A short-term fasting-mimicking diet helped ease symptoms and lower inflammation markers in patients with mild-to-moderate Crohn’s disease, according to results from a national randomized controlled trial.
The study offers new evidence on dietary approaches for a chronic condition that affects roughly one million Americans and has long lacked clear nutritional guidance from physicians.
Patients in the diet group reported meaningful symptom relief after following the plan for just five days each month.
Researchers from Stanford Medicine and collaborating institutions tested the fasting-mimicking diet in 97 adults with mild-to-moderate Crohn’s disease. Sixty-five participants followed the plan — consuming roughly 700 to 1,100 calories per day of plant-based meals for five consecutive days each month — while 32 continued their usual eating habits as a control group. The trial lasted three months.
By the end of the study, about two-thirds of those on the fasting-mimicking diet reported improvement in their symptoms. Fewer than half of those in the control group saw similar gains, which researchers attributed to natural disease fluctuations and standard medications. No serious side effects occurred, though some participants noted temporary fatigue and headaches.
The diet also produced measurable biological changes. Levels of fecal calprotectin — a key marker of gut inflammation — dropped significantly in the diet group compared with the control group. Other inflammation-related molecules and immune-cell signals decreased as well.
“We have been very limited in what kind of dietary information we can provide patients,” said Sidhartha R. Sinha, MD, assistant professor of gastroenterology and hepatology at Stanford Medicine and senior author of the paper. “This study will give physicians evidence to support recommendations in an area that patients are very curious about.”
Sinha added that researchers were “very pleasantly surprised that the majority of patients seemed to benefit from this diet” and noted clinical benefits appeared after even one cycle.
The results were originally published in Nature Medicine. First authors were Stanford’s Chiraag Kulkarni, MD, and Touran Fardeen. The study also involved researchers from the University of Southern California and the University of California, San Francisco.
Crohn’s disease causes inflammation in the digestive tract, leading to diarrhea, cramping, abdominal pain, and weight loss. For mild cases, steroids remain the only approved treatment, but they carry long-term side effects.
Researchers said more work is needed to understand the diet’s biological mechanisms, including possible effects on the gut microbiome. They plan further studies to identify which patients respond best.
