“High Protein Causes Kidney (and liver) problems”
You’ve heard it said lots of times and it’s a categorically incorrect statement. Do you know where the logic comes from? It’s usually derived from circular logic of people’s experiences in renal wards where there’s little doubt that lower protein diets can help extend a persons’ health and life due to the lower urea and therefore less ‘work’ filtering such substances by the kidney. The incorrect circular logic that is then applied is that ‘therefore’ [sic] high protein diets cause renal disease. That’s poor logic, flawed reasoning, and just plain wrong. I’m never really sure why the liver gets thrown in as an organ that may be affected by high protein but my suspicion is that it’s an internal organ that is important in amino acid metabolism and it’s sort of pinkish-brown in colour and so belongs in the same ‘family’ as the kidney? It’s certain that folks with chronic liver disease have problems with metabolizing aromatic amino acids, which can result in a condition known as hepatic encephalopathy, but that’s not cause by high protein. So in truth the folks who say this kind of stuff are preaching poor information, in fact to say it is, in my view disinformation (i.e., deliberately spreading false information). Here’s my reason why…
There is no data that links higher protein diets to renal disease: the FAO/WHO report (i.e., the folks who set protein requirements on a worldwide basis) says this as does the current IOM (Institute of Medicine) document that sets the DRI (Dietary Reference Intakes) for North Americans! In the most recent round of discussions in setting the new DRI, the IOM concluded, “…that protein content of diet is not related to progressive decline in kidney function with age.” In addition, From the WHO/FAO report: “…the suggestion that the decline of glomerular filtration rate that occurs with advancing age in healthy subjects can be attenuated by reducing the protein in the diet has no foundation.” Those are some learned folks who are saying that dietary protein content is not related to a decline in kidney function! Wait need a few more references?
E.L. Knight et al. Ann Intern Med 138: 460–467, 2003. Stated, “… [there was] no significant association between protein intake and change in glomerular filtration rate in women with normal renal function,* and a sub-analysis of animal protein, dairy protein, and vegetable protein showed that none of the individual sources of protein were associated with a change in GFR…” (Note: GFR – is glomerular filtration rate and is measure of kidney function). While it’s true in the same report there are people who have low GFR (read the paper for more details) who are advised not to consume higher protein; however, that DOES NOT mean that higher protein caused the decline in renal function!
One more; Bernstein et al. JADA 2007 Apr;107(4):644-50. “From these studies, we cannot conclude whether or not there is a long-term association between amount of animal or vegetable protein intake and change in normal renal function.” This is a paper from the Harvard group who, believe me, if they could have found some damning association between protein (especially animal source protein) and renal disease you’d have seen it in every newspaper (sort of like the press that showed protein ‘causing’ [sic] cancer - see here for a debunking of that garbage: twitpl.us/t/LJeb). So allow me some license to re-write their conclusion “We could not find a relationship between protein intake and renal function.”
So, the next time you hear someone say, write, or suggest that “Protein leads to kidney and liver problems” then pause, take a breath, and ask them for their best ‘gold standard’ evidence that shows this is true. Seriously, ask them… and in the muted silence that follows perhaps cite these references and calmly tell them that neither the WHO or IOM see any evidence for higher protein leading to kidney disease. Oh and the liver? Well that's just guilt by association!
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