Why should I be careful not to eat too much protein if I'm a teen?

Eating too much protein, as we do in the United States, can do us harm. The body uses protein to make deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and muscle, the basic building blocks of all body functions. Any protein the body doesn't use for these processes is flushed out as waste. During this process, protein is broken down in the liver to ammonia, a highly toxic chemical. Your liver then turns the ammonia into urea, a precursor to urine, which has to be excreted by the kidneys. When more than 15 percent of your daily calories come from protein, the strain on your liver and kidneys can become too much to bear. Under this strain, your liver and kidneys enlarge and the kidneys change their physiology. This may cause, among other ailments, significant calcium loss, pulled from your bones into your urine.