Dietary Modifications: Kidney Stone Prevention
Diet Can Predispose to Kidney Stone Formation
- Increasing urine volume to at least 2 liters per day (1/2 gallon) can reduce the recurrence of stone disease by up to 40 to 50%. Fluid intake mainly should include water but any fluid is better than no fluid. One need to drink as much as twice this amount especially in the summer to make 2 liters of urine a day.
- Sufficient calcium intake, i.e. 1200 mg per day, is crucial, because it allows for binding of oxalate in the intestine thus increase in urinary oxalate can be avoided.
- Low intake of animal protein (meat, fish, poultry) i.e. 50 to 60 g/day is recommended since animal proteins increase urinary calcium, oxalate and uric acid, and lower citrate. Following a diet rich in alkali (vegetables, fruit) is associated with a lower risk of stone formation.
- Dietary oxalate restriction (<100 mg/day) is also useful in lowering urinary oxalate excretion. Avoiding foods rich in oxalate: fruits such as raspberries, figs, and plums; vegetables such as spinach, rhubarb, cucumber, green peppers, sweet potato and beets; most nuts, tea, wheat bran, chocolate, soya bean, popcorn, and high amounts of vitamin C.
- Increasing urinary citrate (lemons and oranges) reduces the stone recurrence
- Low intake of dietary sodium, refined sugars; and soft drinks and colas.
A “common sense diet” containing sufficient amounts of fluids, 1200 mg of calcium per day and reduced amounts of flesh protein as well as salt is able to reduce the 5 year stone recurrence rate in calcium stone formers by 50%.
Once lifestyle changes are undertaken, repeat 24 hour urine measurements are obtained to guide therapy.