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What's the best probiotic?

Updated: Oct 25, 2019

There is a common misconception that we should all be taking probiotics to maintain good gut health, and I often get asked in passing what the best probiotics are. But the answer is very individual. So without taking a case history, and often without looking at your microbiome analysis results, it’s not really possible to prescribe probiotics effectively. Why is this?

Myths persist

Until fairly recently, practitioners would prescribe probiotics based on a sort of shot-in-the-dark approach, advising their clients to take one brand for 6 weeks and see if it helps, or keep switching brands until they found one that suited them. Despite the research having moved on dramatically in the past 5 years or so, this expensive and often ineffective approach persists. It is often accompanied by the suggestion that probiotics can ‘reseed’ the gut to establish new populations of beneficial bacteria, and so you should also rotate brands to maximise the diversity of your microbiome. Sadly we now understand this is just not borne out in practice. Although some probiotics may remain in the gut for a few weeks after ingestion, they have not been found to set up stable populations in the gut longer term. We now know the best way to increase populations of beneficial bacteria in your gut is to selectively feed them up.

While these myths persist, and while their customers don’t know better, some probiotic companies focus on marketing the “toughest” probiotics that are guaranteed survive your stomach acid, or the most fancy capsule to ensure delivery to the gut. Unfortunately, without pharmaceutical funding, very few companies have invested in clinical trials of their probiotic formulae. While of course it’s important to know the probiotic strains can survive the manufacturing process and transit to your intestine, a major issue that a few probiotic companies seem to avoid discussing is that the therapeutic action of probiotics is very much strain-specific.

Strain specificity is vital

Strain specificity means one strain of a species commonly found in probiotics called Lactobacillus acidophilus could have a very different action to another strain of Lactobacillus acidophilus. It’s helpful to understand what we mean by strain – which is different to species. One way to understand this better is to look at two different canine species – Canis lupus, the wolf, and Canis familiaris, the domestic dog. We can think of strains like different breeds of dog within the species known as Canus familiaris. A Chihuahua has a very different effect on an unwelcome visitor to a Rottweiler – one may encourage the visitor to accept your instantly-regretted offer of a cup of tea, while the other may immediately chase them off the premises!

When we look at probiotics, we find the behaviour of different strains can be as different as a Chihuahua and a Rottweiler. For example, taking one particular strain of Lactobacillus rhamnosus, known as GR1, will have a beneficial impact on the vaginal microbiome (eg Petricevic 2008), preventing UTIs, whereas Lactobacillus rhamnosus GG will not. Instead, Lactobacillus rhamnosus GG is a good choice if you want to avoid the unwanted symptoms caused by a course of oral antibiotics.

Clinical trials have proven therapeutic benefits of certain strains

There is now a wealth of information from randomised controlled clinical trials that shows particular strains have particular therapeutic effects. For example, there are strains that heal gastric ulcers and those that prevent migraines, while others enhance recovery from bone fractures, alleviate constipation or increase iron absorption – potentially helping patients with anaemia.

Unfortunately many probiotic manufacturers don’t put the strain details in the ingredients list, and only give you species information. This may indicate that the strains they are selling do not have any proven therapeutic effects (although there may still be anecdotal evidence of them helping certain conditions, and practitioners may even have seen benefits borne out in their practice). There is also a big difference between brands in the number of bacteria that are alive on ingestion (Hamilton-Miller 1999). This is a problem because probiotics are classed as foodstuffs, not medicines, so the manufacturers’ claims don’t fall under the same legislative scrutiny.

I prescribe targeted probiotics and prebiotics

In my Microbiome Analysis practice, I tend to prescribe prebiotics rather than probiotics. Prebiotics are foods and supplements that selectively feed up the beneficial bacteria already in your gut (for example, blackcurrants are excellent for feeding up Lactobacillus species). But one of my favourite probiotics to prescribe is the Optibac Every Day formula. It contains two strains that have been shown in clinical trials to help reduce anxiety (Messaoudi 2011), which clients commonly suffer from alongside the digestive issues that may have caused them to seek treatment initially. These two strains are: Lactobacillus acidophilus R0052 and Bifidobacterium longum R0175. The formula also contains other strains, including one that has been shown to treat atopic eczema and another that has been shown to prevent colds and flu (in a trial of almost 600 stressed undergraduate students – Langkamp-Henken 2015)!

This formula is actually a completely different mix of bacteria to the Optibac Every Day Extra Strength formula – despite the name confusingly suggesting that this one is just a stronger version of Optibac Every Day. I prescribed Optibac Every Day Extra Strength recently because it contains another strain of Lactobacillus acidophilus, known as NCFM, that has been shown to effectively treat allergic rhinitis (Ouwehand 2009). I have noted it also contains other strains that help prevent upper respiratory tract infections in both adults and children, which could come in handy as the winter cold season approaches.

Now we have enough research on probiotic strains, we all need to spread the word to reduce the market for the few probiotic manufacturers that play into these persistent myths and the hopes of their customers. It’s time for practitioners to hold manufacturers to account by busting these myths and to make powerful, targeted decisions when prescribing probiotics.

And if you ask me what’s a good probiotic for general gut health? I’m much more likely to prescribe you a local workshop on making your own fermented foods, or point you in the direction of the wholefood shop selling a multitude of different live sauerkrauts, kimchis, kefir or delicious, unpasteurised olives! That’s a far better choice for your guts, your wallet and your taste buds. Yum!

Trust and independence is important to me, and so I do not accept commission or affiliate fees for any of the probiotic or prebiotic supplements I may recommend. This is so you can be completely sure I only recommend these supplements on the basis of quality and in the interest of your health, and not for any financial gain. 


Hamilton-Miller, J., Shah, S. & Winkler, J. (1999). Public health issues arising from microbiological and labelling quality of foods and supplements containing probiotic microorganisms. Public Health Nutrition, 2, 223-229.

Langkamp-Henken B et al (2015) Bifidobacterium bifidum R0071 results in a greater proportion of healthy days and a lower percentage of academically stressed students reporting a day of cold/flu: a randomised, double-blind, placebo-controlled study. British Journal of Nutrition. Feb 14;113(3):426-34.

Messaoudi M et al (2011) Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects. British Journal of Nutrition. 2011 Mar;105(5):755-64

Ouwehand, AC et al (2009) Specific probiotics alleviate allergic rhinitis during the birch pollen season. World J Gastroenterol. 15(26): 3261–3268. 

Petricevic L, Unger FM, Viernstein H, Kiss H. (2008) Randomized, double-blind, placebo-controlled study of oral lactobacilli to improve the vaginal flora of postmenopausal women. Eur J Obstet Gynecol Reprod Biol. 141(1):54-7.

Viola Sampson BSc RCST BCST is a Microbiome Analyst practising in London UK and online. For appointments, please book online.

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