- With Mayo Clinic nutritionist
Katherine Zeratsky, R.D., L.D.
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Katherine Zeratsky, R.D., L.D.
Katherine Zeratsky, R.D., L.D.
As a specialty editor for the Food & Nutrition Center, Katherine Zeratsky helps you sort through the facts and figures, the fads and the hype to learn more about nutrition and diet.
A Marinette, Wis., native, she is certified in dietetics by the state of Minnesota and the American Dietetic Association. She has been with Mayo Clinic since 1999.
She is active in nutrition-related curriculum and course development in pediatrics at Mayo Clinic Rochester and nutrition education related to the physiology and recommended intakes for premature infants.
Other areas of interest include breast milk and formula safety, neonatal feeding, and nutrition for breast-feeding mothers.
She graduated from the University of Wisconsin-Madison, served a dietetic internship at the University of Iowa Hospitals and Clinics, and worked as a registered dietitian and health risk counselor at ThedaCare of Appleton, Wis., before joining the Mayo Clinic staff.
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Healthy diets (8)
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Healthy menus and shopping strategies (6)
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Nutritional supplements (15)
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Question
High-protein diets: Are they safe?
Are high-protein diets generally considered safe? What do the kidneys do with excess protein?
Answer
from Katherine Zeratsky, R.D., L.D.
High-protein diets are generally well tolerated by healthy adults. But a dramatic increase in protein-rich foods may be dangerous for people with liver or kidney disease because they lack the ability to get rid of the waste products of protein metabolism.
Some protein is essential to human life. Protein is found in your bones, muscles, skin, organs, blood, hormones and enzymes.
Your body can't store excess protein. During digestion and metabolism, protein is broken down into amino acids — the building blocks of protein. Your body uses these amino acids to make enzymes and other proteins. But any "extra" amino acids are stripped of nitrogen. The non-nitrogen parts of amino acids are used for energy or converted into fat, and the remaining nitrogen is eventually excreted by your kidneys and liver. These waste products have been shown to cause kidney injury, and in the presence of liver disease, excess nitrogen can cause further problems. High-protein diets may also increase the risk of kidney stones and osteoporosis. If you have kidney or liver disease or any chronic health condition, talk to your doctor before starting a new diet.
For most healthy people, a short-term high-protein diet generally isn't harmful. However, if followed long term, high-protein diets may limit other healthy foods, such as whole grains, fruits and vegetables. In addition, many high-protein foods — such as meat, milk, cheese and eggs — are also high in fat and cholesterol, which can increase your risk of heart disease, stroke and other health problems. So choose your protein sources wisely. Good choices include fish, beans, lentils and low-fat dairy products.
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