Is your gut all tied up?

We test the gastro health market to find out what really works

There is something uniquely unsettling about sending a sample of your own poo in the post - as I, and hundreds of thousands of us, have been doing lately - to work out the state of our guts.

While I've never suffered from obvious problems such as IBS or bloating, since entering my 40s I've become more concerned about underlying issues - particularly my recurring insomnia - and taking all manner of tests. Gut health is my latest obsession.

In addition to exacerbating sleep problems, gut health is increasingly linked to brain diseases such as Parkinson's or Alzheimer's, as well as hormonal and immunity issues. And the business of the microbiome is booming - the global microbiome diagnostics market is projected to grow from $146mn in 2023 to $300mn in 2028.

"The gut microbiome is home to 100 trillion microbes (tiny organisms that live in your gut) that support digestion, immunity and overall health," says Dr Emily Leeming, a microbiome scientist at King's College London and author of Genius Gut. "The microbes' job is breaking down your food, releasing energy and making important vitamins and short-chain fatty acids that support your gut and overall health". Adds Dr Mohammed Enayat, a GP and founder of the HUM2N clinic: "We used to think of the gut as just a food processor, but now we know it's more like mission control for your entire body."

Our collective gut health is getting worse. "We're quite concerned in the field that most people's microbiome is messed up," says Jens Walter, a microbiome professor at University College Cork. Studies show that the modern western diet - low in fibre and high in ultra-processed foods and sugar - has led to a significant decrease in the microbiome's diversity. Says Dr Walter: "Our western diet essentially overfeeds the human whilst starving the microbiome. Mechanistically, that might be responsible for these pathologies skyrocketing."

I took a test with a biotech tracking company, Stride, which functions as an Oura ring or a Whoop band for our insides. It finds my gut in fine fettle: I scored 93.2 per cent overall, with a near-perfect diversity score and an above-average balance between good and bad bacteria. I put this down to my mother's disregard for best-before dates, but also a (newish) rigorously healthy diet that has involved cutting out the family-sized pack of Maltesers and bottle of wine a night, upping the vegetables (fibre), sprinkling seeds on everything, and eating more lean protein (which I did for weight loss, but studies show it also helps with gut-cell repair).

But it wasn't all good news. When a Stride scientist called to explain my results, I discovered I am lower than average in three main bacteria: faecalibacterium, which may play a part in controlling obesity, bifidobacterium, which helps with immune resistance, and lactobacillus, which is involved with musculoskeletal health. The advice was to take in more probiotic foods such as sauerkraut, miso and kimchi; eat the rainbow (the different colours in fruits and vegetables indicate different phytonutrients, which feed the gut); and get out in nature more (which has the double whammy of both exposing the body to different microbes from soil, if you're a gardener or like to roll around on the grass with your dog, as well as reducing stress, which helps the gut further).

Then a different test with the HUM2N clinic reveals that I probably have a "leaky gut" - an alarming, non-medical term used to describe a condition whereby the gut barrier is compromised, allowing partially digested food, toxins and bacteria to "leak" into the bloodstream. HUM2N's nutritionist-prescribed plan was to avoid dairy and gluten for a month (both can cause inflammation) and take supplements including a digestive enzyme, which breaks down food more easily, and helps the gut absorb nutrients efficiently.

Leaky gut has become a catchword for a condition that is still under-researched and medically contested. Dr Megan Rossi, founder of The Gut Health Clinic and a research fellow at King's College London, is especially concerned about using commercial tests such as the one I tried. Though she doesn't dispute the term - scientists tend to refer to it as "increased intestinal permeability" - her clinical trials use "gold-standard" urine tests for gut leakiness. She worries at-home blood tests "can be misleading". She adds that while its prevalence is hard to define (due to lack of accurate testing), "everyone" gets a leaky gut on occasion, I for instance, after a high-fat meal, bouts of intense exercise or psychological stress".

But the real concern is that my gut report card might be totally meaningless, according to Dr Leeming: "Our microbiome changes hour by hour. It's a living ecosystem. What you're testing is just a snapshot in time." The other problem is that "for the everyman - rather than the scientist studying large trends of data - it's not going to give you any information that is useful, bar telling you what bacteria you have in your gut and at what levels". While Leeming believes there is potential, commercial tests are "not there yet at giving personalised, specific advice".

"It's right to be cautious," says Dr Enayat, with whom I did a gut test at the HUM2N clinic. "Many tests are ahead of the science in terms of interpretation, and we still don't have a universal definition of what a 'healthy' microbiome looks like. It's incredibly individual. But that doesn't make these tests useless. Sometimes they reveal significant imbalances and, for some people, seeing their data is the push they need to make real changes. It's important to see tests as one piece of a much bigger puzzle, not a crystal ball."

Andrew Steele, the ex-Olympian turned health-tech entrepreneur who founded Stride, with whom I did the second gut test, believes "you get the most valuable insights by testing over time". Unlike single-use commercial gut-health tests, he says, Stride's advantage is its newly launched membership platform that retests members every six months.

Having identified the problem, however, one must then navigate the host of supplements and pills marketed at improving gut health. Some have huge bodies of research behind them; others, not so much. Symprove, for example, a liquid probiotic developed by a British farmer experimenting with germinated grains for his livestock in the 1980s, has had several major clinical studies, including a 2014 paper that saw significant improvement for users suffering with IBS. Myota, a prebiotic fibre blend created by scientists using a decade of research from MIT, has clinical trials and a patent protected formula. Meanwhile, IM8, a vitamin supplement brand co-founded by David Beckham, has a clinical trial that showed improvements in participants' energy and digestion after 30 days.

Or there's a free option. A study published in January (of which Dr Walter was the lead researcher) showed that following a plant-heavy (but not totally meat-free), low-processed, wheat-free diet for three weeks could significantly improve our microbiome, with benefits including weight loss, reducing blood sugar by six per cent and decreasing "bad" cholesterol by 17 per cent.

"If you eat around the patterns that we propose, you can extend your life by 10 years," says Dr Walter. He has made the diet - and recipes - available as a free download (thenimediet.com). And, Dr Leeming adds, "for the 96 per cent of us who don't currently eat enough fibre, that's what's really going to make the most difference to our microbiome".

The tests might not tell me as much as I first thought, but I've found them a useful focusing exercise. I'm keeping my chia seeds on the countertop, colour-coordinating my vegetable drawer and adding a teaspoon of fermented food to my salad per day.