same problem, including delayed-release shells and enteric coatings. See do probiotics survive stomach acid and our broader drinks vs capsules comparison.
| Feature | Symprove | OptiBac |
|---|---|---|
| Model | One product for everyone | A product per situation |
| Named strains | Yes — NCIMB numbers | Yes — consistently |
| Format | Water-based drink | Capsules, sachets, gummies, drops |
| Daily routine | Empty stomach, 10-minute wait | Swallow and go |
| Cost per day | ~£2.81 | ~47p–67p |
| Travel and storage | Bulky, chill once opened | Shelf stable |
| Includes a yeast option | No | Yes — S. boulardii |
Being straightforward: at the time of writing, Symprove is sold out and the entire OptiBac range is showing as out of stock. Both are widely stocked by UK pharmacies and other retailers, and we'd rather say so than let you click through to fifteen dead ends.
If you need something today, our best probiotics guide covers what's currently available, and supplements for IBS covers the in-stock options with trial evidence behind them.
Both are well tolerated by most people. Wind and bloating in the first week or two are common and usually settle — see probiotic side effects.
Speak to a doctor before taking either if you
Symprove contains Enterococcus faecium. It is used safely in commercial products, but is a further reason to seek advice first if you are immunocompromised. More in probiotics safety.
On labelling: probiotics carry no authorised health claim in GB or the EU. Both are sold as food supplements and cannot legally be marketed as treating any condition.
See your GP — or seek urgent care — if you have:
Spending more on a probiotic is not the answer to symptoms that aren't improving. See when to see a GP and bowel cancer screening.
It depends whether you have a specific reason for buying. OptiBac builds a different product for each situation and costs roughly a sixth as much per day. Symprove offers one formulation with a research programme behind its delivery system.
At around £2.81 a day it's roughly £236 over the recommended 12-week course, against about £40 for OptiBac's everyday product over the same period. The evidence doesn't show a six-fold difference in benefit — you're paying for the format and the brand's research.
They're dosed to reflect the research on those particular strains rather than to win a numbers comparison. A well-matched strain at its studied dose beats a larger total of organisms you can't look up.
OptiBac's antibiotics product, which uses named strains for that purpose. Take it a few hours apart from the antibiotic.
OptiBac, clearly. Its travel formula uses S. boulardii — a yeast, unaffected by antibacterials — and is shelf stable. Carrying 500ml bottles that need chilling is impractical.
That's the manufacturer's protocol, and it's part of the delivery rationale — 70ml first thing, then a ten-minute wait before eating. Capsules are more forgiving.
The mechanism is plausible, but there's no good head-to-head trial against an equivalent capsule for a clinical outcome. Treat better survival as a proxy, not a proven advantage.
No safety reason not to, but little point — you'd be paying twice and unable to tell which was doing anything.
Symprove recommends an initial 12-week course. For capsules, allow at least four weeks. See how long probiotics take to work.
At the time of writing, neither is available here — Symprove is sold out and the OptiBac range is showing as out of stock. Both are widely available from UK pharmacies.
Medical disclaimer: This article is for general information and education only and does not constitute medical advice, diagnosis or treatment. Food supplements are not a substitute for a varied and balanced diet, and are not intended to diagnose, treat, cure or prevent any disease. Probiotic effects are strain-specific. Claims regarding survival through the stomach are surrogate measures and not demonstrations of clinical benefit. Probiotics should be discussed with a doctor before use if you are immunocompromised, critically unwell, have an indwelling venous line, or have inflammatory bowel disease; yeast-containing products carry an additional caution for people with central venous catheters. Products marketed for pregnancy should still be discussed with a midwife or GP. Severe or bloody diarrhoea during or after antibiotics requires medical assessment. Stock status is stated as at the time of writing; both brands were out of stock and availability should be checked before ordering. Prices and review counts are correct at the time of writing and may change.
About the author
Dr Zeeshan Afzal (MBBS) is a practising medical doctor and Welzo's Medical Content Lead. He writes and reviews Welzo's health content to ensure it is accurate, evidence-based and aligned with current UK clinical guidance.
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