When you are a renal patient, your kidneys have a reduced capacity to filter toxins from your blood. For this reason, the typical renal diet is designed to limit the harmful buildup of substances in your blood between dialysis treatments. A key area of focus is limiting foods rich in potassium, sodium or phosphorus, with the typical renal diet revolving around foods low in these minerals. Depending on your unique situation, your doctor may make other considerations, so follow his dietary advice.
Foods Low in Potassium and Phosphorus
Eating foods low in potassium and phosphorus prevents these minerals from building up to dangerous levels in your blood. Renal diet foods in this category include breads, cheese, eggs, cottage cheese, rice, oatmeal and pasta. Certain vegetables such as cabbage, cauliflower, eggplant, turnips and snow peas are included as well. Fruits such as apples, blueberries, apricots, peaches, blackberries, peaches, plums and cranberries get the green light also. Most meat and seafood are high in phosphorus. However, beef, chicken, lobster, oysters and tuna contain a moderate amount of phosphorus and may be allowed with restricted portion size.
Limiting Sodium Intake
It's important to pay special attention to your sodium intake on a renal diet. Because your kidneys aren't working well, eating a diet rich in sodium can cause you to retain too much fluid. Check the labels of the foods you eat so that you know the sodium content. Foods low in sodium contain less than 100 milligrams per serving. Fresh fruits and vegetables are naturally low in sodium and good to eat given they're on the low potassium and phosphorus list also. Avoid adding salt to your food and instead use herbs and salt-free seasonings to flavor your meals. High-sodium foods contain more than 300 milligrams per serving.
With some practice, you'll become familiar with portion sizes. Foods on the low phosphorus list contain less than 100 milligrams per serving, and foods on the low potassium list contain less than 150 milligrams per serving. The serving size for many low potassium foods is about 1/2 cup and a serving size for meat and fish is 3 ounces -- about the size of a deck of playing cards. Your doctor or a registered dietitian can help you become familiar with portion sizes.
Other Renal Diet Restrictions
If you're at risk for kidney stones, your doctor may instruct you to limit your intake of purines and oxalates, substances in food that your body converts to uric acid. Elevated uric acid levels increase the risk of kidney stones. Most foods low in potassium and phosphorus are fine for you to eat because they're low to moderate in purines and oxalates. However, additional restrictions apply if your doctor recommends restricting these compounds. Of the low potassium and phosphorus foods, asparagus, cauliflower, green peas, mushrooms, spinach, lima beans, oatmeal, tuna, lobster and oysters are high in purines. Of the low potassium vegetables, green beans, wax beans, eggplant and parsnips are high in oxalates.