Protein and early stage kidney disease
Your body needs protein to be healthy. But when you have early stage kidney disease, excessive protein intake can put strain on your kidneys, causing more damage. A carefully planned, reduced protein diet may help slow the progression of kidney disease in some people. Your doctor and renal dietitian may recommend limiting dietary protein if this change could help delay your progression of kidney failure. Your dietitian will also assess your individual needs and help you manage sodium, phosphorus and potassium if needed.
The importance of protein
The human body is made up of 75% protein. Protein allows your body to counteract everyday wear and tear, heal from injury, stop bleeding and fight infections. Protein is made from chains of amino acids that are often called the “building blocks of life.” There are 20 amino acids that keep your body healthy. Eleven of these amino acids are produced by your liver while the other 9 “essential” amino acids come from food.
When a food has all nine essential amino acids, it is considered a “complete” protein food. Most animal-based proteins are complete proteins, including: cheese, eggs, fish, red meat, milk and poultry. Soy beans and many products made from soy are also considered complete proteins.
Plant proteins such as grains, legumes, nuts and seeds are considered incomplete proteins, because they have low amounts or are missing one or more essential amino acids. If you follow a vegetarian diet and have kidney disease, you can work with a dietitian to create well-balanced, complete protein meals on the kidney diet.
Eating enough protein is important because the body breaks down long chains of amino acids from protein-containing foods into single amino acids. The body’s cells use these amino acids to manufacture new proteins. These proteins are used to:
- Repair and heal tissues
- Make hormones
- Produce antibodies and enzymes
- Help balance acid-base, fluid and electrolytes
- Provide some of the body’s energy
The right amount of protein
Healthy adults need 0.8 grams of protein per kilogram of body weight. For a 150 pound person, this is about 55 grams of protein a day. If you are eating a balanced diet, 10 to 15% of your calorie intake should come from protein. Many people eat much more protein than is required. The recommendation for people in early stages of chronic kidney disease (stages 1, 2 and 3) is 0.75 grams of protein per kilogram of body weight. Studies show that reducing protein intake may slow the progression of chronic kidney disease. As kidney disease progresses to later stages, a further decrease in protein can help control the amount of waste build-up in the blood, but, at this point, it does not stop the decline of your kidneys.
If protein intake is too low, you are at risk for malnutrition and this can worsen your health. It’s important to work with a dietitian to find out how much protein you need to eat and which foods are the best sources to be sure you get enough of the essential amino acids. Your doctor and dietitian will monitor the effect of your diet on your health to help you avoid protein malnutrition and muscle wasting.
Kidneys and protein
Kidneys continually maintain your body’s chemistry. Your kidneys’ primary job is to filter out waste from your blood stream. Each kidney contains approximately one million tiny clusters of blood vessels called glomeruli that act as filters.
When protein is eaten and used by your body, protein waste products are made. The millions of glomeruli filter this waste, which is removed from the body through urination. A person with early stage kidney disease still has the ability to remove protein waste because they still have enough working glomeruli. As kidney function worsens, more protein waste accumulates in the body.
Eating the correct amount of protein can be tricky for people with kidney disease. If you are in stages 1, 2, or 3 of chronic kidney disease, your protein consumption may be reduced. Your dietitian will assess your nutrition and to determine if a lower protein diet is right for you. Some blood tests may also help determine what your protein intake should be.
Blood tests that measure protein waste include blood urea nitrogen (BUN) and creatinine. Urea is a waste product created as the liver metabolizes protein. Urea is removed from the blood by the kidneys and excreted from the body in the form of urine.
Creatinine is a waste product produced from creatine, a molecule that provides energy to your muscles. Blood levels of creatinine remain constant within a small range. When you have kidney disease blood creatinine level rises because the kidneys can no longer remove it from the blood. Healthy kidneys filter out the excess waste of urea and creatinine through the urine. These tests help your doctor determine how well your kidneys are working.
Diabetes, chronic kidney disease and protein
If you have early stage kidney disease as a result of diabetes, your dietitian and doctor will help teach and encourage you to manage your diabetes through lifestyle changes. Glucose and blood pressure control can help slow down the progression of kidney disease. Your dietitian will determine the level of protein you need and develop an eating plan that will help control your diabetes and kidney disease.
Although you may need to limit protein intake, you can still eat a variety of foods on the kidney diet. Your dietitian will help you navigate in the right direction by coaching you about a lower protein, kidney-friendly diet. Lifestyle changes and working with your health care team can help you feel better and may slow the progression of kidney disease.
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