Nutrition

The Truth About High Protein Diets and Kidney Damage

Kris Gunnars makes a case for increased protein intake not only to be harmless but potentially even have a protective effect.

A common myth in health and nutrition circles is that eating too much protein can harm the kidneys. This does not make much sense, given that humans evolved as omnivores who ate a relatively high-protein diet and that we are made of protein. But as with many myths in nutrition, they tend to linger and often reach a state of dogma, even among health professionals.

The Function of the Kidneys

The kidneys are a remarkable organ. Two are next to the vertebral column, right under our lowest ribs. Their primary function is to filter substances that we don't need out of the blood: excess fluid, various electrolytes, toxic metabolism products, and even artificial substances like pharmaceutical drugs.

Among the waste products that the kidneys secrete are protein breakdown products, mainly nitrogen. Nitrogen is secreted from the kidneys as urea or ammonia. This has led some people to argue that eating a high protein diet increases stress on the kidneys.

Well, stress is what the kidneys are designed for. They are remarkably efficient organs that filter about 180 litres of blood daily. Adding protein to the diet has a minimal effect on the total workload of the kidneys.

A 2005 review article^[1] examined the association of protein intake with kidney health. No evidence was found that high-protein diets harm healthy people's kidney function.

The Two Main Risk Factors for Kidney Failure

Two main risk factors for kidney failure are diabetes and hypertension (elevated blood pressure). These risk factors may play a causal role in developing kidney disease.

Therefore, if we can improve these factors, we could argue that increased protein intake might protect against kidney failure. In type II diabetics, a high-protein diet improves blood sugar control and various other health biomarkers ^[2,3].

Additionally, studies in hypertensive patients reveal that increasing protein intake leads to lower blood pressure ^[4,5].

The Truth About High Protein Intake

People with kidney disorders may need to watch their protein intake according to their doctor's instructions. However, in otherwise healthy people, there does not appear to be any data to back up the idea that high-protein diets could have detrimental effects on kidney function.

High-protein diets have favourable effects on the two most important risk factors for kidney disease. Given other documented health benefits, such as weight loss and improved blood lipids, increasing protein intake should probably be encouraged.

References

MARTIN, W.F. et al. (2005) Dietary protein intake and renal function. Nutrition & Metabolism, 2, p. 25
GANNON, M.C. et al. (2003) An increase in dietary protein improves the blood glucose response in persons with type 2 diabetes. Am J Clin Nutr. 78 (4), p .734-741
GANNON, M.C. et al. (2004) Effect of a High-Protein, Low-Carbohydrate Diet on Blood Glucose Control in People With Type 2 Diabetes. Diabetes 5 (9), p. 2375-2382
APPEL, L.J. et al. (2005) Effects of Protein, Monounsaturated Fat, and Carbohydrate Intake on Blood Pressure and Serum Lipids. JAMA. 294 (19), p. 2455-2464
ALTOF-VAN DER KUIL, W. et al. (2010) Dietary protein and blood pressure: a systematic review. PLoS One. 5 (8), e. 12102

Page Reference

If you quote information from this page in your work, then the reference for this page is:

GUNNARS, K. (2013) The Truth About High Protein Diets and Kidney Damage [WWW] Available from: https://www.brianmac.co.uk/articles/article120.htm [Accessed

About the Author

Kris Gunnars is a medical student and a certified personal trainer. He publishes articles on evidence-based nutrition on his website.


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A common myth in health and nutrition circles is that eating too much protein can harm the kidneys. This does not make much sense, given that humans evolved as omnivores who ate a relatively high-protein diet and that we are made of protein. But as with many myths in nutrition, they tend to linger and often reach a state of dogma, even among health professionals. The Function of the Kidneys The kidneys are a remarkable organ. Two are next to the vertebral column, right under our lowest ribs. Their primary function is to filter substances that we don't need out of the blood: excess fluid, various electrolytes, toxic metabolism products, and even artificial substances like pharmaceutical drugs. Among the waste products that the kidneys secrete are protein breakdown products, mainly nitrogen. Nitrogen is secreted from the kidneys as urea or ammonia. This has led some people to argue that eating a high protein diet increases stress on the kidneys. Well, stress is what the kidneys are designed for. They are remarkably efficient organs that filter about 180 litres of blood daily. Adding protein to the diet has a minimal effect on the total workload of the kidneys. A 2005 review article^[1] examined the association of protein intake with kidney health. No evidence was found that high-protein diets harm healthy people's kidney function. The Two Main Risk Factors for Kidney Failure Two main risk factors for kidney failure are diabetes and hypertension (elevated blood pressure). These risk factors may play a causal role in developing kidney disease. Therefore, if we can improve these factors, we could argue that increased protein intake might protect against kidney failure. In type II diabetics, a high-protein diet improves blood sugar control and various other health biomarkers ^[2,3]. Additionally, studies in hypertensive patients reveal that increasing protein intake leads to lower blood pressure ^[4,5]. The Truth About High Protein Intake People with kidney disorders may need to watch their protein intake according to their doctor's instructions. However, in otherwise healthy people, there does not appear to be any data to back up the idea that high-protein diets could have detrimental effects on kidney function. High-protein diets have favourable effects on the two most important risk factors for kidney disease. Given other documented health benefits, such as weight loss and improved blood lipids, increasing protein intake should probably be encouraged. References MARTIN, W.F. et al. (2005) Dietary protein intake and renal function. Nutrition & Metabolism, 2, p. 25 GANNON, M.C. et al. (2003) An increase in dietary protein improves the blood glucose response in persons with type 2 diabetes. Am J Clin Nutr. 78 (4), p .734-741 GANNON, M.C. et al. (2004) Effect of a High-Protein, Low-Carbohydrate Diet on Blood Glucose Control in People With Type 2 Diabetes. Diabetes 5 (9), p. 2375-2382 APPEL, L.J. et al. (2005) Effects of Protein, Monounsaturated Fat, and Carbohydrate Intake on Blood Pressure and Serum Lipids. JAMA. 294 (19), p. 2455-2464 ALTOF-VAN DER KUIL, W. et al. (2010) Dietary protein and blood pressure: a systematic review. PLoS One. 5 (8), e. 12102 Page Reference If you quote information from this page in your work, then the reference for this page is: GUNNARS, K. (2013) The Truth About High Protein Diets and Kidney Damage [WWW] Available from: https://www.brianmac.co.uk/articles/article120.htm [Accessed About the Author Kris Gunnars is a medical student and a certified personal trainer. He publishes articles on evidence-based nutrition on his website.