Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
1 Mar

Is Eating Too Much Protein Going to Harm My Kidneys?

Dear Mark,

I am studying to become a nurse and am taking my first nutrition class at a local college. As one of our assignments we had to record everything we ate for an entire week. After looking at my results my teacher was dumbfounded. To make a long story short, my teacher told me that I should only be eating 38 grams of protein each day, and that any more than that could harm my kidneys. I’ve been Primal for 2 years and am healthier than ever. I am 5′ 2″ and and a very lean 105 pounds. Should I be concerned?


Well, Renee, I’m sorry to break it to you, but all those subjective health markers – like being “healthier than ever,” a “very lean 105 pounds,” and satisfied enough to be “Primal for 2 years” – mean absolutely nothing because you are destroying your kidneys by exceeding your daily allotment of six ounces of animal protein. In fact, it’s highly likely that feeling good and maintaining a trim, lean figure are byproducts of impending kidney failure. The human body, you see, is a cruel practical joker dead set on destroying itself (hence the daily internal manufacturing of that poison known as cholesterol); it’s only trying to keep you pacified with regards to your health long enough for outright kidney failure to commence.  You should be extremely concerned. I only hope this message reaches you in time.

Seriously, though – the notion that eating more than 0.3g protein per pound of bodyweight (which appears to be how your teacher came to her conclusion) will definitively harm human kidney function leaves me dumbfounded. I’m reminded of the time I had to take Buddha in for a quick checkup at an unfamiliar vet and the woman examining him mentioned that I’d probably want to switch him to a low-protein diet or risk certain renal failure. Because, you know, the kidneys of dogs, close relative of the carnivorous wolf, are unable to process all that meat and protein. It’s ridiculous on its face, and rather than waste a lot of space debunking what Dr. Eades calls one of the “Vampire Myths” (it just won’t die; get it?), I’ll just link to a few papers that have already done so.

There’s this one from the Journal of the International Society of Sports Nutrition, a massive review of the evidence in favor of and in opposition to the AHA’s weasel warnings about “high protein diets,” namely, that people who engage in such risky behaviors as limiting carbs and increasing protein “are [at] risk for … potential cardiac, renal, bone, and liver abnormalities overall.” Long story short: there’s far more evidence in opposition to the claim than evidence in favor of it. The AHA recommendations are at best incorrect and at worst deliberately misleading, and the sum of the actual evidence points to protein as being protective against heart disease, osteoporosis, kidney disease, and liver problems – all things protein is supposed to initiate or worsen.

Another review, this time focusing strictly on whether or not protein intake can precipitate kidney disease in healthy people, is even better. I mean, that’s the important thing, isn’t it? If we want to exonerate or condemn protein, we must study its effects on healthy kidneys. We have to see if it creates problems rather than potentially worsens them. And, according to the exhaustive analysis of Martin et al, there exists no evidence that protein intake negatively influences renal health in otherwise healthy, active individuals. There is some evidence that already impaired renal function might worsen with increased protein, but the experts, as is their wont, can’t resist applying the same recommendations to everyone, regardless of renal health. The result is a nutrition teacher sowing misinformation across the student body in an introductory course, i.e. one that is intended to establish foundational knowledge that the students will carry on through life as a cornerstone of their thinking.

Simply put, healthy kidneys can handle plenty of protein; heck, they are meant to handle protein. One of their primary functions is to process the metabolic waste that results from protein metabolism. Yeah, protein “works” the kidneys, but that’s what they’re there for! Strength training works the muscles. You might even say it strains them. But is that a problem? Compromised kidneys in patients with renal disease (either full-blown or still in development) may not be able to handle as much protein as healthy kidneys, but even that’s up in the air – and protein is not the cause of the problem.

So what causes kidney disease, if not too many deck of cards-sized pieces of deadly animal protein in the diet?

The top two conditions responsible for chronic kidney disease (CKD) are, respectively, diabetes (45% of CKD cases) and hypertension, or high blood pressure.”Even” the Wikipedia entry on renal failure fails to mention “excess protein in the diet” as a cause (even potentially) of CKD. If you have CKD, chances are fairly high that you’re either diabetic, hypertensive, or both.

You know what’s even better? High-protein diets, when compared to the high-carb diet commonly recommended, improve glucose tolerance and blood sugar control in type 2 diabetics without changing kidney function. And, since type 2 diabetes often leads to CKD and is characterized partly by poor glucose tolerance and blood sugar control, you might even say that eating more protein is actually protective against renal failure.

As for hypertension, the latest systematic review concludes that more protein in the diet seems to correlate with lower, or at least normalized, blood pressure in humans. That doesn’t necessarily mean anything definitive, but it’s certainly interesting, and it doesn’t support the standard position.

Of course! Anyway, unless it’ll compromise your grade in the class, I’d speak up about it. Engage your teacher, for without disagreement, especially when warranted, there can be no progress. At the very least, defend your stance, perhaps wielding the aforementioned papers, and by all means: don’t feel the need to limit yourself to 38 grams of protein per day! While that may be adequate – that is, you’ll live – you definitely have room for more.

You need protein for a number of reasons:

It’s required for good skeletal health; contrary to what many vegetarians will scream, animal protein doesn’t leach calcium from the bones, leading to osteoporosis. In fact, inadequate protein intake is a huge risk for the debilitating bone disease.

It provides amino acids, which play multiple roles in the human body. They act as building blocks for most bodily structures, including hair, organs, skin, and muscles. Using amino acids, we build new tissue and repair damaged tissue. Lifting weights “damages” muscle tissue; we repair the damage with amino acids. Amino acids also act as precursors to hormones and neurotransmitters, like serotonin (the amino acid tryptophan) and dopamine (the amino acid tyrosine).

It’s good for quality of life, especially in the later years where folks are more susceptible to skeletal muscle wasting. You try keeping up with your grandkids while experiencing severe systemic muscle atrophy!

It’s good for satiety. Younger and older men eating 1g protein per kg of bodyweight had greater satiation than similarly aged men eating either 0.75g/kg or 0.5g/kg, and they reported a superior ability to stick to an eating plan.

(Animal protein is best, of course. A recent study found that due to reduced bioavailability of plant protein, vegetarians should probably increase their total protein intake to make up for the deficiency.)

Most people don’t need a ton of protein. If asked, I say I eat roughly 1 gram per pound of bodyweight, but it’s not something I’m militant about and I’m no longer hitting the weights like I used to. I just eat to satiety. Since it’s a satiating macronutrient, I find there’s a natural, relatively organic limit to how much pure protein I even want. Lean chicken breasts? I’m lucky if I can get through a whole one. A nice juicy grass-fed ribeye festooned with fat? I’m licking the plate.

Other people will need more protein. Highly active athletes, Crossfitters, powerlifters, folks trying to gain mass and strength, folks trying to lose a bunch of weight – they all can benefit from an increased protein intake, either by increasing satiety (thus improving diet adherence) or providing amino acids for muscle recovery and repair. One gram or protein per pound of lean body mass is a good average number to shoot for over a range of a few days.

Renee, if you’re feeling good with your current level (how much protein are you eating, by the way?), you’re performing well, you’re lean (and you apparently are), and you’re healthy (free of diabetes and hypertension), I don’t see any reason to curtail your protein intake. And certainly not because it’s going to destroy your kidneys. There is some contention that protein restriction (or protein cycling) can extend lifespan, but as I said in the fasting post, I’d rather have a fantastic quality of life (which for me means plenty of lean mass, plenty of physical activity, and plenty of meat on my plate) than live a few extra, protein-restricted years.

I hope this proves helpful for your situation – though I’d hesitate to even classify it as a real “situation.” I wouldn’t worry.

How about everyone else? How much protein do you typically eat in a day? What’s your activity level like? Ever had any kidney problems?

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. I just figured out that I only need 65-93 grams of protein which I figured is only 2 1/2- 3 oz per day. Here I was thinking I was not getting enough protein but 3 oz of meat throughout a whole day is not much at all. I have to refigure my proteins so I can have faster results! So far, I am liking this way of eating and really enjoy your Quick & Easy cookbook esp grated cauliflower! Thank you!

    Line wrote on May 3rd, 2012
  2. That first paragraph had me laughing out loud. Thanks Mark! 😀

    Cristina wrote on May 8th, 2012
  3. Hi Mark

    I read this post with interest having caught a programme in the UK on BBC2 last night Horizon-about fasting.

    It suggested that research was showing that calorie restriction had an impact on increasing life span but that it also impacted on the growth hormone IGF-1 which was attributed to age-related diseases such as cancer and diabetes. High levels of IGF-1 could indicate that a person stood a higher chance of contracting these age-related diseases and that limiting protein intake was also crucial in this. As a relative newbie to the Paleo way of living I struggle to maintain my protein intake to anything lower than 70g a day. I exercise 5-6 days a week running, weights, HIT training and walking or dancing. :) I’m 113lb so on evidential basis i should be consuming a lot less than this in order to maintain a healthy lifestyle. However i think i’d struggle hugely to lessen my protein intake and maintain saiety but i’m concerned about the impact my current levels might have on my long-term health.

    What’s your take on this research? I’d love to know.


    Tracey wrote on August 7th, 2012
  4. My trainer and I were talking about this today. I used to be all about the protein when I was training for contests but that all stopped because of two genetic diseases: Ehlers Danlos and Polycystic Kidney Disease. I have been struggling for almost two decades with this. What are your thoughts since I have a genetic kidney disease (and I have had some problems in the last decade with stones, infection) and a connective tissue disease where my tendons and ligaments tear and rupture easily. I’m torn about animal protein. There is so much conflicting info and it goes against kidney diet guidelines. but I’m all about breaking the rules if it makes sense! Thanks for your thoughts!

    deborah wrote on February 11th, 2013
  5. Are you capable of manual me for your website owner or even the man who looks after your site, I would like to know if it might be possible to be described as a guests poster.

    using skips for work wrote on April 9th, 2013
  6. Well, I am actually concerned that my protein intake may have been affecting my kidneys. No, I am not obese, my BP is perfect etc, perfect health except…
    – two of my teeth have broken off by themselves (no tooth decay), just “weak”
    – I get muscle cramps (more like fasciculations)
    – I eat animal and vegetarian protein, mostly eggs and fish, some nuts also lots of veggies and a small amount of fruit
    – no gluten – only the odd 1/2 wholemeal pitta bread as a “treat”

    My last set of blood tests showed some strange values relating to kidney function, such as low phosphatase and high phosphate (plus a sex hormone binding glubulin (SHBG) level which is 3 times as high as it should be: high SHBG is a problem often reported by bodybuilders).
    I then looked up phosphate food sources only to find out virtually everything I eat (except vegetables) are high in phosphorus. Most high protein foods are high in phosphorus, so I can see why they would think that high protein diets may harm the kidneys.

    Body-builders have been eating high protein diets for decades, but then I know of several who died at 40 (though some other factor may be to blame here, such as steroid use). However, I have never seen any statistics on this. I wonder why?

    I know paleo is not about packaged foods, but there is undoubtably a protein-based industry out there, using the lure of the benefits of protein to sell their rather artificial wares.

    I am now not sure what to do about my strange blood results and I worry that my teeth and bones are at risk. Doctor has been unable to help.

    Has anyone had any issues with their kidneys? While this article addresses “protein and healthy kidneys”, can anyone be totally sure their kidneys are 100% healthy? My kidneys have always been healthy, I have no known condition, though approaching 50 and female. According to traditional Chinese medicine, women around my age tend to be low in “kidney energy”, if that kind of thing makes sense to you.

    Please read with an open mind. I read everyone’s comment (and the main article: thank you for it and for the many useful references) and respect everyone else’s opinion.

    Health and vitality to you all.

    cis wrote on April 24th, 2013
  7. Just came across this post–yes I know it is old. However, just wanted to throw it out that I have been Paleo (a few cheats here and there) for over a year. I have more than tripled my protein intake from what it was a short two years ago. I have recently due to age and family history had a complete physical with a colonoscopy and mammogram. Every single test came back with ideal results. I am soon to be 45 and feel I have not been this healthy since I was a kid. And I have become a bacon lover.(always uncured though) Cheers! 😉

    Terri wrote on May 1st, 2013
  8. It really worries me that so many of your readers think a high protein diet is beneficial. In all seriousness, you can laugh at vegans and think big muscle bound men are “hard to kill” but you cannot change science. Hundreds of studies, which are all available for you on Pubmed, confirm that high protein diets raise your IGF levels which drive cancer. And certainly you have got to know by now that protein excess is the main cause of heart disease. Only a “caveman” would deny these truths. But good luck with your few good years. By the time you all reach 60 you’ll be dropping like flies. Hope you have good insurance. Cancer drugs are expensive.

    Amanda wrote on May 2nd, 2013
    • Are you so mean because you are so hungry?

      Colleen wrote on May 2nd, 2013
  9. I Delimaris (2013) Adverse effects associated with protein intake above the Recommended Dietary Allowance for adults ISRN Nutrition, vol. 2013, Article ID 126929, 6 pages, 2013. doi:10.5402/2013/126929

    Ramya wrote on August 10th, 2013
  10. Mark,
    Thank you for this article! I am concerned about my kidney health because I donated my left kidney to my sister-in-law on 11/13/13. I have been paleo since the beginning of March.

    My creatinine level on 12/3/13 was 1.23 and on 4/29/14 it was 1.41.

    When I go to my 6 month post-donation checkup, the doctors are not going to be happy with my lifestyle choice or the fact that my creatinine has gone up. Should I limit my protein?


    Jackie wrote on April 30th, 2014
  11. Hello iam using your information for my research paper. thanks

    Dalton wrote on May 9th, 2014
  12. Very good info. Lucky me I recently found your website by accident (stumbleupon).
    I have saved as a favorite for later!

    Ernie wrote on July 9th, 2014
  13. Here is an interesting article ; Ioannis Delimaris, “Adverse Effects Associated with Protein Intake above the Recommended Dietary Allowance for Adults,” ISRN Nutrition, vol. 2013, Article ID 126929, 6 pages, 2013. doi:10.5402/2013/126929 @

    Pat wrote on August 5th, 2014
  14. I think the admin of this web page is truly working hard in support of his web page, as here every material is quality based stuff.

    Rosa wrote on August 15th, 2014
  15. For those looking for pasture-based organic meat (lol…not Karla, but maybe some of you), but don’t like the hassle of procuring it, here’s what I use:

    Just choose your state. I like not having to go to the farm, or to a drop off location. Some places don’t deliver, but the farm I use, in Tennessee, packs plenty of ice packs into a boxed cooler, and ship to anyplace within a 2 day radius. My meat arrives solidly frozen, and is soooo tasty! Thanks, Mark Sisson, for finally motivating me to spend the perhaps $2/day extra (for just me), over supermarket Frankenmeat. It was the only really important thing I wasn’t doing, as far as eating healthily, and primally. Over $150, and the shipping is even free. I wish I’d done it years ago.

    That’s for my beef. I found another farm, 27 miles away, also in Tn, for pork, milk, and eggs. They want $10 shipping, or free, over $100. But since they butcher in my town almost every week, one or the other of the owners will drop my smaller (usually around $60) order off at my house for free. So if you look around that site, almost all people can find producers that suit their needs.

    I’m 5’9″, and in 7/11 I weighed 187. Following Mark Sisson’s “diet for health”, as I think of it, as opposed to a reducing diet, in 1/13 I weighed 137. With minimal exercise (walking, pushups, toe raises, and knee bends), I gained a little muscle, go about 145, and am never hungry. The better diet, itself, may have added some of that new muscle. In 2 months I’ll be 65, and I feel better than I have in at least 25 years.

    Thank you Mark!

    James wrote on December 31st, 2014

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