If you're eating a high-protein diet to lose weight or increase muscle mass, your body may be producing high amounts of urea, a byproduct of protein metabolism. Urea builds up in your blood, and the excess is excreted by the kidneys through your urine. Consuming too much protein may strain your kidneys, and if your kidneys aren't working well, it may cause further damage. Consult your doctor before starting a high-protein diet.
Protein is found in every cell, tissue and organ in your body, and these proteins need constant replacement. That makes the protein in foods you eat essential for good health. Protein is found in a number of different types of foods, including meats, poultry, fish, beans, soy foods, dairy, nuts, seeds, grains and vegetables. When you eat protein, your body breaks it down into amino acids, which are used to replace the protein in your body. Your body cannot store excess protein, and the extra amino acids are catabolized into energy and ammonia. The ammonia is then turned into urea and eliminated from your body.
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Testing Urea Levels
Two tests measure urea levels in your body: the urea nitrogen urine test and the blood urea nitrogen, or BUN, test. Normally, you excrete 12 to 20 grams of urea nitrogen a day in your urine. If you're excreting more than normal levels in your urine, it may indicate that you are consuming too much protein. The BUN is a blood test, and like the urine test, an elevated BUN may indicate that you're consuming more protein than your body needs. However, an elevated BUN may also be due to kidney disease, congestive heart failure, a recent heart attack or dehydration and may require further testing.
Concerns of Too Much Protein
While high intake of protein causes your kidneys to work harder, a 2005 review article published in Nutrition and Metabolism found that consuming more protein than your body needs does not lead to kidney disease in healthy adults. The authors noted that more research is necessary, however. If you have chronic kidney disease, a high-protein diet may further tax your kidneys and accelerate the progression of your disease.
How Much Protein
Most Americans have no problem getting enough protein in their diet, according to the Centers for Disease Control and Prevention. The recommended dietary allowances for protein are 46 grams for women and 56 grams for men. You can meet your needs by eating a varied diet. For example, 1 cup of milk contains 8 grams of protein, 3 ounces of chicken has 21 grams and 1 cup of beans provides 16 grams.
- MedlinePlus: Urea Nitrogen Urine Test
- Lab Tests Online: BUN
- Nutrition and Metabolism: Dietary Protein Intake and Renal Function
- Centers of Disease Control and Prevention: Protein
- Elmhurst College: Protein Metabolism
- The Nephron Information Center: Dietary Protein for the Person With Chronic Kidney Disease