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The amount of misinformation regarding this topic is truly aggravating. You hear that protein is bad for your kidneys from most doctors, the layperson, morning talk shows and the media[SUB](4)[/SUB] as well as most nutritionists. (I say most because sports nutritionist know that this may be true under specific clinical circumstances, and only for some individuals)
This article serves to elaborate on Dylan's great video on the topic found here:
Time to put this puppy to bed. Once and for all.
This article will compact vast in-field and in-clinic knowledge, experience and info analysis from epidemiological studies (prevalence, correlation and causation) and clinical human studies, involving the highest level of information quality in a significant volume – over 100 studies, all of which I will cite here. I will also include the studies that go all the way back from 1950s that initially postulated proteins as a problem. Thus both sides of the coin will be presented. Only one shall prevail.
I will equip you here with the knowledge to combat these false claims. After this - if anyone should debate you on this topic, feel free to print all 57,000 pages of over 100 studies on the thickest paper you can find and throw it in their face, out of a moving car, wrapped in ball bearings, bowtied with razor wire.
The basis for this controversy started when the concern that regular high intake of dietary protein may produce excessive pressure on the kidney filtration mechanisms[SUB](2,3)[/SUB]; Now, in fact, we already know that the effect proteins have on kidney functions[SUB](1)[/SUB] are a part of normal, very much needed physiological adaptation[SUB](5,6,7,8,9,10,112)[/SUB]. Our kidney is genetically designed to modify its function in the presence of proteins. It needs to.
The WHO (World Health Organization) recommended a protein consumption of 0.6-0.8 gram/kg/day. One of the bigger studies looked into long term dietary intake of over 1.5 gram/kg/day[SUB](11)[/SUB] without any ill-effects. Even the Institute of Medicine Dietary Reference Intake found that there is no reason or evidence to place any upper limit of protein intake[SUB](11)[/SUB], even in light of the current trends in high protein diets for exercising and body weight management[SUB](12,13,14,15,16)[/SUB], an overwhelming academic evidence has been presented that higher protein diets may actually be beneficial[SUB](12,16,17,18,19,20,21,22,23,24)[/SUB].
A study did demonstrate that patients with existing kidney disease do benefit from low protein diets[SUB](71)[/SUB] however, imposing these guidelines on healthy individuals with intact kidney function is improper scientific conduct – and it bit us in the ass.
One can argue that increase protein strains the kidney in the same way that exercises strains the muscle, however exercise definitely doesn't increase the risk of muscular diseases, on the contrary.
Funny thing is that proponents of this theory that say this strain is negative on the kidney cite a publication[SUB](83)[/SUB] that does not say that at all. Here's a quote from the head author of that very publication:
“The word "strain" is misleading given its negative connotation. Scientific research is often misrepresented in this context. Research from our laboratory [SUB](83) [/SUB]which is cited in the press release, does not support these contentions.”
Having said that, much like Dylan mentions with respect to protein consumption “eating more and in excess may interfere with your heath” - I also believe that high protein diets have a place and a time, and need to serve a purpose, rather than BE the purpose.
References won't even fit, so you may access them in the following link:
http://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-2-25
This article serves to elaborate on Dylan's great video on the topic found here:
Time to put this puppy to bed. Once and for all.
This article will compact vast in-field and in-clinic knowledge, experience and info analysis from epidemiological studies (prevalence, correlation and causation) and clinical human studies, involving the highest level of information quality in a significant volume – over 100 studies, all of which I will cite here. I will also include the studies that go all the way back from 1950s that initially postulated proteins as a problem. Thus both sides of the coin will be presented. Only one shall prevail.
I will equip you here with the knowledge to combat these false claims. After this - if anyone should debate you on this topic, feel free to print all 57,000 pages of over 100 studies on the thickest paper you can find and throw it in their face, out of a moving car, wrapped in ball bearings, bowtied with razor wire.
The basis for this controversy started when the concern that regular high intake of dietary protein may produce excessive pressure on the kidney filtration mechanisms[SUB](2,3)[/SUB]; Now, in fact, we already know that the effect proteins have on kidney functions[SUB](1)[/SUB] are a part of normal, very much needed physiological adaptation[SUB](5,6,7,8,9,10,112)[/SUB]. Our kidney is genetically designed to modify its function in the presence of proteins. It needs to.
The WHO (World Health Organization) recommended a protein consumption of 0.6-0.8 gram/kg/day. One of the bigger studies looked into long term dietary intake of over 1.5 gram/kg/day[SUB](11)[/SUB] without any ill-effects. Even the Institute of Medicine Dietary Reference Intake found that there is no reason or evidence to place any upper limit of protein intake[SUB](11)[/SUB], even in light of the current trends in high protein diets for exercising and body weight management[SUB](12,13,14,15,16)[/SUB], an overwhelming academic evidence has been presented that higher protein diets may actually be beneficial[SUB](12,16,17,18,19,20,21,22,23,24)[/SUB].
So how did all of this idea start? The Brenner hypothesis - 1982
This is the go-to publication cited with respect to demonizing proteins as harmful to the kidney. It has been demonstrated that increased dietary protein increases filtration of blood through the kidney[SUB](1)[/SUB], which was later deemed to be simply a part of our kidney normal physiology. This research and others imply that increase in kidney filtration may cause progression to kidney disease[SUB](3,72,73,74,75)[/SUB]. Sadly the study was largely made on animals, and the humans involved all had pre existing renal disease. A study did demonstrate that patients with existing kidney disease do benefit from low protein diets[SUB](71)[/SUB] however, imposing these guidelines on healthy individuals with intact kidney function is improper scientific conduct – and it bit us in the ass.
In that case - why is the kidney said to be under strain by protein consumption?
“The lay public is often told that high protein diets "overwork" the kidney and may negatively impact renal function over time”[SUB](78,79)[/SUB] Why? Well, increase in protein consumption causes increase in production of urea, a waste product eliminated by the kidneys. This is how the human body normally eliminates excess Nitrogen. Forming and eliminating urea costs energy to the kidney, thus the assumption that it is “straining” to the kidney, an assumption, not a fact[SUB](80)(81)[/SUB]. This theory dates back to an unsubstantiated article from 1954[/SUB].
One can argue that increase protein strains the kidney in the same way that exercises strains the muscle, however exercise definitely doesn't increase the risk of muscular diseases, on the contrary.
Funny thing is that proponents of this theory that say this strain is negative on the kidney cite a publication[SUB](83)[/SUB] that does not say that at all. Here's a quote from the head author of that very publication:
“The word "strain" is misleading given its negative connotation. Scientific research is often misrepresented in this context. Research from our laboratory [SUB](83) [/SUB]which is cited in the press release, does not support these contentions.”
Evidence in healthy individuals
Later academic studies actually found that there are no reports whatsoever to compromised kidney function due to protein rich intake in healthy individuals even those prone to develop kidney disease[SUB](14,15,22,85,86,87)[/SUB]. Another randomized replication study later supported that[SUB](65)[/SUB].
Sports nutritionists are in the know
This is where nutritionists are distinguished from one another. Athletes, particularly in sports requiring strength and power, consume high levels of dietary protein[SUB](89,90)[/SUB]. In fact, many athletes habitually consume protein in excess of 2.0 g/kg/day[SUB](91)[/SUB], even supplementing with amino acids extracts[SUB](92)[/SUB]. A specific research cooperating with sports nutritionalists looking into these subset of individuals, found no evidence that they are placed in any greater risk to develop kidney disease[SUB](90)[/SUB].
Why is it that nephrologists (“kidney doctors”) say that protein IS bad for the kidneys?
Nephrologists tend to patients with kidney problems, chronic decline in kidney functions as well as anatomical defects in the kidneys. All of whom tend to have a form of reduced kidney function or susceptibility to develop one. In this case increased protein intake, may indeed be detrimental to those particular patient subset. Also, and this is somewhat shameful for me to admit, it is this author's opinion that the overwhelming majority of doctors are less than knowledgable in proper nutrition, let alone sports nutrition.What about AAS? Do they make it better, or worse?
Due to the concept of a more advantageous nutrient partitioning, the body's metabolic centres better process amino acids, causing a substantial decrease in the free fraction of amino acids in the blood, as they are being better utilized. Er go - AAS employing athletes are less likely to overwhelm the enzymatic machinery involved in protein metabolism in the kidney. (this is not a clinical recommendation to administer AAS to avoid kidney damage)
Conclusions
High protein intake remains a health concern in individuals with pre-existing renal disease. However, there's an overwhelming lack of research demonstrating a link between protein intake and kidney disease in healthy individuals. Evidence suggests that changes in kidney function due to increase dietary protein are likely a normal adaptive mechanism well within the functional limits of a healthy kidney[SUB](112)[/SUB].
Having said that, much like Dylan mentions with respect to protein consumption “eating more and in excess may interfere with your heath” - I also believe that high protein diets have a place and a time, and need to serve a purpose, rather than BE the purpose.
References won't even fit, so you may access them in the following link:
http://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-2-25
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