This study aims to determine the daily rate of endogenous synthesis of oxalate using fasted urine collection and a low-oxalate controlled diet in patients with Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD).

Urinary oxalate excretion is derived from both dietary sources and endogenous synthesis. This study will use a low-oxalate controlled diet, repeat fasted urine collections and 24-hr urine collections on a low-oxalate diet, to determine the daily rate of endogenous oxalate synthesis in individuals with Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD).

Inclusion Criteria:

• age >18 years
• History of MASLD, with liver fat content > 5%
• Normal kidney function
• Stable medication for at least 1 month for diabetes mellitus if any
• Willingess to ingest fixed diets and stop dietary supplements for the study and come to UAB for visits

Exclusion Criteria:

• Age < 18 years
• Inaccurate 24-hour urine collections
• Liver fat content <5%
• Liver cirrhosis
• Evidence of other chronic liver disease, viral hepatitis
• history of alcoholism within 2 years of enrollment
• Contra-indication to Magnetic Resonance Imaging
• Chronic kidney disease with estimated Glomerular Filtration rate < 60 ml/min/1.73m2
• Type 1 Diabetes Mellitus or treatment with insulin
• Uncontrolled diabetes
• Pregnancy, lactation or intention to be
• Uncontrolled hypertension
• Use of weight loss medication, SGLT2 inhibitors, GLP-1 receptor agonists, osteoporosis medication, chronic NSAID
• History of gastric or intestinal surgery or resection that could potentially alter oxalate absorption
• Chronic fat malabsorption
• Use of immunosuppressive medications
• Known immuno-compromised status
• Active malignancy or treatment for malignanacy within the last 12 months