I keep seeing outdated information about the effects of a high protein diet on kidney health. Just because it's inconvenient news doesn't mean we should act like it doesn't exist. Over the last 5 years multiple studies have shown High protein diets are rough on the kidneys over the very long term.
This is an extremely simplified explanation of what the most recent research is showing, to my best understanding:
Forcing your kidneys to work at their maximum "Filtering" capacity, for any reason, very very slightly damages them. Processing a crap load of protein is a quick way to make them work at 100% capacity. Do this over the course of many decades and that tiny tiny amount of damage adds up.
@kpatrick1111 Definitely open to hearing both sides of this however the main issue is the measurement criteria in these studies. They use eGFR calculated by creatinine.
The problem with using that in our population is that we regularly engage in activities which artificially increase creatinine such as:
Lifting weights
Having high levels of muscle mass
Eating a lot of protein
Sweating. Hydration can effect this too.
However that doesn't necessarily mean your kidneys are damaged. For example a friend of mine accidentally scheduled his blood test after a leg day, his creatinine was over 200. Within the next test it was back down to the normal range.
Cystatin-C test is a much more accurate marker for our population as it doesn't rely on creatinine levels, which are very commonly high in our population.
If you are worried about a poor eGFR calculated via creatinine, take a Cystatin-C test to be sure. You can also get a kidney scan.
@buna eGFR measured with creatinine has a huge blind spot - unless it's down by 50% your lab result is normal. So they always freak out if it's out of bounds. And the e stands for estimated, they don't measure directly. You would need to compare serum and urine levels, they are just assumed, often not even adjusted for height, weight.
I always tell my doc that I supplement with creatine and need the cystatin test. Some labs even do this automatically if the first result is out of bounds.
@buna I’m not the most muscular but had the same issue. Lift weights, take protein and creatine. Went to primary, elevated creatinine and mildly decreased gfr. Went to nephrology who said it was a common error due to weight lifting/ muscle mass. Ordered a cystatin c which was entirely normal and told me not to come back
@buna "They use eGFR calculated by creatinine." "The problem with using that in our population is that we regularly engage in activities which artificially increase creatinine" This does make analyzing fitness prone people more difficult. These studies are not only looking at active lifestyle people though.
The studies referenced in the Meta study are not only looking at eGFR calculated by creatinine. If you look under the "Outcome (HP versus LP)" in Table 2 you'll see many of the studies tracked through Cystatin-C and Albuminuria, in addition to Creatine Clearance. It's a pain, but If you go into the individual studies for Table 1 you'll see many of them didn't rely solely on Creatine Clearance as well(Full disclosure I only checked 3 of them, but they didn't rely on only CC).
@buna This needs to be stickied for anyone getting into weight lifting. Even mild lifting with protein intake will raise your creatinine and throw off your eGFR.
@buna I skimmed through the first study and the measurement criteria was definitely something that stood out. There was also the fact that even in the worst case scenario the odds ratio is not that high. The intake of sodium/carbs/overall energy was also much higher in the high protein quartile. It is definitely statistically significant but not something that is going to have me shaking in my boots. Then you look at the adjustment model and it practically stabilizes the odds ratio.
I sometimes have moments of going overboard with my protein intake and I have been doing this for decades. I don't necessarily think that the extra protein will help but those are the foods I have come to enjoy. I get tested regularly and have never had any signs of kidney disfunction or deterioration. The best thing we can do is make healthy choices and get tested regularly allowing ourselves to review our overall health status. I'm not going to stop eating protein because some study shows a statistically significant but low risk.
@buna Omg omg, Faz himself! One of my favorite content creators. Thank you for everything!
On topic: i do general bloodwork at least every 6 months. They call me on phone before sending the results that i urgently must go to a hospital as i am near liver failure. Every. Single. Time. And i answer that i am a powerlifter. Every. Single. Time. And i hear the penny dropping on the other side of the line so loud it hurts my ear. Every. Single. Time. And they of course dont make a note anywhere of this. Any. Single. Time.
@kpatrick1111 People with impaired renal function need to be on a renal diet, including limiting nitrogenous products such as proteins.
Limited research does show very high protein intake can impair renal function over the long term in people with otherwise healthy renal function.
Unfortunately, you’re on a body building sub and they will not heed the advice and they will disregard the research. To be fair, the research on people with normal renal function isn’t exhaustive as it is in people with chronic renal disease.
@laura02375 That's one of the studies I linked, just from a different host.
I still consume a ton of protein everyday. I just think people should make their own informed decisions.
Edit:I just did a quick skim to see what they considered as a "High protein diet" in that study. I didn't pick out every other study they referenced, but the 2 examples I first saw were "25% of daily caloric intake", so ~125g protein/ day and "there is a lack of consensus regarding the formal definition... most definitions set a threshold between 1.2 and 2.0 g/kg per day"
@laura02375 I was thinking about that when I wrote it last night. After thinking it through I'm not so sure that's how it works, but I'm really not an expert. Eating 5000 calories a day would be putting 312g protein through your system a day at 25%. Eating 1500 calories a day would be putting 94g protein through your system a day at 25%. There's no way those two amounts, 312g & 94g, stress your system the same amount, even though they both are 25% of your daily calories in protein.
Realistically the 25% is probably just a quick estimate for people that don't fall to the high or low calorie intake extremes.
@loida Actually protein does only have 3.2 cals per gram, so dude isn't wrong. The reason we live by 4 is the Atwater factors of metabolizable energy. These numbers are based on heat production and not based on our body's capacity for energy expenditure.
However, the original 4 cal/g is kept out of simplicity and it would be very challenging to literally change the entire system at this point.
