Can I prolong my kidney function through diet?

Q: As a newly diagnosed chronic kidney disease (CKD) patient, can I prolong my kidney function through diet? And if so, how?

A. There has been, and continues to be, much research about whether lowering the protein in the diet can slow the decrease of kidney function. The results of these studies continue to be inconclusive. There are benefits, however, to changing the diet once a diagnosis of kidney disease is made. Some of these changes may influence kidney function indirectly.

Protein restriction may or may not help with delaying progression of kidney function. Recommended amounts of protein range from 0.6-0.8 grams of protein per kilogram of desired body weight. Lowering dietary protein decreases the waste product of protein from accumulating and may help prevent loss of appetite, nausea and vomiting in some cases. It is essential adequate calories are used with these diets, so it is very important a knowledgeable dietitian design and follow up with the diet plan.

Good blood pressure control has been shown to be essential in protecting kidney function. Doctors often overlook the use of sodium restriction in blood pressure control because there are so many medications available. Sodium restriction can lower blood pressure and also prevent edema (or swelling
in the body’s tissues), such as in the lower legs and feet. Most people are not aware that about 75 percent of the sodium in the U.S. diet comes from salt or sodium added to foods before it is purchased, not from salt that is added in cooking or at the table!

Selected High Sodium Foods:
• Canned soup
• Processed meats such as bacon, sausage, ham and luncheon meats
• Cheese
• Chicken purchased as ready-to-eat
• Most turkey, unless fresh when purchased
• Seasoned salt, garlic salt, onion salt, etc.
• Canned vegetables
• Snacks such as popcorn, chips, crackers
• Pickles and olives
• Bouillon cubes or granules
• Canned, boxed or frozen foods

Some types of blood pressure lowering drugs are selected because they add even more protection to the kidneys than just good blood pressure control. These are commonly referred to as angiotensinconverting enzymes (ACEs) or angiotensin II receptor blockers (ARBs). Sometimes these drugs cause potassium to be held in the body, making the blood level of potassium high. Because high potassium is dangerous to the heart, the doctor sometimes stops the drugs. Well-designed low potassium diets will generally prevent discontinuation of these drugs.

In diabetics, it is essential blood sugar remain in the normal level in order to prevent a faster drop in kidney function. Diet control is one of the standard ways to control blood sugar along with medication. The diabetic diet can be combined with other diet changes needed for a person with kidney disease.

There is some evidence from research that shows reducing the phosphorus coming into the body also helps protect kidney function. Whether this is true or how this may be possible is unclear. It is known, however, that as kidney function lowers, dietary phosphorus becomes more than the kidneys can eliminate in the normal way.

Phosphorus comes into the body through foods, as almost everything that is eaten has some phosphorus. The best way to find out if the kidneys are not handling phosphorus normally is to check a parathyroid hormone (PTH) level. If the PTH is above established target levels, the phosphorus should be controlled with a low phosphorus diet and/ or phosphorus lowering medications called binders. Without phosphorus control, bone disease can result.

Before making any changes in your diet, it is best to discuss this with your doctor who can then refer you to a renal dietitian who can prepare a diet and educate you on the best diet for you. Continued follow up with the dietitian is also important in order to be sure no other changes are needed and to be sure the diet is as successful for you as possible.

Kathy Norwood, MS, RD, LD, has 30 years of experience in renal nutrition including education and counseling for chronic kidney disease (CKD), hemodialysis, peritoneal and transplant patients. She manages renal bone disease in her patients and has published several peer-reviewed journals on the issue. Ms. Norwood is currently the renal dietitian for the Chromalloy American Kidney Center at the Washington University School of Medicine in St. Louis, MO.

This article originally appeared in the March 2008 issue of aakpDelicious!

http://www.aakp.org/aakp-library/prolong--kidney-function-through-diet/