@apod Thank you for the links. One difficulty here is determining how much protein is optimal for one’s health. I eat vegan (non-processed foods) with lots of pulses (fairly high in protein) with some fish (2-3 times/wk: sardines, salmon) & solo road cycle (~18-21mph avg) for about 7-10h/wk (135mi-200mi/wk). A quick calculation shows me that my protein use is ~1.2g/kg, 85g/d (I weigh 160#), but I know many people taking large amounts of whey protein who are encouraged by supplement manufacturers & their surrogates (magazines, web, etc.) to increase their protein with no downside stated. But there is a downside of up regulating IGF-1, see https://source.wustl.edu/2006/12/does-t
This stuff is really tricky since the original paper I quoted is a meta study & does not have much granularity, but I am surprised that this associating wasn’t mentioned in Dale Bredesen’s, End of Alzheimer’s, book, which i’ve Been following the recode protocol since 11/17. And besides individual characteristics, my exercise goals are longer term, not individual performances. This study makes me question if I shouldn’t increase my protein to 1.5g/kg. I am APOE3/4.
Interestingly, here's where my IGF1 last measured while supplementing Whey Protein Isolate + leucine-rich BCAAs and eating ~100-125g protein/d:
Reference range by age (at least, in southern China...): I believe this puts me within the lower reference range for a senior citizen (I'm active and in my 30's.) Looking at some charts, it appears as though my levels are lower than women in their 80's
. In this study, going any lower than this lower 70-80 range where I sit was associated with increased mortality: https://www.ncbi.nlm.nih.gov/pubmed/21795450
-- All-cause mortality was increased in subjects with low as well as high IGF-I, with a hazard ratio (HR) of 1.27 (95% CI = 1.08-1.49) and HR of 1.18 (95% CI = 1.04-1.34), respectively, so it appears that low-IGF1 could be more of a health risk than high IGF1. I should probably measure hormones again sometime.
Thinking more about my diet / lifestyle, this makes me wonder if IGF1 might be more closely associated with caloric intake / carbohydrate intake / nutrient timing / other hormones rather than protein intake. Or, perhaps I have some other genetic / epigenetic factors at play. It would be interesting to look at IGF1 and Leptin (I generally run minimal, near-undetectable levels of leptin while eating low-carb with low body fat.) I think I was also supplementing TMG at the time, which raises IGF1 in theory.
From what I've read, higher levels of IGF1 is associated with greater telomere length, lower incidences of cognitive decline & higher neurotrophic factor levels, lower levels of inflammation, higher antioxidant status, improved blood sugar control, greater amounts of functional muscle tissue & strength, faster recovery, etc. On paper, IGF1 looks fairly cardioprotective and supportive to mitochondrial health & function. Whey provides cysteine in a form that boosts glutathione (which is in large part stimulated by insulin) -- this is an interesting article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569588/
That said, I do subscribe to the idea that lower intakes of protein generally makes more sense to me than higher intakes for overall health & longevity. Right now, I sort of hedge my protein intake with 1-2tbs/d of marine collagen peptides (rich in Glycine) while supplementing creatine / methyl donors in an attempt to balance out the methionine.
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