I've been reading about protein shakes, it's benefits and side effects. However i've used it many times as my post workout recovery drink.

I have no doubt in the benefits i get in my protein shake, i gained mass ( i was a skinny guy back then) , and i'm not talking about fat mass, i gained muscle, Now i've read that protein shakes actually damage the kidneys and the liver since the body cannot synthesize the protein very well.

This article i've read says it damages the kidney and liver:


But other articles suggest that protein only damages more those persons who have already pre-damaged their kidneys, in other words it only worsens it , but does not cause the damage itself.

Because of conflicts in what i should believe in. I'd like to ask from you, who have experienced drinking protein shakes, probably long term or short term. How true are these side effects? And can you mention how long have you been taking protein shakes?and your experiences on this. Thanks!

  • Questions about Nutrition are off topic according to the help center. You might be interested in the Nutrition proposal on Area51, though.
    – Baarn
    Oct 31, 2013 at 10:38
  • Protein: How much is too much?
    – Baarn
    Oct 31, 2013 at 10:39
  • 2
    Question: are we talking about healthy people, or people with renal problems because the answers are completely different. Oct 31, 2013 at 12:30
  • @Berin, very true. However, apparently healthy people may have early kidney dysfunction without knowing it. Accd'g to the NIH, "kidney disease often has no symptoms until it is very advanced." Certain populations are at higher risk for kidney disease (HBP, family history, diabetes, age etc.). So the better question may be, are we talking about healthy people, or people at risk for renal problems? Oct 31, 2013 at 22:41
  • healthy people of course! and @Baarn , this might be a nutrition question, however, i figured i'd find body builders here who have used protein shakes, and thought i'd find more sensible answers here.
    – muffin
    Nov 4, 2013 at 2:04

7 Answers 7


Some quick research returned the following articles:

Who Knew Preventing Kidney Stones Was this Easy?

"In the 1990s when the Atkins diet reached huge popularity, critics claimed that high
protein intake leads to kidney stones. This turned out to be a complete myth, but the
misinformation is still being circulated.

Although protein restricted diets are helpful for people who already have kidney     
disease, eating meat does not cause kidney problems[7]. Furthermore, the fat-soluble 
vitamins and saturated fat found in animal foods are pivotal for the proper functioning 
of your kidneys."

High Protein Diets: Separate Fact from Fiction

"The claim that protein intake leads to kidney stones is another popular myth that is         
not supported by the facts. Although protein restricted diets are helpful for people 
who have kidney disease, eating meat does not cause kidney problems (10). Furthermore, 
the fat-soluble vitamins and saturated fatty acids found in animal foods are pivotal 
for properly functioning kidneys."

Cons Of High Protein Diets

  • Look at the header titled - Possible Kidney Damage

I have concluded that while consuming a large amount of protein daily -

  • Not drinking enough water can cause kidney stones
  • Genetic deffects can make stones more likely
  • Not eating healthy, not getting enough fiber
  • Some research suggested that: Large amounts of protein while cutting out carbs may increase risk of kidney problems. (Again, the previous points may prevent this)

My Personal opinion - I think that if you maintain a healthy diet and drink PLENTY of water you shouldn't have any problems. I'm at about 300 grams of protein a day which includes 12oz of chicken, salmon, peanuts, 2 whey protein shakes, a mass gainer shake (50g of protein) and a casein shake. I have been on this diet for 3 months now and haven't had any issues.


I've been using protein shakes for a few years, not daily but perhaps 3 times a week after heavy weight training (as opposed to after cardio, for example). I was told by a personal trainer many years back that people do damage their kidneys because they use excessive amounts. He said it's usually those entering competitions that have the mindset of "if HE is taking one scoop, I'll take TWO and get bigger faster". Your kidneys can't cope with excessive amounts.

My experience of a few years has, as I said, been to use it a few times a week after heavy weight work and always the amount recommended on the box.

  • We should eat our protein and not drink it. I'll keep my money away from the supplement mafia. I'm speaking as someone who used to drink 2 N-Large2 shakes a day - in my younger days - for about 3 years straight. Jan 17, 2014 at 16:17

@muffin, the responses from Dan Andrews and backinshapebuddy are the most important things to continue.

From personal experience, the signs of kidney damage really are that subtle that you'll think you are healthy until your kidneys have finally had enough. Also, the foods you eat most likely have more than adequate protein. I was active, ate relatively well, and was pretty fit. However, lack of portion control and too many protein shacks overworked my kidneys causing the damage you're talking about. This was between high school and college, so it was really unexpected.

The problem is mainly consuming too much protein which is very easy to do. Most foods naturally contain more protein than you'd expect per serving. If you live in the US or similar countries, the portions you're used to eating can be multiple servings. The same goes for drinks. Most serving sizes are an 8 ounce cup, but most glasses hold much more than 8 oz. So, you might be getting even more protein through shakes, milk, etc than you think.

Typically, it's recommended that bodybuilders get ~1 to 1.5 grams of protein per kilogram of body weight. Again, that's kilogram not pound. So, for a 160 pound person that would be about 73 to 109.5 grams. Depending on your level of activity, you'll probably only need that 73 which is really easy to get.

I'd suggest limiting the shakes to days when you actually lift. And even then, just one shake tops. And of course, see a doctor if it really worries that much. A general practitioner could probably order you blood work and refer you to a nephrologist if there actually is a problem.

*Edited: you can have kidney damage without ever getting a kidney stone!!! I have never had a kidney stone in my life, yet my kidney function is extremely impaired. I'm not so bad that I have to be on dialysis, but I have to closely monitor my diet to prevent it from getting worse. it won't get much better, but if I monitor my diet(which sucks) I can avoid dialysis and kidney transplantation(which would suck worse)

Tl;dr: It's very easy for bodybuilders to ingest too much protein. Lots of steaks, chicken breasts, plus protein can be overkill if you don't monitor your portions. See a doctor if it really concerns you.


I am a doctor, I have studied different causes of renal failure but supplement proteins were not amongs them I have used different protein supplement for the past couple of years and I am not concerned abou it. But if sombdy who already have a kidney problem should avoid it bcs it may aggravate their problem. Keep drinking keep drinking keep drinking plenty of water alongside your protein.

  • 1
    It's hard to take you seriously when your answer has 8 typos in 4 lines, doctor. You might want to revisit that. Other than that, I totally agree.
    – user8119
    Apr 19, 2014 at 12:06
  • 2
    @LarissaGodzilla - Tell you what, try typing your comment in Hindi or whatever language this person considers native and see how many typos you come up with.
    – JohnP
    Apr 20, 2014 at 16:40
  • @JohnP: I'm not one to call out the occassional typo, we all make mistakes. But come on, eight typos in four lines? 'bcs', missing the full stop between sentences? That person didn't read this text once before sending it. That's what I'm calling out, not the typo.
    – user8119
    Apr 20, 2014 at 17:19
  • But that's what you would expect from a typical overworked doctor. Jun 24, 2015 at 14:56

Can eating too much protein be bad for you?

Answered under the premise that protein shakes are a direct protein supplement to diet, ignoring their detailed composition and basing answer on the above title. As with ALL supplements, read and understand the ingredients list and what makes those ingredients up. Look for full disclosure of ingredients on the labels and you can always check most supplements on labdoor.com.

Click the next link for a comprehensive answer tailored to Whey Protein

Healthy kidneys

When looking at active male athletes and measuring urinary creatinine, albumin, and urea no significant changes were seen in protein dosage ranges of 1.28-2.8g/kg bodyweight.2 The aforementioned study lasted 7 days, but survey research supports this lack of association (in post-menopausal women). 2

Too much, too fast

There do appear to be functional changes in the kidneys related to protein intake [4]. As protein does modulate renal function,[5][6] these interactions may lead to damage if imposed acutely onto mice (from 10-15% of the diet, up to 35-45% of the diet immediately)[7][8] and one study in healthy humans going from 1.2g/kg to 2.4g/kg (doubling) was associated with higher than normal blood values of protein metabolites; a trend was noted for adaptation (increasing GFR) but it was not enough to clear uric acid and BUN over 7 days.[9]

These studies are likely indicative of a 'too much, too fast' situation, as controlled changes do not lead to adverse changes in kidney function.[10] Thus, it would be prudent to slowly change protein intake over a moderate length of time.

Damaged or unhealthy kidneys

Restricted protein diets are recommended for those with kidney damage, as it slows the seemingly inevitable progression of kidney damage.[11][12] If protein was not controlled for in those with renal damage, it would accelerate (or at least not reduce) the decline in function.[3]

The role of the Kidneys

Kidneys can acutely increase the Glomerular filtration rate (GFR), or the rate of filtration of the blood. They do this in response to dietary protein intake[13], and the lack of this compensation in some forms of kidney damage are a reason protein intake is controlled for in kidney disease management.[14]

Additionally, the kidneys serve to regulate acid-base balance in the body via the sodium-bicarbonate buffering system.[15] Disorders in acid:base balance can further pathophysiology (symptoms and signs of the disease) of renal complications.[16][17]

These protective measures appear to be preserved in healthy kidneys, but begin to fail when they kidneys are otherwise damaged.

In Summary:

Don't worry about it if you have healthy kidneys and control your protein intake if you have damaged kidneys. It may be prudent to gradually increase protein intake to higher levels rather than jumping in both feet at a time, but there isn't much on this topic.

It is generally recommended to consume more water during periods when protein intake is being increased. Whether or not this has biological basis is not known, but it may be prudent to do


Major: Examine.com


  1. Poortmans JR, Dellalieux O Do regular high protein diets have potential health risks on kidney function in athletes . Int J Sport Nutr Exerc Metab. (2000)
  2. Beasley JM, et al Higher biomarker-calibrated protein intake is not associated with impaired renal function in postmenopausal women . J Nutr. (2011)
  3. Knight EL, et al The impact of protein intake on renal function decline in women with normal renal function or mild renal insufficiency . Ann Intern Med. (2003)
  4. Brändle E, Sieberth HG, Hautmann RE Effect of chronic dietary protein intake on the renal function in healthy subjects . Eur J Clin Nutr. (1996)
  5. King AJ, Levey AS Dietary protein and renal function . J Am Soc Nephrol. (1993)
  6. Dietary protein intake and renal function
  7. Wakefield AP, et al A diet with 35% of energy from protein leads to kidney damage in female Sprague-Dawley rats . Br J Nutr. (2011)
  8. Aparicio VA, et al Effects of high-whey-protein intake and resistance training on renal, bone and metabolic parameters in rats . Br J Nutr. (2011)
  9. Frank H, et al Effect of short-term high-protein compared with normal-protein diets on renal hemodynamics and associated variables in healthy young men . Am J Clin Nutr. (2009)
  10. Wiegmann TB, et al Controlled changes in chronic dietary protein intake do not change glomerular filtration rate . Am J Kidney Dis. (1990)
  11. Levey AS, et al Effects of dietary protein restriction on the progression of advanced renal disease in the Modification of Diet in Renal Disease Study . Am J Kidney Dis. (1996)
  12. [No authors listed Effects of dietary protein restriction on the progression of moderate renal disease in the Modification of Diet in Renal Disease Study . J Am Soc Nephrol. (1996)
  13. von Herrath D, et al Glomerular filtration rate in response to an acute protein load . Blood Purif. (1988)
  14. Bosch JP, et al Renal functional reserve in humans. Effect of protein intake on glomerular filtration rate . Am J Med. (1983)
  15. Skelton LA, Boron WF, Zhou Y Acid-base transport by the renal proximal tubule . J Nephrol. (2010)
  16. Yaqoob MM Acidosis and progression of chronic kidney disease . Curr Opin Nephrol Hypertens. (2010)
  17. Kraut JA, Madias NE Consequences and therapy of the metabolic acidosis of chronic kidney disease . Pediatr Nephrol. (2011)

This is a myth from 30 years ago when it was discovered that eating more protein increases GFR, rate of blood filtration through the kidneys http://www.ncbi.nlm.nih.gov/pubmed/6650549

But just because GFR is increased doesn't mean that anything is happening to the kidneys, some studies go as high as 3.1g of kg without any side effects on the kidneys http://www.researchgate.net/publication/257350851_A_Systematic_Review_of_Dietary_Protein_During_Caloric_Restriction_in_Resistance_Trained_Lean_Athletes_A_Case_for_Higher_Intakes


Well I can't answer for sure and it cannot be concluded. After being on Protein supplements for 2 years I developed issues with my Lever including fatty lever/inflammation and a failed SGPT report. I don't drink Alcohol/Smoke or use Tobacco. For me this was a accidental finding and I am on many medicines now and hope to recover 100%. My liver was all well 2 years ago. My Doctors have advised me against using Protein shakes. I have been very conscious of what I eat all my life so there is little opportunity to suspect anything else that might have caused it. Now I am in the process of losing all muscle that I made with these shakes :-)

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