How the rumour started:
Whilst there doesn’t appear to be a specific publication, the confusion of this rumour appears to date back to the mid 1970’s and as been perpetuated multiple times over the the last 50 years with poorly conducted studies, or conclusions that aren’t represented in the numbers measured. While there may sometimes be a correlation between poor kidney function and protein intake, no-one had stopped to check whether the protein itself was causing the problem – and by the time they did, the rumours had already firmly rooted themselves.

The other question that hadn’t been asked loudly enough was, ‘is the measure by which we are using to asses kidney malfunction actually the correct metric, or have we completely mis-understood how the kidneys function on the whole? 


What the research actually shows:
In summary

A) In the general population (without any identifiable kidney issues), increased protein intake has not been shown to cause disease. 

B) The markers we use to asses kidney function – especially eGFR, may not actually be helpful, as the kidneys adapt their filtration rate and abilities based on the environment which they are expected to function. 

C) Depending on the individual, damaged kidneys may struggle to process the nitrogen byproducts from protein metabolisation – but in other individuals, kidney function may actually improve when placed on carnivorous diets.

D) At a population level, the bigger concerns and likely cause of kidney disease is metabolic disease (often presenting itself as diabetes and higher blood pressure). By deduction, high carbohydrate diets and processed foods including seed oils are implicated strongly.

E) The popularly quoted RDA for protein being 0.8g protein per kg of lean body weight is likely way too little, and an intake of 1.5-2g/Kg of lean body mass could be considered a healthy minimum for most people, and as much as 4-5g may be appropriate in more active or naturally larger (muscularly) individuals.


A top tip for health:
Aim to ingest 50g of protein for every meal (including any snack) (if eating 3 meals per day). If eating two, aim for 75g per meal. 

If eating quality meat, you’ll proportionally ingest a healthy and appropriate quantity of fat whenever just by focussing on protein. 

Limit carbohydrate consumption and avoid processed foods – in any case, after eating an appropriately sized portion of protein, you likely won’t have room or desire for anything of lower nutritional value.