Groundbreaking study finally discovers the best diet for millions with debilitating digestive disorder
Scientists have identified a diet plan proven to reduce symptoms of a debilitating digestive disease and reduce markers of inflammation in patients’ bodies.
Stanford University researchers placed dozens of people with Crohn’s disease, a chronic inflammatory bowel disease (IBD) that causes swelling and irritation in the digestive tract, on a highly restrictive diet that included fasting for five consecutive days per month for three consecutive months.
About three dozen participants with the condition followed their regular diets. Both groups followed their respective diets for three consecutive months.
By the end of the trial period, two-thirds of the diet group that limited daily calories to roughly 700 to 1,100 saw noticeable improvement in their symptoms, which typically include persistent diarrhea, cramps, abdominal pain, fatigue, weight loss, reduced appetite, fever and rectal bleeding.
Less than half of the people in the control group saw such improvements in their Crohn’s disease, which affects between 780,000 and over 1 million Americans.
Researchers also tested participants’ blood and stool samples for evidence of proteins indicative of systemic inflammation and found far fewer in the people who followed the fasting-mimicking diet (FMD).
Dr Sidhartha R Sinha, a gastroenterologist at Stanford and the senior author on the paper, said in a statement: ‘We have been very limited in what kind of dietary information we can provide patients.
‘We were very pleasantly surprised that the majority of patients seemed to benefit from this diet. We noticed that even after just one FMD cycle, there were clinical benefits.’
Crohn’s disease is characterized by persistent diarrhea, cramping abdominal pain and fatigue. These are often accompanied by weight loss, diminished appetite, fever and rectal bleeding (stock image)
The latest study, published in the journal Nature Medicine, enrolled 97 patients with Crohn’s disease between 2019 and 2023 and divided them into two groups: 65 would follow the FMD, while 32 would follow their typical diets.
The main goal was to see if patients achieved a significant reduction in Crohn’s disease symptoms or entered remission after the three diet cycles.
Stanford researchers also set out to measure various blood and stool markers of inflammation, patient-reported symptoms, quality of life and endoscopic healing, the definitive visual proof that treatment has resolved gut inflammation in Crohn’s disease.
Those assigned to the FMD group followed a specific, very low-calorie meal plan for five consecutive days every month for the three-month study period. The prepackaged meals, which included soups, meals and bars, were provided by the research team.
Daily calories ranged from 725 to 1,090, with a specific balance of fats, proteins and carbohydrates. Participants were instructed to eat only the provided food with substitutions allowed only if approved by a study dietitian.
The FMD was significantly more effective at reducing Crohn’s symptoms. After three months, about 69 percent of the FMD group achieved measurable clinical improvement compared to about 44 percent of the control group.
More people in the FMD group also entered clinical remission, 65 percent, compared to 38 percent of people in the control group. Benefits were seen as early as the first FMD cycle.
Blood markers such as C-reactive protein CPR, which is produced by the liver and released into the bloodstream in response to inflammation somewhere in the body, did not change dramatically.
This bar chart shows that after three monthly cycles, nearly 70 percent of patients on the FMD achieved a clinically meaningful improvement compared to only about 44 percent of patients in the control group who continued their usual diet
But there was a significant drop in fecal calprotectin, a key stool marker for gut inflammation, in the FMD group.
Overall, those patients felt better. They reported better control of their abdominal pain and diarrhea, a higher quality of life and were more likely to personally rate themselves as being in remission.
The diet was effective for people with mild or moderate disease and for those with inflammation in the colon or in both the ileum and the colon. It was also effective for patients not taking any advanced Crohn’s medications, with over 75 percent of this subgroup showing improvement.
The most common side effects of the FMD were mild, temporary fatigue and headaches. There were no severe adverse events linked to the diet and adherence was good, with participants completing about 77 percent of all required diet cycles.
After the FMD, patients showed a reduction in specific pro-inflammatory fatty acids and a decrease in the activity of genes related to inflammation in immune cells. This suggests the diet may work by calming down the underlying inflammatory pathways that drive Crohn’s disease.
Dr Sinha said: ‘The effects seen on inflammatory markers made this an appealing diet to study in Crohn’s disease since many patients with this disease also have elevated inflammatory markers.
‘There’s still a lot more to be done to understand the biology behind how this and other diets work in patients with Crohn’s disease.’
Crohn’s disease is currently incurable. Studies show the burden is rising, particularly among children. A 2024 report in the journal Gastroenterology estimated that more than 100,000 American youth under the age of 20 live with inflammatory bowel disease.
This chart demonstrates that the FMD was also superior at putting patients into full clinical remission. Over 64 percent of the FMD group achieved remission versus 37.5 percent of the control group
The study reported increases of about 22 percent for Crohn’s disease and 29 percent for ulcerative colitis in the pediatric population compared with 2009 prevalence data.
Crohn’s disease most often begins in early adulthood, with an average age of onset around 30. The majority of new cases are diagnosed in people in their 20s and 30s, and a smaller, second rise in incidence occurs near age 50.
While the condition can cluster in families, genetic factors alone do not fully explain it. About 10 percent to 25 percent of patients have an immediate family member with the disease, and even among genetically identical twins, only one twin develops Crohn’s in half of such pairs.
Scientists believe the increasing prevalence of Crohn’s disease is connected to modern, industrialized lifestyles. A leading theory points to the Western diet, high in meat and processed foods, as a potential trigger.
Another prominent idea is the ‘hygiene hypothesis,’ which suggests that living in an overly clean environment may alter immune system development, causing it to mistakenly attack the body’s own tissues rather than fighting germs.
There is no cure for Crohn’s disease and treating its milder forms presents a significant challenge.
With no dedicated drugs for mild Crohn’s, doctors are left to face a risky dilemma: prescribe powerful immunosuppressants that can be taken for life but increase infection risk, or short-term corticosteroids that carry long-term risks of weight gain, bone loss and diabetes.
However, the diet treatment burden is low. It only requires five consecutive days of restrictive dieting per month, after which people can return to their normal diets. This is considerably easier to adhere to than a permanent restrictive diet or a lifetime of pills and injections.
