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By Sara Colman, RDN, CDE, Balanced Habits RD

Since what you eat can have an impact on your kidneys I would like to focus on diet and kidney function.

Functions of the kidneys include…

  • clean waste from the blood 
  • manage fluid in the body
  • control blood pressure
  • make red blood cells
  • balance blood acidity and mineral composition

Unfortunately, like high blood pressure, loss of kidney function is silent. Many people do not know they have kidney failure. The National Kidney Foundation has developed a staging system to help people easily know about their kidney health. It requires the most recent blood test result to creatinine and a glomerular filtration rate (GFR) calculator. By entering your creatinine, race and age the calculator provides a number that corresponds with your level of kidney function. For example, a GFR value of 50 means you have 50% kidney function. Kidney function stages range from stages 1-2 (mild decline in kidney function) to stage 5 (kidney failure requiring dialysis or transplant).

So how does diet play a role in kidney function? The two major causes of chronic kidney disease (CKD) are diabetes and high blood pressure. To prevent loss of kidney function it is important to keep blood glucose levels in the normal range and to manage blood pressure with a low sodium diet and medications if prescribed.

One of the treatments for CKD is a lower protein diet to reduce the workload and waste buildup that occurs with kidney disease. If you are at risk for kidney disease, eating a very high protein diet can increase risk of kidney disease progression. The average American diet protein intake is 1.2 to 1.5 g/kg/day for meat eaters and1.0 g/kg/day for vegetarians. For a 150 pound person this equals 85 to 105 grams of protein per day. For people with mild CKD recommended protein intake is 0.8 to 1.0 g/kg/day, and for those with advanced kidney disease 0.6 to 0.8 g/kg/day is recommended.

High-protein diets may lead to changes in the kidney like high levels of filtration, increased protein in the urine, and faster progression of CKD for those at risk. Some kidney doctors recommend against high-protein diets in people at risk for or who have CKD.

So what does this mean for you? First, take a kidney disease risk quiz, then use a GFR calculator to determine your current level of kidney function. If you are not at risk and levels are normal there is no reason to restrict protein intake. If you are at risk, or have early stage CKD (GFR greater than 60 mL/min/1.73m), consider following a lower sodium diet and reducing protein intake. If your GFR level is less than 60 mL/min/1.73m make an appointment with your doctor to discuss kidney disease monitoring and treatment and recommended dietary goals.


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