It is often reported (and with very good reason!) that everything should be taken in moderation. This is nowhere more true than with factors that affect your precious self! So, needless to say that media reports suggest an effect a deleterious effect of overconsumption of the overtly masculinised, required macro-nutrient, protein.
You’ve probably heard that too much protein is not good. Reported by media outlets and your mother or father (I know mine do!) too much protein puts stress upon your renal system and causes bone calcium excretion. This isn’t just a housewives tale however, but has credence in that this evidence was drawn from good quality published articles.
BUT ladies and gentleman, it is my feeling that this knowledge requires an update and until that time no conclusion can be made as to protein and its negative effects upon the renal system and bone calcium health.
So let’s break down my reasoning by looking at the studies cited as the evidence for not consuming more protein than the RDA..
Protein and Renal Disease
This is a classic case of media outlets causing a hubbub while taking information out of context. The main point of debate is that an excess intake of protein above the RDA causes chronic renal disease through increased glomerular pressure and hyperfiltration. The data for this is sound enough, with the frontier study that caused the media excitement being that of Barry M, et al, 1982.
This article is methodologically well put together and is deserved of its title as a frontier study (that which leads the way, as being the first study, for further research in its field). However, picking it apart (unfortunately it’s behind a paywall: 1.usa.gov/1aLkB0j) I came to realise the incorrectness of its use as a study to back up protein moderation in a healthy individual.
- The majority of the evidence used is cited from animal models.
- Another group of evidence collection is that of patients with co-existing renal disease.
- No healthy individuals are used as an evidence model.
Therefore, I conclude that this study is not suitable to be used in order to draw association between increased protein intake and renal disease onset.
Don’t want to take my word for it?
Why would you? But there are published article’s out there without the media spotlight upon them that back up what I’m saying:
Martin W, et al (2005): Concluded that –
“Although excessive protein intake remains a health concern in individuals with pre-existing renal disease, the literature lacks significant research demonstrating a link between protein intake and the initiation or progression of renal disease in healthy individuals.”
Further, Martin went on to say –
“there is not sufficient proof to warrant public health directives aimed at restricting dietary protein intake in healthy adults for the purpose of preserving renal function.”
Knight E, et al (2003) designed a prospective cohort study (which is a study using a group of individuals and following them from the outset to the end of the study, measuring predetermined outcomes overtime. These usually include both a control and treatment group). It was concluded that high protein intake was not associated with renal function decline in women with normally (healthy) operating kidneys.
Blum M, et al (1989), in a study using both vegetarians (a group which is demonstrated to have lower protein intake) and non-vegetarians, both displayed similar deterioration in renal health with age. It concluded no difference in age, sex, weight and kidney function between groups.
Kidney health and the bodybuilder's diet?
You may be reading this and wondering whether any studies have been conducted regarding us (a very broadly termed "us"). Us athletes and our high protein diets to aid weight loss, or high protein diets and resistance training or endurance.
Well, to the best of my knowledge, no credible studies have focused in on these topics. However, what can be taken away from this to begin with is that at the current time, no authority should be warranted towards decreasing protein intake in order to maintain renal function.
In my opinion, it would appear that protein intake over the RDA, even so far as 1.4-2g/kg (a range commonly stated as that required for exercising individuals) of bodyweight show no risk factors for decreased kidney function, in healthy, exercising individuals. It should still be prudent to mention that those individuals with mild renal insufficiency should monitor their intakes more closely, as evidence shows that protein intake may be closely related to the progression of renal disease.
Well, that went on for a bit longer than I thought it might today! I’ll be bringing you part 2 as soon as I can, debunking protein intake linked to decrease bone health. In the meantime, if you have any thoughts or could highlight any studies relevant to increased protein intake (over 100g per day) regarding kidney health, I’d more than appreciate taking a read!