A very small Italian study using a similar commercial probiotic, Sivomixx, piqued his interest after it suggested acute Covid patients treated with it might be less likely to end up in ICU or to die, and eight times less likely to suffer respiratory failure. Bjarnason is hoping to start a larger study in the next few months. I knew the gut microbiome was important to our health and I wanted to focus my future career on understanding how": Meet James Kinross Spector’s 30-year-long study of 15,000 twins, TwinsUK, and his PREDICT studies have shown that even genetically identical people respond to the same foods very differently (our microbiomes are so variable that twins share only 30% of the same gut microbes). By feeding participants the same meals on different days, he was able to show that responses to the same meals also vary hugely between individuals, influenced by both the microbiome and genetics. This matters, says the ZOE team, because our response to food is linked to our risk of heart disease, type 2 diabetes and obesity, but also because it blows apart the tired and useless mantra “calories in, calories out”, which doesn’t make sense in a world where two people’s blood glucose levels can be hugely different after eating the same slice of cake. And how the biome is affected by your social environment; the brain-gut axis looks to be key to our survival.

I've long been interested in the microbiome, and have been eagerly awaiting a book that might uncover some of its mysteries. This is that book Heston Blumenthal I was keen to bring together all the work going on in microbiome science, because it creates such a compelling argument for taking it seriously. It’s not just about the gut: it’s about the human microbiome. A spellbinding explanation of microbiology that will help you get to the bottom of health and happiness -- John Vincent, Co-Founder of LeonIt’s also becoming clear that samples from some donors are much more effective than those from others. These are known as “super donors” and their faeces seems to contain a magical ingredient that makes it particularly effective. But we don’t understand why this happens, or whose poo will be most effective. A spellbinding explanation of microbiology that will help you get to the bottom of health and happiness John Vincent, Co-Founder of Leon

Ray was readmitted to St Mary’s critically unwell and was soon diagnosed with Clostridium difficile (C diff) infection (officially, this bacteria has now been renamed Clostridiodes). A “hospital-acquired infection”, this disease is a complication of 20th-century medicine and an unintended consequence of Alexander Fleming’s discovery of penicillin, the first effective mass-produced antibiotic, in 1928. It is a global problem that afflicts 500,000 people in the United States each year and it kills 29,000 of them.

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Fermented foods are now thought to be integral to a healthy gut because they provide a vast amount of natural probiotics which can boost immunity and soothe the digestive tract. Johnny Drain is a materials scientist and a chef who believes in the benefits of fermentation, and has looked worldwide for innovations in techniques and flavours. The scale of the task is huge: there is 1.5kg of bacteria in our guts.’ Illustration: Lisa Sheehan/The Observer

My general hypothesis is that we are experiencing a fundamental change in the type, number and function of micro-organisms that live within us in the developed world. That has happened over a very short timeframe and the reason for that is not just about diet and food. It’s also about our rapidly changing environment (particularly urbanised environments), which we call the exposome, and the fact that we are now taking lots of medicines, especially antibiotics. Clearly diet is a major driver too and in America and Europe, we now eat a kind of globalised, processed, white, gloopy diet which is very low in plant-based fibres and very high in animal fats and refined sugars.Kinross makes it clear that the composition of the microbiome has been implicated in many conditions, but the truth is that this is really nothing new. The great unknowns are the exact mechanisms by which the composition of the microbiome may (and I stress may) be a factor in these conditions, and the science is so young that there simply isn't the evidence to make any definitive claims; given the extreme number of confounders, it's very unlikely we ever will.