If I was the gambling sort, I’d put money on you having a bottle, sachet or box somewhere in the back of a kitchen cupboard. Because over the last half decade, probiotic supplements have gone from obscure to ubiquitous. Every year, we in the UK spend about three quarters of a billion pounds on them. Yet as many as eight in 10 (77%) report having no significant health improvements while taking them, and a new study suggests that’s because – for many people taking many brands – it’s an entirely pointless exercise.
“Our Smart Strains research revealed that one in five of us are now regular users of probiotics,” says Dr Megan Rossi, gut health scientist and registered dietitian. “Of these, 56% of women are taking them to aid their ‘general gut health and digestion’. However, scientific research shows that if you’re healthy, there’s actually no evidence to support the use of a daily probiotic for your gut bacteria – it’s like a drop in the ocean.”
Why?
Dr Rossi’s study suggests that half of UK probiotic users mistakenly believe that the probiotic products they purchase are clinically proven. In fact, she says, the majority of products available today are not backed by clinical trials.
Worse, she says, many brands also include additives such as emulsifiers and added sugars. Sugar can promote the growth of harmful bacteria and yeast, actually counteracting the benefits of probiotics. Some probiotics can die on the shelf or in your kitchen cupboard, because they’re sensitive to factors such as temperature, light or humidity.
In fact, research commissioned in 2023 by nutritional science brand Heights found that – despite labels boasting billions of colony forming units (CFUs) – some of the world’s leading probiotics were delivering less than 1% of their bacteria to the colon alive.
“A lot of the probiotic products on the market are poorly formulated (that is, they’re not capable of delivering large numbers of viable probiotic bacteria to the gut),” says Simon Gaisford, professor of pharmaceutics and probiotics expert at University College London. “Because of this, a lot of studies on probiotic supplementation don’t see a positive effect.”
Many probiotic supplements come dried and encapsulated. This, says Professor Gaisford, can present a problem. When you swallow yours, “the stomach releases hydrochloric acid and digestive enzymes in response to the arrival of food (protein and fat).” That acid will kill many of the probiotic species you’ve paid for. There’s more: “Solids contain bacteria that have been desiccated – thus, they have to rehydrate in order to recover viability. Doing this in the stomach is a big ask, as there’s a high chance they’ll imbibe acid.”
That’s not to say, however, that all probiotics are pointless. Far from it, says Professor Gaisford. “Imagine being asked to test drive the latest Ferrari and give an opinion on its performance but it’s delivered with no fuel in – you’d think it was rubbish, but the car is good; it’s the way it was delivered that was at fault,” he explains. Similarly: “I believe that a properly formulated probiotic supplement will support and enhance good gut health.”
Choose water-based
“For me, properly formulated means a water-based product,” says Professor Gaisford. “A water-only probiotic doesn’t trigger digestion because there’s no fat or protein to digest, and it should empty to the small intestine within 10 mins. This is why water-based products are effective in delivering live bacteria.”
Professor Gaisford takes and recommends Symprove, a once-daily liquid probiotic. A 2019 clinical trial showed that it reduces intestinal inflammation among people with gastrointestinal diseases.
Try kefir
Yogurts and kefirs count, too, says Professor Gaisford: “Yogurts have a higher fat content, so may trigger digestion, but if taken on their own, I also think they should empty relatively fast (because stomach emptying is triggered when no large food particles are detected, and a yogurt is smooth). Taking a probiotic with dinner however… Not good!”
To maximise the probiotic power, look for naturally fermented, non-pasteurised products like kefir: “a fermented milk, produced using grains containing a mix of microorganisms (usually bacteria and yeast), [which] should not be pasteurised.”
Try… Good Housekeeping’s favorite kefirs
Get specific
Dr Rossi agrees that probiotics can have a powerful impact on your health, if they’re well formulated and properly used. By way of example, she points to a study involving 192 infants with colic, which found that a specific live bacteria formula achieved a 50% reduction in daily crying and fussing time in almost three times as many participants compared to the placebo. Yet more research, involving 48 women with thrush, found a specific live bacteria formula not only reduced symptoms, but also significantly reduced recurrence.
Specificity is key, says Dr Rossi. “While the idea of a ‘one-size-fits-all’ supplement for gut health sounds appealing, unfortunately, it’s outdated – and consumers are wasting their money,” says Dr Rossi. “The latest science shows us how crucial it is to get specific.”
Studies link specific probiotic strains with different impacts on your health. For example, saccharomyces boulardii has been shown to reduce antibiotic-associated diarrhoea in some people, whereas Lactobacillus plantarum LP01 and Bifidobacterium breve BR03 help some people with constipation.
To that end, Dr Rossi has launched a new collection of probiotic supplements called Smart Strains – four different products, targeted to four different health concerns and containing bacterial strains whose efficacy in treating each is backed by international health bodies.
Not ready to give up on the pack in your cupboard? You can, of course, do some due diligence yourself. Check whether the strains of bacteria listed in the ingredients have been tested in a human clinical trial. Don’t forget to run the numbers either. Your box may boast 50bn bacteria, but each type (or strain) of bacteria is required at a specific dose to have an effect on human health. The website US Probiotic Guide is a useful tool here – designed to translate scientific evidence available for probiotic products to practical, clinically relevant information.
Because when it comes to probiotics, it seems, quantity and quality matter.
