Where is the proof that high protein diets are bad?

[Branson]

Of course I am talking high vegan protein.

This woe is 10% protein.

What if it became 30% maybe from not eating any low protein starch, but all high protein starch like lentils, garbonzo bean flour for tortillas, low fat soymilk, low fat tofu, all the high protein veggies like broccoli etc

I am quite serious. Is there a study that shows that this is harmful, not optimal?

Maybe it is not. Maybe it is just as good as low protein? How come there isnt any study? Id sure like to find one.

The seventh day adventist do eat higher fat. I dont know if some necessarily eat higher protein too?

[pundit999]

High protein diet is hard on kidneys, at least.

Dr Kempner reversed thousands of patients' end stage kidney disease, high blood pressure, eye problems, heart disease, diabetes with the 5% protein diet of rice, sugar and fruit, decades ago. He published scores of papers. So look there.

In any case, why keep asking these questions.

Dr McDougall and other great WFPB doctors have much experience with this stuff and they have devised a plan to follow.
If you have followed this diet, have you not experienced great benefits? If you have , why worry about studies and what not?

[Werner1950]

Sometimes it's not anxiety that motivates a question. Sometimes it's a thirst for knowledge, plain and simple.

[arugula]

here's a good, free, relatively recent paper. fontana and longo are on the author list.

http://dx.doi.org/10.1016/j.cmet.2014.02.006

Highlights
•High protein intake is linked to increased cancer, diabetes, and overall mortality
•High IGF-1 levels increased the relationship between mortality and high protein
•Higher protein consumption may be protective for older adults
•Plant-derived proteins are associated with lower mortality than animal-derived proteins

[Branson]

here's a good, free, relatively recent paper. fontana and longo are on the author list.

http://dx.doi.org/10.1016/j.cmet.2014.02.006

Highlights
•High protein intake is linked to increased cancer, diabetes, and overall mortality
•High IGF-1 levels increased the relationship between mortality and high protein
•Higher protein consumption may be protective for older adults
•Plant-derived proteins are associated with lower mortality than animal-derived proteins

That is pretty close it says
. These associations were either abolished or attenuated if the proteins were plant derived.

So what is attenuated, how much what percentage and of course what percentage were these associations abolished? Doesnt sound like plant proteins are damning whereas the flesh is damning.

Thanks for that!

Wonder what else is out there?

[hazelrah]

here's a good, free, relatively recent paper. fontana and longo are on the author list.

http://dx.doi.org/10.1016/j.cmet.2014.02.006

Highlights
•High protein intake is linked to increased cancer, diabetes, and overall mortality
•High IGF-1 levels increased the relationship between mortality and high protein
•Higher protein consumption may be protective for older adults
•Plant-derived proteins are associated with lower mortality than animal-derived proteins

Wow,

These results suggest that low protein intake during middle age followed by moderate to high protein consumption in old adults may optimize healthspan and longevity.

Now if they could just replicate these results with Snickers bars, less than a decade to go before I'm in heaven ( metaphorically I mean).

Mark

[Crider]

If you eat excessive protein, your body will convert it into carbohydrates. So what's the point?

[Skip]

Many studies have shown that high animal based proteins are unhealthy. Studies have shown that substituting plant based protein for animal based protein is healthy. I don't know of any studies that compare the affects of 10% plant protein vs 30% plant protein but I suspect that it wouldn't make much difference in health outcomes.

Who's would pay for such a study? Who has a vested interest in doing such a study?

[arugula]

it's almost impossible to get 30% of your kcals from protein from whole foods unless you eat mostly soybeans and spinach. i consider the point to be moot.

i am not convinced that protein powders are a healthy choice, even when they are from plants. all of the fiber and much of the protective phytochemicals have been removed, so why bother with them? they are not whole foods.

the aging finding--that more protein is beneficial after 65 in the Cell Metabolism paper--is something to consider. i suspect it's due to reduced uptake of protein when we are aged because our stomachs produce less HCl and do not break down our foods as well as in youth.

i don't know what the ideal solution is for that. but i do know that the okinawan centenarians did not worry about it. they did great with very low protein intakes in the 70s, 80s, 90s, and beyond. so maybe there are confounding factors in the study.

[Skip]

it's almost impossible to get 30% of your kcals from protein from whole foods unless you eat mostly soybeans and spinach.

Agree, 30% would be hard to do, but not impossible

[colonyofcells]

As a caution, Dr Mcdougall tells patients to avoid overconsuming protein so there is a 1 cup limit on cooked beans, peas and lentils. I am not aware of any proof that overeating beans, peas and lentils is harmful. I tend to be conservative and I prefer to mimic most of the traditional diets which did not overeat on beans, peas and lentils for whatever reasons. For example, the 1949 okinawa diet was mostly sweet potato rather than mostly soy bean. The historical reason was sweet potato was easier to grow in okinawa rather than rice.

[arugula]

cronometer lists

lentils, cooked from dried as 26.9% protein by kcals.
spinach, raw, 30% protein.
romaine, 17.4% protein

uses USDA nutrient database.

[petero]

The thing is, Branson, that nitrogen balance studies show that you can only utilize so much. That depends on what you do, and ranges from the RDA of 0.8g/kg to about (IIRC) 1.2-1.4g/kg for strength athletes and up to 1.6-1.8g/kg for endurance athletes. The rest is (converted to glucose and) burned or stored like anything else. So, yeah, what's the point? For most people, there are no positives, but there are negatives like kidney strain.

I suppose Fontana's work suggests you should raise this as you get older. It would also be interesting to find out if the methionine restriction to mimic CRON is relative or absolute--that might be another reason to avoid large absolute quantities of protein.

(I eat high absolute amounts of protein now, but that's because I'm increasing my exercise significantly and not taking any chances. I realize I'm making a possible trade off, though. I'll kick myself when I get cancer. Depends on your goals I suppose.)

Edit: Also: From what I know, protein is an absolute need based on body weight, not a percent of calories. Eating too high a percent will edge out carbohydrates and be a useless waste. If I was eating 5000 kcals a day and 20% protein it would be way too much protein. If I'm eating 5 megacalories it's because I need the carb energy. For me it would be something like 12% protein and that's the high end of the utilization potential. (Off the deep end, in fact, if needs are g/kg of lean body weight.) So there is a lot of truth in the idea that you will naturally meet any extra protein needs because your calorie needs will increase. And that's what the experts on the board say will happen.

[f1jim]

The original poster has answered their own questions. Eating a very high plant protein diet hasn't been studied to my knowledge. Jeff Novick may have some data on this I am unaware off. No large successful population has consumed this type of diet historically. That is almost enough to satisfy me as there is probably a reason why they haven't.
It's an interesting hypothetical with no compelling reason for someone to spend the money researching. We already have a good handle on the amount of protein humans need. A study on greatly exceeding that number with plant based sources? I would rather see the research money funneled elsewhere. Frankly, having excess protein levels far above our nutritional needs from whatever their source seems intuitively risky. Why overtax the bodies systems that have evolved to process much lower amounts?
Certainly worth speculating on but probably not worth spending research dollars on.
f1jim

[geo]

The OP has it wrong to begin with. The McDougall program is NOT a 10% protein program. It does not specify protein requirements. Rather , it specifies FOOD as the key ingredient and further goes on to explain how the food meets all your dietary needs for macro/micro/phyto nutrients specified by all nutritional agencies (except for B-12, take a suppliment or eat somre dirt ).

While on the program you may find your protein levels may be about 10% +/- 5 points, but that has nothing to do with any program recommendation for protein levels. Its about the food, plain and simple.

The real question the OP should be asking is why would you want to eat 30% protein, since its way more than all nutritional food regulatory agencies world wide recommend? Where is the science that says 30% protein is a good thing to have?

And one other point, typical Americans eating SAD already consume at least twice as much protein as standards recommend, have you notice any improvement in Americans health as a result? Do you really think adding in even more protein will help?