There are many causes of kidney damage. You must pay attention to those you can control. Fats and cholesterol in the diet promote atherosclerosis in the kidney arteries, which is one of the leading causes for failing kidneys. Add to this diabetes or high blood pressure and you invite almost certain kidney trouble by eating too well, but not at all wisely.
Among the most subtle and important of the many toxic threats to the kidneys are the excess amounts of proteins that are consumed by the average person who eats our rich American foods. The daily intake of more proteins than the body really needs means that the excess must be eliminated through the kidneys. We’re equipped with no storage depots for proteins, as we are for fats.
The proteins not used for body repair and growth float around in the blood stream until they are metabolized by the liver and their remnants are removed by the kidneys. The filtering units in the kidneys are called nephrons. Destruction of these nephrons occurs directly from exposure to those proteins or to the products of their degradation. The damage from excessive intake of proteins is so common that, in an otherwise healthy person, 25-50% of the functional capacity of the kidneys will be destroyed after eight decades of high living American-style. Even so, we’re lucky to have much reserve tissue to rely on: with only 25% of kidney function remaining, plenty of tissue cells still survive to handle the waste products of body metabolism, and the damaged and failing kidneys go unnoticed. Our bodies are very forgiving!
But not forever. This damaging effect from a high protein diet becomes a life and death matter with someone who has already lost kidney tissue from one or more other causes. For example, a person with diabetes, high blood pressure, atherosclerosis, physical injury, or surgical loss will be under a great disadvantage. Unfortunately, serious instruction about the value of a low protein diet is an important part of essential education that is missing from the medical care given most patients who have lost part of their kidney function.