A new study led by Stanford Medicine has found that a short-term, calorie-restrictive diet can significantly improve symptoms of mild-to-moderate Crohn’s disease. The research, which will be published in Nature Medicine on January 13, is among the few large-scale clinical trials to examine dietary interventions for inflammatory bowel diseases.
The randomized controlled trial involved 97 participants across the United States who were diagnosed with mild-to-moderate Crohn's disease. Of these, 65 patients followed a fasting mimicking diet while 32 continued their regular eating habits over three months. The fasting mimicking group restricted their caloric intake to between 700 and 1,100 calories per day for five consecutive days each month using plant-based meals provided during this period; the rest of the month they resumed their normal diets.
At the end of the study, researchers observed that about two-thirds of those following the calorie-restricted regimen experienced improvement in symptoms such as diarrhea, cramping, abdominal pain and weight loss. "We were very pleasantly surprised that the majority of patients seemed to benefit from this diet," said Sinha, one of the study investigators. "We noticed that even after just one FMD cycle, there were clinical benefits."
In comparison, fewer than half of those in the control group reported symptom improvement—a result likely influenced by natural fluctuations in Crohn’s disease symptoms and ongoing standard treatments.
No serious side effects occurred among participants who followed the calorie-restrictive diet. Some did report fatigue and headache during restriction periods.
Researchers also tracked biological indicators associated with inflammation. According to Sinha: "Our goal in collecting these and other biospecimens was to dig deeper into why there's this differential response," adding that they hope to identify mechanisms behind patient responses and potential predictors for who may benefit from such diets.
Findings showed significant declines in fecal calprotectin—a protein indicating gut inflammation—in those on the fasting mimicking diet compared to controls. Other markers tied to inflammation also decreased among these participants' stool and blood samples. Ongoing research is examining whether changes in gut microbiome might further explain some observed benefits.
"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," Sinha noted.
Stanford Medicine’s Chiraag Kulkarni, MD (instructor in gastroenterology and hepatology), and Touran Fardeen (assistant clinical research coordinator) are first authors on this publication. Colleagues from University of Southern California and University of California San Francisco contributed as well.
One author, Valter Longo, PhD, holds equity interest in L-Nutra—the company supplying fasting mimicking meals—and has filed patents related to this dietary approach.
Funding came from multiple sources including The Leona M. and Harry B. Helmsley Charitable Trust; National Institutes of Health; Plant Based Diet Initiative at Stanford University; Kenneth Rainin Foundation; Doris Duke Foundation Physician Scientist Fellowship Award; CZ Biohub Physician Scientist Scholar Award; Colleen and Robert D. Hass fund; and Chan-Zuckerberg Biohub Investigator Program.
