Isocaloric Navy-Bean Substitution in Adults With MASLD

This study is a 24-week randomized crossover feasibility trial evaluating an isocaloric navy-bean dietary substitution in 40 adults with metabolic dysfunction-associated steatotic liver disease (MASLD) and intermediate-stage (F2-F3) fibrosis. Participants are randomized to one of two sequences-habitual diet followed by a navy-bean-rich diet, or a navy-bean-rich diet followed by habitual diet-with each 12-week phase guided by registered dietitians so that navy beans replace an equivalent caloric load without changing total energy intake. The primary aim is to establish feasibility and acceptability, measured by recruitment and retention, adherence with biomarker (plasma pipecolic-acid) concordance, and patient acceptability.

Inclusion Criteria: * Adults 18-75 years of age with capacity to provide informed consent * Clinical diagnosis of MASLD, confirmed by imaging (MRI-PDFF or VCTE) or prior liver biopsy. * Intermediate-stage fibrosis (F2-F3) confirmed by one of the following (most recent qualifying result): VCTE (FibroScan) 8.0-14 kPa, MRE 3.0-4.6 kPa (2D EPI @ 60 Hz), or liver biopsy read as F2-F3 * Body mass index 25-45 kg/m² * Stable medications for ≥12 weeks for diabetes, hypertension, dyslipidemia, or weight management * Alcohol intake below MASLD thresholds (≤15 drinks/week for men, ≤10 drinks/week for women) * Willing and able to consume study navy beans and complete dietary recalls (ASA-24/DSQ) * Able to undergo MRI and MRE (no contraindications) and attend study visits * Agrees to biospecimen collection (blood, stool, saliva) and patient-reported outcomes Exclusion Criteria: * Other chronic liver disease (hepatitis B, hepatitis C, autoimmune hepatitis, hemochromatosis, Wilson's disease, alpha-1 antitrypsin deficiency, primary biliary cholangitis, primary sclerosing cholangitis) * Decompensated liver disease (ascites, variceal bleeding, encephalopathy) or Child-Pugh B/C cirrhosis, or clinical portal hypertension/decompensation * Heavy alcohol use above MASLD thresholds, or alcohol use disorder within 12 months * Legume/bean allergy or intolerance * Initiation or dose change of antidiabetic, lipid-lowering, antihypertensive, or weight-loss medications within the past 12 weeks, or anticipated changes during the trial * Recent initiation of agents known to affect hepatic fat or fibrosis (e.g., GLP-1 receptor agonist, SGLT2 inhibitor, pioglitazone, resmetirom) within 12 weeks * Use of hepatotoxic drugs likely to confound liver enzymes in the prior 12 weeks (per investigator judgment) * New supplements targeting weight loss, liver health, or the microbiome within 8-12 weeks (e.g., berberine, high-dose omega-3, pre/probiotics) * Antibiotics, probiotics, or colonoscopy preparation within 8 weeks * Planned bariatric surgery or other major weight-loss intervention during the study * Recent weight change \>5% within 8-12 weeks prior to baseline * Severe gastrointestinal disease (inflammatory bowel disease, celiac disease, short bowel syndrome) that may impair tolerance * Uncontrolled diabetes (HbA1c \>10%), severe renal dysfunction (eGFR \