Is a High Protein Bodybuilding Diet Damaging to Kidney Health?

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Question: Is Eating a High Protein Diet Damaging To Your Kidney Health?

I am often asked if eating the amount of protein required of a bodybuilding diet will lead to kidney damage. Let's look at the research and recommendations from sports authorities as to whether athletes are at risk with a high protein diet.

The key question is - do you have normal kidney function? Silent conditions such as high blood pressure and normal aging may be reducing your kidney function and you don't know it.

Regular medical checkups can uncover conditions you may be developing that can reduce kidney function.

Answer: Little Risk for a Healthy Person with Good Kidney Function

A review of studies of high protein dietary intake and renal function found no link between developing renal disease in healthy people. The evidence pointed to the body actually adapting to the higher protein in the diet. Kidney function keeps up with increased demands to eliminate the waste products of protein metabolism. A person who has normal kidney function shouldn't worry about that aspect of a high protein diet.

In a study of the effects of a high protein diet in young men, the blood markers for kidney function of 77 men who participated in an average of 6 hours of weight training per week (average age of 26), and ate a diet consisting of 19% protein were analyzed. Their protein intake came out to be about 0.76 grams of protein per pound bodyweight, which is very close to the 1 gram per pound minimum that is typically recommended for bodybuilders.

Primary blood tests for kidney function were run in which blood urea nitrogen, uric acid and creatinine levels were monitored. The measurements showed that all of these items were within normal parameters in all participating men.

Caution for People with Impaired Kidney Function

People who already have a pre-existing kidney condition need to be concerned with keeping their protein in check.

A study of women with normal kidney function and those with mild renal insufficiency found no problems for those with healthy kidneys. However, the women who had mild insufficiency had an accelerated decline in kidney function when they had a high intake of non-dairy animal protein.

It must be mentioned that kidney function naturally declines with age due to the gradual loss of nephrons, which are the kidney's filtering units. This loss can be caused by ailments like heart disease since in this case the blood flow to the kidneys is reduced. Also untreated high blood pressure can lead to kidney damage as well as long term use of prescription and non-prescription pain relievers such as aspirin.

Keep Your Kidneys Healthy

I always caution bodybuilders that in order to keep their kidneys healthy some aerobic exercise needs to be performed on a weekly basis as this will help keep the blood pressure in check and the heart healthy. I also recommend to drink plenty of water as this fluid is of utmost importance for protein processing and cleansing of waste product produced by protein metabolism. Also, eating vegetables as well helps with protein digestion.

Setting a Protein Limit

More is not always better.

A research study of bodybuilders concluded that a protein intake under 2.8 grams per kilogram bodyweight (1.3 grams per pound) does not impair renal function in well-trained athletes. Know what your intake is to keep it in bounds.

Sources:

William F Martin, Lawrence Armstrong and Nancy Rodriguez. Review: "Dietary protein intake and renal function." Nutrition & Metabolism 2005 2:25 DOI: 10.1186/1743-7075-2-25.

LaBounty, P, et al. (2005). Blood markers of kidney function and dietary protein intake of resistance trained males. J Int Soc Sports Nutr.2:5.

Eric L. Knight, MD, MPH, et. al. "The Impact of Protein Intake on Renal Function Decline in Women with Normal Renal Function or Mild Renal Insufficiency." Ann Intern Med. 2003;138(6):460-467.

Poortmans JR, Dellalieux O. "Do regular high protein diets have potential health risks on kidney function in athletes?" Int J Sport Nutr Exerc Metab.

2000 Mar;10(1):28-38.