Your kidneys work silently behind the scene 24 hours a day, seven days a week, filtering unneeded fluid and chemicals from your body. Though nature built redundancy into your renal system, it is possible you may damage or reduce your kidney function though your diet or drugs. Researchers have studied the impact of high protein intake on kidney function. If you have less than normal kidney function, however, talk with your physician before you take a high protein dietary supplement such as whey protein isolate.
Whey protein isolates are a purified form of whey, the by-product of cheese manufacturing. Whey protein isolates have most of the water, fat and lactose of whey removed, leaving a product consisting of 90 per cent protein. Whey protein isolates contain the branched chain amino acids leucine, isoleucine and valine that are prized by bodybuilders. There are no medical indications for whey.
Despite whey protein isolates' superiority as a protein source, your body treats it like a county fair corn dog. Whey is digested and broken down into its constituent amino acids like any other dietary protein. The amino acids enter the blood stream, where your body uses them as needed to build new human proteins. Excess amino acids are used as a calorie source or eliminated through the kidneys
Whey and Kidney Function
It is possible to consume more protein from whey protein isolate than your body can use. There is no evidence, however, that this protein overload will adversely affect a normal, healthy kidney. A 2003 study published in the "Annals of Internal Medicine" examined the impact of daily protein intake on the kidney function of 1,624 women ages 42 to 68. The researchers found no difference in kidney filtration rate in women with normal kidney function, regardless of the amount and type of protein they consumed. A study published in the "Journal of the American Society of Nephrology" in 2009 also looked for correlations between protein intake and decreased kidney function. This study involved 8,461 male and female subjects with normal renal function. The subjects were followed for an average of seven years. The researchers found no evidence linking higher protein intake with a degradation in kidney function.
Too much whey protein isolate can be a problem if you already have reduced kidney function. You should be cautious with your protein intake from whey or any other source if you have chronic kidney disease, or CKD. The extra load of chemicals to filter and excrete puts added pressure on an already over-burdened organ. The 2003 "Annals of Internal Medicine" study found that higher intakes of dietary protein did, in fact, further erode the renal function of women who had poorly performing kidneys at the start of the study.
- "Annals of Internal Medicine"; The Impact of Protein Intake on Renal Function Decline in Women with Normal Renal Function or Mild Renal Insuf?ciency; Eric L. Knight, et al.; March 18, 2003
- "Journal of the American Society of Nephrology"; High Protein Intake Associates with Cardiovascular Events but not with Loss of Renal Function; Nynke Halbesma, et al; March 2009
- Harvard Gazette : Too much protein may cause reduced kidney function