No, Protein Is Not Bad For Your kidneys

As my patients – and regular readers of this blog – know, one of my frequent recommendations for better health is to increase the intake of dietary protein. Dietary protein is satiating, which tends to lead to lower overall caloric intake, and thus less fat mass. At the same time, dietary protein supports muscle mass, particularly when combined with a regular program of physical activity. The combination of less fat and more muscle leads to lots of desirable outcomes, from improved health (lower blood pressure, lower blood glucose, improved metabolism, lower risk for frailty with aging) to a more visually appealing body aesthetic. Does this strategy work for everyone? No, we’re all unique. But for a lot of people it’s quite helpful.

However, frequently when I make this recommendation to patients, I am met with one particular concern: “won’t all of that extra protein harm my kidneys?”

I remember first hearing the oft touted idea that protein is bad for the kidneys back when I was in college, and for years I believed that it was settled science that high protein diets were harmful to our kidney health. I was surprised therefore when, as a medical student back around 2008 or 2009, I heard a brilliant nephrologist on rounds one day discussing how there is really no evidence that protein intake is harmful to a healthy kidney. 

I subsequently learned that, because there is some evidence that high-protein diets are harmful to people who already have advanced kidney disease, it became dogma in the 1980s that one of the ways to prevent kidney disease would be to consume a low-protein diet throughout one’s life. However, this idea began to fall away in the 1990s as study after study did not corroborate this theory. Even the idea that eating less protein is helpful to people who already have kidney disease was partially debunked by a study published in the New England Journal of Medicine back in 1994, which showed only a very small benefit of protein restriction in these patients.

In 2018, a group of researchers at McMaster University did a “meta-analysis,” in which they reviewed 28 different studies conducted over a four decade period, and found no association between high protein intake and later development of chronic kidney disease. 

Then last year, a paper published in JAMA showed not only that there was no increased risk for kidney disease in high protein consumers, but that in fact they had a slightly reduced risk for death from kidney disease.

So no, there is no good evidence to suggest that eating more protein will lead to kidney failure. If you currently have healthy kidneys and you find that a higher protein diet works well for you, there’s no particular reason to worry that continuing your eating pattern will increase your risk of developing kidney disease later in life.