NOT so long ago, the very idea of swallowing live bacteria to boost our health would have seemed utterly ridiculous.
But in the past two decades, the market for drinks, foods and pills that promise to boost our beneficial gut bugs - which studies are now linking to everything from reducing the risk of depression to shrinking the size of our waistlines - has dramatically expanded.
First came probiotic supplements - so-called 'friendly bacteria'. Then prebiotics, which provide the fuel these bacteria feed off. Now comes a new breed of biotic supplement: the postbiotics.
In basic terms, explains Glenn Gibson, a professor of food microbiology at Reading University and a leading probiotic researcher, postbiotics are the leftover by-products once digestive good bacteria have broken down fibre in the gut.
The idea is that by taking a supplement of these by-products, you get all the benefits without needing the actual live bacteria. Some manufacturers claim postbiotic supplements are even better than probiotics, delivering faster results.
Certainly, an increasing number of experts - including microbiologists at the Wageningen University in the Netherlands, where some early studies have taken place, and independent UK pharmacist Aidan Goggins - think that when it comes to better gut health, postbiotics may turn out to be the most crucial element.
US brand Sane says its Viscera-3 postbiotic, which is endorsed by Harvard Medical School, as well as the respected Mayo Clinic, is "more powerful" than pro or prebiotics because it contains the "final by-product" - the components "that actually improve your gut health".
Meanwhile, Holland & Barrett has brought out what is thought to be the first UK supplement that contains a blend of pro, pre and postbiotics.
But is this latest spin on 'biotics' just a way to get us spending yet more on our wellbeing - or can they really boost our health?
The appetite for probiotics - the marketing name for the good bacteria such as bifidobacteria and lactobacillus that naturally live in our gut - has boomed since the mid-1990s and the launch of the Japanese yoghurt drink Yakult in the West.
These good bacteria form part of what is called our gut microbiome - a complex collection of microbes including viruses, fungi and yeasts - which studies are finding play a vital role in our digestive health and in helping to break down food, and also in our immune system and even our mood and behaviour.
Our natural levels of good bacteria can get depleted due to a range of factors, including poor diet, long-term stress or taking a course of antibiotics (which kill not just harmful bacteria but also some beneficial strains).
Nor is it just the number that's important; we also need to have a good diversity of different types of bacteria.
To replenish numbers, you can take probiotic supplements or add more fermented foods that naturally contain them (such as live yoghurt, kefir, sauerkraut or kimchi) to your diet.
But these good bacteria also need feeding, which is where prebiotics come in. The best food sources include bananas, onions and leeks, but prebiotics are also available as supplements, both on their own and as 'synbiotic' (a blend of prebiotics and probiotics in one capsule).
Increasing prebiotic intake has been linked to similar gut health benefits as probiotics, but more clinical trials are needed to confirm this, according to a 2020 review by the University of Rome.
And just as different brands of probiotics may contain differing bacteria, the same goes for postbiotic supplements.
Simon Gaisford, a professor of pharmaceutics at University College London, who has studied these by-products, says that from research he has conducted so far, "the most important type of postbiotics are the short-chain fatty acids acetate, propionate and butyrate, which are very important in maintaining good gut health".
Other research shows they may also encourage a strong immune system and have an anti-inflammatory effect on cells in the gut lining. One study by Naples University in 2011 found that supplementing butyrate reduced abdominal pain for IBS sufferers.
Yet not all of these are marketed specifically as postbiotics. For more than a decade, BodyBio, a UK-based supplement company, has sold a butyrate supplement which it says "improves digestion".
Holland & Barrett's postbiotic product contains calcium lactate, which, it claims, "contributes to the normal function of digestive enzymes".
But these products aren't cheap. The BodyBio product costs £17.99 for 60 capsules, while Holland & Barret's Expert Triple Action Biotic Gut Formula costs £29.99 for 60 capsules. Given that they are supposed to be taken daily, are they worth it?
Professor Gibson feels this new product may be a "biotic too far".
"Postbiotics are the latest addition to the 'biotic' family, but there's much less research on their use," he cautions.
"No doubt this will change in the future, but at the moment, I'm not convinced of their unique selling point and of what differentiates them or makes them superior to pro or prebiotics."
As Professor Gibson points out, while more than 100 studies are currently underway, there is very little published research on postbiotics supplementation. (One small study published in the journal Digestive Diseases in 2011 found that taking a postbiotic milk culture for four weeks eased IBS symptoms.)
Indeed, despite the evident popularity of probiotics, there still isn't an overall scientific consensus about their effectiveness.
While some studies do show that certain strains of good bacteria may help prevent antibiotic-associated diarrhoea, and others could offer constipation relief, in 2020, a review of current research by the American Gastroenterological Association found little evidence to recommend them for most digestive conditions, echoing the result of a 2017 review by the respected Cochrane Library.
"To me, probiotic supplements have, in the most part, failed to live up to their early promise," says Aidan Goggins, an adviser to the supplements industry.
Much past criticism of probiotic supplements has focused on whether these bacteria survive the digestion process and remain live by the time they reach the gut.
"Studies have shown the bacteria [in supplements] often don't make it to the gut intact, or that they contain drop-in-an-ocean amounts that fail to make any significant difference to the overall number of good bacteria in the gut," says Aidan Goggins.
However, with postbiotics, there's nothing alive to be killed off. That means postbiotics provide the nutritional benefits in an easily absorbable form that the body can use straight away.
"It's still too early to see if these supplements will live up to the hype, but this is definitely the next generation of good gut health that we should be looking at," Aidan Goggins concludes.
However, there is one simple way to increase levels of all three biotics: up your fibre intake. The more fibre your gut bacteria can ferment and break down, the more beneficial nutrients it can release.
"But not all fibre is created equal and your standard bowl of bran flakes, for example, isn't very good at stimulating probiotic bacteria to ferment and create postbiotics because it's not high in the prebiotic fibre inulin," says Professor Gibson.
"Good food sources of inulin include bananas, artichoke, onion and leeks,' he adds.
Yet another reason to eat up your fruit and veg...
© Daily Mail
