A Stanford Medicine-led randomized trial in the United States found that a five-day-per-month fasting-mimicking diet was linked to improved patient-reported symptoms and lower biological markers of inflammation in adults with mild-to-moderate Crohn’s disease. The results were published in Nature Medicine.
Researchers from Stanford Medicine and collaborating institutions reported results from a national randomized controlled trial testing a “fasting-mimicking diet” (FMD) in adults with mild-to-moderate Crohn’s disease.
Trial design
The study followed 97 patients across the United States for three months. Sixty-five participants were assigned to the fasting-mimicking diet, while 32 continued their usual eating habits as a control group.
Participants in the FMD group reduced calories for five consecutive days each month, consuming roughly 700 to 1,100 calories per day from plant-based meals, and then returned to their normal diet for the remainder of each month.
Reported symptoms and side effects
By the end of the study, about two-thirds of participants in the fasting-mimicking group reported improvement in their symptoms, compared with fewer than half of participants in the control group. Researchers attributed improvements in the control group to factors such as natural fluctuations in disease activity and ongoing standard treatments, including medications.
No serious side effects were observed. Some participants in the fasting-mimicking group reported fatigue and headaches.
Sidhartha R. Sinha, MD, an assistant professor of gastroenterology and hepatology at Stanford and the study’s senior author, said clinicians have lacked strong evidence to guide patients who ask what they should eat. “We have been very limited in what kind of dietary information we can provide patients,” Sinha said.
Biological markers of inflammation
Beyond patient-reported symptoms, the researchers analyzed blood and stool samples. They reported that fecal calprotectin—a protein used as a marker of inflammation in the gut—dropped significantly in the fasting-mimicking group compared with the control group. The team also reported reductions in certain inflammation-related molecules, including lipid mediators derived from fatty acids, and found that immune cells produced fewer inflammatory signals.
Sinha said the team was surprised by how many participants appeared to benefit. “We were very pleasantly surprised that the majority of patients seemed to benefit from this diet,” he said.
Researchers said they are continuing to investigate potential mechanisms, including whether shifts in the gut microbiome help explain the observed effects and whether biological signatures can predict which patients respond.
Context and disclosures
Crohn’s disease is a long-term condition that affects roughly one million Americans and can cause symptoms including diarrhea, cramping, abdominal pain and weight loss. The Stanford Medicine summary of the study noted that, for mild cases, steroids are currently the only approved treatment, but long-term use can bring serious side effects.
The study’s first authors were Chiraag Kulkarni, MD, and Touran Fardeen. Contributors included researchers from the University of Southern California and the University of California, San Francisco.
Stanford Medicine disclosed that author Valter Longo, PhD, has an equity interest in L-Nutra, the company from which the fasting-mimicking meals were purchased, and that he has filed patents related to the diet.
