An estimated 26 million American adults are currently living with one of the five stages of chronic kidney disease (CKD). While there are several different ways to prevent CKD from progressing to a more severe stage, physicians agree that diet modification is among the most effectual. Due to the kidney’s physiology, restricting dietary protein is more than a suggestion for most CKD patients – it is a necessity.
The result of physical injury or a disease that damages the kidneys like diabetes or high blood pressure, chronic kidney disease describes the permanent loss of kidney function. When the kidneys are damaged, they do not remove waste and extra water from the blood as well as they should. Thankfully, the kidneys don’t typically fail all at once. For those lucky enough to detect CKD early enough, its progression can be slowed or stopped.
Determined by glomerular filtration rate – a measure of how well the kidneys are cleaning the blood – there are five stages of chronic kidney disease. According to standards set by the National Kidney Foundation, each CKD stage is described below:
- Stage 1 – Signs of mild kidney disease with a glomerular filtration rate of 90 percent or more.
- Stage 2 – Mild kidney disease with a reduced glomerular filtration rate of 60 to 89 percent.
- Stage 3 – Moderate chronic kidney disease with a glomerular filtration rate of 30 to 59 percent.
- Stage 4 – Severe chronic kidney disease with a glomerular filtration rate of 15 to 29 percent.
- Stage 5 – End stage kidney disease with a glomerular filtration rate of less than 15 percent. These individuals need dialysis or a kidney transplant to survive.
Protein and CKD
Found in almost all food, protein is needed for growth, upkeep and repair of all parts of the body. A waste byproduct of protein metabolism, the body produces urea that must be eliminated by the kidneys. If the kidneys are not functioning well, the urea will stay in the blood.
Eating more protein than your body needs may put an extra burden on the kidneys and cause kidney function to decline faster. Thus, decreasing the amount of dietary protein reduces the amount of urea that must be excreted. With less urea to get rid of, there is a lighter workload on the kidneys of someone with CKD.
Details on Protein Restriction
Doctors have long recommended that patients with CKD eat moderate or reduced amounts of protein. In the 1990s, a major clinical trial evaluated protein restriction for kidney patients. The Modification of Diet in Renal Disease (MDRD) Study assigned groups of CKD patients to diets with different levels of daily protein intake. The study found that patients who reduced their daily protein intake by 0.2 grams for each kilogram of body weight for one year, had healthier levels of urea in their blood.
According to an interview with Emily Creamer, MS, RD, LDN, a registered dietician providing nutritional counseling at a dialysis center in Chicago, having kidney disease should not automatically exclude all dietary sources of protein. Creamer cautions those with CKD against completely eliminating protein from their diet. She explains that we need protein to function, and its absence will force the body to break down its own tissues to find it – a biological compensation that can cause irreparable damage. Thus, working closely with a dietician to eat the right amount of protein is crucial for those with CKD.
In addition, Creamer says that those in stage 5 of CKD have different protein needs. This is because dialysis removes protein from the body artificially, so the body’s tissues have a greater demand for protein. Hence, individuals undergoing dialysis are often placed on a high protein diet to help replace the muscle and other tissue lost from this procedure.
Unless we are under strict doctor’s orders, most of us pay little attention to the amount of protein in our diet. However, those with chronic kidney disease must work with a dietician to consume the right quantity of protein. Our ability to break down protein relies on kidney function. Therefore, the amount of protein consumed can make the difference between preventing CKD from worsening and having it escalate to a more advanced stage of disease.