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.