Q: I am a 28 years old married women. My left kidney, operated for stag horn, is presently functioning only 2 % but the right kidney is normal. How much water is appropriate to drink? I am drinking 4 ½ liters a day. Some people say this will put a load on the right kidney - is this true? What are the foods/drinks I need to have and which do I need to avoid? Any particular dos and don'ts to avoid infection or stone? Does the herb red mushroom revive the kidney function? I am planning to conceive too; is it safe for me to take folic acid?

A:Perhaps the most important step you can take towards preventing kidney stones is drinking 12 full glasses of water a day. If your remaining kidney is healthy and your kidney tests are reported normal there is no need to exercise water restriction. Drinking lots of water helps to flush away the substances that form stones in the kidneys. You can also drink ginger ale, lemon-lime sodas, and fruit juices. But water is best. Having enough water in your body will help to reduce the concentration of calcium in the fluid that your kidney filters. High concentrations of calcium and oxalate, phosphate or other minerals are needed to form stones. Another approach to preventing kidney stones in adults is to eat calcium rich foods and avoid oxalates. This works in two ways 1) reducing the amount of oxalate available, and 2) if calcium is present in the diet with oxalate, then calcium and oxalate bind in the intestine. This way, less calcium and oxalate enter the blood so that oxalates are not available to bind with calcium in the kidney. You should not use calcium supplements unless you talk to your doctor. Very high intakes of sodium and protein may cause kidney stones. You should use little salt in cooking or at the table and avoid many high sodium processed foods. See the low-sodium diet section for more details. Most people should have 2 portions of protein foods per day. The portions should be about the size of a deck of cards or a quarter-pound hamburger after it is cooked. High Oxalate Foods to Avoid If you avoid the foods listed below you can reduce your oxalate intake. If you eat a large amount of foods on this list, eating less may be helpful.