Answer. Protein is an extremely important nutrient for all people. Mainly found in muscles, protein is essential for life and is a major part of the body. We need protein for the growth and repair of tissues. During digestion, proteins are broken down into smaller units called amino acids. There are about 20 different amino acids in protein. However, the body cannot make nine of them, called essential amino acids. The others are called non-essential amino acids. Only animal sources contain all the essential amino acids, but by combining different plant proteins, you can also make complete protein foods. The table below, provided by the Energy Zone (click here (click here), lists the protein content of some common foods.

Usually a person should eat 0.8-1.0 gram of protein each day for every kilogram they weigh. A 70 kg person should eat 60-70 grams of protein a day. Depending on your kidney function, the amount will vary. People with chronic kidney disease (CKD) have to closely monitor protein intake. To determine how much protein you should eat each day, you need to check with your doctor and/or dietitian. In many instances, the doctor will work with the dietitian to prepare a plan for you. The dietitian will meet with you to review the types of food you like to eat and figure how you can best achieve that plan.

The Dangers of Eating Too Much Protein

Several studies have shown eating too much protein can be dangerous to your kidneys if you already have kidney disease. After the protein is eaten, it is absorbed into the body, which metabolizes the proteins. Proteins in the blood (albumin) and protein waste products (blood urea nitrogen or BUN) are eventually filtered by the kidney. If there are high levels of protein filtered by the kidney, this can cause damage to the small filtering cells in the kidney. Over time, this can lead to decreased kidney function. In addition, if your kidneys are not working well, they cannot filter protein waste products. This will show up as a high BUN level on your blood test, which will make you feel bad. It is for these reasons your doctor or dietitian will work with you to make sure your protein intake is not too high.

At the same time, it is important to make sure your protein intake is not too low. Too little protein intake can lead to poor nutrition that can lead to muscle loss and increase the chance of infections. It can also increase the risk of hospitalization and even dying. Because of these factors, it is a fine balance to find just the right amount of protein. It is also important to find the right types of proteins.

Some proteins have more essential amino acids needed by the body. These essential amino acids can only come from specific proteins. In some instances, the dietitian may prescribe special protein supplements to make sure you get the right amount and types of proteins. The dietitian may suggest a protein supplement called keto acids, which are a chemically different form of amino acids. They are created in the laboratory. The body turns them into the essential amino acids it needs. Both keto acid supplements and amino acid supplements provide essential amino acids the body needs, but in a pure form. This way it does not overload the diseased kidneys with too much phosphorus or BUN that would come from foods. These supplements can also be expensive. The dietitian can review your diet and medical condition with you and your doctor to decide what is best for you.

Another reason monitoring protein intake is important is because protein is a source of phosphate. For many CKD patients, it is also important to closely monitor phosphate intake. Eating high amounts of protein can lead to higher phosphate levels, which can be dangerous. This is important for people with advanced kidney disease who are not yet on dialysis. Once a patient is on dialysis, the risk of protein further damaging kidney function is not as important. Dialysis helps remove BUN. Although dialysis does a relatively good job of removing BUN, it does not remove phosphorus well. The risk of high phosphate levels is a big problem for a kidney patient, even if they are on dialysis. Much of the phosphate may come from protein. Balancing how much protein and what type of protein is very important. That is why the dietitian is so crucial for patients with kidney disease. The dietitian helps to make sure each patient’s nutritional status is as good as possible without running into problems of high levels of BUN or phosphate in the blood. Remember to check with your dietitian. They can usually make a plan for you using foods you like to eat. This way you will be both healthy and happy.

Portion of food                                           Protein (g)     

150g (5 oz) lean meat or poultry                      40       

150g (5 oz) fish                                                 33       

150g (5 oz) soy beans                                      21       

150g (5 oz) tofu, lentils, kidney beans              12       

135g (4.5 oz) baked beans                               10       

240 ml (8 oz) milk                                              9         

30g (1 oz) cheddar cheese                                8         

1 egg                                                                 7         

2 slices of bread                                                6         

Answer provided by Keith Norris, MD. Dr. Norris is a faculty member in the Department of Internal Medicine and the Associate Dean for Research at Charles R. Drew University in Los Angeles. Dr. Norris is also a member of the AAKP Medical Advisory Board.

The American Association of Kidney Patients presents Ask the Doctor, an opportunity for readers to submit kidney related health questions to healthcare professionals who specialize in an area of concern. The answers are not to be construed as a diagnosis and therefore, alterations in current healthcare should not occur until the patient’s physician is consulted.

This article originally appeared in the March/April 2005 issue of Kidney Beginnings: The Magazine, Vol. 4, No. 1.

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