Dr Alan Desmond: The Gastroenterologist Who Answers “What About Food?”
In 2004 a young man with Crohn’s disease asked his doctors what he should eat, and was told to have a McDonald’s. The most junior doctor on the ward never forgot it. Two decades, two books and 179,000 followers later, Dr Alan Desmond is still answering the question.
Dr Alan Desmond is a consultant gastroenterologist in Devon, England, originally from Blarney in County Cork, who describes himself as a full-time NHS consultant with a special interest in inflammatory bowel disease. He graduated from University College Cork in 2001 and became a consultant in 2012. He says a 2004 ward round, when a 19-year-old with Crohn's disease asked what to eat and was told it did not matter, led him to make evidence-based dietary advice part of his practice; his family has eaten a plant-based diet since 2016. He wrote The Plant-Based Diet Revolution (2021, with Bob Andrew) and What Your Doctor Isn't Telling You About Food (Yellow Kite, 18 June 2026), hosts The Eat This Podcast, and has about 179,000 Instagram followers. His signature idea is a three per cent swap of calories from animal to plant protein, drawn from a 2016 Harvard cohort study. Research links more fiber and less ultra-processed food with lower risk of developing Crohn's disease; evidence for diet as an IBD treatment is limited, and he presents diet as working alongside medical care. Educational, not medical advice.
Every gastroenterologist hears the same three words, usually at the end of an appointment, often with a coat already half on. “What about food?” Dr Alan Desmond has built a career, two books and an audience of 179,000 people on Instagram out of taking that question seriously. He is a consultant gastroenterologist in Devon, in the south-west of England, where he describes himself as “a full-time NHS Consultant” with a special interest in inflammatory bowel disease, and in June he published What Your Doctor Isn’t Telling You About Food. The title sounds like a conspiracy. The book, and the man, are much gentler than that. His one-line version: “The most powerful tool we have to transform our health isn’t a high-tech prescription or the latest online wellness trend — it’s the food on our plate,” he told the Irish Examiner.
The ward roundA question nobody answered
Desmond is from Blarney in County Cork and graduated from the medical school at University College Cork in 2001. He tells his origin story the same way each time, and it starts with someone else’s answer. It was 2004, his first stint on a gastroenterology ward, and a 19-year-old with Crohn’s disease was recovering on strong anti-inflammatory treatment. On the ward round the young man asked the team the question. “What about food? Is there anything I should eat? Anything I should avoid?” The consultant in charge, Desmond recalled on the PLANTSTRONG podcast, told him it did not matter, that he needed calories. His mother, at the bedside, asked if that was really true. “And my boss said, ‘Really. Does he like McDonald’s? Why don’t you bring him in a McDonald’s?’”
Desmond was the most junior doctor on the team and said nothing. But the question stayed with him. “As I went through my career and I decided I wanted to be a gastroenterologist, I noticed that every single patient would ask the same question,” he said: people with diverticular disease, polyps, Crohn’s, colitis, fatty liver. He trained in Ireland and at the John Radcliffe Hospital in Oxford, published research from Cork on how much radiation people with Crohn’s were getting from repeated scans (in the journal Gut in 2008, among others), and in 2012 moved to Devon as a consultant. That was the moment the answer changed. “When my patients started asking me, ‘What about food, doc,’ because they all do, I didn’t tell them that it didn’t matter,” he said. “I started telling my patients that it really did matter.”
“I didn’t tell them that it didn’t matter. I started telling my patients that it really did matter.”
The kitchenTaking his own advice
The personal switch came four years later. “In 2016, I decided a plant-based diet was best for me and my family and we have eaten that way since,” he told the Irish Examiner when his first book, The Plant-Based Diet Revolution, written with Bob Andrew, came out in January 2021. The new book is broader. Its publisher pitches it as an explanation of “how the modern food environment is quietly reshaping our biology”, and adds, pointedly: “This is not another diet book.”
What makes Desmond easy to listen to is that he does not sell the switch as all or nothing. His signature idea is the three per cent swap: move a sliver of your protein from animal to plant sources and keep going from there. In a spaghetti bolognese, he suggests swapping about 75 grams of the minced beef for a cup of cooked beans or lentils. “You still get a hearty satisfying meal but you’ve nudged it towards more fibre, more plant protein, and less saturated fat.” Then, the line that sums up his whole approach: “But why stop at 3%?” The same tone runs through the post pinned to his X profile since 2022: “It’s true that no dietary change can make us disease-proof. But if a plant-based diet was a pill, your doctor would prescribe it all day long.” Note the first sentence. He writes it every time.
The clinicFood and medicine, not food or medicine
This is the part of Desmond that tends to get lost in the plant-based conversation online, and it is the part that matters most for anyone with a gut condition. He is a working hospital doctor who prescribes, scopes and treats, and he talks about diet as something that sits alongside medicine rather than replacing it. “Every patient with IBD asks about food — they deserve evidence-based answers,” reads his page on the condition. On the podcast where he told the ward-round story, he ended his advice to listeners by sending them back to their own doctors: “Because low risk is not no risk. So just be mindful. Your doctor’s always on your team basically.”
He is also disarmingly modest for someone with two books and a following most doctors would not know what to do with. “I haven’t been a doctor for that long really,” he said in 2021, nearly twenty years after qualifying. “I view myself still as on the learning curve.” He hosts The Eat This Podcast, writes a newsletter, and in his short videos does something rare: he puts the study reference in the title, so you can go and read it yourself.
What the research actually measuredThe studies behind the swap
Desmond is a doctor who cites his sources, so it is fair to read them at their real size. Most of the evidence for what he recommends is observational: large groups of people followed for years, which can show that two things travel together but cannot prove one causes the other. It is, however, very consistent.
On fiber, the anchor is a 2019 set of reviews in the Lancet pooling 185 long-term studies and 58 clinical trials. People who ate the most fiber had 15 to 30 percent lower rates of death from any cause, heart disease, stroke, type 2 diabetes and colorectal cancer than those who ate the least, with the biggest benefit at 25 to 29 grams a day; the trials, which are shorter, showed lower weight, blood pressure and cholesterol. Most people are nowhere near that: about 5 percent of Americans meet the fiber recommendation. Our fiber calculator will tell you where you land.
On inflammatory bowel disease, his home subject, the data are suggestive and worth stating carefully. In the Nurses’ Health Study, 170,776 women followed for 26 years, the highest fiber intake, a median of 24.3 grams a day, went with a 40 percent lower risk of developing Crohn’s disease, mostly from fruit fiber, and no clear difference for ulcerative colitis. In a 2021 study in the BMJ of 116,087 adults across 21 countries, eating five or more servings a day of ultra-processed food went with an 82 percent higher risk of IBD than eating less than one. A 2022 analysis in Gut estimated that a healthy lifestyle could have prevented roughly 43 to 61 percent of Crohn’s cases in its US cohorts. Treatment is thinner ground. A small Japanese study of people with Crohn’s in remission found 15 of 16 on a semi-vegetarian diet stayed in remission over two years against two of six who ate as usual, but it was 22 people and not randomized. Desmond co-authored a 2019 case report of one patient’s remission on a plant-based diet; a case report describes one person, and it cannot say how many others would respond the same way.
The three per cent swap comes from a 2016 Harvard study of 131,342 health professionals. Each 3 percent of calories from plant protein went with a 10 percent lower risk of death over the follow-up, and swapping plant protein in for processed red meat showed the largest difference. One honest wrinkle the headlines skip: the link showed up in people with at least one lifestyle risk factor, such as smoking, heavy drinking, inactivity or excess weight, and not in those with none. Read together, this is solid support for more fiber, more plants and less ultra-processed food as a direction of travel, and weaker support for diet as a treatment. That is roughly how Desmond himself frames it. For how fiber and probiotics differ, see our explainer; for another gastroenterologist who works the same beat, our profile of Dr Will Bulsiewicz.
The disclosure mapWhere his interests sit
Desmond earns from his two books and his private practice, the Devon Gut Clinic at Mount Stuart Hospital in Torquay, alongside his NHS work. His podcast is sponsored by Linwoods, a seed and flaxseed brand, and his link page carries discount and affiliate links for several supplement, coffee and course products. He is an ambassador for Plant-Based Health Professionals UK and an international adviser to Doctors For Nutrition, and he co-authored his 2019 case report with researchers from the Physicians Committee for Responsible Medicine, which also hosts his podcast appearances. Gut Health Times has no commercial relationship with him or with any of these companies and was not sent the book. This profile is educational, is not medical advice, and was prepared without input from Dr Desmond. Anyone with IBD or ongoing digestive symptoms should make diet changes with their own care team.