To my eyes this seems like just another reductive click-bait headline. Our bodies have exquisite algorithms to deal with excess protein (e.g., excess protein is slowly and inefficiently turned into glucose). Protein is vitally important to our body’s many structures, and as we get older we absorb less and less of the protein we ingest anyway.
What would seem far worse would be to be eating tons of carbs and sending yourself into metabolic dysfunction (ending up with T2 diabetes, etc.). However even an excess of carbs can be managed with an active lifestyle.
There are so many factors in atherosclerosis, I’d like to know how an unquantified bump in mTOR activity compares with having excess insulin circulating in one’s body every day. Add to that the fact that high-protein foods are some of the most nutrient-dense, least processed foods available, and I won’t be lowering my protein intake anytime soon.
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Arhu
#22
Even more than leucine carbohydrates stimulate mtor but unlike leucine carbohydrates rot your teeth and don’t build muscle beside that ITP aleady tested leucine and found no effect either good nor bad on lifespan but then again humans are not small mice living in safe laboratory cages but we are large mammals in a world where trips and falls kill
And here is low protein advocate Dudley Lamming top right with the blue t-shirt
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Arhu
#23
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This is yet another study where “high protein / low carbohydrate” kinda isn’t.
Nutritional breakdown of the smoothies (high versus low protein)
High protein drink nutrition: 500 kcal per serving, 50% protein, 17% fat, and 36%
carbohydrate.
Low (standard) protein drink nutrition: 500 kcal per serving, 10% protein, 17% fat, and
73% carbohydrate.
I would not describe a diet with 36% carbs as low carb. You have to be under 25% or better yet under 10%.
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JKPrime
#25
The argument goes that we need to intake extra protein because unlike lab animals we need to build larger muscles and are exposed to pathogens, etc. Hence, large muscles are somehow healthy and desirable. Further there is this assumption that if we build large muscles in our thirties and later, we will be able to maintain them in our old age and have them available when we become sick and bedridden. In my opinion, there is no solid proof for this strategy. Instead I think that one needs a simple daily exercise routine routine to maintain health and muscles. Such routine may not require to have any access to the gym. You should be able to do this routine when you are 30 or 70. With respect of protein you just need enough to maintain your muscles and keep yourself lean. I would be very careful in taking in extra proteins as the link to cvd is just too troublesome to ignore.
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Things that are potentially bad for your heart: carbs, protein, fat
What macronutrients are we left with 
?
Its been a long time since I looked at the Leucine data from the ITP. It seems there was a small decrease in lifespan in the male mice with higher leucine intake, but perhaps not statistically significant:
Interestingly, the reverse is true in females:
Source: MPD: ITP survival analysis: L-leucine
I will also add, that while nobody would ever accuse Dudley of being athletic, that really doesn’t have anything to do with the validity of his scientific arguments, or the quality of work from his lab.
Also, a question for those who have studied this area more than I. I know that its muscle strength that is important in longevity (not just bulk/size). Is there the same relationship of Leucine intake and strength of muscle, as there is with bulk/size of muscle? Is leucine’s benefits in muscle the same (and same magnitude) for both strength, and for bulk?
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adriank
#28
It is not the percentage. It is the quantity.
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bobo
#29
If you look at the diets/protein intake of people that live in the “Blue Zones”, where many people live to be 100 plus, what do you find? The inhabitants of these zones eat little or no meat. It’s one of the Blue Zone common denominators. On a no meat or fish diet there is no way of reaching the protein levels that Attia suggests. I’m a vegan and supplement 25 grams of rice and pea protein twice a day. When you mix the two you get a complete protein profile. I started the protein supplement as a result of reading Outlive, Attias book. 50 grams plus maybe another 25 grams or so in food. If I consumed protein in Attia amounts I probably would never stop throwing up. I’m certainly not wasting away, and apparently neither are the Blue zone inhabitants.
I have been intermittent fasting for about 4 years. I eat from 11AM to 4:00PM or so. I’m 75 years old, 5’10" 245 pounds. And I exercise.
I also think the high protein/fat/suger American diet is Looney Tunes!
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I’m on a high protein diet (and animal protein mosrtly), and i am regularly lifting heavy. But i also try to water fast for days every 1.5-2 months (specifically for autophagy). In fact i just ended a four day fast, and my last one was in mid-Jan. So this may help with the misfolded and glycated proteins floating around.
I guess I’m “on the protein train” as Woody Allen or Groucho Marx quipped. But I’m not closed-minded and i know everything comes with tradeoffs — massive tradeoffs I’m trying to build muscle and lower my overall cancer risk with low carb and fasting. But I’m also aware there are likely tradeoffs such as saturated fat and methionine. I’m hoping i make the correct guess and don’t take two steps back for every step forward, but its a risk.
I’m a believer in the centenarian olympics philosophy, as i watched my father suffer sarcopenia for years. If you saw what i saw, you’d drop everything and head to the gym this instant. I don’t wish it on any of us, and i fear that as many of us extend our lifespan, our healthspan isn’t sufficiently buttressed to carry us through our longer lives, and we will be miserable for a longer portion of the end of it. This seems suboptimal to me, and I’m willing to take some damage to build a better physiology to carry me happily farther. And hopefully ill be healthier to heal whatever parts i screwed up.
I figure i might be able to diminish the negative impact of methionine from more animal protein by taking lots of extra glycine, and some extra NAC/NACET.
I’m thinking my high LDL (164 at last test, but unchanged before my keto and carnivore diets over years) probably should eventually be dealt with via a PCSK9 inhibitor . I was thinking berberine could be a poor man’s solution but i just heard a Peter Attia interview in which he said berberine is a mitochondrial poison, so now I’m flummoxed. I am also considering a 1x per year nattokinase course as a precaution.
Do i now need to deal with leucine overconsumption? Is there something to do other than not eat as much protein?
And i eat fish regularly, but definitely not every day. Do i have an issue with saturated fats? — i keep reading such bifurcated thinking on this.
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JKPrime
#31
Berberine will only lower ldl-c by 20% so for you it would go down from 164 to about 130. Medical grade PCSK9 inhibitors like Repatha are much more effective and should lower your ldl-c to 80, which would be good.
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Medscape: Why High-Protein Diets May Lead to Atherosclerosis
It makes some sense that high-protein diets would be good for you. Good things inside your body (such as muscles) are made of protein, and you are what you eat right? But the data don’t necessarily support the contention that high-protein is really very healthy.
Animal studies fairly consistently show that higher protein diets are associated with more atherosclerosis. And some, but by no means all, epidemiologicstudies in humans also show a link between protein intake and heart disease.
…
Taken together, this paper paints an intriguing explanation for what I might call the “protein paradox”: If high-fat, high-carb, and high-protein diets are bad, are we supposed to just not eat?
Of course, maybe the answer is that a balanced diet is optimal. But all this talk about macros ignores the fact that these studies controlled total calorie intake completely; they matched calories and varied the proportion of calories from each macro. That might not be how the real world works. If a certain diet is high in protein, but it leads you to consume fewer calories than you otherwise would have, then the benefit of taking in fewer calories may easily outweigh any hypothetical harm from the extra leucine.
But if you’re still worried about protein, remember that leucine lives predominantly in animal proteins. That means if you want to continue to favor protein as your macro of interest, the best place to get it may be from plant sources. We may be able to add a few more points in the column for the leader of the diet wars, 2020s edition: the plant-based diet.
https://www.medscape.com/viewarticle/1000179
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Published online 2023 Mar 12
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Study conclusion: “according to our study results, high protein consumption does not affect cardiovascular prognosis.”
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My hunch is that mTor pathway’s relationship to protien synthesis and impact on longevity is much more complex than a simple low = good for longevity and high = bad for longevity, therefore, calorie restriction and rapa is good and protein, especially lucien is bad. There are too many datapoints that contradict that narrative.
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jnorm
#36
Its been a long time since I looked at the Leucine data from the ITP. It seems there was a small decrease in lifespan in the male mice with higher leucine intake, but perhaps not statistically significant:
Wild-type mice are relatively atherosclerosis resistant, which maybe prevents leucine from having a significant effect there. The mouse models of atherosclerosis usually have to knockout APOE or LDLR first, in which case maybe you’d see reduced lifespan with leucine treatment. Perhaps humans should be more concerned with these results than mice.
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You may be interested in the full thread reply to Dudley (who missed a second post pre-dating his comment):
Dudley is a friend and does good research. His statement is literally correct (there were different components, including human), my shorthand for mouse study referred to the core basis of the title of “eating too much protein is bad for your arteries…” in the press release I posted because I do not feel for humans the evidence is as strong as the experimental data.
I do not route for particular diets, only where the evidence takes me, so I’m agnostic to the results. I was pleased to see my 2nd post was “liked” by Stephan Guyenet PhD whom I have a great deal of respect for (as I do for Dudley ,both great people, just think the messaging needs to be more nuanced).
After reading the thread (linked to here, the image is to just a part of it) I’d be curious and interested in other perspectives. I rarely comment on posts (usually I just quote) but the title was so misleading in this case “bad for your arteries,” I wanted to highlight the main more definitive finding was from rodent data and jury still out for more definitive work in humans. In retrospect, I should have unpacked it. with clients. Much less room for misunderstanding and much more room
Like all things (including posting my work at agingdoc.com) I try to be fair, balanced and transparent. If you have other ideas/suggestions please DM directly.
Hope that helped or was interesting from the science communication side… healthy longevity for all!
Dr Barzilai / Agingdoc / “David” 
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Here’s the thread reply @RapAdmin -
Best, agingdoc:man_health_worker:t2: 
https://x.com/agingdoc1/status/1759945539821383985?s=20
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If you’re interested in maintaining or building muscle, you’ll need the leucine, 2 or 3 grams per meal, which in most animal proteins translates into 25 g, or higher in most plant protiens. I personally havent seen much evidence that this will cause cardiovascular issues in people. The saturated fat that is more common in meat is another matter, having been linked to ASCVD. I’ve reduced my intake by having one or two fish or seafood meals a day, which also delivers omega 3 protection. When I eat meat I stick with lean cuts.
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