Oxalate Formation From Ascorbic Acid

Kidney stones are an extremely painful condition, and calcium oxalate stones are by far the most common type. Oxalate is a natural compound found in many foods, and some people's bodies may also convert vitamin C (ascorbic acid) into oxalate — but exactly how much this contributes to stone formation is not well understood. This study aims to carefully measure how much oxalate the body produces after consuming ascorbic acid, and whether this differs between people who have had kidney stones and those who have not. Participants will follow a controlled diet prepared at a clinical research unit and take ascorbic acid supplements under observation. Urine and blood samples will be collected at regular intervals to track oxalate levels. Understanding the link between vitamin C intake and oxalate production could help doctors better advise patients who are prone to kidney stones. You may be eligible if: - You are 19 or older - You have had a calcium oxalate kidney stone (more than 50% calcium oxalate, no uric acid) within the past 3 years, OR you are a healthy individual with no history of stones - You are willing to stay on a controlled research diet - Your kidney function is normal (eGFR ≥ 60 mL/min) - You can stop vitamins and supplements for 2 weeks before and during the study You may NOT be eligible if: - You have diabetes, gout, or hypertension - Your kidney function is reduced (eGFR < 60 mL/min) - You have primary hyperoxaluria, nephrotic syndrome, enteric hyperoxaluria, or renal tubular acidosis - You have liver disease or an autoimmune disorder - You have had bariatric surgery - You are pregnant or breastfeeding - You have had cancer treatment within the past 12 months Talk to your doctor to see if this trial is right for you.