Most newly diagnosed patients ask whether dietary changes or supplements can help maintain renal function. For example, since celiac disease is very occasionally associated with kidney disease, many patients immediately start a gluten-free diet.
The bottom line is that dietary changes are usually not needed until the latter stages of kidney disease--and even then, any changes should be in response to the individual patient's lab results. Patients should work closely with their nephrologist and get a consult with a dietitian if extra help is needed. By focusing upon lab results, patients will not have to unnecessarily restrict themselves.
Conflicting Opinions
For decades, the conventional wisdom was that kidney patients should follow a low-protein diet. Since most kidney patients have high urine protein, many doctors felt that lowering dietary protein would minimize the amount of protein spilled by the kidneys. This wisdom has come under scrutiny as of late. Very few doctors advocate protein restriction for children, because the benefit of the protein outweighs any possible detriment. Moreover, since so many patients reach end-stage disease malnourished, protein restriction is considered unwise.
A 2008 meta-analysis published in the "Annals of Internal Medicine" showed that even though a subset of diabetic kidney patients had lower urine protein when on a low-protein diet, the diet was not associated with improved renal function.
Benefits
Taking the time to figure out what to eat and what not to eat yields huge rewards for patients with low renal function. Patients who are well-nourished and in good physical shape make the transition to dialysis better than patients who are malnourished. Likewise, patients who have paid attention to diet and exercise heal faster after kidney transplant. Moreover, patients who pay attention to their labs and make dietary changes as appropriate are hospitalized less often for bone fractures and cardiac issues. Working with a nephrologist to determine whether changes need to be made is critical as renal function drops. Being proactive and asking about dietary issues every 3 to 6 months is appropriate once renal function starts to slide.
Liquid Restriction/Dialysis
Diet issues get more complicated when patients are on dialysis. Since many kidney patients are unable to make urine as effectively as they used to, fluids build up in their bodies between dialysis sessions. Because they are unable to get rid of these fluids, restricting the amount of fluids consumed becomes necessary. Often patients have difficulty remembering that foods such as gelatin and fruits such as grapes count as liquids. Patients on dialysis should learn how much liquid they can safely consume between dialysis sessions. By restricting fluid consumption and getting dialyzed regularly, fluid issues can be minimized.
Warning
Bone loss can be a very real problem for patients with low renal function. This bone loss is insidious as it occurs slowly, silently and irreversibly. Bone loss occurs when serum phosphorus levels get too high or serum calcium levels get too low. Unfortunately, high phosphorus levels are relatively common in patients with advanced disease because the kidneys can no longer keep phosphorus levels within a safe range. When phosphorus levels get too high, calcium is leached out of the bones. This can be controlled by monitoring phosphorus levels, taking phosphorus binders and restricting dietary phosphorus if necessary. Patients should talk with their nephrologists regarding phosphorus and seek the advice of dietitian. If controlling dietary phosphorus is necessary, using a nutrient counter such as the online one provided by the U.S. Department of Agriculture can be very helpful.
Prevention
Healthy kidneys get rid of excess potassium and keep potassium levels in between 3.5 and 5.5 milliequivalents/liter. Keeping potassium within this narrow range is critical because potassium is intimately related with nervous conduction and cardiac output. When renal function drops, kidneys are no longer able to regulate potassium levels. The only way to prevent potassium levels from becomingly dangerously high is by controlling dietary intake. DaVita urges patients to talk to their nephrologists and learn whether their potassium levels are appropriate. The online nutrient counter provided by the U.S. Department of Agriculture can be very helpful.
Patients can avoid serious cardiac issues by controlling dietary potassium.
