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Evidence Explorer · MS-N291 · Nutrition and dietary patterns · Appraised November 10, 2026

A 44-person randomized trial reported less grade 3 vomiting and neutropenia and more favorable imaging/pathology response categories with a fasting-mimicking diet. The small sample, multiple outcomes and absence of recurrence or survival data make the result preliminary.

Evidence at a glance

  • Population: 44 newly diagnosed people with HER2-negative breast cancer, randomized 22 per group during neoadjuvant chemotherapy.
  • Intervention: a three-day fasting-mimicking diet immediately before and during chemotherapy, repeated every three weeks for eight cycles, versus the participant’s regular diet.
  • Reported findings: grade 3 vomiting and neutropenia were more frequent in control; higher Miller–Payne response categories and complete/partial imaging response were reported more often with the diet.
  • Other outcomes: selected blood counts, glucose, insulin, IGF-1 and inflammatory markers differed between groups.
  • Evidence label: preliminary randomized signal; no demonstrated recurrence or survival benefit.
  • Evidence label: Small randomized signal; uncertain cancer-control meaning.

What was studied

The trial combined toxicity, laboratory, metabolic, imaging and pathology outcomes. The paper reports statistically favorable differences for several measures, but a small study with many comparisons is vulnerable to chance findings and exaggerated effect estimates.

Pathologic regression categories can be informative during neoadjuvant therapy, yet they are not interchangeable with recurrence-free or overall survival. Imaging response, biomarkers and laboratory changes also cannot establish durable cancer control.

What this evidence cannot establish

The study was single-country and small, blinding was not feasible, the hierarchy of primary and secondary endpoints was not fully clear from the accessible report, and confidence intervals for several clinically important comparisons were not reported in the abstract. Adherence, missing data and chemotherapy-regimen generalizability need independent confirmation.

Safety and practical context

Fasting can worsen weight loss, sarcopenia, dehydration, nausea, hypoglycemia and inadequate protein intake. It should not be copied from a publication without nutritional screening and oncology-dietitian supervision. People with diabetes, eating disorders, frailty or poor intake need particular caution.

Questions for the care team

  • Was toxicity reduction a prespecified primary endpoint, and how many participants contributed to each comparison?
  • Am I at any risk of malnutrition or muscle loss before considering a restrictive regimen?
  • Would any dietary change interfere with oral medicines, steroid schedules or supportive-care intake?

Sources and identifiers

Funding and conflicts: The authors declared no commercial or financial relationships that could be construed as conflicts. Detailed grant support was not independently verified.

Source access and dates: Primary reports, registries and official guidance available through the links above were checked November 10, 2026. Last literature search November 10, 2026. Fields unavailable from accessible full text are labeled not reported or not verified rather than assumed absent.

Educational evidence summary, not individualized medical advice. Restrictive diets or supplements should not replace established cancer treatment or adequate nutrition. Symptom, weight, biomarker, laboratory, imaging, pathology or animal findings do not by themselves establish tumor control, recurrence prevention or longer survival.