High-protein Diets & Kidneys

Various high-protein diets have been promoted for weight loss without regard to the negative health effects they may have on people prone to kidney problems. If your kidneys are not functioning properly, a high-protein diet can cause further damage by overworking the organs as they attempt to go about their normal job of eliminating waste from your body.

Diet Plans

High-protein weight loss diets, such as the Zone, Atkins, Protein Power, Sugar Busters and Stillman diets, are not balanced food plans because they generally don't provide all the nutrients you need, in the amounts you need, to maintain good health, according to the American Heart Association. This imbalance of nutrients can result in too much protein and saturated fat from animal foods and too little of the fiber, vitamins and minerals found in plant foods.

Kidney Function

When your kidneys are healthy, they eliminate waste from your body and at the same time catch any protein that passes through in filters known as glomeruli. That protein circulates back into your body in your bloodstream. Damaged kidneys allow protein to pass into urine and the results, which are seen in laboratory tests, are high protein levels in your urine and low protein levels in your blood. If you have a kidney disorder, your doctor or dietitian may tell you to avoid high-protein diets and limit the amount of protein you eat at each meal.

Protein Effects

High-protein diets increase the glomerular filtration rate, which is the rate at which your blood passes through your kidneys for filtering. A test known as glomerular filtration rate is one measure of your kidneys' health and ability to function properly. High-protein diets also lower the pH of urine, increase the amount of calcium lost in urine and increase uric acid levels in urine and blood. Over time, these imbalances of substances that normally pass through blood and urine can lead to various medical conditions, such as kidney stones and gout.

Protein Sources

Protein from animal foods appears to have a more detrimental effect on kidney function than protein from plant foods such as vegetables and grains, according to a study published in a 2003 issue of "Annals of Internal Medicine." The concern is not that a high-protein diet causes kidney problems but that if you already have a kidney disorder, this type of diet may encourage the progression of disease. In this study, researchers found that a diet consistently high in animal protein had no effect on the kidneys of women with normal kidneys, but may speed up the loss of kidney function in women with even mild kidney dysfunction. These researchers also concluded that nondairy animal protein appears to have a more detrimental effect on kidneys than protein from dairy or vegetable sources.