One of the most frequently posed questions by individuals diagnosed with inflammatory bowel disease is, “What should I eat?”
However, this question is not easy to answer. Inflammatory bowel disease, which includes conditions like ulcerative colitis and Crohn’s disease, has not been extensively researched in relation to diet. There have been few large, controlled studies investigating dietary changes.
Researchers from Stanford Medicine and partnering institutions are beginning to address this gap. In a national randomized controlled trial, they discovered that a short-term calorie-restricted eating plan significantly improved both symptoms and biological markers in patients with mild-to-moderate Crohn’s disease. The findings were published recently in Nature Medicine.
Examining diet presents various challenges. Study participants may not always accurately report their food intake, and the placebo effect can complicate results since individuals are aware of their dietary regimen. Nonetheless, the results were noteworthy. Patients reported feeling better and showed significant reductions in inflammation in biological samples. These findings may enable doctors to offer clearer dietary advice to their patients.
“We have often felt constrained in the dietary guidance we could provide our patients,” remarked Sidhartha R. Sinha, MD, an assistant professor of gastroenterology and hepatology and the senior author of the study. “This research will furnish physicians with the evidence needed to support recommendations in an area of great interest to patients.”
Crohn’s Disease and Limited Treatment Options
Crohn’s disease is a chronic condition affecting approximately one million Americans. It leads to inflammation in the digestive tract, producing symptoms such as diarrhea, cramping, abdominal pain, and weight loss.
Currently, for mild cases, steroids remain the only approved treatment. However, their prolonged use can cause serious side effects.
How the Fasting Mimicking Diet Was Tested
The clinical trial involved 97 patients with mild-to-moderate Crohn’s disease across the United States. Among these participants, 65 adhered to a fasting mimicking diet while 32 continued with their regular eating habits as a control group. The study lasted for three months.
The participants following the fasting mimicking diet restricted their calorie intake for five consecutive days each month, consuming approximately 700 to 1,100 calories per day. They were provided with plant-based meals during this period and returned to their normal diets for the remainder of the month.
Significant Symptom Improvement
By the end of the study, about two-thirds of those in the fasting mimicking group reported noticeable improvement in their symptoms.
“We were pleasantly surprised to find that the majority of patients benefited from this diet,” stated Sinha. “Even after just one cycle of the fasting mimicking diet, we observed clinical advantages.”
In contrast, less than half of the control group indicated a similar improvement in symptoms. Researchers noted that these observations might be attributed to natural variations in the disease and ongoing standard treatments, including medications.
While some individuals in the fasting mimicking group experienced fatigue and headaches, no severe side effects were reported.
Measurable Reductions in Inflammation
The researchers also examined what was happening at a biological level beyond reported symptoms.
Sinha’s interest in the fasting mimicking diet stemmed from previous studies indicating it could reduce C-reactive protein levels, an inflammation marker, in individuals with high baseline levels. “Considering that many patients with Crohn’s disease also present elevated inflammatory markers, the potential effects on inflammation made this diet a compelling choice for study,” he explained.
To investigate further, the team collected and analyzed biological samples, including blood and stool, to measure changes in inflammation.
“Our objective in gathering these biospecimens was to delve deeper into why there is such a differential response,” Sinha elaborated. “Can we uncover mechanisms that explain these findings and identify signatures that might predict diet responders among patients?”
They discovered that levels of fecal calprotectin, a protein indicating gut inflammation, decreased notably in the fasting mimicking group compared to the control group. Reductions in other inflammation-related molecules, including specific lipid mediators derived from fatty acids, were also observed. Furthermore, immune cells in these participants exhibited fewer inflammatory signals.
Researchers are now examining whether changes in the gut microbiome could further clarify these benefits.
What Comes Next for Diet and Crohn’s Research
“Much remains to be understood regarding the biological mechanisms behind how this and other diets affect patients with Crohn’s disease,” Sinha noted.
The study’s first authors are Chiraag Kulkarni, MD, an instructor in gastroenterology and hepatology at Stanford Medicine, and assistant clinical research coordinator Touran Fardeen. Contributors included researchers from the University of Southern California and the University of California, San Francisco.
It’s worth noting that author Valter Longo, PhD, has a financial interest in L-Nutra, the company from which the fasting mimicking meals were sourced, and has filed patents related to the diet.
This research received support from The Leona M. and Harry B. Helmsley Charitable Trust, the National Institutes of Health (grants UM1TR004921, 2L30 DK126220, T32DK007056, K08DK134856, and NIDDK R01DK085025), the Plant Based Diet Initiative at Stanford University, and several other foundations and programs.
