A fasting mimicking diet is not a fast. It is five consecutive days of a low calorie plant based menu designed to produce the metabolic signature of fasting while people keep eating. The Crohn's Disease Activity Index used as the primary outcome is built largely from symptoms the patient reports, which matters when nobody was blinded. Faecal calprotectin is different. It is a protein released by white cells into the gut, measured in stool, and it does not respond to what a patient believes.
Drawn from standard clinical definitions, not from this paper.
Short cycles of a fasting mimicking diet lower systemic inflammatory markers in healthy people, and the authors note that the potential benefits had never been investigated in Crohn's disease. This is the one place in the current literature where a fasting protocol beats its control on a clinical outcome rather than on a surrogate.
Drawn from the paper's introduction.
Open label randomised controlled trial. Patients in the diet group followed the fasting mimicking diet for five consecutive days per month for three consecutive months, returning to their regular baseline diet on all other days. Control participants continued their baseline diet.
The primary outcome was clinical response, defined as a fall of at least seventy points in the Crohn's Disease Activity Index or an index of one hundred and fifty or below, measured after the third cycle.
Forty five of sixty five patients in the diet group met it, 69.2 percent, against fourteen of thirty two in the control group, 43.8 percent, at p equals 0.03.
Clinical remission, a secondary outcome: forty two patients, 64.6 percent, against twelve, 37.5 percent, at p equals 0.02.
Faecal calprotectin fell 22.0 percent from baseline in the diet group and rose 8.0 percent in the control group, p equals 0.03.
Exploratory analyses of plasma metabolites and gene expression in peripheral blood mononuclear cells showed decreases in key inflammatory lipid mediators and immune effector transcripts after the diet, which the authors describe as concordant with the reduction in disease activity.
| Clinical response, primary outcome | 45 of 65, 69.2 percent, against 14 of 32, 43.8 percent, p equals 0.03 |
| Clinical remission, secondary outcome | 42 of 65, 64.6 percent, against 12 of 32, 37.5 percent, p equals 0.02 |
| Faecal calprotectin change from baseline | minus 22.0 percent against plus 8.0 percent, p equals 0.03 |
| Protocol | five consecutive days per month for three consecutive months |
| Control arm | continued their baseline diet, with no diet intervention |
Proposed by the authors This is the explanation the authors offer in their discussion. This study did not test it.
The authors point at inflammation resolution rather than at anything gut specific. Plasma metabolite profiling showed decreases in key inflammatory lipid mediators after the diet cycles, and gene expression in peripheral blood mononuclear cells showed reduced immune effector transcripts, both of which they describe as concordant with reduced disease activity. They present this as a reason to investigate the approach in chronic inflammatory disease generally, not as a demonstrated pathway.
Drawn from the paper's exploratory analyses.
Three monthly cycles of a five day diet produced clinical response in about seven in ten patients against about four in ten continuing as normal, and an objective stool marker moved in the same direction.
Adults with mild to moderate Crohn's disease, over three months, alongside their existing treatment.
A blinded trial with a sham diet arm and an endoscopic endpoint, which the calprotectin result is strong enough to justify.
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