Jordan Haworth: How “Mr Gut Health” Went From Fruitarian to Myth-Buster

Jordan Haworth would like you to know that gut health is simpler than your feed makes it look. “The term has been hijacked by supermarkets and supplement companies,” he told Newsweek in August. “The good news is, gut health doesn’t need an expensive probiotic pill or green powder.” That is the whole pitch of Mr Gut Health, the Instagram account where 419,000 people follow a Manchester lab scientist through what he eats, what he avoids and which viral hacks he thinks are nonsense. It is also the pitch of his first book, How to Gut Health, published by Vermilion in June. What makes him worth listening to is less the confidence than the backstory: before he spent his days debunking wellness myths, he believed one of the worst of them.

The advertAn accidental gut scientist

Haworth did not set out to work on guts. “It might surprise you that I had no initial interest in gut health,” he writes in the book’s introduction. He studied biomedical sciences, loved immunology, did his final-year project on CAR-T cancer therapy, and applied for a scientist training place in the field. He did not get an interview. Then, the day after his last undergraduate exam, he saw an advert for a graduate scientist job at The Functional Gut Clinic, a specialist testing clinic, which was training a new generation of gastrointestinal physiologists. He joined in 2017 and is still there. A physiologist, in his definition, is a scientist who specialises in how a body system works and how its problems are diagnosed; for his, that is “the gut, from the mouth right through to the anus.” In practice that means running the tests gastroenterologists order, such as breath tests and pressure studies of the gullet and bowel. He is not a doctor or a dietitian, and he does not call himself one.

He is also a working researcher, which is rarer among gut creators than it should be. He is first author on a 2025 study in the American Journal of Gastroenterology of 731 patients who had breath tests at his clinic, asking which symptoms actually predict a positive result, and on a 2024 review of how common rumination syndrome is, a condition in which food comes back up without effort. He is now working on a PhD on gut health in athletes. “When I first started, I didn’t realize gut health was a thing,” he told Newsweek.

The rabbit holeThirty bananas and a Tesco receipt

The part of his story Haworth tells most carefully is the one that explains the account. In his early twenties he was diagnosed with an autoimmune skin condition, and went looking online for the perfect diet. This was before TikTok, and YouTube, he writes, was “the original home of health misinformation.” He found creators preaching that humans are meant to live on fruit, and became a fruitarian. The book’s account of it is funny and then isn’t: most of those creators lived somewhere tropical, “and there I was in Big Tesco spending £20 a day on mangoes and blueberries. Suffice to say, it didn’t heal me.” It turned into orthorexia nervosa, an eating disorder built around rigid rules about ‘pure’ food. He credits his family and therapy with getting him out, and science with keeping him out: becoming a better scientist, he writes, taught him “to question harmful rules and to trust evidence over fear.”

A master’s degree in clinical research gave him the tools. “I learned how to properly critique studies and spot BS (bad science) a mile off,” he writes. “That’s why I started my Instagram account, @mrguthealth, to stop others from falling down the same rabbit holes I did.” He also helped set up Tummy MOT, a free education account whose motto is “the truth will set your tummy free.” Anyone who has had a difficult relationship with food will recognise how much it costs to write that chapter in your own first book. If that is you, the UK eating-disorder charity Beat and, in the US, the National Alliance for Eating Disorders are good places to start.

The feedMediterranuary and the foods he never eats

The account itself is mostly cheerful. There are what-I-eat-in-a-day videos, supermarket hauls, fermented-food recipes and myth-busts on gluten, dairy, seed oils and the carnivore diet, which he calls a contrasting yet equally harmful trend reaching boys the age he was when he went down his own rabbit hole. His signature experiment was Mediterranuary: a month on a Mediterranean diet in January 2024, with tests before and after. He says he hasn’t looked back. “Yes, the Mediterranean Diet is NOT a diet but a set of principles,” he wrote a year later, in a post about keeping it up.

His most useful idea may be the least glamorous one. “Food poisoning is the single biggest wrecker of gut health,” he told Newsweek, because the bugs behind it can leave lasting problems. So he skips raw oysters, rare burgers and mixed bagged salads. He cited this summer’s Cyclospora outbreak linked to iceberg lettuce, which we covered from start to finish: “If I want to eat spinach, I’ll buy spinach by itself and wash it thoroughly.” It is a very Haworth piece of advice: evidence-led, a little unexpected, and free.

The bookA scientist, not a chef

How to Gut Health: Science-backed hacks for immunity, metabolism and better sleep came out on June 18 in paperback, ebook and audio. It covers how the gut works, gut-health myths, supplements (“superstars vs fraudsters”, in the chapter title) and a chapter on common problems, and ends with his own recipes. “I wrote this book because gut health has become way more complicated than it needs to be,” he writes. The recipes are deliberately low-effort. “I’m a scientist, not a chef, so if a recipe needs multiple pans or dozens of ingredients, it’s not in here.” The introduction signs off like he talks: “in true Manchester fashion, let’s get mad for gut health!”

What the research actually measuredThirty plants, fermented foods and food poisoning

Haworth’s advice rests on a handful of well-known findings, and he would be the first to say they should be read at their real size.

Thirty plants a week. The number comes from the American Gut Project, a 2018 citizen-science study of more than 10,000 people who mailed in stool samples and diet questionnaires. Its most-quoted finding was that the number of different plants people ate tracked their gut microbial diversity better than labels like ‘vegan’ or ‘omnivore’ did. The headline comparison, more than 30 plants a week against fewer than 10, was made in a subset of about 85 people chosen from the two extremes, using self-reported diets. It is a striking association and a good rule of thumb. It is not a trial, and there is nothing magic about 30. For a different angle on plant counting, see our profile of Dr Megan Rossi.

Fermented foods and the Mediterranean diet. These are better tested. In a 2021 Stanford trial, 36 healthy adults were randomly assigned to a high-fermented-food diet or a high-fiber diet over a 17-week study. The fermented group’s microbial diversity rose steadily and several inflammation markers fell; diversity in the fiber group did not change. The trial’s main immune measure did not move in either group, and it was small, but it was randomized. The Mediterranean evidence is larger. In the NU-AGE study, 612 older adults in five European countries were profiled before and after a year on a Mediterranean-style diet. The people who stuck to it most closely showed microbiome shifts that went with lower frailty and inflammation markers. Our fermented-foods guide covers the practical side.

Food poisoning. His strongest claim has the best evidence. A 2017 meta-analysis in Gastroenterology pooled 45 studies of 21,421 people who had had an episode of infectious gastroenteritis. About 10 percent had irritable bowel syndrome a year later, and in the first year their risk was about four times that of people who had not been ill. The rate was 13.8 percent after bacterial infections and 41.9 percent after parasites and protozoa, the family Cyclospora belongs to. Avoiding the riskiest foods is not paranoia; it is one of the few gut-health habits with a clearly measured downside to skipping.

The disclosure mapWhere his interests sit

Haworth works for The Functional Gut Clinic, a private clinic that sells diagnostic tests, including breath tests and stool microbiome analysis, and that runs trials for industry sponsors; his link page promotes one of them. He earns from his book. He wrote a gut-health guide for Activia’s UK site, a Danone brand, in February. The page does not say whether he was paid, and it tells readers much what he says elsewhere: “You don’t need a fancy supplement or a strict diet.” He is a gastrointestinal physiologist and PhD researcher, not a medical doctor or dietitian, and his account of his own health is his experience, not advice. Gut Health Times has no commercial relationship with him, the clinic or his publisher, and was not sent the book. This profile is educational, is not medical advice, and was prepared without input from him. Anyone with ongoing digestive symptoms, or worries about their relationship with food, should start with their own doctor.