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. Mark from your previous response to “”Renee — 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 read you and understand/believe that meat is good for you and a limited (???) amount will probably to certainly not hurt healthy kidneys. What, if any, is the limit for one MASSIVE meal of meat? For example I have been on the Atkins diet before (20 lbs lost) and hear/read that one/dieters can eat ALL of the “no = none = zero carbohydrates” such as plain cooked beef meat one wants. Hence, after days of hard work on travel with no common home food, I did eat (not proud of this Lion behavior) 2/two HUGE/MASSIVE > 1″ OR MORE thick layers/SLABS (rare & solid – tiny fat if any) of prime rib at one meal. — Perhaps unrelatedly, 2 days after my return home and constant long hours of work at home, I (“in slow motion then suddenly/boom”)came down with a VERY near fatal bladder, urinary tract, and maybe kidney(?) infection that required emergency intubation and two weeks of hospitalization to cure. Diagnosis was complicated by emergency treatments to save my life as well as 3 powerful antibiotics and so — I was told by Drs that I probably “”developed sepsis”” — from this initial bladder>kidney>infection>heart failure, etc.. I am 74 obeise, slightly elevated
    BP, normal pulse, 274 lb active male but am somewhat sugur intolerant – but not dietetic yet = average of 120 “plasma calculation” blood sugur for years. Obviously now I am carefully reducing my weight and eating smaller portions of meat. Could there be/have-been a link to HUGE PORTION of prime rib & my bladder infection = probably by e-coli (suspected culprit)?? — And the answer for maximum limit on meat intake at one time is_______? Thanks for whatever answers or comments that you can provide. Colin

    colin sandwith wrote on March 5th, 2011
  2. I’m also very lean, about 5 ft and about 105-110lbs.

    I don’t count my protein. I just eat real food, eggs, fatty cuts of meat, green leafy vegetables (spinach, broccoli, cauliflower, etc). If I need to eat more, I eat more food: meat, eggs, veggies. It’s that simple.

    If I had to estimate, it’s about 1.5 grams or ~ 150 gr protein every day. According to fit day: 2088 cals, i feel like i need to eat more though

    Chris wrote on March 6th, 2011
  3. Phenomenal article – thank you, as a national natural NPC figure competitor, I’m eating each day for my competitive goals year round & I’m as healthy as can be naturally headed to 40, yet the amount of protein my husband and I consume is significantly higher than the average person, and yet our health is significantly better than most as well from the inside to the outside. It’s upsetting to me that protein intake is so demonized and grossly misunderstand. Our coaching clients are always shocked at the protein & fat intake we give them for weight loss in meal plans. I absolutely love your work, Mark. Great stuff. Thank you. What’s misunderstood about protein is you can take in higher amounts safely, it’s what sources of it you take in and what you counterbalance that intake with nutritionally with other macros to ensure great health that is key to effectiveness.

    Heather Dube wrote on March 6th, 2011
  4. Thanks for the informative article.Few studies have claimed that too much pressure pressurizes the kidney too much and in long run, may damage it. A recent study published in the Annals of Internal Medicine revealed that too much of protein does not harm women with normal kidney function, though it may have a negative impact on women suffering from reduced kidney function.

    Albert wrote on March 7th, 2011
  5. Along with the study Albert points to in the above comment, Renee may be interested in this one from the Journal of the American College of Nutrition: Dietary Protein: An Essential Nutrient for Bone Health (

    I’ve been researching the topic for my own blog… a higher protein diet has been found to increase bone mineral content in animals, and to increase IGF-1 growth factor (which promotes bone growth) in men and women.

    Interstingly, in men, a hormone released from bone cells promotes testosterone production and is associated with testosterone levels, sperm count and reproductive success.

    The same effect of osteocalcin on women’s estrogen/fertility levels has not been found yet, but interesting stuff!

    Mark Anderson wrote on March 8th, 2011
  6. Appreciate the high quality article you have out here. Really helped me out!! keep it up.

    Sheldon wrote on March 11th, 2011
  7. Kidney failure is a frequent effect of taking medical drugs. They euphemistically call it “side effect”, while in fact it is the basic effects, related to what drugs are. These are synthetic chemicals that kidneys have to remove from the blood, and in fact a percent of them gets into urine, polluting rivers.

    Tomasz R. wrote on March 17th, 2011
  8. I started drink protien shacks about a month ago everyday, and beefed up my 5k run to 5 times a week, I had developed shin splints and had to get new shoes and stop running for 3 days I woke up the 2nd day and It was like a bomb when off in my stomach, i started loosing weight like crazy, I thought I had food poison or tape worm. I got a feavor and starting to gorge food 4 one day. I laid down and slept 4 awhile, while googling everything, i came up with 2 much protien burning fat so fast, I would eat and fell real hungry and my stomach would hurt burning my food instantly. I feel back 2 normal now and going 2 do it again.

    John hudson wrote on October 3rd, 2011
  9. I just wanted to thank Mark for the post. I have been primal for about 100 days and like Renee feel better than ever! More important MDA has provided for such great content and answered almost everything I have a question about, like this one about too much protein being hard on kidneys, there is an answer for it right here. My wife is 7 weeks pregnant and she asked the mid wife today about our primal lifestyle. She’s pretty well stuck with it since I’m not leaving my homeostatic, high energy lovin,, no mood swinging and cross country traveling without eating any crap in the airport from one coast to the next while I fast and feel fine, since I am the cook in the kitchen. Any how, I digress, the point is that the mid wife said that the high protein, low carb diet could be hard on the kidneys in general not necessarily on the baby, but I had to check MDA before I allowed my wife to convince me that I needed to start using bulgur wheat or some other form of “better for you” gimmicks.

    Since finding my inner grok I’d like to add that I am no longer allergic to avacados – which historically I loved, but hated the itching in the back of my throat after eating & my wifes Asthma and use of an inhaler from 3-5 times a day has been reduced to once every other day if that.

    I don’t want to leave out the daily deuce, which having since starting the diet I no longer hate to have. I know the MDA crowd can handle this so I’m dropping the deuce so to speak!

    Seriously, it’s perfect almost every time. I would solely suggest based on my experience that any IBS could easy be traced back to gluten/wheat intake. Perhaps there’s more posts more appropriate to drop this, I just haven’t looked for it.

    I also find myself so impassioned to talk more about the overall MDA subject once I get started. So much that it’s probably annoying – oh well!

    Grok on!

    Michael wrote on October 24th, 2011
  10. I had severe kidney reflux as a kid, and chronic kidney infections, I know what pain in the kidney feels like. I have been eating paleo for a few months (not perfectly, I have to admit) and since yesterday I’ve been experiencing pain in one kidney. I have zero symptoms of an infection, though I will be seeing the doctor to make sure. In the past few days I have been eating even more protein than I had been previously. Is there ever a point where a person would consume too much protein? Or could I take in a million grams a day (I know, I know) and experience no ill effect?

    Shannyn wrote on March 30th, 2012
  11. 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
  12. That first paragraph had me laughing out loud. Thanks Mark! 😀

    Cristina wrote on May 8th, 2012
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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
  18. 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
  19. 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
  20. 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
  21. Hello iam using your information for my research paper. thanks

    Dalton wrote on May 9th, 2014
  22. 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

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