Gut Kidney Axis in Enteric Hyperoxaluria

Diets will contain 16% protein, 30% fat, and 54% carbohydrate, and are controlled in the amounts of calcium (400mg), oxalate (250mg), ascorbic acid (50mg), fiber (30 grams) and, other nutrients. Each controlled diet will be consumed for four days. On days of controlled diets, subjects will be provided with 2 liters of bottled water per day to ensure adequate hydration. After the controlled diet period, there will be a three-day washout period, where participants will consume Ad-lib diets supplemented with a daily intake of oxalate in the form of cooked spinach to be taken with breakfast daily for a total of 2 weeks.