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Hi Jeff,

I am wondering if there are any negative issues with high protein consumption (ranging closer to 20%, which would put the ratios at 70/10/20) from only plant foods (legumes) over a long time period? I read that most high protein issues arise from methionine overconsumption, which is minimal in plant foods.

I have read the studies by McDougall that mention 10% is more than adequate, but how much is too much and why is it bad for you if it's from plant foods? I know 80% carbs are the ideal, but does reducing it to 70% make a difference in long term health?

Thank you.

Is it okay to bump this thread for anyone who might know? I'm aware that some old articles mention that protein should be 10%, but I was thinking that the position was changed lately, because plant protein was found to be less/not(?) harmful?

viewtopic.php?f=22&t=9463&p=70291

In Health
Jeff

Jeff, wow, that was very informative. Would you be able to clarify just how dangerous higher IGF-1 would be, if sources are not from artificially-based processed soy products? The bioavailability would probably be lower if the products were not soy-based legumes, as well? I'm not really sure if there are any clinical studies demonstrating higher incidences of cancer or IGF-1-related problems for people on only plant-based foods? Would it be reasonable to believe there would be damage, anyway? Thank you very much for the help, again!

Isolated &/or excess vegetable proteins can raise IGF-1 as much if not more than isolated &/or excess animal proteins.

Here adding 40 grams of Soy Protein Isolate doubled IGF-1.

Arjmandi BH, Khalil DA, Smith BJ, Lucas EA, Juma S, Payton ME, Wild RA. Soy protein has a greater effect on bone in postmenopausal women not on hormone replacement therapy, as evidenced by reducing bone resorption and urinary calcium excretion. J Clin Endocrinol Metab. 2003 Mar;88(3):1048-54.

Yu H. Role of the insulin-like growth factor family in cancer development and progression. J Natl Cancer Inst. 2000 Sep 20;92(18):1472-89.


In Health
Jeff

Jeff, is the increase in IGF-1 binding protein with soy an ameliorating factor?

http://www.pritikinresearchfoundation.org/pdf/OrnishSoyStudy07.pdf

So maybe problematic but less so than animal protein?

Some studies, as above, show it is as bad or worse so context may be important.

However, from the conclusion of the study you posted

"These results suggest that dietary protein and soy isoflavones, in the context of comprehensive lifestyle 25 changes, may not significantly alter IGF-1. However, given the recent literature indicating that high intake of protein rich in essential amino acids (animal or soy protein) may increase IGF-1, it may be prudent for men with early stage prostate cancer not to exceed dietary protein recommendations."

The original trials by this group included soy protein but after they saw IGF-1 levels were still high, then removed the soy protein from subsequent trials.

The CR research also limits all protein, though, I do agree that in some aspects animal protein (ie, methionine), may be worse

In Health
Jeff

Thank you for clarifying that!